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ATTENTION

I'm rewriting this tool in Go

New Repo: https://github.com/berttejeda/bert.tasks

Overview

ansible-taskrunner is a cli app that is essentially an ansible wrapper.

It reads an ansible playbook file as its input, which serves as a task manifest.

If no task manifest is specified, the app will search for 'Taskfile.yaml' in the current working directory.

The inspiration for the tool comes from the gnu make command, which operates in similar fashion, i.e.

  • A Makefile defines available build steps
  • The make command consumes the Makefile at runtime and exposes these steps as command-line options

If you are running this tool from Windows, please read the section on Bastion Mode

TL;DR

  • Ever wanted to add custom switches to the ansible-playbook command? Something like this:
    ansible-playbook -i myinventory.txt -d dbhost1 -w webhost1 -t value1 myplaybook.yaml
  • Well, you can through the use of an ansible-playbook wrapper
  • That's where tasks comes in:
    tasks -s -b bar -f foo1
    translates to:
    ansible-playbook -i /tmp/ansible-inventory16xdkrjd.tmp.ini \ -e "{'some_foo_variable':'foo1'}" -e "{'some_bar_variable':'bar'}" -e "{'playbook_targets':'local'}" Taskfile.yaml
  1. Jump down to the usage examples to see this in action
  2. Review the installation instructions if you want to test-drive it
  3. Read on if you want to dig deeper into the tool

Use case and example

Given

  1. An enterprise-grade application named contoso-app
  2. Multiple teams:
    • Development
    • Engineering
    • DBA
    • Operations
    • QA
  3. Ansible is the primary means of invoking business and operational processes across the numerous environments

The Challenge

You must ensure all teams adopt a standardized approach to running ansible workloads

Investigation

Upon investigating the current approach, you observe the following:

  • Users tend to create wrapper scripts that call the ansible-playbook command
  • These scripts don't follow any naming convention, as you've noted:
    • run.sh
    • start.sh
    • playbook.sh
  • These shell scripts have common attributes:
    • Dynamically populate ansible-playbook variables via the --extra-vars option
    • Dynamically creating ansible inventories
    • Performing pre/post-flight tasks
    • Providing a command-line interface

Assessment

Advantages to the above approach:

  • Quick-n-dirty, anyone can get started relatively quickly with writing ansible automation

Disadvantages:

  • Lack of standards:
  • Leads to difficulty in collaboration and code refactoring
  • Decreased re-usability of codebase
    • This design encourages standalone playbooks
    • Makes it more difficult to package actions as roles
    • Duplicate efforts across codebase

Proposed Solution

Employ a pre-execution script that operates at a layer above the ansible-playbook command:

  • Accomplishes the same as the above, but in more uniform manner
  • Support for custom command-line parameters/flags
  • Dynamic inventory expression
  • Embedded shell functions

Advantages to this approach:

  • Easier to manage
    • If you know YAML and Ansible, you can get started relatively quickly with writing ansible automation
  • Single executable (/usr/local/bin/tasks)

Disadvantages:

  • Target ansible controller needs to have the tasks command installed

Back To Top

Technical Details

As stated in the overview, this tool functions much like the make command in that it accepts an input file that essentially extends its cli options.

We create a specially formatted ansible-playbook that serves as a task manifest file (by default, Taskfile.yaml).

This task manifest file:

  • Extends the tasks command
  • Is a valid ansible playbook (Taskfile.yaml), and can thus be launched with the ansible-playbook command
  • Variables available to the pre-execution phase are also available to the ansible execution phase

Creating a task manifest file

In the following sections, we'll be building a sample manifest/playbook.

Start by opening up your favorite text/IDE/editor and creating a new task manifest file named Taskfile.yaml.

Add the hosts block

Add hosts, gather_facts, etc:

Click to Expand

Taskfile.yaml

### The hosts block
- hosts: myhosts
  gather_facts: true
  become: true

Add the vars block

Remember, the task runner will ultimately be calling the ansible-playbook command against this very same file,
so it must be a valid ansible playbook.

Let's add the 'vars' block, which allows us to populate some default values:

Click to Expand

Taskfile.yaml

### The hosts block
- hosts: myhosts
  gather_facts: true
  become: true
### The vars block
  vars:

Populate the vars block - defaults

Let's add some default variables to the playbook:

Click to Expand

Taskfile.yaml

### The hosts block
- hosts: myhosts
  gather_facts: true
  become: true
  ### The vars block  
  vars:
    var1: value1
    var2: value2
    var3: value3
    var4: |-
      This is a multi-line value
      of type string
    var5:
      - listvalue1
      - listvalue2
      - listvalue3
      - listvalue4
    var6:
      some_key:
        some_child_key: dictvalue1
    var7: $(echo some_value)
    var8: 8000
    dbhosts:
      - dbhost1
      - dbhost2
      - dbhost3
    webhosts:
      - webhost1
      - webhost2
      - webhost3


As you can see, we've defined a number of variables holding different values.

The rules for evaluation of these are as follows:

Variable                                     | Ansible Evaluation      | Shell Function Evaluation
-------------------------------------------- | ----------------------- | -----------------------
str_var: value1                              | String                  | String
bool_var: True                               | Boolean                 | String
num_var: 3                                   | Integer                 | Integer
multiline_var: |                             | Multiline String        | String (heredoc)
  This is a multi-line value                 |                         |
  of type string                             |                         |
list_var:                                    | List Object             | String (heredoc)
  - item1                                    |                         |
  - item2                                    |                         |
dict_var:                                    | Dictionary Object       | JSON String (heredoc)
  key1: somevalue1                           |                         |
  key2: somevalue2                           |                         |
shell_var: $(grep somestring /some/file.txt) | String                  | Depends on output

Additionally, arguments supplied from the command-line conform
to the type specified in the options definition, with "string" being the default type.

Back To Top

Populate the vars block - define global options

Global options are available to all subcommands.

These are defined under the vars.globals.options key.

Let's add a simple example:

Click to Expand

Taskfile.yaml

### The hosts block
- hosts: myhosts
  gather_facts: true
  become: true
  ### The vars block  
  vars:
    var1: value1
    var2: value2
    var3: value3
    var4: |-
      This is a multi-line value
      of type string
    var5:
      - listvalue1
      - listvalue2
      - listvalue3
      - listvalue4
    var6:
      some_key:
        some_child_key: dictvalue1
    var7: $(echo some_value)
    var8: 8000
    dbhosts:
      - dbhost1
      - dbhost2
      - dbhost3
    webhosts:
      - webhost1
      - webhost2
      - webhost3
    globals:
      options:
          my_global_option:
            help: "This is my global option"
            short: -g
            long: --global
            var: some_global_variable

Populate the vars block - define subcommands

Next, we define the available subcommands and their options.

Let's add a sub-command named run along with its command-line options:

Click to Expand

Taskfile.yaml

### The hosts block
- hosts: myhosts
  gather_facts: true
  become: true
  ### The vars block  
  vars:
    var1: value1
    var2: value2
    var3: value3
    var4: |-
      This is a multi-line value
      of type string
    var5:
      - listvalue1
      - listvalue2
      - listvalue3
      - listvalue4
    var6:
      some_key:
        some_child_key: dictvalue1
    var7: $(echo some_value)
    var8: 8000
    dbhosts:
      - dbhost1
      - dbhost2
      - dbhost3
    webhosts:
      - webhost1
      - webhost2
      - webhost3
    ### Global Options Block
    globals:
      options:
          my_global_option:
            help: "This is my global option"
            short: -g
            long: --global
            var: some_global_variable    
    ### The commands block
    commands:
      run:
        options:
          foo:
            help: "This is some foo option"
            short: -f
            long: --foo
            type: choice
            var: some_foo_variable
            required: True
            not_required_if: 
              - some_bar_variable
            options:
              - foo1
              - foo2
          bar:
            help: "This is some bar option"
            short: -b
            long: --bar 
            type: str
            var: some_bar_variable
            required: False
            required_if: 
              - hello
              - some_baz_variable
          baz:
            help: "This is some baz option"
            short: -z
            long: --baz
            type: str
            var: some_baz_variable
            required: False
            mutually_exclusive_with: 
              - some_bar_variable
              - some_foo_variable
          envvar:
            help: "The value for this argument can be derived from an Environmental Variable"
            short: -E
            long: --env-var
            type: str
            var: env_var
            env_var: SOME_ENVIRONMENT_VARIABLE
            env_var_show: True
          num:
            help: "This is a numeric argument"
            short: -n
            long: --number
            var: some_num_variable
            type: int
            required: False 
            env_var_show: True
          targets:
            help: "Playbook targets"
            short: -t
            long: --targets
            type: str
            var: playbook_targets
            required: True
          multiple:
            help: |-
              This option can be specified multiple times
            short: -m
            long: --multiple
            type: str
            var: multiple_arg
            allow_multiple: True
          some_switch:
            help: |-
              This is some boolean option, behaves like Click's switches,
              holds the value of True if specified
              see: https://github.com/pallets/click
            short: -s
            long: --some-switch
            is_flag: true
            var: some_switch
            required: True
          say_hello:
            help: "Invoke the 'hello' embedded shell function"
            short: -hello
            long: --say-hello
            type: str
            var: hello
            is_flag: True
          say_goodbye:
            help: "Invoke the 'goodbye' embedded shell function"
            short: -goodbye
            long: --say-goodbye
            type: str
            var: goodbye
            is_flag: True
          hidden_option:
            help: "This is a hidden option"
            short: -O
            long: --hidden-option
            is_hidden: True
            type: str
            var: hidden
            is_flag: True            
          verbose:
            help: |-
              This is a sample paramter that supports counting, as with:
              -v, -vv, -vvv, which would evaluate to 1, 2, and 3, respectively
            short: -v
            allow_counting: True
            var: verbosity

As you can see, commands are defined via YAML, and the syntax is mostly self-explanatory.

Currently, the parameters available to any given option are
consistent with click version 8.1.x, see API — Click Documentation (8.1.x)

Important Notes:

  • An option's var key:
    • In the case of standard options, this variable holds the value of the arguments passed to the option
    • In the case of flags/switches, this variable is a Boolean
    • The variable is available during the entire runtime
  • In the above example, the -hello and -goodbye options point to special mapped
    variables that themselves map to corresponding shell functions defined in the subcommand's
    functions directive. We'll discuss this more in section embedded-shell-functions.

Populate the vars block - cli options - mapped variables

As I mentioned before, the above mapped variables can be used during runtime.
That is, they can be referenced in any defined shell functions,
dynamic inventory expression logic, as well as during ansible execution.

Consider the -f|-foo from the example.

Whatever argument you pass to this option becomes the value for the mapped variable some_foo_variable.

Again, this variable is made available to the underlying subprocess call, and thus to ansible.

So when we call the tasks command like so tasks run -f foo1, the value for the some_foo_variable becomes foo.

Populate the vars block - help/message

Next, we add the help/message section:

Click to Expand

Taskfile.yaml

### The hosts block
- hosts: myhosts
  gather_facts: true
  become: true
  ### The vars block  
  vars:
    var1: value1
    var2: value2
    var3: value3
    var4: |-
      This is a multi-line value
      of type string
    var5:
      - listvalue1
      - listvalue2
      - listvalue3
      - listvalue4
    var6:
      some_key:
        some_child_key: dictvalue1
    var7: $(echo some_value)
    var8: 8000
    dbhosts:
      - dbhost1
      - dbhost2
      - dbhost3
    webhosts:
      - webhost1
      - webhost2
      - webhost3
    ### Global Options Block
    globals:
      options:
          my_global_option:
            help: "This is my global option"
            short: -g
            long: --global
            var: some_global_variable 
    ### The commands block
    commands:
      run:
        options:
          foo:
            help: "This is some foo option"
            short: -f
            long: --foo
            type: choice
            var: some_foo_variable
            required: True
            not_required_if: 
              - some_bar_variable
            options:
              - foo1
              - foo2
          bar:
            help: "This is some bar option"
            short: -b
            long: --bar 
            type: str
            var: some_bar_variable
            required: False
            required_if: 
              - hello
              - some_baz_variable
          baz:
            help: "This is some baz option"
            short: -z
            long: --baz
            type: str
            var: some_baz_variable
            required: False
            mutually_exclusive_with: 
              - some_bar_variable
              - some_foo_variable
          envvar:
            help: "The value for this argument can be derived from an Environmental Variable"
            short: -E
            long: --env-var
            type: str
            var: env_var
            env_var: SOME_ENVIRONMENT_VARIABLE
            env_var_show: True
          num:
            help: "This is a numeric argument"
            short: -n
            long: --number
            var: some_num_variable
            type: int
            required: False 
            env_var_show: True
          targets:
            help: "Playbook targets"
            short: -t
            long: --targets
            type: str
            var: playbook_targets
            required: True
          multiple:
            help: |-
              This option can be specified multiple times
            short: -m
            long: --multiple
            type: str
            var: multiple_arg
            allow_multiple: True
          some_switch:
            help: |-
              This is some boolean option, behaves like Click's switches,
              holds the value of True if specified
              see: https://github.com/pallets/click
            short: -s
            long: --some-switch
            is_flag: true
            var: some_switch
            required: True
          say_hello:
            help: "Invoke the 'hello' embedded shell function"
            short: -hello
            long: --say-hello
            type: str
            var: hello
            is_flag: True
          say_goodbye:
            help: "Invoke the 'goodbye' embedded shell function"
            short: -goodbye
            long: --say-goodbye
            type: str
            var: goodbye
            is_flag: True
          hidden_option:
            help: "This is a hidden option"
            short: -O
            long: --hidden-option
            is_hidden: True
            type: str
            var: hidden
            is_flag: True            
          verbose:
            help: |-
              This is a sample paramter that supports counting, as with:
              -v, -vv, -vvv, which would evaluate to 1, 2, and 3, respectively
            short: -v
            allow_counting: True
            var: verbosity
        help:
          message: |
            Invoke the 'run' command 
          epilog: |
            This line will be displayed at the end of the help text message
          examples:
            - example1: |
                tasks $command
            - example2: |
                Usage example 2

Running tasks run --help should return the list of parameters along with the help message you defined.

Populate the vars block - embedded shell functions

Add embedded shell functions:

Taskfile.yaml

### The hosts block
- hosts: myhosts
  gather_facts: true
  become: true
  ### The vars block  
  vars:
    var1: value1
    var2: value2
    var3: value3
    var4: |-
      This is a multi-line value
      of type string
    var5:
      - listvalue1
      - listvalue2
      - listvalue3
      - listvalue4
    var6:
      some_key:
        some_child_key: dictvalue1
    var7: $(echo some_value)
    var8: 8000
    dbhosts:
      - dbhost1
      - dbhost2
      - dbhost3
    webhosts:
      - webhost1
      - webhost2
      - webhost3
    ### Global Options Block
    globals:
      options:
          my_global_option:
            help: "This is my global option"
            short: -g
            long: --global
            var: some_global_variable 
    ### The commands block
    commands:
      run:
        options:
          foo:
            help: "This is some foo option"
            short: -f
            long: --foo
            type: choice
            var: some_foo_variable
            required: True
            not_required_if: 
              - some_bar_variable
            options:
              - foo1
              - foo2
          bar:
            help: "This is some bar option"
            short: -b
            long: --bar 
            type: str
            var: some_bar_variable
            required: False
            required_if: 
              - hello
              - some_baz_variable
          baz:
            help: "This is some baz option"
            short: -z
            long: --baz
            type: str
            var: some_baz_variable
            required: False
            mutually_exclusive_with: 
              - some_bar_variable
              - some_foo_variable
          envvar:
            help: "The value for this argument can be derived from an Environmental Variable"
            short: -E
            long: --env-var
            type: str
            var: env_var
            env_var: SOME_ENVIRONMENT_VARIABLE
            env_var_show: True
          num:
            help: "This is a numeric argument"
            short: -n
            long: --number
            var: some_num_variable
            type: int
            required: False 
            env_var_show: True
          targets:
            help: "Playbook targets"
            short: -t
            long: --targets
            type: str
            var: playbook_targets
            required: True
          multiple:
            help: |-
              This option can be specified multiple times
            short: -m
            long: --multiple
            type: str
            var: multiple_arg
            allow_multiple: True
          some_switch:
            help: |-
              This is some boolean option, behaves like Click's switches,
              holds the value of True if specified
              see: https://github.com/pallets/click
            short: -s
            long: --some-switch
            is_flag: true
            var: some_switch
            required: True
          say_hello:
            help: "Invoke the 'hello' embedded shell function"
            short: -hello
            long: --say-hello
            type: str
            var: hello
            is_flag: True
          say_goodbye:
            help: "Invoke the 'goodbye' embedded shell function"
            short: -goodbye
            long: --say-goodbye
            type: str
            var: goodbye
            is_flag: True
          hidden_option:
            help: "This is a hidden option"
            short: -O
            long: --hidden-option
            is_hidden: True
            type: str
            var: hidden
            is_flag: True            
          verbose:
            help: |-
              This is a sample paramter that supports counting, as with:
              -v, -vv, -vvv, which would evaluate to 1, 2, and 3, respectively
            short: -v
            allow_counting: True
            var: verbosity
        ### The help message
        help:
          message: |
            Invoke the 'run' command 
          epilog: |
            This line will be displayed at the end of the help text message
          examples:
            - example1: |
                tasks $command
            - example2: |
                Usage example 2
        ### Embedded shell functions
        functions:
          hello:
            shell: bash
            help: Say hello
            source: |-
              echo Hello! The value for var1 is $var1
          goodbye:
            shell: bash
            help: Say goodbye
            source: |-
              echo The value for var1 is $var1. Goodbye!

Again, notice the two switches -hello and -goodbye, with mapped variables hello and goodbye, respectively.

These mapped variables correspond to keys in the functions block with matching names.

As such, specifying either or both -hello and -goodbye in your tasks run invocation
will short-circuit normal operation and execute the corresponding functions
in the order in which you call them.

Try it yourself by running:

  • tasks run -t local -s -b bar -m one -m two -vvv -O -hello -goodbye
  • tasks run -t local -s -b bar -m one -m two -vvv -O -goodbye -hello

There is also a special flag ---invoke-function that is globally available to all subcommands.

Invocation is as follows: tasks <subcommand> ---invoke-function <function_name>.

In our example, we would run: tasks run -t local -s -b bar -m one -m two -vvv -O ---invoke-function hello

For more usage examples, see the appendix.

More about embedded shell functions

Let's briefly side-step into embedded shell functions.

The syntax for nesting these under the functions key is as follows:

          name_of_function:
            shell: bash, ruby, or python
            help: Help Text to Display
            hidden: false/true
            source: |-
              {{ code }}

Back To Top

Bash example:

          hello:
            shell: bash
            help: Hello World in Bash
            hidden: false
            source: |-
              echo 'Hello World!'

Python example:

          hello:
            shell: python
            help: Hello World in Python
            hidden: false
            source: |-
              print('Hello World!')

Ruby example:

          hello:
            shell: ruby
            help: Hello World in Ruby
            hidden: false
            source: |-
              puts 'Hello World!'

Back To Top

Populate the vars block - dynamic inventory expression

A useful feature of this tool is the ability to define your ansible
inventory as a dynamic expression in the Taskfile itself.

To do so, we populate the with the inventory_expression key.

When the inventory is defined in this manner, the logic is as follows:

  • The inventory expression is evaluated
  • An ephemeral inventory file is created with the
    contents of this file being the output, or result, of that expression
  • The fully qualified path to the ephemeral inventory file is specified as the
    argument to the ansible-playbook inventory parameter -i

Let's define our inventory expression:

Click to Expand

Taskfile.yaml

### The hosts block
- hosts: myhosts
  gather_facts: true
  become: true
  ### The vars block  
  vars:
    var1: value1
    var2: value2
    var3: value3
    var4: |-
      This is a multi-line value
      of type string
    var5:
      - listvalue1
      - listvalue2
      - listvalue3
      - listvalue4
    var6:
      some_key:
        some_child_key: dictvalue1
    var7: $(echo some_value)
    var8: 8000
    dbhosts:
      - dbhost1
      - dbhost2
      - dbhost3
    webhosts:
      - webhost1
      - webhost2
      - webhost3
    ### Global Options Block
    globals:
      options:
          my_global_option:
            help: "This is my global option"
            short: -g
            long: --global
            var: some_global_variable 
    ### The commands block
    commands:
      run:
        options:
          foo:
            help: "This is some foo option"
            short: -f
            long: --foo
            type: choice
            var: some_foo_variable
            required: True
            not_required_if: 
              - some_bar_variable
            options:
              - foo1
              - foo2
          bar:
            help: "This is some bar option"
            short: -b
            long: --bar 
            type: str
            var: some_bar_variable
            required: False
            required_if: 
              - hello
              - some_baz_variable
          baz:
            help: "This is some baz option"
            short: -z
            long: --baz
            type: str
            var: some_baz_variable
            required: False
            mutually_exclusive_with: 
              - some_bar_variable
              - some_foo_variable
          envvar:
            help: "The value for this argument can be derived from an Environmental Variable"
            short: -E
            long: --env-var
            type: str
            var: env_var
            env_var: SOME_ENVIRONMENT_VARIABLE
            env_var_show: True
          num:
            help: "This is a numeric argument"
            short: -n
            long: --number
            var: some_num_variable
            type: int
            required: False 
            env_var_show: True
          targets:
            help: "Playbook targets"
            short: -t
            long: --targets
            type: str
            var: playbook_targets
            required: True
          multiple:
            help: |-
              This option can be specified multiple times
            short: -m
            long: --multiple
            type: str
            var: multiple_arg
            allow_multiple: True
          some_switch:
            help: |-
              This is some boolean option, behaves like Click's switches,
              holds the value of True if specified
              see: https://github.com/pallets/click
            short: -s
            long: --some-switch
            is_flag: true
            var: some_switch
            required: True
          say_hello:
            help: "Invoke the 'hello' embedded shell function"
            short: -hello
            long: --say-hello
            type: str
            var: hello
            is_flag: True
          say_goodbye:
            help: "Invoke the 'goodbye' embedded shell function"
            short: -goodbye
            long: --say-goodbye
            type: str
            var: goodbye
            is_flag: True
          hidden_option:
            help: "This is a hidden option"
            short: -O
            long: --hidden-option
            is_hidden: True
            type: str
            var: hidden
            is_flag: True            
          verbose:
            help: |-
              This is a sample paramter that supports counting, as with:
              -v, -vv, -vvv, which would evaluate to 1, 2, and 3, respectively
            short: -v
            allow_counting: True
            var: verbosity
        ### The help message
        help:
          message: |
            Invoke the 'run' command 
          epilog: |
            This line will be displayed at the end of the help text message
          examples:
            - example1: |
                tasks $command
            - example2: |
                Usage example 2
        ### Embedded shell functions
        functions:
          hello:
            shell: bash
            help: Say hello
            source: |-
              echo Hello! The value for var1 is $var1
          goodbye:
            shell: bash
            help: Say goodbye
            source: |-
              echo The value for var1 is $var1. Goodbye!
    ### The inventory expression              
    inventory_expression: |
      [local]
      localhost ansible_connection=local
      [web_hosts]
      $(echo -e "${webhosts}" | tr ',' '\n')
      [db_hosts]
      $(echo -e "${dbhosts}" | tr ',' '\n')
      [myhosts:children]
      web_hosts
      db_hosts

As you can see, the inventory expression is dynamic, as
it gets evaluated based on the output of inline shell commands.

Let's focus on the variable $webhosts.

As per the logic described above, the variable $webhosts is a heredoc with a value of:

webhosts='
webhost1
webhost2
webhost3
'

As such, the web_hosts group in the inventory expression ...

      [web_hosts]
      $(echo -e "${webhosts}" | tr ',' '\n')

... will evaluate to:

[web_hosts]
webhost1
webhost2
webhost3

Also, notice how the inline shell command transforms commas into newline characters by way of the transform (tr) command.

This makes it so that if we were to have defined the webhosts variable
in the Tasksfile as webhosts: webhost1,webhost2,webhost3, it would have had the same outcome
as defining it as a list object in the vars block.

Populate the vars block - inventory file

We can specify an inventory file instead of an inventory expression with the inventory_file key.

Click to Expand

Taskfile.yaml

### The hosts block
- hosts: myhosts
  gather_facts: true
  become: true
  ### The vars block  
  vars:
    var1: value1
    var2: value2
    var3: value3
    var4: |-
      This is a multi-line value
      of type string
    var5:
      - listvalue1
      - listvalue2
      - listvalue3
      - listvalue4
    var6:
      some_key:
        some_child_key: dictvalue1
    var7: $(echo some_value)
    var8: 8000
    dbhosts:
      - dbhost1
      - dbhost2
      - dbhost3
    webhosts:
      - webhost1
      - webhost2
      - webhost3
    ### Global Options Block
    globals:
      options:
          my_global_option:
            help: "This is my global option"
            short: -g
            long: --global
            var: some_global_variable 
    ### The commands block
    commands:
      run:
        options:
          foo:
            help: "This is some foo option"
            short: -f
            long: --foo
            type: choice
            var: some_foo_variable
            required: True
            not_required_if: 
              - some_bar_variable
            options:
              - foo1
              - foo2
          bar:
            help: "This is some bar option"
            short: -b
            long: --bar 
            type: str
            var: some_bar_variable
            required: False
            required_if: 
              - hello
              - some_baz_variable
          baz:
            help: "This is some baz option"
            short: -z
            long: --baz
            type: str
            var: some_baz_variable
            required: False
            mutually_exclusive_with: 
              - some_bar_variable
              - some_foo_variable
          envvar:
            help: "The value for this argument can be derived from an Environmental Variable"
            short: -E
            long: --env-var
            type: str
            var: env_var
            env_var: SOME_ENVIRONMENT_VARIABLE
            env_var_show: True
          num:
            help: "This is a numeric argument"
            short: -n
            long: --number
            var: some_num_variable
            type: int
            required: False 
            env_var_show: True
          targets:
            help: "Playbook targets"
            short: -t
            long: --targets
            type: str
            var: playbook_targets
            required: True
          multiple:
            help: |-
              This option can be specified multiple times
            short: -m
            long: --multiple
            type: str
            var: multiple_arg
            allow_multiple: True
          some_switch:
            help: |-
              This is some boolean option, behaves like Click's switches,
              holds the value of True if specified
              see: https://github.com/pallets/click
            short: -s
            long: --some-switch
            is_flag: true
            var: some_switch
            required: True
          say_hello:
            help: "Invoke the 'hello' embedded shell function"
            short: -hello
            long: --say-hello
            type: str
            var: hello
            is_flag: True
          say_goodbye:
            help: "Invoke the 'goodbye' embedded shell function"
            short: -goodbye
            long: --say-goodbye
            type: str
            var: goodbye
            is_flag: True
          hidden_option:
            help: "This is a hidden option"
            short: -O
            long: --hidden-option
            is_hidden: True
            type: str
            var: hidden
            is_flag: True            
          verbose:
            help: |-
              This is a sample paramter that supports counting, as with:
              -v, -vv, -vvv, which would evaluate to 1, 2, and 3, respectively
            short: -v
            allow_counting: True
            var: verbosity
        ### The help message
        help:
          message: |
            Invoke the 'run' command 
          epilog: |
            This line will be displayed at the end of the help text message
          examples:
            - example1: |
                tasks $command
            - example2: |
                Usage example 2
        ### Embedded shell functions
        functions:
          hello:
            shell: bash
            help: Say hello
            source: |-
              echo Hello! The value for var1 is $var1
          goodbye:
            shell: bash
            help: Say goodbye
            source: |-
              echo The value for var1 is $var1. Goodbye!
    ### Inventory file
    inventory_file: '/some/path/some/inventory.yaml'

Notes of Importance:

  • The value you provide to the inventory_file key supports templating
    • That is, any of the variables available runtime variables can be used, for example:
      • inventory_file: '/some/path/some/inventory_$foo_variable.yaml'
      • inventory_file: '/some/path/some/inventory_$var1.yaml'
  • You should not be specifying both an inventory_file and an inventory_expression, as you get unexpected results.

Back To Top

Add tasks

Finally, let's add some proper ansible tasks!

Click to Expand

Taskfile.yaml

### The hosts block
- hosts: myhosts
  gather_facts: true
  become: true
  ### The vars block  
  vars:
    var1: value1
    var2: value2
    var3: value3
    var4: |-
      This is a multi-line value
      of type string
    var5:
      - listvalue1
      - listvalue2
      - listvalue3
      - listvalue4
    var6:
      some_key:
        some_child_key: dictvalue1
    var7: $(echo some_value)
    var8: 8000
    dbhosts:
      - dbhost1
      - dbhost2
      - dbhost3
    webhosts:
      - webhost1
      - webhost2
      - webhost3
    ### Global Options Block
    globals:
      options:
          my_global_option:
            help: "This is my global option"
            short: -g
            long: --global
            var: some_global_variable 
    ### The commands block
    commands:
      run:
        options:
          foo:
            help: "This is some foo option"
            short: -f
            long: --foo
            type: choice
            var: some_foo_variable
            required: True
            not_required_if: 
              - some_bar_variable
            options:
              - foo1
              - foo2
          bar:
            help: "This is some bar option"
            short: -b
            long: --bar 
            type: str
            var: some_bar_variable
            required: False
            required_if: 
              - hello
              - some_baz_variable
          baz:
            help: "This is some baz option"
            short: -z
            long: --baz
            type: str
            var: some_baz_variable
            required: False
            mutually_exclusive_with: 
              - some_bar_variable
              - some_foo_variable
          envvar:
            help: "The value for this argument can be derived from an Environmental Variable"
            short: -E
            long: --env-var
            type: str
            var: env_var
            env_var: SOME_ENVIRONMENT_VARIABLE
            env_var_show: True
          num:
            help: "This is a numeric argument"
            short: -n
            long: --number
            var: some_num_variable
            type: int
            required: False 
            env_var_show: True
          targets:
            help: "Playbook targets"
            short: -t
            long: --targets
            type: str
            var: playbook_targets
            required: True
          multiple:
            help: |-
              This option can be specified multiple times
            short: -m
            long: --multiple
            type: str
            var: multiple_arg
            allow_multiple: True
          some_switch:
            help: |-
              This is some boolean option, behaves like Click's switches,
              holds the value of True if specified
              see: https://github.com/pallets/click
            short: -s
            long: --some-switch
            is_flag: true
            var: some_switch
            required: True
          say_hello:
            help: "Invoke the 'hello' embedded shell function"
            short: -hello
            long: --say-hello
            type: str
            var: hello
            is_flag: True
          say_goodbye:
            help: "Invoke the 'goodbye' embedded shell function"
            short: -goodbye
            long: --say-goodbye
            type: str
            var: goodbye
            is_flag: True
          hidden_option:
            help: "This is a hidden option"
            short: -O
            long: --hidden-option
            is_hidden: True
            type: str
            var: hidden
            is_flag: True            
          verbose:
            help: |-
              This is a sample paramter that supports counting, as with:
              -v, -vv, -vvv, which would evaluate to 1, 2, and 3, respectively
            short: -v
            allow_counting: True
            var: verbosity
        ### The help message
        help:
          message: |
            Invoke the 'run' command 
          epilog: |
            This line will be displayed at the end of the help text message
          examples:
            - example1: |
                tasks $command
            - example2: |
                Usage example 2
        ### Embedded shell functions
        functions:
          hello:
            shell: bash
            help: Say hello
            source: |-
              echo Hello! The value for var1 is $var1
          goodbye:
            shell: bash
            help: Say goodbye
            source: |-
              echo The value for var1 is $var1. Goodbye!
    ### The inventory expression
    inventory_expression: |
      [local]
      localhost ansible_connection=local
      [web_hosts]
      $(echo -e "${webhosts}" | tr ',' '\n')
      [db_hosts]
      $(echo -e "${dbhosts}" | tr ',' '\n')
      [myhosts:children]
      web_hosts
      db_hosts            
  tasks:
    - name: Show Variables
      debug:
        msg: |-
          {{ hostvars[inventory_hostname] | to_nice_json }}

The task above will display all available host variables.

Usage Examples

Quick usage examples:

  • Display help for main command
    tasks --help
  • Display help for the run subcommand
    tasks run --help
  • Initialize your workspace
    tasks init
  • Run the Taskfile.yaml playbook, passing in additional options to the underlying subprocess
    tasks run -t local -s -b bar -m one -m two
  • Don't do anything, just echo the underlying shell command
    tasks run -t local -s -b bar -m one -m two -O ---echo
    Result should be similar to:
    ansible-playbook -i /var/folders/5f/4g4xnnv958q52108qxd2rj_r0000gn/T/ansible-inventorytlmz2hpz.tmp.ini \ -e "{'var1':'${var1}'}" ... Taskfile.yaml
  • Run the embedded function hello
    tasks run -t local -s -b bar -m one -m two -hello
  • Run the embedded functions hello and goodbye
    run -t local -s -b bar -m one -m two -hello -goodbye

Back To Top

Installation

Ansible-taskrunner consists of the tasks command.

It can be installed in a few ways:

  1. pip install ansible-taskrunner
  2. pip install git+https://github.com/berttejeda/ansible-taskrunner.git
  3. Obtaining a release (these lag behind the pip distributions)

Note: You'll need to pre-install a python distribution for the Windows MSI release. Not yet sure if I am doing something wrong or if that's by design. I lean toward the former :|

More Examples

Review the examples directory for more hands-on usage samples.

Appendix

The Options Separator

When you pass the --- options separator to any subcommand, anything after the separator is passed directly to the ansible subprocess.

Bastion Mode

If you're launching the tasks command from a Windows host, this tool will automatically execute in Bastion Mode

Under Bastion Mode, the tasks command will:

  • Execute the ansible-playbook subprocess via a bastion host, i.e. a remote machine that should have ansible installed
  • This is done via ssh using the paramiko module

Running in Bastion Mode requires a configuration file containing the ssh connection settings.

To initialize this configuration file, you can simply run tasks init.

For full usage options, enter in tasks init --help.

Once you've initialized the configuration file, you should see sftp-config.json in your workspace.

This configuration file is fashioned after the sftp
plugin for Sublime Text and is thus compatible.

Special Variables

ansible_playbook_command

If you define the playbook variable ansible_playbook_command, this will override the underlying ansible-playbook command invocation.

As an example, suppose I define this variable in the above Taskfile.yaml, as follows:

- hosts: myhosts
  gather_facts: true
  become: true
  vars:
    ansible_playbook_command: 'python ${HOME}/ansible_2.7.8/ansible-playbook'
    var1: value1
    var2: value2
    var3: value3
    # ...

Upon invoking the tasks command with the ---echo flag:

  • The temporary inventory would be revealed as:
inventory_is_ephemeral=True
if [[ "$inventory_is_ephemeral" == "True" ]];then
echo -e """${inventory_expression}"""| while read line;do
 eval "echo -e ${line}" >> "/var/folders/some/path/ansible-inventoryo4fw4ttc.tmp.ini";
done
fi;

*The above inventory file path will differ, of course

  • And the underlying shell command would be revealed as:
python ${HOME}/ansible_2.7.8/ansible-playbook \
-i /var/folders/some/path/ansible-inventoryo4fw4ttc.tmp.ini \
-e "{'var1':'${var1}'}" \
-e "{'var2':'${var2}'}" \
-e "{'var3':'${var3}'}" \
... Taskfile.yaml

Back To Top

pre_execution

Anything defined under the pre_execution variable will be evaluated before all other statements in the underlying shell expression.

As an example, suppose I define the pre_execution variable in the above Taskfile.yaml, as follows:

- hosts: myhosts
  gather_facts: true
  become: true
  vars:
    pre_execution: |-
      export pxe_var=some_value
      touch /tmp/.run.lock

Upon invoking the tasks command with the ---echo flag:

  • The underlying shell expression would be revealed as:
...
export pxe_var=some_value
touch /tmp/.run.lock
...

The commands above are always placed before
all variables declarations in the underlying shell expresison.

post_execution

This is similar to pre_execution, except that anything defined under the post_execution variable will be evaluated after all other statements in the underlying shell expression.

environment_vars

By defining the playbook dictionary variable environment_vars,
the following occurs:

  • For each dictionary key: value pair:
    • A corresponding export statement is defined in the underlying shell expression

As an example, suppose I define this variable in the above Taskfile.yaml, as follows:

- hosts: myhosts
  gather_facts: true
  become: true
  vars:
    ansible_playbook_command: 'python ${HOME}/ansible_2.7.8/ansible-playbook'
    var1: value1
    var2: value2
    var3: value3
    some_path: /some/path
    environment_vars:
      MY_ENV_VAR1: "${some_path}/${var1}"    
      MY_ENV_VAR2: "${some_path}/${var2}"    
    # ...

Upon invoking the tasks command with the ---echo flag:

  • The underlying shell expression would be revealed as:
var1="value1"
var2="value2"
export MY_ENV_VAR1="${some_path}/${var1}"
export MY_ENV_VAR2="${some_path}/${var2}"

These export statements are always placed after
all variables declarations in the underlying shell expresison.

ANSIBLE_ Variables

Any variables matching ANSIBLE_.* will automatically be expressed as export statements.

As an example, suppose I define such variables in the above Taskfile.yaml, as follows:

- hosts: myhosts
  gather_facts: true
  become: true
  vars:
    var1: value1
    var2: value2
    ANSIBLE_VAULT_PASSWORD_FILE: /some/path/some/password_file
    ANSIBLE_CALLBACK_PLUGINS: /some/other/path/some/plugins
    # ...

Upon invoking the tasks command with the ---echo flag:

  • The underlying shell expression would be revealed as:
var1="value1"
var2="value2"
export ANSIBLE_VAULT_PASSWORD_FILE="/some/path/some/password_file"
export ANSIBLE_CALLBACK_PLUGINS="/some/other/path/some/plugins"

cli_provider

You can override the underlying command-line provider in two ways:

  • Via the tasks config file (see examples)
  • By defining the variable cli_provider in the specified Taskfile

As an example, suppose I define this variable in the above Taskfile.yaml, as follows:

- hosts: myhosts
  gather_facts: true
  become: true
  vars:
    cli_provider: bash
    # ...

Upon invoking the tasks command, you will note that the app no longer operates in an ansible-playbook mode, but rather as yaml-abstracted bash-script.

There are three cli-providers built in to the tasks command:

  • ansible
  • bash
  • vagrant

ansible_run_flags

Apart from utilizing the --- options separator, you can specify additional options to pass to the underlying ansible-playbook subprocess by setting an appropriate value for __ansible_run_flags__ via Environmental variable or Taskfile, as with:

__ansible_run_flags__: --diff

or

export __ansible_run_flags__='--diff'

tasks_file

The __tasks_file__ variable points to the current Taskfile.

It is available to the underlying subprocess shell.

command

The __command__ variable points to the name of the invoked subcommand.

It is available to the underlying subprocess shell.

Back To Top

Mutually Exclusive Options

This tool supports the following advanced options:

Suppose you want a set of options such that:

  • You want to accept one option but only if another, related option has not been specified

You can accomplish this by defining your option with the following parameters:

  - required: False
  - mutually_exclusive_with: 
    - some_bar_variable
    - some_foo_variable

In the above configuration, calling this option along with options
-f|-foo and -b|-bar will trigger an illegal usage error, since you've
marked the option as mutually exclusive with either of these two options.

Feel free to review the Taskfile.yaml, as you'll find an example of:

  • mutually exclusive
  • mutually inclusive
  • conditionally required

Cloned subcommands

There might exist edge cases in which you need two different subcommands to be defined with identical commandline options.

This could be useful for, say, subcommands like install or uninstall, where the only differentiating factor between the two would be the name of the subcommand being invoked.

To enable this, simply declare your subcommand with a pipe | delimiter, as with:

    commands:
      install|uninstall:
        options:
          foo:
            help: "Install/Uninstall an app"
            short: -n
            long: --app-name
            type: choice
            var: app_name
            required: True

Simple Templating

As of version 1.1.5, simple templating is available to the following objects:

  • Help messages
  • Examples
  • Options
  • Options values

What this means is that we expose a limited set of internal variables to the above.

As an example:

        help:
          message: |
            Invoke the 'run' command 
          epilog: |
            This line will be displayed at the end of the help text message
          examples:
            - example1: |
                tasks -f $tf_path --foo foo --bar bar
            - example2: |
                tasks -f $tf_path --foo foo --baz baz

In the above strings, $tf_path will expand to the internal variable tf_path, which holds the relative path to the current tasks file.

Below is a list of available variables for your convenience:

Variable        | Description
-------------   | -------------
__command__     | The name of the current subcommand
cli_args        | The current command-line invocation
cli_args_short  | The current command-line invocation, minus the executable
sys_platform    | The OS Platform as detected by Python
tf_path         | The relative path to the specified Taskfile

Additionally, all currently set environmental variables are available for templating.

Back To Top

Single-Executable Releases

This script also ships as a zipapp executable (similar to a windows .exe).

Head over to the releases page for release downloads.

You can also build your own single-executable zipapp, as follows:

  1. Make sure you have the make-zipapp executable in your path
  2. Invoking build tasks
  • Build zipapp: python ansible_taskrunner/cli.py -f Makefile.yaml run ---make zipapp

Read More on zipapps: zipapp — Manage executable Python zip archives — Python 3.7.4rc2 documentation

Unit Testing

To run all tests, simply call the test script, as with:

python tests/test_ansible_taskrunner.py

TODO - Add more tests!

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License and Credits

This project adopts the the MIT distribution License.

Releases come bundled with the following opensource python packages:

  • click, licensed under BSD-3-Clause
  • pyYaml, licensed under MIT

Lastly, this package was created with Cookiecutter and the audreyr/cookiecutter-pypackage project template.