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About

A basic Alpine image with a few tools to enable you to better start of your work.

Mostly useful for Docker and Kubernetes init containers as well as debugging your own containers.

If you are missing anything, send in a merge request. Let's just not overdoit, folks. Currently available:

AWS scripts:

  • s3 A bash script for downloading secure files from AWS s3 without the need for the full fledged AWS client
  • ecr-get-authorization-token A bash script for getting AWS ECR repository authorization token without the need for AWS client.
  • ecr-get-login A script that mimics the aws ecr get-login output
  • ecr-describe-repositories is a call to Describe Repositories API
  • esc-create-repository is a call to Create Repository API

AWS

The scripts (e.g. s3 and get-authorization-token) will require you set propery environment variables before invoking them, namely: AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY and AWS_REGION. If you're an AWS user, you'll know what they eman.

Usage

export AWS_ACCESS_KEY_ID=xxx 
export AWS_SECRET_ACCESS_KEY=yyy 
export AWS_REGION=eu-central-2 

s3 bucket path/file.ext > file.ext
ecr-get-authorization-token
$(ect-get-login)

Wait for service in Kubernetes

This image also includes a bash script wait-for-service, which will wait for a given service to be up before continuing. It's API/parameter compatible with fabric8-dependency-wait-service but since it's written in BASH and not GO:

  • the image is much smaller
  • there's no need to include different binaries for different platforms
  • more platforms are automatically supported out of the box (e.g. wherever BASH works)

Environment variables

The following variables can be used to control the service:

Variable Possible values Default value Description
DEPENDENCY_LOG_VERBOSE true/false true Puts out a little extra logging into output. (like fabric8)
DEPENDENCY_POLL_INTERVAL A positive integer 2 The interval, in seconds, between each poll of the dependency check. (like fabric8)
DEPENDENCY_CONNECT_TIMEOUT A positive integer 5 How long to wait before the service timeouts, in seconds. (not possible with fabric8)
SCRIPT_TIMEOUT A positive integer 0 A total time the script is allowed to run. 0 means "no timeout"

Usage

This utility is used as part of the init containers.

Usage:

  wait-for-service [parameters] [tcp://host:port | postgres://[user@]host[:port] | http[s]://host[:port] | ... ] [-- command args]

  wait-for-service will wait for the specified service to be up and running before returning / exiting from the function.
    It will optionally run the command(s) at the end of the line after the commnad completes successfully.

    Available parameters:
    -t | --timeout=TIMEOUT            Script timeout parameter
    -v | --verbose                    Be verbose. 
                                      Alias for DEPENDENCY_LOG_VERBOSE=true
    -q | --quiet                      Be quiet. 
                                      Alias for DEPENDENCY_LOG_VERBOSE=false
    -c | --connection-timeout=TIMEOUT Timeout before the service is deemed inaccessible (default is 5 seconds).
                                      Alias for DEPENDENCY_CONNECT_TIMEOUT
    -p | --poll-interval=INTERVAL     Interval in seconds between polling retries.
                                      Alias for DEPENDENCY_POLL_INTERVAL
    -C | --colo[u]r                   Force colour output.

    tcp://host:port                   Wait for the given service to be available at specified host/port. Uses Netcat.
    postgres://[user@]host[:port]     Wait for PostgreSQL to be available. Uses pg_isready.
    http[s]://host[:port]             Wait for HTTP(s) service to be ready. Uses curl.
    
    -- COMMAND ARGS                   Execute command with args after the test finishes

An example is given below:

spec:
  initContainers:
    - name: web-for-services
      image: "boky/alpine-bootstrap"
      command: [ 'wait-for-service', 'postgres://user@host:port', 'https://whole-url-to-service', 'tcp://host:port', ... ]
      # Or, using the fabric8-compatible symlink
      command: [ 'fabric8-dependency-wait-service-linux-amd64', 'postgres://user@host:port', 'https://whole-url-to-service', 'tcp://host:port', ... ]
      env:
        - name: DEPENDENCY_POLL_INTERVAL
          value: "10"
        - name: DEPENDENCY_LOG_VERBOSE
          value: "false"
        - name: DEPENDENCY_CONNECT_TIMEOUT
          value: "10"

Supported protocols

The following protocols are supported:

  • HTTP: Anything that starts with http:// or https:// is considered a HTTP protocol. curl is used to make a HTTP HEADrequest. Automatically falls back to TCP check if curl is not available. A service is considered up if:

    • It doesn't time out
    • It returns a result in the range 2xx

  • POSTGRES: The syntax is: postgres://[<user>@]<host>[:<port>]. The given postgres url is parsed for username, host, and port and passed to the pg_isready utility. Automatically falls back to TCP check if pg_isready is not avaiable. The db is considered up when pg_isready returns a zero exit code.

  • TCP: The syntax is: tcp://<host>:<port>. Netcat is used to connect to the service. Service is considered up when netcat successfully connects and return a zero exit code. If netcat is not avaialbe, uses /dev/tcp to send open up a port.