Templ

Note	This library is a work in progress

Templ is a library to allow loading structured data (YAML/JSON/TOML) and applying go-like templating to the string fields, enabling relative references to the same document.

Example usage

os.Setenv("SOME_ENV_VAR", "some_env_var_value")

params := map[string]string{
  "param_name": "param_value"
}

expandedTree, err := templ.New().Params(params).File("./service.yaml").Execute()

Example service.yaml input

data:
  string: Hello World
  array:
    - Array
    - of
    - strings
  object:
    key: val
example_env: ${ env `SOME_ENV_VAR` }
example_param: ${ param `param_name` }
example_self_1: ${ self `data.string` }
example_self_2: ${ self `data.array` }
example_self_3: ${ self `data.object` }

Example output

data:
  string: Hello World
  array:
  - Array
  - of
  - strings
  object:
    key: val
example_env: some_env_var_value
example_param: param_value
example_1: Hello World
example_2:
  array:
  - Array
  - of
  - strings
example_3:
  object:
    key: val

Inspired by

• Serverless framework templating

• Yaml Expander (PHP)

Contributing

Install Tool Dependencies

# install golanglint-ci into ./bin
curl -sfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s v1.16.0
# Install gobin globally
env GO111MODULE=off go get -u github.com/myitcv/gobin

Build tasks

Note	if this repo is cloned into you GOPATH you will need to prefix all commands with GO111MODULES=on

• test: go test ./...

• lint: ./bin/golangci-lint run ./...

• codegen: go generate ./... code gen with versioned tool dependencies

CLI Example (example/ folder)

• codegen: go generate ./...

• build: go build -o stencil example/*.go

• run: ./stencil package --cwd=example/

Project ideas & potential features

• Preserve the key order when Unmarshalling JSON/YAML/TOML

• Implement as a lexer/parser/ast

  • Possibly use https://github.com/alecthomas/participle#introduction

• Implment Unmarshal-ing the tree into your own custom data types

• Support for "Layering" Nodes/trees trees similar to onion

• Add ability to provide additional functions that hook-in to the node tree

• Marshal tree back to JSON/YAML/TOML

• Example CLI tool that uses templ library

  • JSON Schema validation

  • Plugin-like ability similar to serverless framework plugins