Template Tool in Golang for All Purpose

Naming: tap means Template All Product.

It's a tool written in Golang, which takes yaml (or json) as input, and renders templates in Golang syntax.

Can be used for all kinds of purposes, hence the name, TAP.

Purpose

Using input values (defined in a single yaml or json file) and template/templates (all golang tempaltes under a given directory, or a single template file) to write rendered files.

It was originally designed to generate config.tf and terraform.tfvars for usage of terraform, but it can be for sure used for other purposes, so the naming changed from "tftpl" (terraform template) to "tap" (template all products).

Templates names end with .tpl, after render, the rendered filename is generated by removing the .tpl of the template filename.

For example, if template name is file.txt.tpl, rendered result will be file.txt (simply removing the .tpl).

Example Input and Templates

Input examples see test/input/test.yaml, test/input/test.json.

Template examples see test/templates/test.tfvars.tpl.

Both are relatively simple examples, but golang template full feature are supported. For example, to render a yaml list into an array with square brackets and comma separated items:

arr = [{{ range  $i, $e := .list }}{{ if $i }}, {{ end }}"{{ $e }}"{{ end }}]

Dependencies

• Golang 1.13.

Tested with golang 1.13.4 darwin/amd64, as well as 1.14 in CircleCI.

Other dependencies can be fetched via go module command go get, see below.

Build

go get ./...
go build

Test

go test ./...

Coverage:

go test ./... -coverprofile=c.out

View coverage as html:

go tool cover -html=c.out

Usage

$ ./tap -h
Usage of ./tap:
  -inputFile string
        input file path and name, example: ./input/eks.yaml (default "./input/eks.yaml")
  -outputDir string
        output directory, example: ./output (default ".")
  -template string
        if given a file, the file of the template to be rendered; if given a directory, all templates under the directory will be rendered (default "./templates")

Run

./tap -inputFile ./test/input/test.yaml -outputDir . -template ./test/templates/
# template can be either a directory (in which case, all templates under it will be rendered), or a file
./tap -inputFile ./test/input/test.yaml -outputDir . -template ./test/templates/a.tpl

Build Docker

docker build -t ironcore864/tap:latest .
docker push ironcore864/tap:latest

Run in Docker

docker pull ironcore864/tap:latest
docker run -it ironcore864/tap:latest

Use with Jenkins Pipeline with Kubernetes Plugin in a Multi-Container Pipeline

podTemplate(label: 'pipeline', cloud: 'kubernetes', containers: [
  containerTemplate(name: 'tap', 
    image: 'docker.io/ironcore864/tap:latest', 
    alwaysPullImage: true,
    ttyEnabled: true,
    args: '',
    command: 'tail -f /dev/null',
    resourceRequestCpu: '100m',
    resourceLimitCpu: '200m',
    resourceRequestMemory: '200Mi',
    resourceLimitMemory: '400Mi'),
  containerTemplate(name: 'jnlp',
    image: 'docker.io/jenkinsci/jnlp-slave:alpine',
    command: '',
    args: '${computer.jnlpmac} ${computer.name}',
    resourceRequestCpu: '50m',
    resourceLimitCpu: '600m',
    resourceRequestMemory: '100Mi',
    resourceLimitMemory: '500Mi')
  ]) {
  node('pipeline') {
    stage("Render Templates") {
      container('tap') {
        unstash 'userinput'
        sh '/app/tap -inputFile ./${USER_INPUT_FILE} -outputDir ./${OUTPUT_DIR} -template ./${TEMPLATE_DIR}'
      }
    }
    stage("XXX") {
      // ...
    }
  }
}