Read a template on standard in (stdin) and apply the environment variables, perform text replacement and write the result to standard out (stdout)

• golang templates require quotes for literals
• env is the method defined to look up the environment variable
• {{ env "VAR" }} performs lookup and replacement of var, fails on missing (unset) environment variable

go get github.com/davidwalter0/applytmpl

build

make # builds a static binary, place in ${GOPATH}/bin

run example

cat example/environment
. example/environment
cat example/template.yaml | applytmpl | tee example/template-processed.yaml

value of template.yaml

# Should succeed if environment is sourced
# source in bash by
# . example/environment
---
- name: '{{ env "PROJECT" }}'
  hosts: {{ env "HOSTS" }}
  # vars:
  tasks:
  - name: echo
    shell: echo {{ env "TEXT" }}

Example errors

cat example/fails.yaml

value of fails.yaml

# Should file, even if environment is sourced, if lowercase project is undefined
# source in bash by
# . example/environment
---
- name: '{{ env "project" }} Pre Process Playbook'
  hosts: {{ env "HOSTS" }}
  # vars:
  tasks:
  - name: echo
    shell: echo {{ env "TEXT" }}

cat example/fails.yaml | ./applytmpl | tee example/fails-processed.yaml

---

New tests in test/

cd test
make