Custom environment variables don't work with string substitution

[june128]

Component

server, agent

Describe the bug

Setting custom environment variables using the environment key can't be used via string substitution.

Steps to reproduce

1. Define a workflow containing the following step:

   - name: test
    image: debian
    environment:
      MY_COOL_TEST_VAR: test
    commands:
      - echo "$CI $MY_COOL_TEST_VAR ${CI} ${MY_COOL_TEST_VAR}"

2. Run the workflow
3. Observe the output in the Web interface

Expected behavior

The output being:

+ echo "$CI $MY_COOL_TEST_VAR test woodpecker "
woodpecker test test woodpecker 

What's actually being output:

+ echo "$CI $MY_COOL_TEST_VAR woodpecker "
woodpecker test woodpecker 

System Info

{"source":"https://github.com/woodpecker-ci/woodpecker","version":"2.7.0"}

Additional context

Woodpecker running on NixOS. Config available here.

Validations

• [X] Read the docs.
• [X] Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• [ ] Checked that the bug isn't fixed in the next version already [https://woodpecker-ci.org/faq#which-version-of-woodpecker-should-i-use]

[qwerty287]

This is the expected behavior and not a bug.

Our current workflow of substitution does not allow to do something like this, it can only work with vars that are equal for the whole workflow.

[zc-devs]

Escape it:

skip_clone: true

steps:
  echo-envs:
    image: alpine
    environment:
      MY_COOL_TEST_VAR: test
    commands:
      - echo "Workspace is $$CI_WORKSPACE"
      - echo "My cool variable is $$MY_COOL_TEST_VAR"

+ echo "Workspace is $CI_WORKSPACE"
Workspace is /woodpecker/src/gitea.example.com/wp/test
+ echo "My cool variable is $MY_COOL_TEST_VAR"
My cool variable is test

or use scripts.

[june128]

@qwerty287 Ahh fair enough, that's unfortunate. I guess having this clarified in the docs would be a good idea and this issue can be considered a feature request then.

[june128]

@zc-devs But I want to have the value of MY_COOL_TEST_VAR, not the variable name. How does escaping it help me then?

[zc-devs]

What is this then?

[june128]

@zc-devs Yeah, it works when using regular environment variables, but it doesn't work with string substitution (${MY_COOL_TEST_VAR}). For commands I can of course just use regular environment variables, however I only used the commands key as a simple example. A use case I have in particular is using the value of a custom environment variable in entrypoint, where only string substitution is available. There one then just can't use custom environment variables.

[june128]

A friend pointed out a workaround for this problem. One can abuse the matrix key for setting values, which then can be accessed using string substitution. Not perfect, but it works.

It might be nice to have a lightweight matrix key named environment to facilitate global environment variables. However this is then another feature request.

[anbraten]

It should work when you try to escape that one as well: $${MY_COOL_TEST_VAR}

[june128]

@anbraten That seems to work only in shells, but not if you want to use the variable in an entrypoint without a shell directly.

[qwerty287]

Could be solved much more easily by doing something like https://github.com/woodpecker-ci/woodpecker/discussions/2473#discussioncomment-10129727 I think