Advanced usage

Advanced YAML syntax

YAML has some advanced syntax features that can be used like variables to reduce duplication in your pipeline config:

Anchors & aliases

You can use YAML anchors & aliases as variables in your pipeline config.

To convert this:

steps:
  test:
    image: golang:1.18
    commands: go test ./...
  build:
    image: golang:1.18
    commands: build

Just add a new section called variables like this:

+variables:
+  - &golang_image 'golang:1.18'

 steps:
   test:
-    image: golang:1.18
+    image: *golang_image
     commands: go test ./...
   build:
-    image: golang:1.18
+    image: *golang_image
     commands: build

Map merges and overwrites

variables:
  - &base-plugin-settings
    target: dist
    recursive: false
    try: true
  - &special-setting
    special: true
  - &some-plugin codeberg.org/6543/docker-images/print_env

steps:
  develop:
    image: *some-plugin
    settings:
      <<: [*base-plugin-settings, *special-setting] # merge two maps into an empty map
    when:
      branch: develop

  main:
    image: *some-plugin
    settings:
      <<: *base-plugin-settings # merge one map and ...
      try: false # ... overwrite original value
      ongoing: false # ... adding a new value
    when:
      branch: main

Sequence merges

variables:
  pre_cmds: &pre_cmds
    - echo start
    - whoami
  post_cmds: &post_cmds
    - echo stop
  hello_cmd: &hello_cmd
    - echo hello

steps:
  step1:
    image: debian
    commands:
      - <<: *pre_cmds # prepend a sequence
      - echo exec step now do dedicated things
      - <<: *post_cmds # append a sequence
  step2:
    image: debian
    commands:
      - <<: [*pre_cmds, *hello_cmd] # prepend two sequences
      - echo echo from second step
      - <<: *post_cmds

References

Persisting environment data between steps

One can create a file containing environment variables, and then source it in each step that needs them.

steps:
  init:
    image: bash
    commands:
      - echo "FOO=hello" >> envvars
      - echo "BAR=world" >> envvars

  debug:
    image: bash
    commands:
      - source envvars
      - echo $FOO

Declaring global variables in `docker-compose.yml`

As described in Global environment variables, one can define global variables:

services:
  woodpecker-server:
    # ...
    environment:
      - WOODPECKER_ENVIRONMENT=first_var:value1,second_var:value2
      # ...

Note that this tightly couples the server and app configurations (where the app is a completely separate application). But this is a good option for truly global variables which should apply to all steps in all pipelines for all apps.

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