Steps

info

For clarity, the steps configuration are showed in a yaml format but you can also use the same keys in a json file and it will still run fine !

Write a step

Steps are written in a workflow file

workflow:
  timeout: 5m
  steps:
    my-step:
      kind: docker
      with:
        image: 'alpine:3.10.0'
        commands: |
          echo "Selflow is love, Selflow is Life !"

In the above example, we are creating a step called my-step. This step has a kind, this is a mandatory field that says the kind of step to use, here "docker". It also has an object passed with the with key with a few properties that the docker step needs. This is also a mandatory field.

Optional configuration

needs

Syntax

workflow:
  timeout: 5m
  steps:
    # ...
    # Other steps definitions
    # ...
    my-step:
      kind: docker
      needs:
        - some-step
        - some-other-step
      with:
        image: 'alpine:3.10.0'
        commands: |
          echo "Selflow is love, Selflow is Life !"

In this example, the step my-step depends on steps some-step and some-other-step so it will start only after both steps stops with a status of SUCCESS.

The nice thing about step dependencies, is that they can share variables.

Example

workflow:
  timeout: 5m
  steps:
    step-a:
      kind: docker
      with:
        image: 'alpine:3.10.0'
        commands: |
          echo "::output::foo::bar"

    step-b:
      kind: docker
      needs:
        - step-a
      with:
        image: 'alpine:3.10.0'
        commands: |
          echo "{{ .Needs "step-a" "foo" }}"

A lot of things are happening there. First we have two steps, step-a and step-b, both docker steps.

The step step-a logs "::output::foo::bar". This syntax is used to tell the docker steps that it needs to output a variable called "foo" with the value of "bar".

The in step-b, with are using this syntax {{ .Needs "step-a" "foo" }}. Here we are using Go Template to declare that the step needs the value of the variable "foo" output by step-a.

So in this example, step-b will output "bar".

You can find more details about how to use Go Template on its great documentation !

if

Syntax :

workflow:
  timeout: 5m
  steps:
    my-step:
      kind: docker
      if: 'false'
      with:
        image: 'alpine:3.10.0'
        commands: |
          echo "This will not be executed"

The if command allows to execute a step only if the specified condition is truthy. The condition is considered truthy if it is contains an empty string, "no" or "false".

It doesn't do much in the example above but you can combine it with step variables as explained in the Needs attribute to make it dynamic !

Example

workflow:
  timeout: 5m
  steps:
    step-a:
      kind: docker
      with:
        image: "alpine:3.10.0"
        commands: |
          # a will be equal to either "true" of "false" at random
          a=$(if [ "$(($RANDOM % 2))" -eq "0" ]; then echo "true"; else echo "false"; fi)
          echo "::output::foo::$a"

    step-b:
      kind: docker
      needs:
        - step-a
      if: "{{ .Needs "step-a" "foo" }}"
      with:
        image: "alpine:3.10.0"
        commands: |
          echo "I might be executed"

It this example, step-b depends on step-a. step-a will output a "foo" variable that will randomly equals "true" or "false". The output is used in the if attribute of the second step to only execute it if step-a returned "true".