Conditional steps in jobs and conditional workflows

Conditional Steps and Workflows: 

With the recent addition of advanced logic in a config file, the option to conditionally trigger steps in a job or to conditionally trigger a workflow is now available.

Specific logic statements can be used to create multiple nested conditions, that will always at the top level result in true or false -- which in turn determines if the workflow or steps are triggered.

Job Step Example

- when:
    condition:
      or:
        - and:
          - equal: [ main, << pipeline.git.branch >> ]
          - or: [ << pipeline.parameters.param1 >>, << pipeline.parameters.param2 >> ]
        - or:
          - equal: [ false, << pipeline.parameters.param1 >> ]
    steps:
      - run: echo "I am on main AND param1 is true OR param2 is true -- OR param1 is false"

Workflow Example

workflows:
  conditional-workflow:
    when:
      and: # All must be true to trigger
        - equal: [ main, << pipeline.git.branch >> ]
        - not: << pipeline.parameters.param1 >>
        - or: [ << pipeline.parameters.param1 >>, << pipeline.parameters.param2 >> ]

    jobs:
      - job-on-condition
 

Conditions can be nested in an arbitrary fashion, according to their argument specifications, and to a maximum depth of 100 levels. This allows for some complex logic, as an example of multiple nested conditions:

- when:
    condition:
      or:
        - and:
          - or:
              - and:
                  - equal: [ main, << pipeline.git.branch >> ]
                  - equal: [ false, << pipeline.parameters.param1 >> ]
              - or:
                  - not: << pipeline.parameters.param3 >>
          - or:
              - equal: [ false, << pipeline.parameters.param3 >> ]
              - or: [ << pipeline.parameters.param1 >>, << pipeline.parameters.param2 >> ]  
        - or:
            - equal: [ true, << pipeline.parameters.param4 >> ]

    steps:
      - run: echo "param 4 is true OR the other nested conditions are true"