Variables

Variables are fundamental to creating dynamic and interconnected Bosun workflows. They allow you to store and reference data throughout your tasks, enabling complex logic and data flow between different steps and agents.

Bosun provides several types of variables, with two common ones being:

• outputs: Used to access the results or output of a previous step.
• for_each.value: Used within a for_each loop to refer to the current item being processed.

Accessing Step Outputs (outputs)

Each step in a Bosun workflow can produce an output. You can reference these outputs in subsequent steps using the outputs.<step_index> syntax, where <step_index> is the zero-based index of the step in the workflow.

Example from Workflow:

  - name: Get source files
    run: find src -name "*.ts" # This is step 0 (0-indexed)

  - name: Analyze files
    for_each:
      from: '{{ outputs.0 | split(pat="\n") | slice(end=5) | json_encode() }}'
      # ...

In this snippet:

• The run: find src -name "*.ts" command is the first step in this example (index 0). It outputs a list of TypeScript file paths.
• The for_each step then uses outputs.0 to retrieve this list. The templating expression {{ outputs.0 | split(pat="\n") | slice(end=5) | json_encode() }} processes this output to prepare it for the loop.

Referencing Outputs by Step ID

When you need more descriptive references than numeric indexes, add an id field to a step:

  - id: fetch_sources
    name: Get source files
    run: find src -name "*.ts"

  - name: Analyze files
    for_each:
      from: '{{ outputs.fetch_sources | split(pat="\n") | filter(value) | json_encode() }}'
      # ...

IDs must start with a letter or underscore and can contain alphanumeric characters, underscores, and hyphens (kebab case).

Iterating with for_each.value

When you use a for_each loop, Bosun automatically makes the current item of the iteration available as for_each.value. This allows the agent or run command within the loop to operate on each item individually.

Example from Workflow:

  - name: Analyze files
    for_each:
      from: '{{ outputs.fetch_sources | split(pat="\n") | slice(end=5) | json_encode() }}'
      agent:
        extends: Coding
        instructions: "Refactor the code in file {{ for_each.value }} to improve readability."
        # ...

Here:

• The for_each loop iterates over the list of file paths.
• For each iteration, {{ for_each.value }} holds the current file path (e.g., src/utils/helper.ts).
• This value is then injected into the instructions for the Coding agent, allowing it to specifically refactor that particular file.