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Check Workflow Prerequisites with require and assert

· 2 min read
Erik Osterman
Erik Osterman
Founder @ Cloud Posse

Workflows often depend on tools, files, and directories being present before they run. Without a first-class check, those prerequisites tend to hide inside brittle shell snippets and ad hoc command checks.

The Problem​

Shell checks work until they have to be portable, readable, and friendly. A workflow might need vhs, ffmpeg, a generated config file, and a local output directory before the real work starts. Encoding that as inline shell makes the workflow harder to scan and usually produces a poor error when something is missing.

The Change​

Atmos now has a declarative require step type for workflow and custom command prerequisites. The assert step type is an alias for the same behavior.

steps:
  - name: require recording tools
    type: require
    tools:
      - vhs
      - ffmpeg
    files:
      - ./Taskfile.yml
    dirs:
      - ./demo
    hint: "on macOS run: brew install vhs ffmpeg"

The step checks that tools are executable on PATH, files exist, and directories exist. If anything is missing, Atmos fails fast with one aggregated error and the remediation hint.

Why It Matters​

  • Prerequisites are visible. The workflow declares what it needs before the work starts.
  • Errors are actionable. Missing tools and paths are reported together with a hint.
  • It is read-only. require never installs tools and never mutates PATH; use dependencies.tools when you want Atmos to manage tool installation.

Get Involved​

See the require step reference for all supported fields and examples.