EAS Workflows Skill

Help developers write and edit EAS CI/CD workflow YAML files.

Reference Documentation

Fetch these resources before generating or validating workflow files. Use the fetch script (implemented using Node.js) in this skill's scripts/ directory; it caches responses using ETags for efficiency:

# Fetch resources
node {baseDir}/scripts/fetch.js <url>

1. JSON Schema — https://api.expo.dev/v2/workflows/schema
   • It is NECESSARY to fetch this schema
   • Source of truth for validation
   • All job types and their required/optional parameters
   • Trigger types and configurations
   • Runner types, VM images, and all enums
2. Syntax Documentation — https://raw.githubusercontent.com/expo/expo/refs/heads/main/docs/pages/eas/workflows/syntax.mdx
   • Overview of workflow YAML syntax
   • Examples and English explanations
   • Expression syntax and contexts
3. Pre-packaged Jobs — https://raw.githubusercontent.com/expo/expo/refs/heads/main/docs/pages/eas/workflows/pre-packaged-jobs.mdx
   • Documentation for supported pre-packaged job types
   • Job-specific parameters and outputs

Do not rely on memorized values; these resources evolve as new features are added.

Workflow File Location

Workflows live in .eas/workflows/*.yml (or .yaml).

Top-Level Structure

A workflow file has these top-level keys:

• name — Display name for the workflow
• on — Triggers that start the workflow (at least one required)
• jobs — Job definitions (required)
• defaults — Shared defaults for all jobs
• concurrency — Control parallel workflow runs

Consult the schema for the full specification of each section.

Expressions

Use ${{ }} syntax for dynamic values. The schema defines available contexts:

• github.* — GitHub repository and event information
• inputs.* — Values from workflow_dispatch inputs
• needs.* — Outputs and status from dependent jobs
• jobs.* — Job outputs (alternative syntax)
• steps.* — Step outputs within custom jobs
• workflow.* — Workflow metadata

Generating Workflows

When generating or editing workflows:

1. Fetch the schema to get current job types, parameters, and allowed values
2. Validate that required fields are present for each job type
3. Verify job references in needs and after exist in the workflow
4. Check that expressions reference valid contexts and outputs
5. Ensure if conditions respect the schema's length constraints

Validation

After generating or editing a workflow file, validate it against the schema:

# Install dependencies if missing
[ -d "{baseDir}/scripts/node_modules" ] || npm install --prefix {baseDir}/scripts

node {baseDir}/scripts/validate.js <workflow.yml> [workflow2.yml ...]

The validator fetches the latest schema and checks the YAML structure. Fix any reported errors before considering the workflow complete.

Answering Questions

When users ask about available options (job types, triggers, runner types, etc.), fetch the schema and derive the answer from it rather than relying on potentially outdated information.