Expo Build Workflow Builder

EAS Workflows Skill

EAS service - costs apply. EAS Workflows run on Expo Application Services, a paid product with free-tier limits. Each workflow job consumes your plan's build/compute minutes, and jobs that build or submit also need paid Apple Developer and Google Play accounts. Review https://expo.dev/pricing before triggering runs.

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

Reference Documentation

Fetch these resources before generating or editing workflow files, or when answering syntax questions. First resolve this skill's directory, then use the fetch script in its scripts/ directory. It is implemented using Node.js and caches responses using ETags for efficiency:

# Fetch resources
node <skill-dir>/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 the workflow YAML structure; EAS CLI remains the authoritative final validator
   • 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). Each file must be 16 KiB or smaller.

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 with EAS CLI from the Expo project root:

npx -y eas-cli@latest workflow:validate .eas/workflows/<workflow.yml> --non-interactive

Run the command separately for each changed workflow file. It requires a logged-in EAS CLI session and a linked Expo project. Unlike schema-only validation, it also checks build profile references against the project's eas.json and performs EAS server-side validation. Fix every reported error and rerun the command until it prints Workflow configuration YAML is valid. Do not replace this command with a local YAML or JSON Schema validator.

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.

Submitting Feedback

If you encounter errors, misleading or outdated information in this skill, report it so Expo can improve:

npx --yes submit-expo-feedback@latest --category skills --subject "eas-workflows" "<actionable feedback>"

Only submit when you have something specific and actionable to report. Include as much relevant context as possible. If an AI agent repeatedly failed or the user had to take over an Expo task, load the expo-skill-feedback skill and follow its eval-candidate flow instead of reusing the command above.