Aws cicd patterns

AWS CI/CD Patterns

Continuous integration and delivery patterns for AWS, emphasizing GitHub Actions with OIDC authentication (configure-aws-credentials@v6) and ECR-based container workflows.

App Runner maintenance mode (April 30, 2026): CI/CD patterns below work for both App Runner and ECS Express Mode — only the deploy step changes.

Core Services

Service	Purpose	Use When
GitHub Actions	CI/CD orchestration	Building, testing, deploying
ECR	Container registry	Storing and managing Docker images
App Runner / ECS Express	Serverless compute	Deploying stateless HTTP workloads
Secrets Manager	Secret storage	Runtime secret injection
S3	Terraform backend	Remote state with S3-native locking (TF 1.11+)

Pipeline Stages

1. Source — Trigger on push/PR
2. Build — Compile, lint, type-check
3. Unit Test — Fast feedback (pytest, coverage gate)
4. Docker Build — Multi-stage build with GHA cache
5. Security Scan — Trivy/Snyk on container image
6. Push to ECR — Tag with SHA, push image
7. Deploy Staging — Automatic on merge to main
8. Deploy Production — Manual approval or canary

GitHub OIDC Authentication (Keyless)

Use aws-actions/configure-aws-credentials@v6 with OIDC — no access keys needed:

permissions:
  id-token: write   # Required for OIDC
  contents: read

steps:
  - uses: aws-actions/configure-aws-credentials@v6
    with:
      role-to-assume: ${{ vars.AWS_DEPLOY_ROLE_ARN }}
      aws-region: ${{ vars.AWS_REGION }}

OIDC setup details (trust policy, IAM role) → see aws-security-hardening skill.

AWS Bootstrap Prerequisites

S3 bucket + DynamoDB lock table for Terraform remote state cannot be created by Terraform itself — bootstrapped manually before terraform init.

1. S3 bucket with versioning, put-public-access-block, and SSE-S3 (each is a separate API call)
2. DynamoDB table with LockID partition key, PAY_PER_REQUEST billing
3. Reference these as data sources in Terraform, not managed resources — prevents terraform destroy from wiping bootstrap infrastructure

AWS CLI gotchas:

• create-bucket requires --create-bucket-configuration LocationConstraint=<region> for any region other than us-east-1
• Billing alarms (AWS/Billing EstimatedCharges) must be created in us-east-1 — other regions produce silent INSUFFICIENT_DATA
• GitHub OIDC create-open-id-connect-provider requires --thumbprint-list even though AWS ignores it for GitHub — use 6938fd4d98bab03faadb97b34396831e3780aea1
• Pre-check OIDC: aws iam list-open-id-connect-providers before creating to avoid EntityAlreadyExists

Rollback Patterns

Method	Speed	Risk
Redeploy previous SHA tag	Fast (image exists)	Low
App Runner revision rollback	Fast (1 API call)	Low
Terraform state rollback	Slow (full plan/apply)	Medium
Git revert + redeploy	Medium (triggers full pipeline)	Low

Preferred: Redeploy previous SHA tag — fastest, most predictable.

Best Practices

• Use OIDC — configure-aws-credentials@v6 eliminates long-lived keys. Scope trust policy to specific repo + branch to prevent cross-repo assumption.
• Build once, promote — Same image through staging → production via SHA tag. Rebuilding per environment risks drift.
• Tag immutably — SHA-based tags as source of truth, latest as convenience alias only.
• Secrets in Secrets Manager — secrets pasted into workflow files, Dockerfiles, or env vars land in build logs, image layers, and the public action run history, where they cannot be revoked retroactively.
• Cache Docker layers — GHA cache (type=gha, 10GB limit) or ECR registry cache (type=registry) for 50-70% faster builds.
• Apply job safety — cancel-in-progress: true on a Terraform apply job kills the runner mid-terraform apply, leaving the state file locked or partially written; the next run then has to manually unlock and reconcile drift.

Reusable Workflow Context

github.event_name inside a reusable workflow resolves to workflow_call, not the caller's event. This silently skips conditions like if: github.event_name == 'push'.

Pattern: Explicit boolean inputs avoid the workflow_call event name shadowing. See examples.md for the explicit boolean input pattern.

• Bare ${{ inputs.push_image }} evaluates to empty string (not false) on non-workflow_call triggers — ${{ inputs.push_image || false }} prevents YAML boolean validation failures
• Without secrets: inherit, the called workflow cannot access the caller's secrets, causing silent access failures

Deploy Safety Patterns

Concurrency: cancel-in-progress: false prevents canceling mid-SSM-command, which can leave instances broken:

concurrency:
  group: deploy-${{ github.ref }}
  cancel-in-progress: false

Shell injection guard: Validating workflow_dispatch inputs before use in SSM commands prevents shell injection. Using the env: block (rather than ${{ }} interpolation in run:) ensures bash's regex check is authoritative. See examples.md for the validation step pattern.

Health check with fail-exit: for loops with curl && break || sleep exit 0 when all attempts fail — the ok flag pattern ensures non-zero exit on exhaustion. See examples.md for health check and migration retry patterns.

Anti-Patterns

Anti-Pattern	Pattern
AWS access keys in GitHub Secrets	OIDC provider + IAM role assumption
latest tag only in ECR	SHA-based tags + latest as convenience alias
No ECR lifecycle policy	Lifecycle rules to prune old/untagged images
Rebuilding image for each environment	Build once, promote through envs via tag
OIDC trust policy with * in sub	Scope to repo:org/repo:ref:refs/heads/main
Skipping security scan before deploy	Trivy/Snyk scan as blocking CI step
github.event_name == 'push' inside reusable workflow	Explicit push_image: boolean input from caller
Both ci.yml and deploy.yml triggering on push: branches: [main]	Single entry point: deploy.yml calls ci.yml via workflow_call
sleep N before docker exec in deploy scripts	Retry loop with fail-exit flag pattern
Health check loop that exits 0 on exhaustion	ok flag variable with `[ $ok -eq 1 ]
Missing ECR login before docker pull in rollback	Include aws ecr get-login-password in rollback procedure

See reference.md for Terraform state locking and ECR lifecycle policies. See examples.md for complete GitHub Actions workflow templates (CI, Deploy, Terraform).

Related

• aws-security-hardening — OIDC trust-policy authoring and IAM role scoping consumed by the pipelines here
• aws-app-runner — the deploy target this pipeline pushes images to (and the ECS Express migration path)
• github-actions-cicd — platform-neutral GHA workflow syntax (reusable workflows, matrix builds) this skill layers AWS specifics on top of