Blueprint and Preview
The blueprint answers one question before deploy:
What exactly is going to happen to this app?
It is the center of the product — a visual pipeline you can read and edit without losing context.
Five preview steps
| Step | What you see |
|---|---|
| Auth and resolve ref | Repo, branch, commit SHA |
| Build | Deploy units, Railpack plans or Dockerfile, CodeBuild output (ECR or S3) |
| Setup | AWS region, Fargate networking or static bucket |
| Deploy | Runtime env vars (Secrets Manager on ECS), ALB host rules |
| Done | Hosted subdomain and public Visit URL |
Each step surfaces artifacts: Railpack plan JSON, Docker build units, ECS prerequisites, and domain routing.
What you can edit in preview
| Field | Effect |
|---|---|
| Branch | Which ref CodeBuild checks out |
| Region | Where AWS resources are created |
| Env vars | Build-time vars to CodeBuild; runtime vars to ECS Secrets Manager |
| Hosted subdomain | Hostname on the platform domain (myapp.example.com) |
Edits stay in the same preview surface — you do not lose the pipeline context.
Reading Railpack artifacts
When the scan used Railpack, the blueprint shows:
- Deploy units — name, root path, framework, port, provider
- Railpack plan — install/build steps and
deploy.startCommand - Build status — passed, failed, or skipped from verification
A missing Railpack plan on a non-Docker unit is a blocker — re-run Smart Analysis or use Improve scan.
See Railpack and Smart Analysis.
Deploy shape indicators
| Shape | Blueprint hint |
|---|---|
server | Container on ECS via Railpack |
static / static_build (no start command) | Static S3 path |
static_build (with start command) | Container serving built assets |
existing_docker | Dockerfile via CodeBuild → ECS |
multi | Multiple deploy units; compose-style builds |
Validation before deploy
The preview model warns when:
- Build status is not passed (when verification ran)
- Railpack plan is missing for a unit
- Required scan data is incomplete
Review warnings in the blueprint before pressing deploy.
After preview
When the plan looks right:
- Deploy from the workspace
- Watch the same stages execute with live logs
- Compare blueprint expectations to actual step output if something fails