Dependencies

Blocks can declare dependencies on services provided by other blocks using consumes. Stackie automatically wires the consuming block to the correct provider and port at startup.

Declaring a Dependency

In your stack file, add a consumes entry that references either a port type or a specific block name:

my-project:
  blocks:
    stackie.postgres:
      serves:
        PORT:
          port: 5432
          type: db

    my-api:
      consumes:
        DATABASE:
          port_type: db

Stackie resolves DATABASE to the postgres block’s port and injects ${consumes.DATABASE.HOST} and ${consumes.DATABASE.PORT} into the consuming block’s environment.

Explicit Block Override

When multiple blocks serve the same port type, specify which one to use:

my-project:
  blocks:
    primary-pg:
      serves:
        PORT: { port: 5432, type: db }

    replica-pg:
      serves:
        PORT: { port: 5433, type: db }

    my-api:
      consumes:
        DATABASE:
          block_override: primary-pg

Resolution Errors

Stackie reports a clear error when:

• No match — no block in the stack serves the requested port type.
• Ambiguous match — multiple blocks serve the same port type and no block_override was provided.
• Missing block — a block_override references a block name that doesn’t exist in the stack.