Inheritance & Worked Example

Both connections and environments support extends: for composition.

Connection inheritance — a base template

extends: on a connection is a base-template pattern. Define the shared fields once:

connections/akeneo-base/definition.yaml

type: zenvara/akeneo
TimeoutSeconds: 120
BatchSize: 100
MaxConcurrency: 4
AutoSanitizeCodes: true

# connections/akeneo-pim-prod/definition.yaml
extends: akeneo-base
BaseUrl: "https://prod.cloud.akeneo.com"
ClientId: "${secret:akeneo/pim-prod/client-id}"
ClientSecret: "${secret:akeneo/pim-prod/client-secret}"
Username: "${secret:akeneo/pim-prod/username}"
Password: "${secret:akeneo/pim-prod/password}"

Three overrides plus one base, instead of four near-identical files.

Environment inheritance

extends: on an environment is a list of parent environments composed in order — single-level only (no transitive chains), to keep the resolution graph easy to read.

environments/staging/definition.yaml

kind: staging
extends:
  - common
connections:
  db: warehouse-staging   # overrides whatever `common` had under db

Worked example: dev → prod for one flow

Two connections (one Postgres, one SFTP), two environments, one flow:

connections/audit-postgres-base/definition.yaml

type: zenvara/postgresql
TimeoutSeconds: 30

# connections/audit-postgres-dev/definition.yaml
extends: audit-postgres-base
ConnectionString: "${secret:audit/dev:connection-string}"

# connections/audit-postgres-prod/definition.yaml
extends: audit-postgres-base
ConnectionString: "${secret:audit/prod:connection-string}"

# environments/dev/definition.yaml
kind: development
connections: { audit: audit-postgres-dev, drop: drop-zone-dev }

# environments/prod/definition.yaml
kind: production
connections: { audit: audit-postgres-prod, drop: drop-zone-prod }

flows/incident-archive/definition.yaml

status: active
output:
  archived: !int

steps:
  - $rows:
      invoke: postgresql.query
      on: audit
      with: { Query: "SELECT * FROM incidents WHERE archived = false" }

  - $upload:
      create: sftp.file
      on: drop
      with:
        Path: "/incidents/${= str(_invocation-id)}.json"
        Input: "${rows.body}"

  - return:
      archived: "${= len(rows.rows)}"

Run it twice:

zen invoke-flow incident-archive --env dev
zen invoke-flow incident-archive --env prod

Same flow, different audit DB, different SFTP drop zone. The environment is the only thing that changed — which is the whole point of the model.