Dependencies

In a microservices architecture, services often have strict startup orders. For example, a backend API cannot accept requests until the database is ready.

Super allows you to define these relationships using the depends_on configuration.

Configuration

# 1. The Provider (Database)
[[programs]]
name = "postgres-db"
command = "/usr/bin/postgres"
# ... args ...

[programs.health_check]
type = "tcp"
port = 5432

# 2. The Consumer (API)
[[programs]]
name = "backend-api"
command = "./api-server"
depends_on = ["postgres-db"]

How it works

When you start backend-api (or when Super autostarts it):

1. Super checks if postgres-db is running.
2. If postgres-db is not running, it starts it.
3. Crucially, Super waits for postgres-db to become Healthy (pass its health check).
4. Only then does backend-api start.

State: “Waiting”

If a dependency is missing or unhealthy, the dependent process enters the Waiting state.

$ super list

ID        Name          Status    Notes
--------  ------------  --------  ------------------------
a1b2...   backend-api   Waiting   Waiting for: postgres-db
c3d4...   postgres-db   Starting  ...

Once postgres-db turns Healthy, backend-api automatically transitions to Starting.