Readiness Checks

A started process is not a healthy service. fuku polls until your service actually accepts requests.

How it works

Poll until healthy

When a service has a readiness check configured, fuku waits for it to pass before marking the service as ready. The next tier only begins after all services in the current tier are ready.

fuku · readiness checks

│ tier foundation
│   ○ auth        checking http localhost:8081/health...
│   ○ gateway     checking http localhost:8082/health...
│   ✓ gateway     ready    1.8s
│   ✓ auth        ready    2.1s
│
│ tier platform
│   ○ api         checking http localhost:8080/health...
│   ✓ api         ready    4.5s

Three check types

Pick the one that matches your service

HTTP

Wait for an HTTP endpoint to respond with a 2xx status code:

fuku.yaml

services:
  api:
    dir: ./api
    readiness:
      type: http
      url: http://localhost:8080/health
      timeout: 30s
      interval: 1s

TCP

Wait for a TCP port to accept connections:

fuku.yaml

services:
  gateway:
    dir: ./gateway
    readiness:
      type: tcp
      address: localhost:9000
      timeout: 10s
      interval: 1s

Log

Wait for a specific pattern to appear in the service's output:

fuku.yaml

services:
  grpc-server:
    dir: ./grpc
    readiness:
      type: log
      pattern: "gRPC server started"
      timeout: 30s

Configuration

Per-service, in fuku.yaml

Field	Description
`type`	`http`, `tcp`, or `log`
`url`	HTTP endpoint to check (http type only)
`address`	Host:port to connect to (tcp type only)
`pattern`	String to match in log output (log type only)
`timeout`	Maximum time to wait before marking as failed
`interval`	Time between check attempts (http/tcp only)

Retries

Automatic retry on failure

If a readiness check times out, fuku can retry the service start based on your retry configuration:

fuku.yaml

retry:
  attempts: 3 # Max retry attempts (default: 3)
  backoff: 500ms # Initial backoff duration (default: 500ms)

Ready to try it out?

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