Application Probes

For more information on each probe type, please see probe fundamentals.

For all probe settings see the reference documentation.

Below is an example that utilzed both readiness and liveness probes.

name: popcorn-controller
version: "1.0"
services:
  - name: popcorn-controller-service
    containers:
      - name: kettle-popper-manager
        image: "registry.gitlab.com/avassa-public/movie-theaters-demo/kettle-popper-manager:v1.0"
        probes:
          readiness:
            exec:
              cmd:
                - /readiness_probe.sh
            # Start probing immediately after startup
            initial-delay: 0s
            # Probe every 10 seconds
            period: 10s
            # Success after first successful probe
            success-threshold: 1
            # Requre 3 consecutive failures before marking container as non-ready
            failure-threshold: 3
          liveness:
            http:
              port: 10000
              path: /live
            # Start probing immediately after startup
            initial-delay: 0s
            # Probe every 10 seconds
            period: 10s
            # Success after first successful probe
            success-threshold: 1
            # Requre 3 consecutive failures before restarting container
            failure-threshold: 3
    mode: replicated
    replicas: 1

Example readiness probe

In the readiness probe we run a script in the container. In the example above it's a simple shell script, but this can be any executable in the container, e.g.

        probes:
          readiness:
            exec:
              cmd:
                - python3
                - /readiness_probe.py

If the command exits with 0 it's considered success, and other exit code is considered a probe failure.

In shell scripts you can control the exit code with

#!/bin/sh

# Success
exit 0

# Failure
exit 1

And in Python

import sys

# Success
sys.exit(0)

# Failure
sys.exit(1)

Example liveness probe

In the liveness probe we instead use a HTTP probe. In this simple example, the Edge Enforcer will do a HTTP GET to http://<application IP>:10000/live.

note

<application IP> above is known by the Edge Enforcer when the application runs.

If a HTTP probe returns with HTTP status codes 2xx or 3xx, it's considered a success, otherwise a failure.

tip

On the HTTP probes, you can also pass query parameters in the path, e.g.

path: /live?foo=bar