当底层 ConfigMap 发生变化时，我将如何运行一个简单的容器来触发 Prometheus 重新加载其配置?

问题描述

在 Kubernetes 中运行 Prometheus 时，我正在通过 ConfigMap 推出新配置.ConfigMap 在容器中作为文件公开.

While running Prometheus in Kubernetes, I'm pushing out new config via a ConfigMap. ConfigMaps are exposed as files in the container.

我希望 Prometheus 在文件更改时自动重新加载其配置.

I would love Prometheus to automatically reload its configuration when the file changes.

这样的东西会起作用吗?

Would something like this work?

inotifywait -q -m -e close_write /etc/prometheus/config.yml |
while read -r filename event; do
  curl -X POST http://localhost:9090/-/reload
done

推荐答案

(我花了一些时间来让它完全工作)这适用于一个小的边车容器.配置可能如下所示:

( I took some time to get this fully to work)this works with a small sidecar container. The configuration could look like this:

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: prometheus
spec:
  replicas: 1
  template:
    ....
    spec:
      containers:
        ... (your actual container config goes here) ...
      - name: refresh
        imagePullPolicy: Always
        args:
        - /etc/prometheus/config.yml
        - http://localhost:9090/-/reload
        image: tolleiv/k8s-prometheus-reload
        volumeMounts:
          - name: config-volume
            mountPath: /etc/prometheus
      volumes:
        - name: config-volume
          configMap:
            name: prometheus

实际检查是用这个脚本完成的，其中观察到的文件和 URL 作为参数传递:

The actual check is done with this script where the observed file and the URL are passed as parameters:

#!/bin/sh
while true; do
   inotifywait "$(readlink -f $1)"
   echo "[$(date +%s)] Trigger refresh"
   curl -sSL -X POST "$2" > /dev/null
done

一切都可以在Dockerhub上的这个容器中找到

使用 -m 保留单个 inotifywait 不起作用，因为当 ConfigMap 更改时 Kubernetes 会进行符号链接处理.

Keeping a single inotifywait with the -m didn't work because of symlink juggling which is done by Kubernetes when the ConfigMap changes.

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