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kubernetes - 如何允许（sidecar）容器在 Kubernetes 部署中终止而不重新启动？

问题描述

我的部署包括：

一旦配置了单独的服务，sidecar 的工作就完成了。但是，它不能终止，因为 Kubernetes 只会重新启动它。它不应该是 init 容器的一部分，因为它不应该阻止服务运行。

由于部署不允许OnFailurerestartPolicy，我目前的实现是让sidecar在完成配置任务后进入睡眠状态。

有没有办法让容器在部署不重启的情况下终止？或者，有没有办法让 init 容器与常规容器一起运行？

解决 XY 问题的一些细节：

例子：

#my-service.yaml
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-service
spec:
  replicas: 1
  template:
    spec:
      initContainers:
        - name: my-service-init
          image: my-service
          imagePullPolicy: IfNotPresent
          env:
          - name: DATABASE_URL
            value: postgres://postgres:postgres_password@$db_host:5432/database
          args: ['init_script.py']
      containers:
        - name: my-service
          env:
          - name: DATABASE_URL
            value: postgres://db_role:db_password@$db_host:5432/database
          image: my-service
          imagePullPolicy: IfNotPresent
          args: ['main.py']
        - name: related-service-configure
          env:
          - name: RELATED_API_SERVICE_ADMIN_ENDPOINT
            value: http://related_api_service/api/
          image: my-service
          imagePullPolicy: IfNotPresent
          args: ['manage_related_service.py']

#related-api-service.yaml
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: related-api-service  
spec:
  replicas: 1
  template:
    spec:
      containers:
        - name: related-api-service
          env:
          - name: DATABASE_URL
            value: postgres://db_role:db_password@$db_host:5432/database
          image: related-api-image
          imagePullPolicy: IfNotPresent
          ports:
          - containerPort: 8080
            name: http
            protocol: TCP

#manage_related_service.py
import time
import requests
import json


def upgrade_metadata(query_url, metadata_file):
    with open(metadata_file) as fp:
        metadata = json.load(fp)

    print(f"Querying {query_url}...")
    rsp = requests.post(query_url, json=metadata)
    response = rsp.json()
    print(f"Response to request was:\n{response}")
    if response.get('success') != 'True':
        raise ValueError("Metadata upgrade was not successful")


if __name__ == '__main__':
    from environs import Env
    env = Env()
    env.read_env()

    RELATED_API_SERVICE_ADMIN_ENDPOINT = env("RELATED_API_SERVICE_ADMIN_ENDPOINT")
    METADATA_FILE = env("METADATA_FILE", "metadata.json")

    upgrade_metadata(RELATED_API_SERVICE_ADMIN_ENDPOINT, METADATA_FILE)

    # Once metadata has been uploaded, sleep forever
    while True:
        time.sleep(3600)

标签： kuberneteskubernetes-deployment

解决方案

我认为您应该创建Kubernestes 作业而不是部署。然后你应该终止sidecar。之后特定的容器也会自动终止。

您可以模拟特定的边车行为。有一个示例脚本可以帮助您这样做：

containers:
  - name: example
    image: gcr.io/some/image:latest
    command: ["/bin/bash", "-c"]
    args:
      - |
        trap "touch /tmp/pod/main-terminated" EXIT
        /my-batch-job/bin/main --config=/config/my-job-config.yaml
    volumeMounts:
      - mountPath: /tmp/pod
        name: tmp-pod
  - name: envoy-container
    image: gcr.io/our-envoy-plus-bash-image:latest
    command: ["/bin/bash", "-c"]
    args:
      - |
        /usr/local/bin/envoy --config-path=/my-batch-job/etc/envoy.json &
        CHILD_PID=$!
        (while true; do if [[ -f "/tmp/pod/main-terminated" ]]; then kill $CHILD_PID; fi; sleep 1; done) &
        wait $CHILD_PID
        if [[ -f "/tmp/pod/main-terminated" ]]; then exit 0; fi
    volumeMounts:
      - mountPath: /tmp/pod
        name: tmp-pod
        readOnly: true
volumes:
  - name: tmp-pod
    emptyDir: {}

您可以在此处找到更多信息：sidecar-terminating，sidecars-behaviour。

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