docker - 如何在kubernetes中将 `args`作为 `command`运行

Question

我有一个要在kubernetes作业中运行的python脚本。我已经使用configMap将其上传到位于dir/script.py中的容器中。

容器可以使用args["load"]正常运行。

我尝试在Job list 中使用postStart生命周期，但它似乎无法运行。

        lifecycle:
          preStop:
            exec:
              command: 
              - /bin/sh
              - -c 
              - /usr/bin/python /opt/config-init/db/tls_generator.py

以下是 list 的摘要

      containers:
      - name: {{ template "gluu.name" . }}-load
        image: gluufederation/config-init:4.0.0_dev
        lifecycle:
          preStop:
            exec:
              command: 
              - /bin/sh
              - -c 
              - /usr/bin/python /opt/config-init/db/tls_generator.py
        volumeMounts:
          - mountPath: /opt/config-init/db/
            name: {{ template "gluu.name" . }}-config
          - mountPath: /opt/config-init/db/generate.json
            name: {{ template "gluu.fullname" . }}-mount-gen-file
            subPath: generate.json
          - mountPath: /opt/config-init/db/tls_generator.py
            name: {{ template "gluu.fullname" . }}-tls-script
        envFrom:
        - configMapRef:
            name: {{ template "gluu.fullname" . }}-config-cm
        args: [ "load" ]

如何在 tls_generator.py之后运行 args["load"] scipt。

dockerFile部分看起来像

ENTRYPOINT ["tini", "-g", "--", "/app/scripts/entrypoint.sh"]
CMD ["--help"]

Answer 1

您正在使用Container Lifecycle Hooks，更具体地说PreStop。

This hook is called immediately before a container is terminated due to an API request or management event such as liveness probe failure, preemption, resource contention and others.

如果要在 pod启动时执行命令，则应考虑使用 PostStart。

This hook executes immediately after a container is created. However, there is no guarantee that the hook will execute before the container ENTRYPOINT. No parameters are passed to the handler.

另一种选择是使用 Init Containers，这是一些带有示例的想法:

• Wait for a Service to be created, using a shell one-line command like:

 for i in {1..100}; do sleep 1; if dig myservice; then exit 0; fi; done; exit 1

• Register this Pod with a remote server from the downward API with a command like:

curl -X POST http://$MANAGEMENT_SERVICE_HOST:$MANAGEMENT_SERVICE_PORT/register -d >'instance=$(<POD_NAME>)&ip=$(<POD_IP>)'

• Wait for some time before starting the app container with a command like

sleep 60

请阅读有关如何使用 Init containers的文档以获取更多详细信息。