通过 sidecar 和 busybox 调试项目

apiVersion: apps/v1 # for versions before 1.16.0 use extensions/v1beta1
kind: Deployment
metadata:
  name: nginx-deployment # deployment的名称
spec:
  selector:
    matchLabels:
      app: nginx # 选择器必须匹配 template中的metadata.labels
  replicas: 3 # tells deployment to run 3 pods matching the template
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.16.0
        ports:
        - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: nginx-svc-cip
spec:
  selector:
    app: nginx
  type: ClusterIP
  ports:
  - port: 80
    protocol: TCP

这边想调试这个项目，进到 nginx 的 pods 中里面想通过 curl 访问 Service 的 ClusterIP，但是由于 nginx 镜像中没有 curl，需要 apt install curl，但是国内的原因无法更新成功，又需要修改镜像源，修改镜像源需要用到 vim ，但是nginx 镜像中还是没有 vim，只能通过 echo 的办法。

$ echo "">sources.list
$ echo "deb http://mirrors.163.com/ubuntu/ artful main restricted universe multiverse">>sources.list
$ echo "deb http://mirrors.163.com/ubuntu/ artful-security main restricted universe multiverse">>sources.list
$ echo "deb http://mirrors.163.com/ubuntu/ artful-updates main restricted universe multiverse">>sources.list
$ echo "deb http://mirrors.163.com/ubuntu/ artful-proposed main restricted universe multiverse">>sources.list
$ echo "deb http://mirrors.163.com/ubuntu/ artful-backports main restricted universe multiverse">>sources.list
$ echo "deb-src http://mirrors.163.com/ubuntu/ artful main restricted universe multiverse">>sources.list
$ echo "deb-src http://mirrors.163.com/ubuntu/ artful-security main restricted universe multiverse">>sources.list
$ echo "deb-src http://mirrors.163.com/ubuntu/ artful-updates main restricted universe multiverse">>sources.list
$ echo "deb-src http://mirrors.163.com/ubuntu/ artful-proposed main restricted universe multiverse">>sources.list
$ echo "deb-src http://mirrors.163.com/ubuntu/ artful-backports main restricted universe multiverse">>sources.list

问题是我这边依然 apt update 更新失败了！

最后我还是想到一个技巧可以试试，应该可以通过 sidecar 的办法访问，所以修改配置文件如下：

apiVersion: apps/v1 # for versions before 1.16.0 use extensions/v1beta1
kind: Deployment
metadata:
  name: nginx-deployment # deployment的名称
spec:
  selector:
    matchLabels:
      app: nginx # 选择器必须匹配 template中的metadata.labels
  replicas: 3 # tells deployment to run 3 pods matching the template
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.16.0
        ports:
        - containerPort: 80
      - name: busybox
        image: busybox:1.33
        command: ["tail","-f" ,"/dev/null"]
---
apiVersion: v1
kind: Service
metadata:
  name: nginx-svc-cip
spec:
  selector:
    app: nginx
  type: ClusterIP
  ports:
  - port: 80
    protocol: TCP

由于 pods 下可以存放多个 container ，所以选择工具箱 busybox，并且为了让 busybox 不主动退出，通过 tail -f /dev/null 模拟 damon 模式 。

有个注意的点 busybox 中没有 bash，只有 sh ：

 kubectl exec -it nginx-deployment-76dd48b5f7-2nnv7 -c busybox -- sh

-c 指定 container