Using sidecar containers

The Operator allows you to deploy additional (so-called sidecar) containers to the Pod. You can use this feature to run debugging tools, some specific monitoring solutions, etc.

Note

Custom sidecar containers can easily access other components of your cluster .

Therefore they should be used carefully and by experienced users only.

Adding a sidecar container

You can add sidecar containers to PostgreSQL instance and pgBouncer Pods. Just use sidecars subsection in the instances or proxy.pgBouncer Custom Resource section in the deploy/cr.yaml configuration file. In this subsection, you should specify at least the name and image of your container, and possibly a command to run:

spec:
  instances:
    ....
    sidecars:
    - image: busybox
      command: ["/bin/sh"]
      args: ["-c", "while true; do echo echo $(date -u) 'test' >> /dev/null; sleep 5; done"]
      name: my-sidecar-1
    ....

Apply your modifications as usual:

$ kubectl apply -f deploy/cr.yaml

Obviously, you cannot name your sidecar container by duplicating an already existing container name in the Pod. Use kubectl describe pod command to check which names are already in use. For example, PostgreSQL instance Pods cannot have custom sidecar containers named as database, pgbackrest, pgbackrest-config, and replication-cert-copy.

Note

More options suitable for the sidecars subsection can be found in the Custom Resource options reference.

Running kubectl describe command for the appropriate Pod can bring you the information about the newly created container:

$ kubectl describe pod cluster1-instance1

Expected output

Name:            cluster1-instance1-n8v4-0
....
Containers:
....
my-sidecar-1:
  Container ID:  docker://f0c3437295d0ec819753c581aae174a0b8d062337f80897144eb8148249ba742
  Image:         busybox
  Image ID:      docker-pullable://busybox@sha256:139abcf41943b8bcd4bc5c42ee71ddc9402c7ad69ad9e177b0a9bc4541f14924
  Port:          <none>
  Host Port:     <none>
  Command:
    /bin/sh
  Args:
    -c
    while true; do echo echo $(date -u) 'test' >> /dev/null; sleep 5; done
  State:          Running
    Started:      Thu, 11 Nov 2021 10:38:15 +0300
  Ready:          True
  Restart Count:  0
  Environment:    <none>
  Mounts:
    /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-fbrbn (ro)
....

Getting shell access to a sidecar container

You can login to your sidecar container as follows:

$ kubectl exec -it cluster1-instance1n8v4-0 -c my-sidecar-1 -- sh
/ #

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Last update: 2024-11-25