copypod

Utility for copying a running Kubernetes pod so you can run commands in a copy of its environment, without worrying about it the pod potentially being removed due to a deploy.

copypod can work in two different modes, depending on if the --interactive flag is provided:

• If the flag is left out, copypod will copy the specified pod and start it. When the pod reaches the "Running" state the name of the pod will be outputted as the only output. This is intended for use in automation scenarios.
• If a command is provided with the --interactive flag, then the pod will be copied and started as before, but when the pod is running kubectl will be called and connect to the pod where the provided command is then run interactively. When the kubectl program exits the pod will be removed. This is intended for running ad-hoc tasks and processes.

Install

You can either install copypod into a virtual environment directly with:

pip install git+ssh://git@github.com/Memrise/copypod.git

then the program will be available as copypod inside the virtual environment, or you can install it by cloning this repository and then use poetry to set up a virtual environment where it will get installed into:

git clone git@github.com:Memrise/copypod.git
cd copypod/
poetry install

Then you can run the program with poetry run copypod.

Usage

$ copypod --help
usage: copypod [-h] [--context CONTEXT] [-n NAMESPACE] (-l SELECTOR | -p POD) [--container CONTAINER] [-c COMMAND] [-i INTERACTIVE] [--image IMAGE] [--cap-add CAP_ADD]

Copy a Kubernetes pod and run commands in its environment.

options:
  -h, --help            show this help message and exit
  --context CONTEXT     Kubectl context to use for configuration (default: None)
  -n NAMESPACE, --namespace NAMESPACE
                        Namespace for where the source pod is located (default: default)
  -l SELECTOR, --selector SELECTOR
                        Label selector of pod to copy (default: None)
  -p POD, --pod POD     Name of the pod to copy (default: None)
  --container CONTAINER
                        Name of container to copy, only needed if the pod has more than one container (default: None)
  -c COMMAND, --command COMMAND
                        Initial command to run in the copied pod (default: sleep infinity)
  -i INTERACTIVE, --interactive INTERACTIVE
                        Command to run in an interactive console (default: None)
  --image IMAGE         Set to alternate Docker image to use for copied pod (default: None)
  --cap-add CAP_ADD     Capabilities to add for the copied pod (default: None)

If the `--interactive` flag is provided, the copied pod will be removed immediately after the command exits, otherwise the name of the pod will be printed.

Examples

Say you wanted to copy the pod named my-great-pod and have the copied pod run until you specifically remove it, you could run:

$ copypod -p my-great-pod
pod-copy-girwak

pod-copy-girwak is then the name of the new pod created for you, and it will by default run sleep infinity as the starting command, meaning it will keep running forever until it's deleted.

At this point you can enter the pod and run commands as you'd like, for instance start a shell inside the pod with:

$ kubectl exec -it pod-copy-girwak -- bash
root@pod-copy-girwak:/#

When you are done you can remove the copied pod again with kubectl:

$ kubectl delete pod pod-copy-girwak
pod "pod-copy-girwak" deleted

---

Say you instead would like to copy a pod, start a shell in the copied pod and have the pod be deleted when you exit the shell, you can do that by supplying the --interactive flag like this:

$ copypod -p my-great-pod -i bash
root@pod-copy-i41u04:/# ps -ef
UID        PID  PPID  C STIME TTY          TIME CMD
root         1     0  0 10:43 ?        00:00:00 sleep infinity
root         7     0  0 10:43 ?        00:00:00 bash
root        13     7  0 10:43 ?        00:00:00 ps -ef

When you are done doing what you needed the pod for, you can exit the shell and the pod will be removed immediately.

The value for the --interactive flag is the command you'd like to start inside the pod.

---

Instead of having to look up the name of a pod before running copypod, you can also specify labels which match one or more pods that you'd like to copy. copypod will then pick the first pod matching the lables and copy that for you. This can be done with the --selector flag. It works the same way as for the kubectl command.

If we for example have one or more pods with the label app: my-great-service we can copy any of those pods without having to know the exact pod name by running:

$ copypod -l app=my-great-service -i bash
root@pod-copy-1gk57f:/#

Note regarding Alpine Linux

The sleep command in images based on Alpine Linux does not support "infinity" as an argument unless the "coreutils" package is installed. As a work around you can instead specify --command "sleep 1d" as an argument to copypod to change the command run in the new pod.