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://[email protected]/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 pipenv to set
up a virtual environment where it will get installed into:

git clone [email protected]:Memrise/copypod.git
cd copypod/
pipenv install

Then you can run the program with pipenv run copypod.

Usage

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

Copy a Kubernetes pod and run commands in its environment.

optional arguments:
  -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         Copy the entire environment of the pod but use this Docker image instead (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.

GitHub

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