mock_k8s_elixir.sh

#!/bin/bash

# It is very common while debugging elixir projects, deployed using mix releases, to
# investigate code logic using "on the fly patches" by entering the running instance iex
# and pasting new code into it (obviously only in dev environment, not production).

# If you're using kubernetes with multiple deployments that must be updated with
# multiple modules definition (like if you're following a bug through multiple steps),
# this process will cost some time.

# This script was created to help mocking multiple pods with multiple files at once.

#### Usage

# ./mock_k8s_elixir [namespace] [deployment_name_comma_separated] [release_binary] [relative_path_to_mocked_files]

# If you have an elixir application, deployed in the namespace "default" and you have
# two deployments "web" and "worker" running from the same binary at the path "/app/my_app"
# and will wish to upload a new mocked module defined at "lib/commands/charge_user.ex" and 
# "lib/repositories/user_repo.ex", you should call:

# ./mock_k8s_elixir default web,worker /app/my_app lib/commands/charge_user.ex,lib/repositories/user_repo.ex

##############
if [ -z "$1" ]
then
  echo "missing first argument: namespace";
  exit 1;
fi
namespace="$1";
echo "Namespace: $namespace";

##############
if [ -z "$2" ]
then
  echo "missing first argument: deployments";
  exit 1;
fi
deployments_arg="$2";

##############
if [ -z "$3" ]
then
  echo "missing second argument: pod_command";
  exit 1;
fi
pod_command="$3"
echo "Command: $pod_command";

##############
if [ -z "$4" ]
then
  echo "missing third argument: file_list [comma separated]";
  exit 1;
fi
filename_arg="$4"
readarray -td, file_list <<<"$filename_arg";
echo "File List Length: ${#file_list[@]}";

######################################################################
pod_array_lines=$(kubectl get pod -l 'app in ('$deployments_arg')' -n $namespace -o name)
readarray -t pod_array <<<"$pod_array_lines";

echo "Pod Length: ${#pod_array[@]}"

echo " ";
echo "-----------------------";
echo " ";

for pod in ${pod_array[@]};
do
  echo "Running for pod $pod";

  for file in ${file_list[@]};
  do
    echo "  Running for File $file";
    echo "  kubectl exec -i ${pod} -n $namespace -c $namespace -- $pod_command rpc \"\$(cat $file)\"";
    output=$(kubectl exec -i ${pod} -n $namespace -c $namespace -- $pod_command rpc "$(cat $file)");
    echo $output;
  done

  echo " ";
done