Script for connecting Erlang Observer to remote node hosted in Kubernetes

iex-observe.sh

#!/bin/bash
# This script provides easy way to debug remote Erlang nodes that is running in a kubernetes cluster.
# Usage: ./erl-observe.sh -l app=my_all -n default -c erlang_cookie
#
# Don't forget to include `:runtime_tools` in your mix.exs application dependencies.
set -e

# Trap exit so we can try to kill proxies that has stuck in background
function cleanup {
  echo " - Stopping kubectl proxy."
  kill $! &> /dev/null
}
trap cleanup EXIT

# Read configuration from CLI
while getopts "n:l:c:" opt; do
  case "$opt" in
    n)  K8S_NAMESPACE="--namespace=${OPTARG}"
        ;;
    l)  K8S_SELECTOR=${OPTARG}
        ;;
    c)  ERL_COOKIE=${OPTARG}
        ;;
  esac
done

# Required part of config
if [ ! $K8S_SELECTOR ]; then
  echo "[E] You need to specify Kubernetes selector with '-l' option."
  exit 1
fi

echo " - Selecting pod with '-l ${K8S_SELECTOR} ${K8S_NAMESPACE:-default}' selector."
POD_NAME=$(kubectl get pods -l ${K8S_SELECTOR} ${K8S_NAMESPACE} -o jsonpath='{.items[0].metadata.name}')

echo " - Resolving Erlang node port on a pod '${POD_NAME}'."
EPMD_OUTPUT=$(echo ${POD_NAME} | xargs -o -I my_pod kubectl exec my_pod ${K8S_NAMESPACE} -i -t -- epmd -names | tail -n 1)
eval 'EPMD_OUTPUT=($EPMD_OUTPUT)'

# By default, cookie is the same as node name
if [ ! $ERL_COOKIE ]; then
  ERL_COOKIE=${EPMD_OUTPUT[1]}
fi

# Strip newlines from last element of output
OTP_PORT=${EPMD_OUTPUT[4]//[$'\t\r\n ']}

echo " - Connecting on port ${OTP_PORT} with cookie '${ERL_COOKIE}'."

# Kill epmd on local node to free 4369 port
if pgrep epmd; then
  killall epmd
fi

# Replace it with remote nodes epmd and proxy remove erlang app port
kubectl port-forward $POD_NAME $K8S_NAMESPACE 4369 $OTP_PORT &> /dev/null &
sleep 1

# Run observer in hidden mode to don't heart clusters health
iex --name [email protected] --cookie $ERL_COOKIE --hidden -e :observer.start