Monit Service Monitor Block for Docker Container

README.md

Tun run a command against a running app inside docker, run the docker exec command non-interactively under bash:

docker exec \
  --tty \
  --interactive \
  ${container_ID} \
  bash -c dspmq

Reaching out into your container to verify is running ok:

docker exec ${container_ID} bash -c "/opt/your_app/bin/docker_agent status"

Convert an existing docker container into a "docker run" command line.

This is useful when trying to debug containers that have been created

by orchestration tools.

Install jq: stedolan.github.io/jq/

function format_run() { cid=$1

json=$(docker inspect $cid 2>&1)

# parse container info
entrypoint=$(  echo $json | jq -r '.[0].Config.Entrypoint | join(" ")'             )
envvars=$(     echo $json | jq -r '(.[0].Config.Env | [" -e " + .[]] | join(""))'  )
image=$(       echo $json | jq -r .[0].Image                                       )
cmd=$(         echo $json | jq -r '.[0].Config.Cmd | join(" ")'                    )

echo "docker run --entrypoint $entrypoint $envvars $image $cmd"

}

monit_block_for_docker_container

# Inside main monitrc

# Check that services are running and also define start and stop commands for them. 
# You will need one of these for each container 
# as well as working out a restarting and/or red
eploying workflow.

check process <container-name> with pidfile /var/run/monit/<container-name>.pid
  start = "/path/to/pid/script start <container-name> '<docker-arguments>'"
  stop = "/path/to/pid/script stop <container-name>"
  if does not exist then alert
  if cpu equal 0%
    and memory equal 0kB
    for 5 cycles then alert

pid_docker_wrapper.sh

#!/bin/bash

# First, create a folder: /var/run/monit
# Then, make sure your user or group owns it: chown user:user /var/run/monit

# USAGE:
# use option one to start or stop
# use option two as the docker name
# use option three as the docker run command it follows '-d' f you are starting a container
#
# Example: 
# $ ./monit_docker_wrapper.sh start my-name "-p 80:80 ubuntu true"
# 
# I would then expect to find /var/run/monit/my-name-docker-container.pid

case $1 in
  start)
    sudo rm /var/run/monit/$2-docker-container.pid;
    sudo echo $$ > /var/run/monit/$2-docker-container.pid;
    sudo docker run --name $2 -d $3
    ;;
  stop)  
    sudo docker stop $2 
    sudo rm /var/run/monit/$2-docker-container.pid;
    ;;
  *)  
    echo "usage: {start|stop} [name] [docker run command]" ;;
esac
exit 0

# This is adapted from the Monit examples. License: MIT.