README.md

Production Ready Process Monitoring

1. Install docker-manger.conf and docker-instance.conf in /etc/init

2. Create a containers file in /etc/docker/ with the following format

    name: image cmd
   

   The name must be unique.

3. sudo service docker-manager start

4. You should now have upstart monitoring your container.

5. Use docker stop to kill your container and notice it gets restarted

Due to a bug in upstart (https://bugs.launchpad.net/upstart/+bug/568288) doing service docker-instance stop NAME=XXXX fails to stop the instance. I'm not actually sure how to work around this.

containers

nginx-0: docker.wdig.com/cws/base-service nginx
nginx-1: docker.wdig.com/cws/base-service nginx
nginx-2: docker.wdig.com/cws/base-service nginx

docker-instance.conf

description     "Docker Container"

stop on stopping docker
# Docker has a timeout of 10 seconds so as long as this
# is longer so we don't kill the wait process
kill timeout 20

# We don't want to TERM the `docker wait` process so we fake the signal 
# we send to it. The pre-stop script issues the `docker stop` command
# which causes the `docker wait` process to exit
kill signal CONT

# Due to a bug in upstart we need to set the modes we consider
# successful exists https://bugs.launchpad.net/upstart/+bug/568288
normal exit 0 CONT

respawn

instance ${NAME}

pre-start script
  [ ! -f /etc/docker/containers ] && { stop; exit 0; }

  if ! grep -q "^${NAME}:" /etc/docker/containers; then
    stop
    exit 0
  fi
end script

script
  LINE=$(grep "^${NAME}:" /etc/docker/containers | cut -d: -f2-| sed 's/^\s*//')

  IMAGE=$(echo "$LINE" | cut -d\  -f1)
  CMD=$(echo "$LINE" | cut -d\  -f2- -s)
  
  [ -f "/var/run/docker/${NAME}.cid" ] && { ID="$(cat /var/run/docker/${NAME}.cid)"; }
  
  START=1
  if [ ! -z "${ID}" ]; then
    if docker ps | grep -q "${ID}"; then
      START=0
    else
      NID=$(docker start ${ID})
      [ "${NID}" = "${ID}" ] && START=0
    fi
  fi

  if [ $START -ne 0 ]; then
    ID=$(docker run -d "${IMAGE}" ${CMD})
    echo ${ID} > /var/run/docker/${NAME}.cid
  fi

  exec docker wait ${ID}
end script

pre-stop script
  [ -f "/var/run/docker/${NAME}.cid" ] && { ID="$(cat /var/run/docker/${NAME}.cid)"; }
  if [ ! -z "${ID}" ]; then
     docker stop "${ID}"
  fi
end script

docker-manager.conf

description     "Manage Docker Containers"

start on started docker
stop on stopping docker

respawn

pre-start script
  # Directory to store run data
  [ ! -d /var/run/docker ] && mkdir -p /var/run/docker

  # Directory to store config
  [ ! -d /etc/docker ] && mkdir -p /etc/docker

  [ ! -f /etc/docker/containers ] && { stop; exit 0; }

  while read line; do
    NAME=$(echo "$line" | cut -d: -f 1)
    start docker-instance NAME="$NAME"
  done < /etc/docker/containers
end script

post-stop script
    for inst in `initctl list | grep "^docker-instance "|awk '{print $2}'|tr -d ')'|tr -d '('`
    do
        stop docker-instance NAME=$inst
    done
end script