docker-compose-prometheus-service-discovery.sh

addPrometheusServiceDiscoveryService 'my_image_name' 8080 'my_container_prefix_' myservice

#
# Function responsible to add specific instances to a prometheus service discovery file
#
function addPrometheusServiceDiscoveryService {
  IMAGE_NAME=$1
  NUM_INSTANCES=$(docker ps | grep -c "$IMAGE_NAME")
  PORT=$2
  CONTAINER_NAME=$3
  SERVICE_NAME=$4

  TARGETS=''
  for ((i=1; i<NUM_INSTANCES+1; i++))
  do
    CONTAINER_EXPOSED_PORT=$(docker port "$CONTAINER_NAME$i" "$PORT" | cut -d':' -f 2)
    TARGETS+="\"host.docker.internal:$CONTAINER_EXPOSED_PORT\", "
  done

  if [ "$NUM_INSTANCES" -gt 0 ]
  then
    TARGETS=${TARGETS::${#TARGETS}-2}

if [ -f "$HOME/targets.json" ] && grep -q "\"job\": \"instances_" "$HOME/targets.json";
then

  CONTENT="\ \ \{ \n \ \ \ \"targets\": [ $TARGETS ]\, \n \ \ \ \"labels\": \{ \n \ \ \ \ \ \"env\": \"local\", \n \ \ \ \ \ \"job\": \"instances_$SERVICE_NAME\" \n \ \ \ \} \n \ \},";

  gsed -i "\$i $CONTENT" "$HOME"/targets.json

else
  echo "[
  {
    \"targets\": [ $TARGETS ],
    \"labels\": {
      \"env\": \"local\",
      \"job\": \"instances_$SERVICE_NAME\"
    }
  },
]" > "$HOME"/targets.json
fi
  fi

}