Logspout + setting the hostname

docker-compose.yml

version: '2'
services:

  example-service:
    build:
        dockerfile: Dockerfile
        context: php/
    container_name: example.php-service
    ports:
      - 3333:3000

  logspout:
    image: gliderlabs/logspout
    container_name: example.logspout
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    command:
      syslog://logs5.papertrailapp.com:xxxx
    environment:
      - SYSLOG_HOSTNAME=my_custom_hostname