Q:

Running dockerized Behat BDD Tests using Zalenium ( scalable selenium grid )

I am trying to Run Behat BDD Tests using docksal/behat docker-compose ( ref: https://github.com/docksal/behat
Looking at the Zalenium documentation
Pull docker-selenium
    docker pull elgalu/selenium

# Pull Zalenium
docker pull dosel/zalenium

# Run it!
docker run --rm -ti --name zalenium -p 4444:4444 \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -v /tmp/videos:/home/seluser/videos \
  --privileged dosel/zalenium start

# Point your tests to http://localhost:4444/wd/hub and run them

integrating docksal/behat and zelenium is not clear
using. the. following docker-compose.yml
# The purpose of this -test example is for the e2e tests of this project
#
# Usage:
#  docker-compose -p grid up --force-recreate
#  docker-compose -p grid scale mock=1 hub=1 chrome=3 firefox=3
version: '2.1'
services:
  hub:
    image: elgalu/selenium
    ports:
      - ${VNC_FROM_PORT-40650}-${VNC_TO_PORT-40700}:${VNC_FROM_PORT-40650}-${VNC_TO_PORT-40700}

  zalenium:
    image: "dosel/zalenium"
    container_name: zalenium
    hostname: zalenium
    tty: true
    volumes:
      - /tmp/videos:/home/seluser/videos
      - /var/run/docker.sock:/var/run/docker.sock
    privileged: true
    ports:
      - 4444:4444
    command: >
      start --desiredContainers 2
            --maxDockerSeleniumContainers 8
            --screenWidth 800 --screenHeight 600
            --timeZone "America/New_York"
            --videoRecordingEnabled false
            --sauceLabsEnabled false
            --browserStackEnabled false
            --testingBotEnabled false
            --cbtEnabled false
            --startTunnel false

  behat:
    hostname: behat
    image: docksal/behat
    volumes:
      - .:/src
    # Run a built-in web server for access to HTML reports
    ports:
     - 8000:8000
    entrypoint: "php -S 0.0.0.0:8000"

#  browser:
#    hostname: browser
    # Pick/uncomment one
#    image: selenium/standalone-chrome
    #image: selenium/standalone-firefox

I can bring up the following containers:
CONTAINER ID        IMAGE                    COMMAND                  CREATED             STATUS              PORTS                                  NAMES
9a1620da4c71        elgalu/selenium:latest   "entry.sh"               4 seconds ago       Up 4 seconds        40001/tcp, 50001/tcp                   zalenium_52g9tn
82975a246be8        elgalu/selenium:latest   "entry.sh"               5 seconds ago       Up 4 seconds        40000/tcp, 50000/tcp                   zalenium_fdCCbk
862017957ba1        docksal/behat            "php -S 0.0.0.0:8000"    2 days ago          Up 8 seconds        0.0.0.0:8000->8000/tcp                 behat-selenium_behat_1
2da2c165a211        elgalu/selenium          "entry.sh"               4 days ago          Up 6 seconds        0.0.0.0:40650-40700->40650-40700/tcp   behat-selenium_hub_1
10df443d8378        dosel/zalenium           "entry.sh start --de…"   4 days ago          Up 8 seconds        0.0.0.0:4444->4444/tcp, 4445/tcp       zalenium

now looking at run-behat in examples directory:
basically executing 
$docker exec $(docker-compose ps -q behat) behat --colors --format=pretty --out=std --format=html --out=html_report "$@"

I get an error:
Error response from daemon: Container 411c6b89d8f382a64ed567dbe4d02a2840f06d4778f1ce7bcf955e720d96ab02 is not running

whereas:
$ docker-compose ps -q behat
411c6b89d8f382a64ed567dbe4d02a2840f06d4778f1ce7bcf955e720d96ab02

Perhaps in behat.yml wd_host: http://localhost:4444/wd/hub
it should not point to localhost,  but rather the hub? since wd_host should point to the selenium grid running in the container? 

A:

This
hub:
    image: elgalu/selenium
    ports:
      - ${VNC_FROM_PORT-40650}-${VNC_TO_PORT-40700}:${VNC_FROM_PORT-40650}-${VNC_TO_PORT-40700}

is not needed at all.
Just point your tests to the zalenium service, since you are using docker-compose.
http://zalenium:4444/wd/hub

