[Blog] PortNumber53.com

[Work-In-Progress post]

This morning, I crafted a few systemd unit files to help me manage running a Selenium Hub. As an extra benefit, I have some stuff ready for whenever I move to using CoreOS. 🙂

I'll keep the files here:

https://github.com/PortNumber53/systemd-stuffs/tree/master/selenium-hub

So if you're familiar with git, systemd and docker, go have fun, otherwise stick around and I'll do my best to guide you through this.

How to take advantage of these scripts:

First of all, those are heavily base on documentation from https://github.com/SeleniumHQ/docker-selenium ( credits to them )

I assume you have decent knowledge of your Linux distribuition. I like ArchLinux so commands will be targetted to it. Feel free to contribute in the comments for other distros and I'll keep the post updated.

1. Install tools you'll need.

[sample@samplearch ~]$ sudo pacman -S git docker
[sudo] password for sample:
resolving dependencies...
looking for conflicting packages...

Packages (6) bridge-utils-1.5-2  containerd-0.2.2-1  perl-error-0.17024-1  runc-0.1.1-1  docker-1:1.11.2-2  git-2.9.0-1

Total Download Size:   16.53 MiB
Total Installed Size:  88.46 MiB

:: Proceed with installation? [Y/n] y
:: Retrieving packages...
 bridge-utils-1.5-2-x86_64                              13.4 KiB  0.00B/s 00:00 [#############################################] 100%
 perl-error-0.17024-1-any                               18.4 KiB  0.00B/s 00:00 [#############################################] 100%
 git-2.9.0-1-x86_64                                      4.5 MiB  2.62M/s 00:02 [#############################################] 100%
 runc-0.1.1-1-x86_64                                  1389.0 KiB  6.25M/s 00:00 [#############################################] 100%
 containerd-0.2.2-1-x86_64                               3.9 MiB  4.07M/s 00:01 [#############################################] 100%
 docker-1:1.11.2-2-x86_64                                6.7 MiB  4.28M/s 00:02 [#############################################] 100%
(6/6) checking keys in keyring                                                  [#############################################] 100%
(6/6) checking package integrity                                                [#############################################] 100%
(6/6) loading package files                                                     [#############################################] 100%
(6/6) checking for file conflicts                                               [#############################################] 100%
(6/6) checking available disk space                                             [#############################################] 100%
:: Processing package changes...
(1/6) installing perl-error                                                     [#############################################] 100%
(2/6) installing git                                                            [#############################################] 100%
Optional dependencies for git
    tk: gitk and git gui
    perl-libwww: git svn
    perl-term-readkey: git svn
    perl-mime-tools: git send-email
    perl-net-smtp-ssl: git send-email TLS support
    perl-authen-sasl: git send-email TLS support
    python2: various helper scripts
    subversion: git svn
    cvsps2: git cvsimport
    gnome-keyring: GNOME keyring credential helper
(3/6) installing runc                                                           [#############################################] 100%
(4/6) installing containerd                                                     [#############################################] 100%
(5/6) installing bridge-utils                                                   [#############################################] 100%
(6/6) installing docker                                                         [#############################################] 100%
Optional dependencies for docker
    btrfs-progs: btrfs backend support
    lxc: lxc backend support
:: Running post-transaction hooks...
(1/1) Updating manpage index...
[sample@samplearch ~]$

2. Clone the repo to any folder you'd like

[sample@samplearch ~]$ git clone https://github.com/PortNumber53/systemd-stuffs
Cloning into 'systemd-stuffs'...
remote: Counting objects: 37, done.
remote: Total 37 (delta 0), reused 0 (delta 0), pack-reused 37
Unpacking objects: 100% (37/37), done.
Checking connectivity... done.
[sample@samplearch ~]$ cd systemd-stuffs/
[sample@samplearch systemd-stuffs]$

3. Create a symlink to the hub unit and start it

[root@samplearch system]# cd /usr/lib/systemd/system
[root@samplearch system]# ln -s /home/sample/systemd-stuffs/selenium-hub/selenium-grid-hub.service
[root@samplearch system]# systemctl start selenium-grid-hub.service
[root@samplearch system]#

After the docker pulls the image and starts the contaner, you can check the status for the service:

[root@samplearch system]# systemctl status selenium-grid-hub.service
* selenium-grid-hub.service - Selenium Grid Hub
   Loaded: loaded (/home/sample/systemd-stuffs/selenium-hub/selenium-grid-hub.service; disabled; vendor preset: disabled)
   Active: active (running) since Tue 2016-07-05 14:09:34 PDT; 18s ago
  Process: 8516 ExecStop=/usr/bin/docker stop selenium-hub (code=exited, status=0/SUCCESS)
  Process: 8629 ExecStartPre=/usr/bin/docker pull selenium/hub:latest (code=exited, status=0/SUCCESS)
  Process: 8589 ExecStartPre=/usr/bin/docker rm selenium-hub (code=exited, status=0/SUCCESS)
  Process: 8577 ExecStartPre=/usr/bin/docker kill selenium-hub (code=exited, status=1/FAILURE)
 Main PID: 8637 (docker)
    Tasks: 6 (limit: 512)
   Memory: 4.5M
      CPU: 66ms
   CGroup: /system.slice/selenium-grid-hub.service
           `-8637 /usr/bin/docker run -p 4444:4444 --name selenium-hub selenium/hub:latest

Jul 05 14:09:35 samplearch docker[8637]: 21:09:35.343 INFO - Launching Selenium Grid hub
Jul 05 14:09:36 samplearch docker[8637]: 2016-07-05 21:09:36.050:INFO::main: Logging initialized @887ms
Jul 05 14:09:36 samplearch docker[8637]: 21:09:36.077 INFO - Will listen on 4444
Jul 05 14:09:36 samplearch docker[8637]: 21:09:36.129 INFO - Will listen on 4444
Jul 05 14:09:36 samplearch docker[8637]: 2016-07-05 21:09:36.137:INFO:osjs.Server:main: jetty-9.2.z-SNAPSHOT
Jul 05 14:09:36 samplearch docker[8637]: 2016-07-05 21:09:36.201:INFO:osjsh.ContextHandler:main: Started o.s.j.s.ServletContextHandl
Jul 05 14:09:36 samplearch docker[8637]: 2016-07-05 21:09:36.224:INFO:osjs.ServerConnector:main: Started ServerConnector@dc1556d{HTT
Jul 05 14:09:36 samplearch docker[8637]: 2016-07-05 21:09:36.224:INFO:osjs.Server:main: Started @1061ms
Jul 05 14:09:36 samplearch docker[8637]: 21:09:36.225 INFO - Nodes should register to http://172.17.0.2:4444/grid/register/
Jul 05 14:09:36 samplearch docker[8637]: 21:09:36.225 INFO - Selenium Grid hub is up and running

If you want to start the hub on boot, do this:

[root@samplearch system]# systemctl enable selenium-grid-hub.service

4. Create a symlink and start the chrome node service:

[root@samplearch system]# ln -s /home/sample/systemd-stuffs/selenium-hub/selenium-chrome-node\@.service
[root@samplearch system]# systemctl start [email protected]
[root@samplearch system]#

Because this unit is a template, you will see that it has an "@" in its name. Also note that when starting the service, you can tell which port should be exposed on the VNC server (you can connect to the node using a VNC client). For this sample I am using port 12000.

This allows you to run multiple chome nodes if you need.

5. Do the same for a Firefox node service:

[root@samplearch system]# ln -s /home/sample/systemd-stuffs/selenium-hub/selenium-firefox-node\@.service
[root@samplearch system]# systemctl start [email protected]
[root@samplearch system]#

For this example, I am exposing port 30000.

Happy times using Selenium