Using Ansible To Install Headless Google Chrome for Selenium
This last week I needed to install Google Chrome on a headless Ubuntu 14.04 server for use with rendering web assets in via Selenium’s Chrome WebDriver. The configuration took a bit of testing and work to get it all together, so I wanted to share it here. I’ll first go over the general method of how everything is installed, then I’ll share the actual Ansible scripts used to do it.
Overview
Xvfb
Xvfb is a headless display. It allows us to run Chrome (or any application with a UI) on a device that doesn’t have an actual physical display.
Fortunately, it is easily installed via apt-get install xvfb.
However, I also wanted xvfb to run on boot but it doesn’t come with a daemon so I had to create one. I just copied the xvfb-init.d-template from below into /etc/init.d/xvfb, set it to default runlevels via update-rc.d xvfb defaults, then started it with service xvfb start.
Chrome
Because Chrome contains some closed-source components, Ubuntu doesn’t include it in any of its default distributed repositories. This means you can’t just download it via apt-get install google-chrome-stable. One option is to add Google’s repository to your apt sources, but I thought it would be easier to just download and install the .deb package that Google provides.
However, dpkg can’t resolve and install dependencies when installing via .deb packages, so you have to follow up the install with apt-get install --fix-broken.
wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
dpkg -i google-chrome-stable_current_amd64.deb
sudo apt-get install --fix-broken
Chrome WebDriver for Selenium
For the Chrome WebDriver, I needed to download the archive, unzip it, and make sure it was owned by the right user so it could be executable when my application ran.
In retrospect, I should have downloaded the Chrome WebDriver in the same way as xvfb and google-chrome-stable: via ansible. But at the time I thought that the driver needed to exist in the same directory as the Java service, which location didn’t exist when Ansible was run. What I did instead was write a rather tedious bash script that was the equivalent of a few lines of ansible. I’ve included it in the Source section below. It may be of some use to you.
Source
Here are the actual Ansible and bash scripts that I ended up using. You may need to tweak them for your own use.
Xvfb Ansible Scripts
- name: Check if xvfb is installed
command: dpkg -s
register: xvfb_check_deb
failed_when: xvfb_check_deb.rc > 1
changed_when: xvfb_check_deb == 1
tags:
- xvfb
- name: Install xvfb package
apt: name=xvfb state=present
sudo: true
when: xvfb_check_deb.rc == 1
tags:
- xvfb
- name: Install xvfb init.d daemon script
action: template src=xvfb-init.d-template dest=/etc/init.d/xvfb mode=0755
tags:
- xvfb
- name: Set xvfb to run on startup
shell: update-rc.d xvfb defaults
sudo: true
when: xvfb_check_deb.rc == 1
tags:
- xvfb
- name: Start xvfb service
action: service name=xvfb state=started
tags:
- xvfb
Xvfb Init Script
# xvfb-init.d-template
### BEGIN INIT INFO
# Provides: Xvfb
# Required-Start: $local_fs $remote_fs
# Required-Stop:
# X-Start-Before:
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Loads X Virtual Frame Buffer
### END INIT INFO
XVFB=/usr/bin/Xvfb
XVFBARGS=":1 -screen 0 1920x1080x24 -ac +extension GLX +render -noreset"
PIDFILE=/var/run/xvfb.pid
case "$1" in
status)
echo "Checking xvfb status"
if [ -f $PIDFILE ]; then
PID=`cat $PIDFILE`
if [ -z "`ps axf | grep ${PID} | grep -v grep`" ]; then
printf "%s\n" "Process dead but pidfile exists"
exit 1
else
echo "Running"
fi
else
printf "%s\n" "Service not running"
exit 3
fi
;;
start)
echo -n "Starting virtual X frame buffer: Xvfb"
start-stop-daemon --start --quiet --pidfile $PIDFILE --make-pidfile --background --startas /bin/bash -- -c "exec $XVFB $XVFBARGS > /var/log/xvfb.log 2>&1"
echo "."
;;
stop)
echo -n "Stopping virtual X frame buffer: Xvfb"
start-stop-daemon --stop --quiet --pidfile $PIDFILE
echo "."
;;
restart)
$0 stop
$0 start
;;
*)
echo "Usage: /etc/init.d/xvfb {start|stop|restart}"
exit 1
esac
exit 0
Google Chrome Ansible Scripts
- name: Check if google-chrome-stable is installed
command: dpkg -s
register: google_chrome_check_deb
failed_when: google_chrome_check_deb.rc > 1
changed_when: google_chrome_check_deb == 1
tags:
- chrome
- name: Download google-chrome-stable
get_url:
url="/"
dest="/home//"
when: google_chrome_check_deb.rc == 1
tags:
- chrome
- name: Install google-chrome-stable
apt: deb="/home//"
sudo: true
when: google_chrome_check_deb.rc == 1
tags:
- chrome
- name: Fix any missing google-chrome-stable dependencies
shell: apt-get install -f
sudo: true
when: google_chrome_check_deb.rc == 1
tags:
- chrome
Ansible Properties
Some of the xvfb and chrome specific properties I supplied in a vars file:
# Google chrome package url and name
google_chrome_package_filename: 'google-chrome-stable_current_amd64.deb'
google_chrome_base_url: 'https://dl.google.com/linux/direct'
google_chrome_package_name: 'google-chrome-stable'
# Xvfb package url and name
xvfb_package_name: 'xvfb'
Chrome WebDriver Install Bash Script
#!/bin/bash
echo "Begin Chrome Driver install script."
if [ -z $SERVICE_USER -a -z $SERVICE_GROUP ]; then
# On maestro deploy, user should be specified with RUN_USER
# On domo vm deploy, user should be specified by SERVICE_USER
SERVICE_USER=$RUN_USER
SERVICE_GROUP=$RUN_USER
fi
CHROME_ZIP="chromedriver_linux64.zip"
if [[ "$OSTYPE" == "linux-gnu" ]]; then
echo "Detected Linux operating system"
CHROME_ZIP="chromedriver_linux64.zip"
elif [[ "$OSTYPE" == "darwin"* ]]; then
echo "Detected OS X operating system"
CHROME_ZIP="chromedriver_mac32.zip"
else
echo "ERROR: Unsupported operating system for DaVinci's Chrome Driver. Exiting now."
exit 1
fi
CHROME_DRIVER="chromedriver"
CHROME_DRIVER_VERSION="2.19"
CHROME_DRIVER_URL="http://chromedriver.storage.googleapis.com/${CHROME_DRIVER_VERSION}/${CHROME_ZIP}"
echo "Checking for Selenium Chrome driver at ./${CHROME_DRIVER}"
if [ -f $CHROME_DRIVER ] ; then
echo "Chrome driver already installed."
else
TRIES=0
while [ $TRIES -lt 5 -a ! -f $CHROME_DRIVER ]; do
echo "Attempt $TRIES at downloading Selenium Chrome driver from ${CHROME_DRIVER_URL}"
if curl -O $CHROME_DRIVER_URL ; then
if file $CHROME_ZIP | grep "Zip archive data"; then
echo "Download successful."
echo "Unzipping $CHROME_ZIP"
if unzip $CHROME_ZIP ; then
echo "$CHROME_ZIP unzipped successfully"
if [ -f $CHROME_DRIVER ] ; then
echo "Chrome driver unzipped and $CHROME_DRIVER located."
echo "Setting $CHROME_DRIVER ownership to ${SERVICE_USER}:${SERVICE_GROUP}"
chown ${SERVICE_USER}:${SERVICE_GROUP} $CHROME_DRIVER
else
echo "ERROR: Chrome driver unzipped successfully but unable to locate ${CHROME_DRIVER}."
fi
else
echo "ERROR: Unzip of Chrome driver failed."
fi
else
echo "Download unsuccessful. $CHROME_ZIP is not a zip archive."
fi
else
echo "ERROR: Download of Selenium Chrome driver failed. Failing prematurely."
exit 1
fi
if [ ! -f $CHROME_DRIVER ] ; then
((TRIES++))
SLEEP=$(($TRIES * 30))
echo "Failed to install Chrome driver. Sleeping for $SLEEP seconds then trying again."
sleep $SLEEP
fi
done
if [ -f $CHROME_ZIP ] ; then
echo "Cleaning up $CHROME_ZIP"
rm $CHROME_ZIP
fi
if [ -f $CHROME_DRIVER ] ; then
echo "Chrome driver installed successfully!"
else
echo "ERROR: Unable to install Chrome driver, service has failed to start. Exiting now."
exit 1
fi
fi