opsdis / check_selenium_docker

Synthetic website monitoring with Selenium and Docker.

check_selenium_docker

• Overview
  • Highlights
• Workflow
• System requirements
  • ITRS OP5 Monitor example
• Docker image
• Plugin
• Add new test scenarios
• Execute the plugin
• License

Overview

Synthetic website monitoring with Selenium and Docker.

check_selenium_docker is a Nagios based plugin that spins up a Docker container, executes the test and, once the test is finished and the result has been reported back to the monitoring solution, removes the Docker container.

Highlights

• Works with any Nagios compatible system such as ITRS OP5 Monitor, Icinga2 or Nagios.
• Every test is executed in a fresh environment. (https://www.selenium.dev/documentation/en/guidelines_and_recommendations/fresh_browser_per_test/)
• Will remove the Docker container as soon as the test is complete. Requires no manual cleanup of stopped containers.

Workflow

Install Selenium IDE for Chrome (https://selenium.dev/downloads).

Record your test.

Export the test and copy the .side file to the server that will run the docker image.

A Docker container will execute the test and report the test results back to the monitoring system.

System requirements

The following prerequisites must be installed on the server that will execute the plugin.

• Python 3 with the docker module
• docker-ce

ITRS OP5 Monitor example

# Install docker-ce
yum install -y yum-utils \
  device-mapper-persistent-data \
  lvm2

yum-config-manager \
    --add-repo \
    https://download.docker.com/linux/centos/docker-ce.repo

yum install docker-ce

# Add user 'monitor' to group 'docker'
usermod -aG docker monitor

# Start and enable docker
systemctl start docker && systemctl enable docker

# Install the docker Python 3 module
pip-3 install docker

# (Optional) Add versionlock to docker-ce
yum install yum-plugin-versionlock
yum versionlock docker-ce

# (Optional) Remove versionlock from docker-ce
yum versionlock clear

Docker image

Build the Docker image:

git clone https://github.com/opsdis/check_selenium_docker
cd check_selenium_docker/dockerimage/
docker build . --tag opsdis/selenium-chrome-node-with-side-runner

Plugin

Copy the plugin to the plugin directory and make it executable:

cp check_selenium_docker.py /opt/plugins/custom/
chmod +x /opt/plugins/custom/check_selenium_docker.py

Add a new check_command to Monitor:

check_selenium_docker
$USER1$/custom/check_selenium_docker.py $ARG1$

Add new test scenarios

Create a new main directory (/opt/plugins/custom/selenium) in the main directory create a new directory preferably named as the URL used in the test (/opt/plugins/custom/selenium/opsdis.com):

mkdir /opt/plugins/custom/selenium
mkdir /opt/plugins/custom/selenium/opsdis.com

Create two subdirectories, out and sides:

mkdir /opt/plugins/custom/selenium/opsdis.com/{out,sides}

Add the side-file to the sides subdirectory and modify the permissions:

chmod 777 /opt/plugins/custom/selenium/opsdis.com/out/
chmod 755 /opt/plugins/custom/selenium/opsdis.com/sides/opsdis.com.side

The directory structure should look like this:

├── opsdis.com
│   ├── out
│   └── sides
│       └── opsdis.com.side

Execute the plugin

/opt/plugins/custom/check_selenium_docker.py /opt/plugins/custom/selenium/opsdis.com
OK: Passed 1 of 1 tests. | 'passed'=1;;;; 'failed'=0;;;; 'exec_time'=6s;;;;

License

check_selenium_docker is licensed under GPL version 3.

check_selenium_docker's Issues

PermissionError: [Errno 13] Permission denied

Im trying to create a selenium check, but keep getting the error
PermissionError: [Errno 13] Permission denied '/opt/plugins/custom/selenium/qaLogin/out/QALogin.json'
when I run it through the Nagios website. The QALogin.json file is set to:
-rw-r--r--. 1 nagios nagios 886 Aug 6 23:17 QALogin.json
I can run it manually as the nagios user and verified the out and sides directories are being mapped to during the docker container run.
It just wont work during the nagios checks and I cannot figure out why. Any help will be appreciated.

Here is the complete error.

(No output on stdout) stderr: Traceback (most recent call last):
File "/usr/lib64/nagios/plugins/check_selenium_docker.py", line 39, in
os.remove(result)
PermissionError: [Errno 13] Permission denied: '/opt/plugins/custom/selenium/qaLogin/out/QALogin.json'

[1596757748.377441] [016.2] [pid=848] Parsing check output...
Short Output: (No output on stdout) stderr: Traceback (most recent call last):
Long Output: File "/usr/lib64/nagios/plugins/check_selenium_docker.py", line 39, in \n os.remove(result)\nPermissionError: [Errno 13] Permission denied: '/opt/plugins/custom/selenium/qaLogin/out/QALogin.json'

inconsistent test running and output processing

At entry_point.sh all side files are processed by runner

selenium-side-runner (...)  /sides/*.side

But plugin script check_selenium_docker.py wait for and process only the first json output:

side = glob.glob(path + '/sides/*.side')
side_file = open(side[0],'r')
(...)
result = path + '/out/' + side_json['name'] + '.json'
(...)
while not os.path.isfile(result) and waitedfor <= timeout:

It also calculates exec_time and prints failureMessage based only on the first failed test. If side file contains more than one Test Suite then could be more failed tests:

int(str(json_input['testResults'][0]['endTime'])[:-3]) - int(str(json_input['startTime'])[:-3])
(...)
  " tests. Error message: " + str(json_input['testResults'][0]['message']) +

And finally runner's output failure messages are quite long and multi-line which is a bit in a contrary with a Nagions Guidelines that encourages brevity.

I fixed it all in my fork. I will do a PR if you would like to merge it.

ps. Good job with this plugin :).

exec_time calculation error in the absence of tests

Traceback (most recent call last):
  File "./check_selenium_docker.py", line 70, in <module>
    exec_time = int(str(json_input['testResults'][0]['endTime'])[:-3]) - int(str(json_input['startTime'])[:-3])
IndexError: list index out of range