Liip Monitor Bundle

This bundle provides a way to run a series of application related health checks. Health checks in the scope of this bundle go beyond simple actions like performing a ping to a server to see if it's alive. For example a Memcache server can be alive and not displaying any errors in your Nagios but you might not be able to access it from your PHP application. Each health check should then implement some application logic that you want to make sure always works. Another usage can be testing for specific requirements, like availability of PHP extensions.

Another design goal of the bundle was to be able to perform the checks using the same configuration and environment that your application is using. In that way you can make sure that if the health check runs successfully then your app should work too.

So each health check will be a class that will implement the CheckInterface::check method which must return a CheckResult object. What happens inside that method is up to the check developer.

Health checks are defined as Symfony services and they have to be tagged as liip_monitor.check in order to be picked up by the health check runner. This gives a lot of flexibility to application and bundle developers when they want to add their own checks.

Checks are run via the command line using a Symfony command or via a REST api that delivers the results in JSON format.

Here's the web interface:

Installation

Add the following code to your composer.json file:

"require": {
    ..
    "liip/monitor-bundle": "dev-master"
},

And then run the Composer update command:

$ php composer.phar update liip/monitor-bundle

Then register the bundle in the AppKernel.php file:

public function registerBundles()
{
    $bundles = array(
        ...
        new Liip\MonitorBundle\LiipMonitorBundle(),
        ...
    );

    return $bundles;
}

If you want to enable the REST API provided by the bundle then add the following to your routing.yml:

_monitor:
    resource: "@LiipMonitorBundle/Resources/config/routing.yml"
    prefix: /monitor/health

And finally don't forget to install the bundle assets into your web root:

$ ./app/console assets:install web --symlink --relative

Enabling built-in health checks

To enable built-in health checks, add them to your config.yml

liip_monitor:
    checks:
        php_extensions: [apc, xdebug]

Adding Health Checks

Once you implemented the class then it's time to register the check service with our service container:

services:
    monitor.check.php_extensions:
        class: Acme\HelloBundle\Check\PhpExtensionsCheck
        arguments:
            - [ xhprof, apc, memcache ]
        tags:
            - { name: liip_monitor.check, alias: php_extensions }

The important bit there is to remember to tag your services with the liip_monitor.check tag. By doing that the check runner will be able to find your checks. Keep in mind that checks can reside either in your bundles or in your app specific code. The location doesn't matter as long as the service is properly tagged. The alias is optional and will then simply define the id used when running health checks individually, otherwise the full service id must be used in this case.

Check groups

All built-in checks are assigned to the group default. See check groups in the LiipMonitor library for details.

Available Health Checks

On top of all the checks provided by the LiipMonitor library this Bundle adds the following Symfony2 specific health checks:

CustomErrorPagesCheck

Checks if error pages have been customized for given error codes.

DepsEntriesCheck

Checks all entries from deps are defined in deps.lock.

SymfonyVersionCheck

Checks the version of this website against the latest stable release.

Running Checks

There are two ways of running the health checks: by using the CLI or by using the REST API provided by the bundle. Let's see what commands we have available for the CLI:

List Checks

$ ./app/console monitor:list

monitor.check.jackrabbit
monitor.check.redis
monitor.check.memcache
monitor.check.php_extensions

Run All the Checks

./app/console monitor:health

Jackrabbit Health Check: OK
Redis Health Check: OK
Memcache Health Check: KO - No configuration set for session.save_path
PHP Extensions Health Check: OK

Run Individual the Checks

To run an individual check you need to provide the check id to the health command:

$ ./app/console monitor:health monitor.check.php_extensions

PHP Extensions Health Check: OK

Run health checks as composer post-install/update scripts

To run health checks as a composer post-install or post-update script, simply add the Liip\\MonitorBundle\\Composer\\ScriptHandler::checkHealth ScriptHandler to the post-install-cmd / post-update-cmd command sections of your composer.json:

    "scripts": {
        "post-install-cmd": [
            "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::buildBootstrap",
            "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::clearCache",
            "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::installAssets",
            "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::installRequirementsFile",
            "Liip\\MonitorBundle\\Composer\\ScriptHandler::checkHealth"
        ],
        "post-update-cmd": [
            "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::buildBootstrap",
            "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::clearCache",
            "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::installAssets",
            "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::installRequirementsFile",
            "Liip\\MonitorBundle\\Composer\\ScriptHandler::checkHealth"
        ]
    },

REST API DOCS

For documentation on the REST API see: http://myproject/monitor/health/. Don't forget to add the bundle routes in your routing.yml file.

Nagios integration

You can find a simple Nagios check written in Perl and Python in the Resources/scripts directory.

Perl Version

This is dependent on perl modules avalible on CPAN Getopt::Std, WWW::Mechanize, and JSON

Copy the script into your scripts directory in Nagios and create a command like this:

define command{
        command_name    check_symfony_health
        command_line    $USER1$/check_symfony2.pl -H $HOSTNAME$
}

Running the command with the Hostname flag (-H) will check both "http://$HOSTNAME$/health/run" and "http://$HOSTNAME$/utils/health/run". You can also use the Address flag (-A) to check a specified URL:

command_line    $USER1$/check_symfony2.pl -A https://mysite.org/somedir/health/run

The plugin can be used with Authentication, Using the Username (-u) and Password (-p) flags:

command_line    $USER1$/check_symfony2.p1 -H $HOSTNAME$ -u username -p password

You can also specify the Warning (-w) and Critical (-c) levels for the check using the standard flags

command_line    $USER1$/check_symfony2.pl -H $HOSTNAME$ -w 1 -c 2

Any flags can be combined except -A and -H. THe -u and -p flags should always be used together.

Python Version

The Python version depends on the nagiosplugin library < 1.0.0.

Copy the script into your scripts directory in Nagios and create a command like this:

define command{
        command_name    check_symfony_health
        command_line    $USER1$/check_symfony2.py -w 0  -c 0 -u https://$HOSTNAME$
}

To use the plugin with HTTP basic authentication, change the command to:

command_line    $USER1$/check_symfony2.py -w 0  -c 0 -u https://$HOSTNAME$ -a username:password

Conneting Check to Host in Nagios

Add a service:

define service{
 hostgroup_name         Symfony2
 service_description    Symfony2 health check
 check_command          check_symfony_health
 use                    generic-service
}

And create a host attached to the Symfony2 hostgroup:

define host{
    use              web-host
    host_name        www.myhost.com
    address          8.8.8.4
    hostgroups       Symfony2
}

And place your host within the Symfony2 hostgroup.

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