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Azure Application Gateway

Overview​

Azure Application Gateway is a web traffic load balancer that enables you to manage traffic to your web applications. Traditional load balancers operate at the transport layer (OSI layer 4 - TCP and UDP) and route traffic based on source IP address and port, to a destination IP address and port.

The Centreon Plugin-Pack Azure Application Gateway can rely on Azure API or Azure CLI to collect the metrics related to the Application Gateway service. Both v1 & v2 versions are supported.

Pack Assets​

Monitored Objects​

  • Azure Application Gateway v1 instances:

    • Backend-Health
    • Connections
    • Health
    • Requests
    • Throughput
  • Azure Application Gateway v2 instances:

    • Backend-Status
    • Backend-Time
    • Clients-Traffic
    • Connections
    • Gateway-Time
    • Health
    • Requests
    • Throughput
    • Units

Discovery rules​

The Centreon Plugin Pack Azure Application Gateway includes a Host Discovery provider to automatically discover the Azure instances of a given subscription and add them to the Centreon configuration. This provider is named Microsoft Azure Application Gateway:

image

This discovery feature is only compatible with the 'api' custom mode. 'azcli' is not supported yet.

More information about the Host Discovery module is available in the Centreon documentation: Host Discovery

Collected metrics & status​

Regarding the version of the Application Gateway, metrics can differ.

Specific to v1​

Metric NameDescriptionUnit
appgateway.backend.healthy.host.countHealthy Host CountCount
appgateway.backend.unhealthy.host.countUnhealthy Host CountCount

Specific to v2​

Metric NameDescriptionUnit
appgateway.backend.response.status.countBackend Response StatusCount

Prerequisites​

To get data from Azure Services, following methods are available:

  • Azure API ('api')
  • Azure CLI ('azcli')

Centreon recommends to use the API instead of the CLI for the following reasons:

  • API is much more efficient by avoiding CLI binary execution
  • API supports application authentication while CLI does not (yet)

To use the 'api' custom mode, make sure to obtain the required information using the how-to below. Keep it safe until including it in a Host or Host Template definition.

  • Create an application in Azure Active Directory:

    • Log in to your Azure account.
    • Select Azure Active directory in the left sidebar.
    • Click on App registrations.
    • Click on + Add.
    • Enter Centreon as the application name (or any name of your choice), select application type(api) and sign-on-url.
    • Click on the Create button.
  • Get Subscription ID

    • Log in to your Azure account.
    • Select Subscriptions in the left sidebar.
    • Select whichever subscription is needed.
    • Click on Overview.
    • Copy the Subscription ID.
  • Get Tenant ID

    • Log in to your Azure account.
    • Select Azure Active directory in the left sidebar.
    • Click on Properties.
    • Copy the directory ID.
  • Get Client ID

    • Log in to your Azure account.
    • Select Azure Active directory in the left sidebar.
    • Click on Enterprise applications.
    • Click on All applications.
    • Select the application previously created.
    • Click on Properties.
    • Copy the Application ID.
  • Get Client secret

    • Log in to your Azure account.
    • Select Azure Active directory in the left sidebar.
    • Click on App registrations.
    • Select the application previously created.
    • Click on All settings.
    • Click on Keys.
    • Enter the key description and select the duration.
    • Click on Save.
    • Copy and store the key value. You won't be able to retrieve it after you leave this page.

Setup​

  1. Install the Centreon Plugin package on every Centreon poller expected to monitor Azure Application Gateway resources:
yum install centreon-plugin-Cloud-Azure-Network-AppGateway-Api
  1. On the Centreon Web interface, install the Azure Application Gateway Centreon Plugin Pack on the "Configuration > Plugin Packs > Manager" page

Configuration​

Host​

  • Log into Centreon and add a new Host through "Configuration > Hosts".

  • In the IP Address/FQDN field, set the following IP address: '127.0.0.1'.

  • Select the Cloud-Azure-Network-AppGateway-custom template to apply to the Host.

  • Once the template applied, some Macros marked as 'Mandatory' hereafter have to be configured. These mandatory Macros differ regarding the custom mode used.

Two methods can be used to set the Macros:

  • full ID of the Resource (/subscriptions/<subscription_id>/resourceGroups/<resourcegroup_id>/providers/Microsoft.Network/<resource_type>/<resource_name>) in AZURERESOURCE
  • Resource Name in AZURERESOURCE associated with Resource Group (in AZURERESOURCEGROUP) and Resource Type (in AZURERESOURCETYPE)
MandatoryNomDescription
XAZURECUSTOMMODECustom mode 'api'
XAZURESUBSCRIPTIONSubscription ID
XAZURETENANTTenant ID
XAZURECLIENTIDClient ID
XAZURECLIENTSECRETClient secret
XAZURERESOURCEID or name of the Application Gateway resource
AZURERESOURCEGROUPAssociated Resource Group if resource name is used
AZURERESOURCETYPEAssociated Resource Type if resource name is used

How to check in the CLI that the configuration is OK and what are the main options for ?​

Once the Plugin installed, log into your Centreon Poller CLI using the centreon-engine user account and test the Plugin by running the following command:

/usr/lib/centreon/plugins/centreon_azure_network_appgateway_api.pl \
--plugin=cloud::azure::network::appgateway::plugin \
--mode=requests \
--custommode=api \
--subscription='xxxxxxxxx' \
--tenant='xxxxxxxxx' \
--client-id='xxxxxxxxx' \
--client-secret='xxxxxxxxx' \
--resource='APP001ABCD' \
--resource-group='RSG1234' \
--timeframe='900' \
--interval='PT5M' \
--aggregation='Total' \
--warning-failed-requests='80' \
--critical-failed-requests='90'

Expected command output is shown below:

OK: Instance 'APP001ABCD' Statistic 'total' Metrics Failed Requests: 0.00, Total Requests: 523.00 |
'APP001ABCD~total#appgateway.requests.failed.count'=0.00;0:80;0:90;0; 'APP001ABCD~total#appgateway.requests.total.count'=523.00;;;0;

The command above checks the requests of an Azure Application Gateway instance using the 'api' custom-mode (--plugin=cloud::azure::network::appgateway::plugin --mode=requests --custommode=api). This Event Hub instance is identified by its id (--resource='APP001ABCD') and its associated group (--resource-group='RSG1234'). The authentication parameters to be used with the custom mode are specified in the options (--subscription='xxxxxxxxx' --tenant='xxxxxxx' --client-id='xxxxxxxx' --client-secret='xxxxxxxxxx').

The calculated metrics are the total values (--aggregation='Total') of a 900 secondes / 15 min period (--timeframe='900') with one sample per 5 minutes (--interval='PT5M').

This command would trigger a WARNING alarm if the number of failed requests is reported as over 80 (--warning-failed-requests='80') and a CRITICAL alarm over 90 failed requests (--critical-failed-requests='90').

All the available options for a given mode can be displayed by adding the --help parameter to the command:

/usr/lib/centreon/plugins/centreon_azure_network_appgateway_api.pl \
--plugin=cloud::azure::network::appgateway::plugin \
--mode=requests \
--help

Troubleshooting​

The Azure credentials have changed and the Plugin does not work anymore​

The Plugin is using a cache file to keep connection information and avoid an authentication at each call. If some of the authentication parameters change, you must delete the cache file.

The cache file can be found within /var/lib/centreon/centplugins/ folder with a name similar to azureapi<md5>_<md5>_<md5>_<md5>.

UNKNOWN: Login endpoint API returns error code 'ERROR_NAME' (add --debug option for detailed message)​

When I run my command I obtain the following error message: UNKNOWN: Login endpoint API returns error code 'ERROR_NAME' (add --debug option for detailed message).

It means that some parameters used to authenticate the API request are wrong. The 'ERROR_NAME' string gives some hints about where the problem stands.

As an example, if my Client ID or Client Secret are wrong, 'ERROR_DESC' value will be 'invalid_client'.

UNKNOWN: 500 Can't connect to login.microsoftonline.com:443​

This error message means that the Centreon Plugin couldn't successfully connect to the Azure Login API. Check that no third party device (such as a firewall) is blocking the request. A proxy connection may also be necessary to connect to the API. This can be done by using this option in the command: --proxyurl='http://proxy.mycompany:8080'.

UNKNOWN: No metrics. Check your options or use --zeroed option to set 0 on undefined values​

This command result means that Azure does not have any value for the requested period. This result can be overriden by adding the --zeroed option in the command. This will force a value of 0 when no metric has been collected and will prevent the UNKNOWN error message.