Zabbix Documentation 2.4

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manual:web_monitoring

8. Web monitoring

Overview

With Zabbix you can check several availability aspects of web sites.

To perform web monitoring Zabbix server must be initially configured with cURL (libcurl) support.

To activate web monitoring you need to define web scenarios. A web scenario consists of one or several HTTP requests or “steps”. The steps are periodically executed by Zabbix server in a pre-defined order.

Since Zabbix 2.2 web scenarios are attached to hosts/templates in the same way as items, triggers, etc. That means that web scenarios can also be created on a template level and then applied to multiple hosts in one move.

The following information is collected in any web scenario:

  • average download speed per second for all steps of whole scenario
  • number of the step that failed
  • last error message

The following information is collected in any web scenario step:

  • download speed per second
  • response time
  • response code

For more details, see web monitoring items.

Data collected from executing web scenarios is kept in the database. The data is automatically used for graphs, triggers and notifications.

Zabbix can also check if a retrieved HTML page contains a pre-defined string. It can execute a simulated login and follow a path of simulated mouse clicks on the page.

Zabbix web monitoring supports both HTTP and HTTPS. When running a web scenario, Zabbix will optionally follow redirects (see option Follow redirects below). Maximum number of redirects is hard-coded to 10 (using CURLOPT_MAXREDIRS cURL option). All cookies are preserved during the execution of a single scenario.

See also known issues for web monitoring using HTTPS protocol.

Configuring a web scenario

To configure a web scenario:

  • Go to: Configuration → Hosts (or Templates)
  • Click on Web in the row of the host/template
  • Click on Create scenario to the right (or on the scenario name to edit an existing scenario)
  • Enter parameters of the scenario in the form

The Scenario tab allows you to configure the general parameters of a web scenario.

General parameters:

ParameterDescription
Host Name of the host/template that the scenario belongs to.
Name Unique scenario name.
Starting with Zabbix 2.2, the name may contain supported macros.
Application Select an application the scenario will belong to.
Web scenario items will be grouped under the selected application in Monitoring → Latest data.
New application Enter the name of a new application for the scenario.
Update interval (in sec) How often the scenario will be executed, in seconds.
Retries The number of attempts for executing web scenario steps. In case of network problems (timeout, no connectivity, etc) Zabbix can repeat executing a step several times. The figure set will equally affect each step of the scenario. Up to 10 retries can be specified, default value is 1.
Note: Zabbix will not repeat a step because of a wrong response code or the mismatch of a required string.
This parameter is supported starting with Zabbix 2.2.
Agent Select a client agent.
Zabbix will pretend to be the selected browser. This is useful when a website returns different content for different browsers.
User macros can be used in this field, starting with Zabbix 2.2.
HTTP proxy You can specify an HTTP proxy to use, using the format: http://[username[:password]@]proxy.mycompany.com[:port]
By default, 1080 port will be used.
If specified, the proxy will overwrite proxy related environment variables like http_proxy, HTTPS_PROXY. If not specified, the proxy will not overwrite proxy related environment variables.
The entered value is passed on “as is”, no sanity checking takes place. You may also enter a SOCKS proxy address. If you specify the wrong protocol, the connection will fail and the item will become unsupported. With no protocol specified, the proxy will be treated as an HTTP proxy.
Note: Only simple authentication is supported with HTTP proxy.
User macros can be used in this field.
This parameter is supported starting with Zabbix 2.2.
Variables List of scenario-level variables (macros) that may be used in scenario steps (URL, Post variables).
They have the following format:
{macro1}=value1
{macro2}=value2
{macro3}=regex:<regular expression>
For example:
{username}=Alexei
{password}=kj3h5kJ34bd
{hostid}=regex:hostid is ([0-9]+)
If the value part starts with regex: then the part after it will be treated as a regular expression that will search the web page and, if found, store the match in the variable. Note that at least one subgroup must be present so that the matched value can be extracted.
The macros can then be referenced in the steps as {username}, {password} and {hostid}. Zabbix will automatically replace them with actual values.
Having variables that search a webpage for a regular expression match is supported starting with Zabbix 2.2.
HOST.* macros and user macros can be used in this field, starting with Zabbix 2.2.
Note: Variables are not URL-encoded.
Headers HTTP headers that will be sent when performing a request.
Headers should be listed using the same syntax as they would appear in the HTTP protocol, optionally using some additional features supported by the CURLOPT_HTTPHEADER cURL option.
For example:
Accept-Charset: utf-8
Accept-Language: en-US
Content-Type: application/xml; charset=utf-8
HOST.* macros and user macros can be used in this field.
Specifying custom headers is supported starting with Zabbix 2.4.
Enabled The scenario is active if this box is checked, otherwise - disabled.

Note that when editing an existing scenario, two extra buttons are available in the form:

Create another scenario based on the properties of the existing one.
Delete history and trend data for the scenario. This will make the server perform the scenario immediately after deleting the data.

If HTTP proxy field is left empty, another way for using an HTTP proxy is to set proxy related environment variables.

For HTTP checks - set the http_proxy environment variable for the Zabbix server user. For example, http_proxy=http://proxy_ip:proxy_port.

For HTTPS checks - set the HTTPS_PROXY environment variable. For example, HTTPS_PROXY=http://proxy_ip:proxy_port. More details are available by running a shell command: # man curl.

The Steps tab allows you to configure the web scenario steps. To add a web scenario step, click on Add.

Configuring steps

Step parameters:

ParameterDescription
Name Unique step name.
Starting with Zabbix 2.2, the name may contain supported macros.
URL URL to connect to and retrieve data. For example:
http://www.zabbix.com
https://www.google.com
GET variables can be passed in the URL parameter.
Starting with Zabbix 2.2, this field may contain supported macros.
Limited to 2048 characters starting with Zabbix 2.4.
Post HTTP POST variables, if any.
For example:
id=2345&userid={user}
If {user} is defined as a macro of the web scenario, it will be replaced by its value when the step is executed.
The information will be sent as is, variables are not URL-encoded.
Starting with Zabbix 2.2, this field may contain supported macros.
Variables List of step-level variables (macros) that may be used for GET and POST functions.
Step-level variables override scenario-level variables or variables from the previous step.
They have the following format:
{macro}=value
{macro}=regex:<regular expression>
For more information see variable description on the scenario level.
Having step-level variables is supported starting with Zabbix 2.2.
Note: Variables are not URL-encoded.
Headers HTTP headers that will be sent when performing a request.
Headers should be listed using the same syntax as they would appear in the HTTP protocol.
Headers on the step level will overwrite the headers specified for the scenario.
For example, 'User-Agent:' with no data will remove User-Agent set on scenario level.
HOST.* macros and user macros can be used in this field.
This sets the CURLOPT_HTTPHEADER cURL option.
Specifying custom headers is supported starting with Zabbix 2.4.
Follow redirects Mark the checkbox to follow HTTP redirects.
This sets the CURLOPT_FOLLOWLOCATION cURL option.
This option is supported starting with Zabbix 2.4.
Retrieve only headers Mark the checkbox to retrieve only headers from the HTTP response.
This sets the CURLOPT_NOBODY cURL option.
This option is supported starting with Zabbix 2.4.
Timeout Zabbix will not spend more than the set amount of seconds on processing the URL. Actually this parameter defines maximum time for making connection to the URL and maximum time for performing an HTTP request. Therefore, Zabbix will not spend more than 2 x Timeout seconds on the step.
For example: 15
Required string Required regular expressions pattern.
Unless retrieved content (HTML) matches required pattern the step will fail. If empty, no check is performed.
For example:
Homepage of Zabbix
Welcome.*admin
Note: Referencing regular expressions created in the Zabbix frontend is not supported in this field.
Starting with Zabbix 2.2, this field may contain supported macros.
Required status codes List of expected HTTP status codes. If Zabbix gets a code which is not in the list, the step will fail.
If empty, no check is performed.
For example: 200,201,210-299
Starting with Zabbix 2.2, user macros can be used in this field.

Any changes in web scenario steps will only be saved when the whole scenario is saved.

See also a real-life example of how web monitoring steps can be configured.

Configuring authentication

The Authentication tab allows you to configure scenario authentication options.

Authentication parameters:

ParameterDescription
Authentication Authentication options.
None - no authentication used.
Basic authentication - basic authentication is used.
NTLM authentication - NTLM (Windows NT LAN Manager) authentication is used.
Selecting an authentication method will provide two additional fields for entering a user name and password.
User macros can be used in user and password fields, starting with Zabbix 2.2.
SSL verify peer Mark the checkbox to verify the SSL certificate of the web server.
The server certificate will be automatically taken from system-wide certificate authority (CA) location. You can override the location of CA files using Zabbix server or proxy configuration parameter SSLCALocation.
This sets the CURLOPT_SSL_VERIFYPEER cURL option.
This option is supported starting with Zabbix 2.4.
SSL verify host Mark the checkbox to verify that the Common Name field or the Subject Alternate Name field of the web server certificate matches.
This sets the CURLOPT_SSL_VERIFYHOST cURL option.
This option is supported starting with Zabbix 2.4.
SSL certificate file Name of the SSL certificate file used for client authentication. The certificate file must be in PEM1 format. If the certificate file contains also the private key, leave the SSL key file field empty. If the key is encrypted, specify the password in SSL key password field. The directory containing this file is specified by Zabbix server or proxy configuration parameter SSLCertLocation.
HOST.* macros and user macros can be used in this field.
This sets the CURLOPT_SSLCERT cURL option.
This option is supported starting with Zabbix 2.4.
SSL key file Name of the SSL private key file used for client authentication. The private key file must be in PEM1 format. The directory containing this file is specified by Zabbix server or proxy configuration parameter SSLKeyLocation.
HOST.* macros and user macros can be used in this field.
This sets the CURLOPT_SSLKEY cURL option.
This option is supported starting with Zabbix 2.4.
SSL key password SSL private key file password.
User macros can be used in this field.
This sets the CURLOPT_KEYPASSWD cURL option.
This option is supported starting with Zabbix 2.4.

[1] Zabbix supports certificate and private key files in PEM format only. In case you have your certificate and private key data in PKCS #12 format file (usually with extention *.p12 or *.pfx) you may generate the PEM file from it using the following commands:

openssl pkcs12 -in ssl-cert.p12 -clcerts -nokeys -out ssl-cert.pem
openssl pkcs12 -in ssl-cert.p12 -nocerts -nodes  -out ssl-cert.key

Zabbix server picks up changes in certificates without a restart.

If you have client certificate and private key in a single file just specify it in a “SSL certificate file” field and leave “SSL key file” field empty. The certificate and key must still be in PEM format. Combining certificate and key is easy:

cat client.crt client.key > client.pem

Display

To view detailed data of defined web scenarios, go to Monitoring → Web or Latest data. Click on the scenario name to see more detailed statistics.

An overview of web monitoring scenarios can be viewed in Monitoring → Dashboard.

Extended monitoring

Sometimes it is necessary to log received HTML page content. This is especially useful if some web scenario step fails. Debug level 5 (trace) serves that purpose. This level can only be set using a runtime control option (-R log_level_increase="http poller,N", where N is the process number). Providing debug level 4 is already set, extended monitoring can be started as demonstrated in the following examples:

Increase log level of all http pollers:
shell> zabbix_server -R log_level_increase="http poller"
Increase log level of second http poller:
shell> zabbix_server -R log_level_increase="http poller,2"

If extended web monitoring is not required it can be stopped using the -R log_level_decrease option.