Metric plugins - mackerel-plugin-apache2

mackerel-plugin-apache2 provides a way to monitor statistics about Apache2 as a metric.

To use this plugin, the Apache Status module (mod_status) must be enabled and accessible from the plugin.

Monitorable metrics

The metrics that can be monitored by mackerel-plugin-apache2 are as follows.

Apache Workers

The number of running server processes and threads can be monitored.

Metric Display Name Metric Name Diff Stacked Description
Busy Workers custom.apache2.workers.busy_workers ✓ The number of busy worker requests/threads
Idle Workers custom.apache2.workers.idle_workers ✓ The number of idle worker requests/threads

Apache Bytes

The amount of data sent out by the httpd process can be monitored.

Metric Display Name Metric Name Diff Stacked Description
Bytes Sent custom.apache2.bytes.bytes_sent ✓ Total traffic bytes per minute

Apache CPU Load

CPU utilization of the httpd process can be monitored.

Metric Display Name Metric Name Diff Stacked Description
CPU Load custom.apache2.cpu.cpu_load CPU utilization

Apache Requests

The number of requests can be monitored.

Metric Display Name Metric Name Diff Stacked Description
Requests custom.apache2.req.requests ✓ The number of requests received per minute

Apache Scoreboard

Each metric on the scoreboard (state of running server processes) can be monitored.

Metric Display Name Metric Name Diff Stacked Description
Waiting for connection custom.apache2.scoreboard.score-_ ✓ The number of processes/threads started and waiting to be accessed
Starting up custom.apache2.scoreboard.score-S ✓ The number of processes/threads running
Reading request custom.apache2.scoreboard.score-R ✓ The number of client requests being read
Sending reply custom.apache2.scoreboard.score-W ✓ The number of responses to clients
Keepalive custom.apache2.scoreboard.score-K ✓ The number of requests waiting for KeepAlive
DNS lookup custom.apache2.scoreboard.score-D ✓ The number of names resolved by DNS
Closing connection custom.apache2.scoreboard.score-C ✓ The number of connections closed
Logging custom.apache2.scoreboard.score-L ✓ The number of logs output
Gracefully finishing custom.apache2.scoreboard.score-G ✓ The number of cases waiting for the end of processing in graceful restart
Idle cleanup custom.apache2.scoreboard.score-I ✓ The number of processes/threads stopped
Open slot custom.apache2.scoreboard.score- ✓ The number of slots available

Configurable options

The options which can be configured in the plugin are as follows.

Option Short Environment Variables Description Default
--http_host -o IP address being listened to by httpd 127.0.0.1
--http_port -p Port number being listened to by httpd 80
--header -H HTTP header to be given at the time of request from plugin
--status_page -s URL path where statistics are available /server-status?auto
--tempfile -t MACKEREL_PLUGIN_WORKDIR Destination path for temporary file
--metric-key-prefix String to be given as prefix to the metric name apache2
--metric-label-prefix String to be assigned to the graph name as prefix Apache
  • Temporary files are created by default under /var/tmp/mackerel-agent or /tmp in the format mackerel-plugin-{Prefix or other string}-{hash string}.

Example configuration

[plugin.metrics.apache2]
command = ["mackerel-plugin-apache2", "-p", "1080"]

To check the above settings manually, you can execute the following at the terminal.

mackerel-plugin-apache2 -p 1080

Configuration for Apache

Make sure that the Apache Status module (mod_status) is enabled in order to use mackerel-plugin-apache2.

The following configuration assumes publication at http://127.0.0.1:1080/server-status.

ExtendedStatus On
<VirtualHost 127.0.0.1:1080>
  <Location /server-status>
    SetHandler server-status
    Order deny,allow
    Deny from all
    Allow from localhost
  </Location>
</VirtualHost>

Troubleshooting

Cannot get metrics

If you are unable to obtain a metric after setting up the plugin, it may be due to a configuration that has not been reflected or an incorrect setting of the Status module on the Apache side. Please check the following points.

  • Whether or not mackerel-agent has been restarted after the plugin has been configured.
    • Restarting mackerel-agent is required for the settings to take effect.
  • Can you connect to the server-status endpoint with the curl command?

    • Please confirm that you can receive the HTTP 200 OK response with the following command when configured as shown in the configuration example.

      curl http://127.0.0.1:1080/server-status

    • If you have a http to https redirect configured in mod_rewrite, the plugin will not track the redirect; the Status module endpoint should be excluded from the redirect.

    • If you cannot get the results of the Status module with the curl command, it may be because it has been incorrectly configured or Apache has not been restarted.

Repository

https://github.com/mackerelio/mackerel-agent-plugins/tree/master/mackerel-plugin-apache2

References