Monitoring Performance, Status and Load with mod_status for Apache Web Server (HTTPD)
With the Apache Status module –
mod_status – server administrators and developers can monitor a bunch of things like:
- How well is the web server performing.
- What is the server load in terms of resource consumption (CPU), requests being served, clients being handled, etc.
- What is the uptime status.
- Some of the current server configuration.
Once the module is enabled, all we need to do is add a
Location block to the main server config (
apache2.conf) or a virtual host block, that would specify the URL endpoint where we would like to monitor our server status. The
Location block must also specify the status module’s handler to handle incoming requests.
<Location "/server-status"> SetHandler server-status Require all granted </Location>
Now when you visit
yoursite.com/server-status you should see a page like this:
A bunch of details are dumped on the page like:
- Number of busy workers serving requests and the number of idle workers.
- Server configuration like version, MPM in use.
- The time when server was started/restarted and its uptime (total running elapsed time).
ExtendedStatus directive is set to
On then additional data is tracked for the entire server and at a per worker level as well for incoming requests and the clients sending those requests:
- Status of each worker, the number of requests they have handled, total number of bytes they’ve processed.
- Total number of requests served and bytes processed by the entire server.
- Average number of requests processed per second, bytes transferred per second, bytes transferred per request, time taken per request.
- CPU usage by all the workers combined and at an individual level as well.
- Current requests being processed by different clients and served off different virtual hosts.
HTTPD ships with a sample
status.conf that looks like this:
<IfModule mod_status.c> # Allow server status reports generated by mod_status, # with the URL of http://servername/server-status # Uncomment and change the "192.0.2.0/24" to allow access from other hosts. <Location /server-status> SetHandler server-status Require local #Require ip 192.0.2.0/24 </Location> # Keep track of extended status information for each request ExtendedStatus On </IfModule>
This sample/default config file may get automatically includes while enabling the module. If not you can do so manually and make changes as required.
It is a good idea to restrict the access to this endpoint to a particular IP or host instead of using
Require all granted.
Machine Readable Format
There’s a machine-readable version of the server dump as well that can be requested by adding
?auto to the end of the URL –
yoursite.com/server-status?auto. It dumps the information in this format:
22.214.171.124 ServerVersion: Apache/2.4.41 (Ubuntu) ServerMPM: event Server Built: 2022-01-05T14:49:56 CurrentTime: Thursday, 24-Feb-2022 10:36:20 UTC RestartTime: Thursday, 24-Feb-2022 09:59:48 UTC ParentServerConfigGeneration: 1 ParentServerMPMGeneration: 0 ServerUptimeSeconds: 2192 ServerUptime: 36 minutes 32 seconds Load1: 0.03 Load5: 0.10 Load15: 0.05 Total Accesses: 137 Total kBytes: 316 Total Duration: 97 CPUUser: .12 CPUSystem: .13 CPUChildrenUser: 0 CPUChildrenSystem: 0 CPULoad: .0114051 Uptime: 2192 ReqPerSec: .0625 BytesPerSec: 147.62 BytesPerReq: 2361.93 DurationPerReq: .708029 BusyWorkers: 1 IdleWorkers: 49 Processes: 2 Stopping: 0 BusyWorkers: 1 IdleWorkers: 49 ConnsTotal: 0 ConnsAsyncWriting: 0 ConnsAsyncKeepAlive: 0 ConnsAsyncClosing: 0 Scoreboard: ______________________________________W___________....................................................................................................
This output can then be used by scripts or some tools that can generate graphs or charts out of the data over a time period. A visual graph or chart based UI is easier to monitor. Some tools will also allow setting alerts for different metrics when they breach a certain level or threshold.
In cases where your server ends up consuming a lot of system resources that you can obviously monitor via tools like
htop, you can use
mod_status output to find the culprit request and client details. For this you’ll need to ensure that
You can easily pick the process IDs from your
htop list for a particular Apache worker and then search for that
pid in the server status output to locate the clients and/or requests causing load problems.
If your browser supports page refreshes via the
Refresh HTTP header, then you can add the
?refresh=N query param to the URL to refresh every
N seconds as well. For instance
yoursite.com/server-status?refresh=5 will make the browser refresh the page every 5 seconds.