Apache HTTP

Auto-Detection

Health Check

Built-in Metrics

Logs

Apache HTTP Server is the most widely deployed open-source web server.

Auto-Detection

Glouton detects Apache by its process and listening port (default: 80).

To enable metrics gathering, ensure Glouton can access the Apache status page at http://server-address/server-status?auto. This is enabled by default on Ubuntu and Debian. If not, add the following to your default virtual host (e.g. the first file in /etc/apache2/sites-enabled/):

LoadModule status_module /usr/lib/apache2/modules/mod_status.so

<Location /server-status>
    SetHandler server-status
    # You may want to limit access only to Bleemeo agent
    # require ip IP-OF-BLEEMEO-AGENT/32
</Location>
ExtendedStatus On

When using Docker, you can set http_path and http_host via labels:

docker run --label glouton.http_path="/readiness" --label glouton.http_host="my-host" [...]

If auto-detected parameters are incorrect, override them manually:

Linux
Windows

sudo tee /etc/glouton/conf.d/99-apache.conf > /dev/null << 'EOF'
service:
  # For an Apache running outside a container
  - type: "apache"
    address: "127.0.0.1"
    port: 80   # HTTP listener, agent does not support HTTPS here
    http_path: "/"   # Path used for availability check, not metrics gathering
    http_host: "127.0.0.1:80"   # Host header sent

  # For an additional Apache running outside a container
  - type: "apache"
    instance: "NAME_ASSOCIATED_WITH_YOUR_ADDITIONAL_SERVICE"
    address: "127.0.0.1"
    port: 81
    http_path: "/"
    http_host: "127.0.0.1:80"

  # For an Apache running in a Docker container
  - type: "apache"
    instance: "CONTAINER_NAME"
    address: "172.17.0.2"
    port: 80
    http_path: "/"
    http_host: "127.0.0.1:80"
EOF

Create or edit C:\ProgramData\glouton\conf.d\99-apache.conf:

service:
  # For an Apache running outside a container
  - type: "apache"
    address: "127.0.0.1"
    port: 80   # HTTP listener, agent does not support HTTPS here
    http_path: "/"   # Path used for availability check, not metrics gathering
    http_host: "127.0.0.1:80"   # Host header sent

  # For an additional Apache running outside a container
  - type: "apache"
    instance: "NAME_ASSOCIATED_WITH_YOUR_ADDITIONAL_SERVICE"
    address: "127.0.0.1"
    port: 81
    http_path: "/"
    http_host: "127.0.0.1:80"

Glouton automatically detects configuration changes.

Service Check

Glouton performs an HTTP check on the configured port and path to verify that Apache is responding.

Built-in Metrics

Metric	Description
`service_status`	Status of Apache
`apache_busy_workers`	Number of busy Apache workers
`apache_busy_workers_perc`	Percentage of busy Apache workers
`apache_bytes`	Network traffic sent by Apache in bytes per second
`apache_connections`	Number of client connections to the Apache server
`apache_idle_workers`	Number of Apache workers waiting for an incoming request
`apache_max_workers`	Maximum number of configured Apache workers
`apache_requests`	Number of requests per second
`apache_uptime`	Time since Apache server start in seconds

Apache tracks server activity in a structure called the scoreboard. Each worker has a slot that holds its current status. The scoreboard size equals the maximum number of concurrent clients Apache can serve.

Metric	Description
`apache_scoreboard_waiting`	Number of workers waiting for an incoming request (same as apache_idle_workers)
`apache_scoreboard_starting`	Number of workers starting up
`apache_scoreboard_reading`	Number of workers reading an incoming request
`apache_scoreboard_sending`	Number of workers processing a client request
`apache_scoreboard_keepalive`	Number of workers waiting for another request via keepalive
`apache_scoreboard_dnslookup`	Number of workers looking up a hostname
`apache_scoreboard_closing`	Number of workers closing their connection
`apache_scoreboard_logging`	Number of workers writing to log files
`apache_scoreboard_finishing`	Number of workers gracefully finishing a request
`apache_scoreboard_idle_cleanup`	Number of idle workers being killed
`apache_scoreboard_open`	Number of empty slots with no worker in the scoreboard

Apache does not start all workers when they are not needed – it reuses idle workers instead. The sum of all scoreboard items equals the maximum concurrent requests Apache can serve, stored in the apache_max_workers metric.

Logs

Glouton collects Apache HTTP access and error logs for analysis in Bleemeo.

Monitoring Troubleshooting

See Troubleshoot a Service Check or Missing Metrics for what applies to every service: finding the address and port Glouton really uses, what each check message means, and how to read the collection error — which does not appear in the agent logs at the default level.

The check and the metrics use two different URLs:

	URL	Configurable
Service check	`http://<address>:<port>/`	Yes, with `http_path` and `http_host`
Metrics	`http://<address>:<port>/server-status?auto`	No — the path is fixed

The Service Check is not OK

The check is an HTTP request, so its status text carries the HTTP code:

Status text	Cause	Fix
`HTTP WARN - http_code=404`	Apache serves nothing at `/` — typically name-based virtual hosts	Point the check at an existing path with `http_path`, and set `http_host` to the virtual host name
`HTTP WARN - http_code=403`	A `Require` directive, or a directory listing refused	Use a `http_path` the agent is allowed to fetch
`HTTP CRITICAL - http_code=500`	Apache is healthy but the application behind it is not	Set `http_path` to a static path served by Apache itself
`HTTP connection failed: ...`	Nothing listening on that port, or the listener is HTTPS-only	The check speaks plain HTTP: point it at the HTTP listener, or use an uptime monitor for an HTTPS endpoint
`Connection timed out after 10 seconds`	A firewall drops the packets, or all workers are busy	Open the port, or investigate the saturation

Metrics are Missing

A passing check says nothing about the metrics: they are collected separately.

Metrics come from mod_status, which Glouton fetches at the fixed path /server-status?auto. http_path does not move it.

Check the endpoint from the machine where the agent runs:

curl -i "http://<apache-address>/server-status?auto"

It must return a Total Accesses: line.

What the endpoint returns	Cause	Fix
`404`	`mod_status` not loaded	Load the module and add the `Location` block shown above
`404`	The `Location` block is missing, or lives in another virtual host	Declare it in the virtual host that answers on the port Glouton uses
`403`	Access restricted to localhost while the agent connects from elsewhere	Add a `Require ip` line for the agent address
the answer has no `CPUUser` line	`ExtendedStatus` disabled	Set `ExtendedStatus On`; without it the per-worker and CPU metrics are not published
a connection error	The listener is HTTPS-only	Expose `server-status` on a plain HTTP listener, even on `127.0.0.1` only