Originally posted in: https://vimalselvam.com/post/prometheus-capturing-username-in-process-exporter/

Recently, stumbled upon a task where we wanted to capture the username of the process with the process exporter and store as a label in prometheus. There is no clear documentation around this on how to accomplish. So I thought let's share what I've learnt which I believe might be useful for someone.

Let's see how to capture the username in the process exporter.

Pre-requisite

• You should be having prometheus running. In case you want to know how to setup, head here.
• To setup the process exporter, refer here.

Process Exporter Config

To make process exporter mine a required process, I've the following sample config yaml file:

process_names:
  - name: "{{.ExeBase}}"
    cmdline:
      - crond'

The ExeBase is the basename of the executable which I wanted to capture. Now I would like to know the user who is executing the crond process. So I'll change the yaml to:

process_names:
  - name: "{{.ExeBase}};{{.Username}}"
    cmdline:
      - crond'

Notice that I've added ;{{.Username}}, the Username captures the user of the given process, here it is crond. The reason that I've added semicolon(;) is because I'll use the metric_relabel_configs in prometheus scrape config to split and store username as a separate label.

I've stored the file as proc-config.yaml and will start the process exporter as:

> process-exporter -config.path proc-config.yaml

For now, if you scrape the process exporter (http://localhost:9256/metrics), you will get the metrics in the following format:

namedprocess_namegroup_num_procs{groupname='crond;vimalraj'} 1

Here, the groupname says the crond process and triggered by user vimalraj.

Now, let's look at how we configure prometheus to store the user as a separate label.

Prometheus Config

Open up the prometheus.yml file and add the new scrape target as follows:

scrape_configs:
  - job_name: 'process_exporter'
    scrape_interval: 15s
    static_configs:
      - targets: 
        - localhost:9256
    metric_relabel_configs:
      - source_labels: ["groupname"]  # the label which needs to be filtered
        regex: "(.*);(.*)"            # the regex to find the expected match
        target_label: "processname"   # add a new label
        replacement: "$1"             # substitute with the 1st match
      - source_labels: ["groupname"]  # the label which needs to be filtered
        regex: "(.*);(.*)"            # the regex to find the expected match
        target_label: "username"      # add a new label
        replacement: "$2"             # substitute with the 2nd match

To know more about the metric_relabel_configs, refer prometheus documentation here.

Now reload the config and query for namedprocess_namegroup_num_procs. You should be seeing the following result:

namedprocess_namegroup_num_procs{groupname='crond;vimalraj', processname='crond', username='vimalraj'} 1

Please note that I kept groupname as it is, in case you want to remove, you can use action to drop that label.

In case you found this post useful, please do share it. For any questions, feel free to open an issue here to discuss further.