feat(process_exporter): add support for recheck-with-time-limit

This CLI flag is useful to prevent process_exporter from putting
processes in the wrong groups if it happens to scan them for the first
time before they change their command line. This can happen for
processes which call exec(3) for example.

The default setting is 0, which leaves the feature disabled. Note that
setting a non-zero value for --recheck-with-time-limit automatically
also sets --recheck so there's no need to set the two CLI flags.

Signed-off-by: François HORTA <[email protected]>

Author: frazew

roles/process_exporter/defaults/main.yml

@@ -25,6 +25,8 @@ process_exporter_names: |
         - '.+'
   {% endraw %}
 
+process_exporter_recheck_time_limit: 0
+
 process_exporter_binary_install_dir: "/usr/local/bin"
 process_exporter_system_group: "process-exp"
 process_exporter_system_user: "{{ process_exporter_system_group }}"

roles/process_exporter/meta/argument_specs.yml

@@ -40,6 +40,13 @@ argument_specs:
           - "Syntax is the same as in"
           - "L(using-a-config-file Default is consistent with deb/rpm packages,https://github.com/ncabatoff/process-exporter#using-a-config-file Default is consistent with deb/rpm packages)"
         default: !unsafe "[{name: '{{.Comm}}', cmdline: [.+]}]"
+      process_exporter_recheck_time_limit:
+        description:
+          - "Enable process rechecking: process names are re-evaluated only this much time after their start, but no longer."
+          - "See L(the time.ParseDuration documentation,https://pkg.go.dev/time#ParseDuration) for the supported duration formats."
+          - "This setting can be useful to make sure processes are grouped correctly if their name changes shortly after they start."
+          - "The default value leaves this feature disabled."
+        default: 0
       process_exporter_binary_install_dir:
         description:
           - "I(Advanced)"

roles/process_exporter/molecule/alternative/molecule.yml

@@ -27,5 +27,6 @@ provisioner:
               cmdline:
                 - crond
           {% endraw %}
+        process_exporter_recheck_time_limit: 180s
         process_exporter_binary_url: "https://github.com/ncabatoff/process-exporter/releases/download/v{{\
                                       \ process_exporter_version }}/process-exporter-{{ process_exporter_version }}.linux-amd64.tar.gz"

roles/process_exporter/templates/process_exporter.service.j2

@@ -14,6 +14,9 @@ ExecStart={{ process_exporter_binary_install_dir }}/process-exporter \
 {% endif -%}
 {% if process_exporter_tls_server_config | length > 0 or process_exporter_http_server_config | length > 0 or process_exporter_basic_auth_users | length > 0 %}
     '--web.config.file={{ process_exporter_config_dir }}/web_config.yml' \
+{% endif %}
+{% if process_exporter_recheck_time_limit != 0 %}
+    '--recheck-with-time-limit={{ process_exporter_recheck_time_limit }}' \
 {% endif %}
     '--web.listen-address={{ process_exporter_web_listen_address }}' \
     '--web.telemetry-path={{ process_exporter_web_telemetry_path }}'