feat: add connection_max_age config (#1340)

## Description

Currently seeing some occasional connectivity issues running behind a
NAT gateway - where connections are limited to 5 minutes. The
gitlab-runner config by defaults limits connections to 15 minutes. Was
looking to set the connection_max_age setting with the module, but could
not find an option to do so.

Add connection_max_age as a configurable option to the runner config.

Co-authored-by: Matthias Kay <[email protected]>

Author: uosjead

main.tf

@@ -150,6 +150,7 @@ locals {
       shared_cache                   = var.runner_worker_cache.shared
       sentry_dsn                     = var.runner_manager.sentry_dsn
       prometheus_listen_address      = var.runner_manager.prometheus_listen_address
+      connection_max_age             = var.runner_manager.connection_max_age
       auth_type                      = var.runner_worker_cache.authentication_type
       runners_docker_autoscaler      = var.runner_worker.type == "docker-autoscaler" ? local.template_runner_docker_autoscaler : ""
       runners_docker_machine         = var.runner_worker.type == "docker+machine" ? local.template_runner_docker_machine : ""

template/runner-config.tftpl

@@ -3,6 +3,7 @@ check_interval = ${runners_check_interval}
 sentry_dsn = "${sentry_dsn}"
 log_format = "json"
 listen_address = "${prometheus_listen_address}"
+connection_max_age = "${connection_max_age}"
 
 [[runners]]
   name = "${runners_name}"

variables.tf

@@ -90,12 +90,14 @@ variable "runner_manager" {
     maximum_concurrent_jobs = The maximum number of jobs which can be processed by all Runners at the same time (concurrent).
     prometheus_listen_address = Defines an address (<host>:<port>) the Prometheus metrics HTTP server should listen on (listen_address).
     sentry_dsn = Sentry DSN of the project for the Runner Manager to use (uses legacy DSN format) (sentry_dsn)
+    connection_max_age = The maximum age of a connection to the Runner Manager (connection_max_age).
   EOT
   type = object({
     gitlab_check_interval     = optional(number, 3)
     maximum_concurrent_jobs   = optional(number, 10)
     prometheus_listen_address = optional(string, "")
     sentry_dsn                = optional(string, "__SENTRY_DSN_REPLACED_BY_USER_DATA__")
+    connection_max_age        = optional(string, "15m")
   })
   default = {}
 }