Best way to reduce pool size outside of business hours

[miyajan]

Hello and thank you for this module. It has helped us so much in building an autoscaling self-hosted runner.

We use ephemeral runners and have set up a large pool size. Then, we try to reduce the pool size after business hours to save money.

We first tried to configure pool_config for business hours and non-business hours, as shown in the example below. (The following example ignores time zone for simplicity.)

        pool_config = [{
          size                = 100
          schedule_expression = "cron(*/3 9-17 * * 1-5 *)"
          }, {
          size                = 1
          schedule_expression = "cron(*/3 0-8,18-23 * * 1-5 *)"
          },
          {
          size                = 1
          schedule_expression = "cron(*/3 * * * 0,6 *)"
        }]

However, we noticed that the pool lambda does not delete instances even when the pool size is exceeded. So if a build is not triggered outside of business hours, the pool size will remain large.

So we plan to use pool_config and idle_config together.

• set pool_config for business hours only
• set minimum_running_time_in_minutes small enough (e.g. 1 hour)
• set idleCount equal to the pool size during business hours and minimize it during non-business hours.

However, idle_config appears to be a configuration for non-ephemeral runners. Do you know if something is wrong with this plan?

We want to know if there is a better way to reduce pool size outside of business hours.

[shashidhar087]

Have been using the runners with same configuration for several months. Working great !