github-aws-runners · iainlane · Oct 21, 2025 · Oct 21, 2025 · Oct 21, 2025
@@ -214,6 +214,7 @@ Join our discord community via [this invite link](https://discord.gg/bxgXW8jJGh)
 | <a name="input_runners_scale_up_lambda_memory_size"></a> [runners\_scale\_up\_lambda\_memory\_size](#input\_runners\_scale\_up\_lambda\_memory\_size) | Memory size limit in MB for scale-up lambda. | `number` | `512` | no |
 | <a name="input_runners_scale_up_lambda_timeout"></a> [runners\_scale\_up\_lambda\_timeout](#input\_runners\_scale\_up\_lambda\_timeout) | Time out for the scale up lambda in seconds. | `number` | `30` | no |
 | <a name="input_runners_ssm_housekeeper"></a> [runners\_ssm\_housekeeper](#input\_runners\_ssm\_housekeeper) | Configuration for the SSM housekeeper lambda. This lambda deletes token / JIT config from SSM.<br/><br/>  `schedule_expression`: is used to configure the schedule for the lambda.<br/>  `enabled`: enable or disable the lambda trigger via the EventBridge.<br/>  `lambda_memory_size`: lambda memery size limit.<br/>  `lambda_timeout`: timeout for the lambda in seconds.<br/>  `config`: configuration for the lambda function. Token path will be read by default from the module. | <pre>object({<br/>    schedule_expression = optional(string, "rate(1 day)")<br/>    enabled             = optional(bool, true)<br/>    lambda_memory_size  = optional(number, 512)<br/>    lambda_timeout      = optional(number, 60)<br/>    config = object({<br/>      tokenPath      = optional(string)<br/>      minimumDaysOld = optional(number, 1)<br/>      dryRun         = optional(bool, false)<br/>    })<br/>  })</pre> | <pre>{<br/>  "config": {}<br/>}</pre> | no |
+| <a name="input_scale_down_parameter_store_tier"></a> [scale\_down\_parameter\_store\_tier](#input\_scale\_down\_parameter\_store\_tier) | SSM Parameter Store tier to use for scale-down configuration parameters. | `string` | `"Standard"` | no |
 | <a name="input_scale_down_schedule_expression"></a> [scale\_down\_schedule\_expression](#input\_scale\_down\_schedule\_expression) | Scheduler expression to check every x for scale down. | `string` | `"cron(*/5 * * * ? *)"` | no |
 | <a name="input_scale_up_reserved_concurrent_executions"></a> [scale\_up\_reserved\_concurrent\_executions](#input\_scale\_up\_reserved\_concurrent\_executions) | Amount of reserved concurrent executions for the scale-up lambda function. A value of 0 disables lambda from being triggered and -1 removes any concurrency limitations. | `number` | `1` | no |
 | <a name="input_ssm_paths"></a> [ssm\_paths](#input\_ssm\_paths) | The root path used in SSM to store configuration and secrets. | <pre>object({<br/>    root       = optional(string, "github-action-runners")<br/>    app        = optional(string, "app")<br/>    runners    = optional(string, "runners")<br/>    webhook    = optional(string, "webhook")<br/>    use_prefix = optional(bool, true)<br/>  })</pre> | `{}` | no |

@@ -98,7 +98,6 @@ module "runners" {
   #        runner_extra_labels             = ["amazon"]
   #        runners_maximum_count           = 1
   #        enable_ephemeral_runners        = true
-  #        scale_down_schedule_expression  = "cron(* * * * ? *)"
   #      }
   #    }
   #  }
@@ -107,6 +106,7 @@ module "runners" {
   subnet_ids                        = module.base.vpc.private_subnets
   runners_scale_up_lambda_timeout   = 60
   runners_scale_down_lambda_timeout = 60
+  scale_down_schedule_expression    = "cron(* * * * ? *)"
   prefix                            = local.environment
   tags = {
     Project = "ProjectX"

@@ -19,7 +19,6 @@ runner_config:
     id_ssm_parameter_arn: ${ami_id_ssm_parameter_arn}
   runners_maximum_count: 1
   delay_webhook_event: 0
-  scale_down_schedule_expression: cron(* * * * ? *)
   runner_hook_job_started: |
     echo "Running pre job hook as $(whoami)"
   runner_hook_job_completed: |

@@ -19,7 +19,6 @@ runner_config:
     - m5a.large
   runners_maximum_count: 1
   delay_webhook_event: 0
-  scale_down_schedule_expression: cron(* * * * ? *)
   userdata_template: ./templates/user-data.sh
   ami:
     owners:

@@ -20,7 +20,6 @@ runner_config:
     - m5a.large
   runners_maximum_count: 1
   delay_webhook_event: 0
-  scale_down_schedule_expression: cron(* * * * ? *)
   userdata_template: ./templates/user-data.sh
   ami:
     owners:

@@ -21,7 +21,6 @@ runner_config:
   enable_on_demand_failover_for_errors: ['InsufficientInstanceCapacity']
   create_service_linked_role_spot: true
   delay_webhook_event: 0
-  scale_down_schedule_expression: cron(* * * * ? *)
   runner_metadata_options:
     instance_metadata_tags: disabled
     http_endpoint: enabled

@@ -13,7 +13,6 @@ runner_config:
     - c5.large
   runners_maximum_count: 1
   delay_webhook_event: 5
-  scale_down_schedule_expression: cron(* * * * ? *)
   runner_boot_time_in_minutes: 20
   ami_filter:
     name:

@@ -298,8 +298,7 @@ async function createInstances(
 }
 
 // If launchTime is undefined, this will return false
-export function bootTimeExceeded(ec2Runner: { launchTime?: Date }): boolean {
-  const runnerBootTimeInMinutes = process.env.RUNNER_BOOT_TIME_IN_MINUTES;
+export function bootTimeExceeded(ec2Runner: { launchTime?: Date }, runnerBootTimeInMinutes: number): boolean {
   const launchTimePlusBootTime = moment(ec2Runner.launchTime).utc().add(runnerBootTimeInMinutes, 'minutes');
   return launchTimePlusBootTime < moment(new Date()).utc();
 }
@@ -14,8 +14,9 @@ declare namespace NodeJS {
     PARAMETER_GITHUB_APP_CLIENT_SECRET_NAME: string;
     PARAMETER_GITHUB_APP_ID_NAME: string;
     PARAMETER_GITHUB_APP_KEY_BASE64_NAME: string;
+    RUNNER_BOOT_TIME_IN_MINUTES: string;
     RUNNER_OWNER: string;
-    SCALE_DOWN_CONFIG: string;
+    SCALE_DOWN_CONFIG_SSM_PATH_PREFIX: string;
     SSM_TOKEN_PATH: string;
     SSM_CLEANUP_CONFIG: string;
     SUBNET_IDS: string;

@@ -37,6 +37,7 @@ export async function adjust(event: PoolEvent): Promise<void> {
   const instanceAllocationStrategy = process.env.INSTANCE_ALLOCATION_STRATEGY || 'lowest-price'; // same as AWS default
   const runnerOwner = process.env.RUNNER_OWNER;
   const amiIdSsmParameterName = process.env.AMI_ID_SSM_PARAMETER_NAME;
+  const runnerBootTimeInMinutes = parseInt(process.env.RUNNER_BOOT_TIME_IN_MINUTES || '5');
   const tracingEnabled = yn(process.env.POWERTOOLS_TRACE_ENABLED, { default: false });
   const onDemandFailoverOnError = process.env.ENABLE_ON_DEMAND_FAILOVER_FOR_ERRORS
     ? (JSON.parse(process.env.ENABLE_ON_DEMAND_FAILOVER_FOR_ERRORS) as [string])
@@ -63,7 +64,7 @@ export async function adjust(event: PoolEvent): Promise<void> {
     statuses: ['running'],
   });
 
-  const numberOfRunnersInPool = calculatePooSize(ec2runners, runnerStatusses);
+  const numberOfRunnersInPool = calculatePooSize(ec2runners, runnerStatusses, runnerBootTimeInMinutes);
   const topUp = event.poolSize - numberOfRunnersInPool;
 
   if (topUp > 0) {
@@ -115,7 +116,7 @@ async function getInstallationId(ghesApiUrl: string, org: string): Promise<numbe
   ).data.id;
 }
 
-function calculatePooSize(ec2runners: RunnerList[], runnerStatus: Map<string, RunnerStatus>): number {
+function calculatePooSize(ec2runners: RunnerList[], runnerStatus: Map<string, RunnerStatus>, runnerBootTimeInMinutes: number): number {
   // Runner should be considered idle if it is still booting, or is idle in GitHub
   let numberOfRunnersInPool = 0;
   for (const ec2Instance of ec2runners) {
@@ -127,7 +128,7 @@ function calculatePooSize(ec2runners: RunnerList[], runnerStatus: Map<string, Ru
       logger.debug(`Runner ${ec2Instance.instanceId} is idle in GitHub and counted as part of the pool`);
     } else if (runnerStatus.get(ec2Instance.instanceId) != null) {
       logger.debug(`Runner ${ec2Instance.instanceId} is not idle in GitHub and NOT counted as part of the pool`);
-    } else if (!bootTimeExceeded(ec2Instance)) {
+    } else if (!bootTimeExceeded(ec2Instance, runnerBootTimeInMinutes)) {
       numberOfRunnersInPool++;
       logger.info(`Runner ${ec2Instance.instanceId} is still booting and counted as part of the pool`);
     } else {