feat: Add option to configure concurrent running scale up lambda (#1415)

Allow > 1 reserved_concurrent_executions for the scale-up lambda
function. This is needed when using a strategy matrix in a workflow.

Author: heathsnow

Diff for: README.md

@@ -417,6 +417,7 @@ In case the setup does not work as intended follow the trace of events:
 | <a name="input_runners_scale_down_lambda_timeout"></a> [runners\_scale\_down\_lambda\_timeout](#input\_runners\_scale\_down\_lambda\_timeout) | Time out for the scale down lambda in seconds. | `number` | `60` | 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` | `180` | 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_subnet_ids"></a> [subnet\_ids](#input\_subnet\_ids) | List of subnets in which the action runners will be launched, the subnets needs to be subnets in the `vpc_id`. | `list(string)` | n/a | yes |
 | <a name="input_syncer_lambda_s3_key"></a> [syncer\_lambda\_s3\_key](#input\_syncer\_lambda\_s3\_key) | S3 key for syncer lambda function. Required if using S3 bucket to specify lambdas. | `any` | `null` | no |
 | <a name="input_syncer_lambda_s3_object_version"></a> [syncer\_lambda\_s3\_object\_version](#input\_syncer\_lambda\_s3\_object\_version) | S3 object version for syncer lambda function. Useful if S3 versioning is enabled on source bucket. | `any` | `null` | no |

Diff for: main.tf

@@ -119,6 +119,8 @@ module "runners" {
   runner_log_files                 = var.runner_log_files
   runner_group_name                = var.runner_group_name
 
+  scale_up_reserved_concurrent_executions = var.scale_up_reserved_concurrent_executions
+
   instance_profile_path     = var.instance_profile_path
   role_path                 = var.role_path
   role_permissions_boundary = var.role_permissions_boundary

Diff for: modules/runners/README.md

@@ -156,6 +156,7 @@ No modules.
 | <a name="input_s3_bucket_runner_binaries"></a> [s3\_bucket\_runner\_binaries](#input\_s3\_bucket\_runner\_binaries) | n/a | <pre>object({<br>    arn = string<br>  })</pre> | n/a | yes |
 | <a name="input_s3_location_runner_binaries"></a> [s3\_location\_runner\_binaries](#input\_s3\_location\_runner\_binaries) | S3 location of runner distribution. | `string` | n/a | yes |
 | <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_sqs_build_queue"></a> [sqs\_build\_queue](#input\_sqs\_build\_queue) | SQS queue to consume accepted build events. | <pre>object({<br>    arn = string<br>  })</pre> | n/a | yes |
 | <a name="input_subnet_ids"></a> [subnet\_ids](#input\_subnet\_ids) | List of subnets in which the action runners will be launched, the subnets needs to be subnets in the `vpc_id`. | `list(string)` | n/a | yes |
 | <a name="input_tags"></a> [tags](#input\_tags) | Map of tags that will be added to created resources. By default resources will be tagged with name and environment. | `map(string)` | `{}` | no |

Diff for: modules/runners/scale-up.tf

@@ -9,7 +9,7 @@ resource "aws_lambda_function" "scale_up" {
   handler                        = "index.scaleUpHandler"
   runtime                        = "nodejs14.x"
   timeout                        = var.lambda_timeout_scale_up
-  reserved_concurrent_executions = 1
+  reserved_concurrent_executions = var.scale_up_reserved_concurrent_executions
   memory_size                    = 512
   tags                           = local.tags
 

Diff for: modules/runners/variables.tf

@@ -163,6 +163,12 @@ variable "lambda_timeout_scale_down" {
   default     = 60
 }
 
+variable "scale_up_reserved_concurrent_executions" {
+  description = "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."
+  type        = number
+  default     = 1
+}
+
 variable "lambda_timeout_scale_up" {
   description = "Time out for the scale up lambda in seconds."
   type        = number

Diff for: variables.tf

@@ -69,6 +69,12 @@ variable "runner_group_name" {
   default     = "Default"
 }
 
+variable "scale_up_reserved_concurrent_executions" {
+  description = "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."
+  type        = number
+  default     = 1
+}
+
 variable "webhook_lambda_zip" {
   description = "File location of the webhook lambda zip file."
   type        = string