feat: lambda snap_start argument (#104)

Co-authored-by: Moritz Zimmer <moritzzimmer@users.noreply.github.com>

Author: dimitriydotsenko

README.md

@@ -422,6 +422,7 @@ No modules.
 | <a name="input_s3_bucket"></a> [s3\_bucket](#input\_s3\_bucket) | The S3 bucket location containing the function's deployment package. Conflicts with filename and image\_uri. This bucket must reside in the same AWS region where you are creating the Lambda function. | `string` | `null` | no |
 | <a name="input_s3_key"></a> [s3\_key](#input\_s3\_key) | The S3 key of an object containing the function's deployment package. Conflicts with filename and image\_uri. | `string` | `null` | no |
 | <a name="input_s3_object_version"></a> [s3\_object\_version](#input\_s3\_object\_version) | The object version containing the function's deployment package. Conflicts with filename and image\_uri. | `string` | `null` | no |
+| <a name="input_snap_start"></a> [snap\_start](#input\_snap\_start) | Enable snap start settings for low-latency startups. This feature is currently only supported for `java11` and `java17` runtimes and `x86_64` architectures. | `bool` | `false` | no |
 | <a name="input_sns_subscriptions"></a> [sns\_subscriptions](#input\_sns\_subscriptions) | Creates subscriptions to SNS topics which trigger your Lambda function. Required Lambda invocation permissions will be generated. | `map(any)` | `{}` | no |
 | <a name="input_source_code_hash"></a> [source\_code\_hash](#input\_source\_code\_hash) | Used to trigger updates. Must be set to a base64-encoded SHA256 hash of the package file specified with either filename or s3\_key. The usual way to set this is filebase64sha256('file.zip') where 'file.zip' is the local filename of the lambda function source archive. | `string` | `""` | no |
 | <a name="input_ssm"></a> [ssm](#input\_ssm) | List of AWS Systems Manager Parameter Store parameter names. The IAM role of this Lambda function will be enhanced with read permissions for those parameters. Parameters must start with a forward slash and can be encrypted with the default KMS key. | <pre>object({<br>    parameter_names = list(string)<br>  })</pre> | `null` | no |

main.tf

@@ -5,7 +5,7 @@ data "aws_partition" "current" {}
 locals {
   function_arn = "arn:${data.aws_partition.current.partition}:lambda:${data.aws_region.current.name}:${data.aws_caller_identity.current.account_id}:function:${var.function_name}"
   handler      = var.package_type != "Zip" ? null : var.handler
-  publish      = var.lambda_at_edge ? true : var.publish
+  publish      = var.lambda_at_edge || var.snap_start ? true : var.publish
   runtime      = var.package_type != "Zip" ? null : var.runtime
   timeout      = var.lambda_at_edge ? min(var.timeout, 5) : var.timeout
 }
@@ -69,6 +69,13 @@ resource "aws_lambda_function" "lambda" {
       subnet_ids         = vpc_config.value.subnet_ids
     }
   }
+
+  dynamic "snap_start" {
+    for_each = var.snap_start ? [true] : []
+    content {
+      apply_on = "PublishedVersions"
+    }
+  }
 }
 
 // Copy of the original Lambda resource plus lifecycle configuration ignoring
@@ -136,6 +143,13 @@ resource "aws_lambda_function" "lambda_external_lifecycle" {
     }
   }
 
+  dynamic "snap_start" {
+    for_each = var.snap_start ? [true] : []
+    content {
+      apply_on = "PublishedVersions"
+    }
+  }
+
   lifecycle {
     ignore_changes = [image_uri, last_modified, qualified_arn, qualified_invoke_arn, s3_object_version, version]
   }

variables.tf

@@ -235,3 +235,9 @@ variable "iam_role_name" {
   default     = null
   type        = string
 }
+
+variable "snap_start" {
+  description = "Enable snap start settings for low-latency startups. This feature is currently only supported for `java11` and `java17` runtimes and `x86_64` architectures."
+  default     = false
+  type        = bool
+}