CCM-12059: Improve Eventpub Lambda Build - Build only when changed

Author: jamesthompson26-nhs

infrastructure/modules/eventpub/lambda_function.tf

@@ -9,8 +9,9 @@ resource "aws_lambda_function" "main" {
   memory_size = 128
   timeout     = 20
 
-  filename         = archive_file.lambda.output_path
-  source_code_hash = archive_file.lambda.output_base64sha256
+  s3_bucket         = aws_s3_object.lambda.bucket
+  s3_key            = aws_s3_object.lambda.key
+  s3_object_version = aws_s3_object.lambda.version_id
 
   logging_config {
     application_log_level = var.log_level

infrastructure/modules/eventpub/s3_object_lambda.tf

@@ -0,0 +1,19 @@
+resource "aws_s3_object" "lambda" {
+  bucket = var.function_s3_bucket
+  key    = "${local.csi}.zip"
+  source = data.archive_file.lambda.output_path
+
+  source_hash = var.force_lambda_code_deploy ? data.archive_file.lambda.output_base64sha256 : null
+
+  metadata = {
+    hash     = data.archive_file.lambda.output_base64sha256
+    function = local.csi
+    commit   = try(data.external.git_commit.result["sha"], "null")
+  }
+
+  lifecycle {
+    ignore_changes = [
+      metadata["commit"]
+    ]
+  }
+}

infrastructure/modules/eventpub/variables.tf

@@ -123,3 +123,14 @@ variable "force_destroy" {
   description = "When enabled will force destroy event-cache S3 bucket"
   default     = false
 }
+
+variable "function_s3_bucket" {
+  type        = string
+  description = "The bucket to upload Lambda packages to"
+}
+
+variable "force_lambda_code_deploy" {
+  type        = bool
+  description = "If the lambda package in s3 has the same commit id tag as the terraform build branch, the lambda will not update automatically. Set to True if making changes to Lambda code from on the same commit for example during development"
+  default     = false
+}