fixes #8230

aws/resource_aws_cloudwatch_log_subscription_filter.go

@@ -54,6 +54,13 @@ func resourceAwsCloudwatchLogSubscriptionFilter() *schema.Resource {
 			"distribution": {
 				Type:     schema.TypeString,
 				Optional: true,
+				DiffSuppressFunc: func(k, old, new string, d *schema.ResourceData) bool {
+					// Ignore unsetting default value
+					if old == "ByLogStream" && new == "" {
+						return true
+					}
+					return false
+				},
 			},
 		},
 	}

aws/resource_aws_cloudwatch_log_subscription_filter_test.go

@@ -35,6 +35,18 @@ func TestAccAWSCloudwatchLogSubscriptionFilter_basic(t *testing.T) {
 						"aws_cloudwatch_log_subscription_filter.test_lambdafunction_logfilter", "distribution", "Random"),
 				),
 			},
+			{
+				Config: testAccAWSCloudwatchLogSubscriptionFilterConfigUnsetDistribution(rstring),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAwsCloudwatchLogSubscriptionFilterExists("aws_cloudwatch_log_subscription_filter.test_lambdafunction_logfilter", &filter, rstring),
+					resource.TestCheckResourceAttr(
+						"aws_cloudwatch_log_subscription_filter.test_lambdafunction_logfilter", "filter_pattern", "logtype test"),
+					resource.TestCheckResourceAttr(
+						"aws_cloudwatch_log_subscription_filter.test_lambdafunction_logfilter", "name", fmt.Sprintf("test_lambdafunction_logfilter_%s", rstring)),
+					resource.TestCheckResourceAttr(
+						"aws_cloudwatch_log_subscription_filter.test_lambdafunction_logfilter", "log_group_name", fmt.Sprintf("example_lambda_name_%s", rstring)),
+				),
+			},
 			{
 				ResourceName:      "aws_cloudwatch_log_subscription_filter.test_lambdafunction_logfilter",
 				ImportState:       true,
@@ -266,3 +278,77 @@ EOF
 }
 `, rstring, rstring, rstring, rstring, rstring)
 }
+
+func testAccAWSCloudwatchLogSubscriptionFilterConfigUnsetDistribution(rstring string) string {
+	return fmt.Sprintf(`
+resource "aws_cloudwatch_log_subscription_filter" "test_lambdafunction_logfilter" {
+  name            = "test_lambdafunction_logfilter_%s"
+  log_group_name  = "${aws_cloudwatch_log_group.logs.name}"
+  filter_pattern  = "logtype test"
+  destination_arn = "${aws_lambda_function.test_lambdafunction.arn}"  
+}
+
+resource "aws_lambda_function" "test_lambdafunction" {
+  filename      = "test-fixtures/lambdatest.zip"
+  function_name = "example_lambda_name_%s"
+  role          = "${aws_iam_role.iam_for_lambda.arn}"
+  runtime       = "nodejs8.10"
+  handler       = "exports.handler"
+}
+
+resource "aws_cloudwatch_log_group" "logs" {
+  name              = "example_lambda_name_%s"
+  retention_in_days = 1
+}
+
+resource "aws_lambda_permission" "allow_cloudwatch_logs" {
+  statement_id  = "AllowExecutionFromCloudWatchLogs"
+  action        = "lambda:*"
+  function_name = "${aws_lambda_function.test_lambdafunction.arn}"
+  principal     = "logs.amazonaws.com"
+}
+
+resource "aws_iam_role" "iam_for_lambda" {
+  name = "test_lambdafuntion_iam_role_%s"
+
+  assume_role_policy = <<EOF
+{
+  "Version": "2012-10-17",
+  "Statement": [
+    {
+      "Action": "sts:AssumeRole",
+      "Principal": {
+        "Service": "lambda.amazonaws.com"
+      },
+      "Effect": "Allow",
+      "Sid": ""
+    }
+  ]
+}
+EOF
+}
+
+resource "aws_iam_role_policy" "test_lambdafunction_iam_policy" {
+  name = "test_lambdafunction_iam_policy_%s"
+  role = "${aws_iam_role.iam_for_lambda.id}"
+
+  policy = <<EOF
+{
+  "Version": "2012-10-17",
+  "Statement": [
+    {
+      "Sid": "Stmt1441111030000",
+      "Effect": "Allow",
+      "Action": [
+        "lambda:*"
+      ],
+      "Resource": [
+        "*"
+      ]
+    }
+  ]
+}
+EOF
+}
+`, rstring, rstring, rstring, rstring, rstring)
+}