Merge pull request #3809 from stack72/f-aws-elasticache-cache-nodes-reduction

provider/aws: Ability to reduce nodes in an ElastiCache cluster

builtin/providers/aws/resource_aws_elasticache_cluster.go

@@ -395,8 +395,18 @@ func resourceAwsElasticacheClusterUpdate(d *schema.ResourceData, meta interface{
 	}
 
 	if d.HasChange("num_cache_nodes") {
+		oraw, nraw := d.GetChange("num_cache_nodes")
+		o := oraw.(int)
+		n := nraw.(int)
+		if n < o {
+			log.Printf("[INFO] Cluster %s is marked for Decreasing cache nodes from %d to %d", d.Id(), o, n)
+			nodesToRemove := getCacheNodesToRemove(d, o, o-n)
+			req.CacheNodeIdsToRemove = nodesToRemove
+		}
+
 		req.NumCacheNodes = aws.Int64(int64(d.Get("num_cache_nodes").(int)))
 		requestUpdate = true
+
 	}
 
 	if requestUpdate {
@@ -426,6 +436,16 @@ func resourceAwsElasticacheClusterUpdate(d *schema.ResourceData, meta interface{
 	return resourceAwsElasticacheClusterRead(d, meta)
 }
 
+func getCacheNodesToRemove(d *schema.ResourceData, oldNumberOfNodes int, cacheNodesToRemove int) []*string {
+	nodesIdsToRemove := []*string{}
+	for i := oldNumberOfNodes; i > oldNumberOfNodes-cacheNodesToRemove && i > 0; i-- {
+		s := fmt.Sprintf("%04d", i)
+		nodesIdsToRemove = append(nodesIdsToRemove, &s)
+	}
+
+	return nodesIdsToRemove
+}
+
 func setCacheNodeData(d *schema.ResourceData, c *elasticache.CacheCluster) error {
 	sortedCacheNodes := make([]*elasticache.CacheNode, len(c.CacheNodes))
 	copy(sortedCacheNodes, c.CacheNodes)

builtin/providers/aws/resource_aws_elasticache_cluster_test.go

@@ -72,6 +72,41 @@ func TestAccAWSElasticacheCluster_snapshotsWithUpdates(t *testing.T) {
 	})
 }
 
+func TestAccAWSElasticacheCluster_decreasingCacheNodes(t *testing.T) {
+	var ec elasticache.CacheCluster
+
+	ri := genRandInt()
+	preConfig := fmt.Sprintf(testAccAWSElasticacheClusterConfigDecreasingNodes, ri, ri, ri)
+	postConfig := fmt.Sprintf(testAccAWSElasticacheClusterConfigDecreasingNodes_update, ri, ri, ri)
+
+	resource.Test(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckAWSElasticacheClusterDestroy,
+		Steps: []resource.TestStep{
+			resource.TestStep{
+				Config: preConfig,
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAWSElasticacheSecurityGroupExists("aws_elasticache_security_group.bar"),
+					testAccCheckAWSElasticacheClusterExists("aws_elasticache_cluster.bar", &ec),
+					resource.TestCheckResourceAttr(
+						"aws_elasticache_cluster.bar", "num_cache_nodes", "3"),
+				),
+			},
+
+			resource.TestStep{
+				Config: postConfig,
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAWSElasticacheSecurityGroupExists("aws_elasticache_security_group.bar"),
+					testAccCheckAWSElasticacheClusterExists("aws_elasticache_cluster.bar", &ec),
+					resource.TestCheckResourceAttr(
+						"aws_elasticache_cluster.bar", "num_cache_nodes", "1"),
+				),
+			},
+		},
+	})
+}
+
 func TestAccAWSElasticacheCluster_vpc(t *testing.T) {
 	var csg elasticache.CacheSubnetGroup
 	var ec elasticache.CacheCluster
@@ -260,6 +295,71 @@ resource "aws_elasticache_cluster" "bar" {
 }
 `
 
+var testAccAWSElasticacheClusterConfigDecreasingNodes = `
+provider "aws" {
+	region = "us-east-1"
+}
+resource "aws_security_group" "bar" {
+    name = "tf-test-security-group-%03d"
+    description = "tf-test-security-group-descr"
+    ingress {
+        from_port = -1
+        to_port = -1
+        protocol = "icmp"
+        cidr_blocks = ["0.0.0.0/0"]
+    }
+}
+
+resource "aws_elasticache_security_group" "bar" {
+    name = "tf-test-security-group-%03d"
+    description = "tf-test-security-group-descr"
+    security_group_names = ["${aws_security_group.bar.name}"]
+}
+
+resource "aws_elasticache_cluster" "bar" {
+    cluster_id = "tf-test-%03d"
+    engine = "memcached"
+    node_type = "cache.m1.small"
+    num_cache_nodes = 3
+    port = 11211
+    parameter_group_name = "default.memcached1.4"
+    security_group_names = ["${aws_elasticache_security_group.bar.name}"]
+}
+`
+
+var testAccAWSElasticacheClusterConfigDecreasingNodes_update = `
+provider "aws" {
+	region = "us-east-1"
+}
+resource "aws_security_group" "bar" {
+    name = "tf-test-security-group-%03d"
+    description = "tf-test-security-group-descr"
+    ingress {
+        from_port = -1
+        to_port = -1
+        protocol = "icmp"
+        cidr_blocks = ["0.0.0.0/0"]
+    }
+}
+
+resource "aws_elasticache_security_group" "bar" {
+    name = "tf-test-security-group-%03d"
+    description = "tf-test-security-group-descr"
+    security_group_names = ["${aws_security_group.bar.name}"]
+}
+
+resource "aws_elasticache_cluster" "bar" {
+    cluster_id = "tf-test-%03d"
+    engine = "memcached"
+    node_type = "cache.m1.small"
+    num_cache_nodes = 1
+    port = 11211
+    parameter_group_name = "default.memcached1.4"
+    security_group_names = ["${aws_elasticache_security_group.bar.name}"]
+    apply_immediately = true
+}
+`
+
 var testAccAWSElasticacheClusterInVPCConfig = fmt.Sprintf(`
 resource "aws_vpc" "foo" {
     cidr_block = "192.168.0.0/16"