Add new field filter to pubsub.

.changelog/3759.txt

@@ -0,0 +1,3 @@
+```release-note:enhancement
+pubsub: added `filter` field to `google_pubsub_subscription` resource
+```

google/resource_pubsub_subscription.go

@@ -168,6 +168,15 @@ Example - "3.5s".`,
 					},
 				},
 			},
+			"filter": {
+				Type:     schema.TypeString,
+				Optional: true,
+				ForceNew: true,
+				Description: `The subscription only delivers the messages that match the filter. 
+Pub/Sub automatically acknowledges the messages that don't match the filter. You can filter messages
+by their attributes. The maximum length of a filter is 256 bytes. After creating the subscription, 
+you can't modify the filter.`,
+			},
 			"labels": {
 				Type:        schema.TypeMap,
 				Optional:    true,
@@ -338,6 +347,12 @@ func resourcePubsubSubscriptionCreate(d *schema.ResourceData, meta interface{})
 	} else if v, ok := d.GetOkExists("expiration_policy"); ok || !reflect.DeepEqual(v, expirationPolicyProp) {
 		obj["expirationPolicy"] = expirationPolicyProp
 	}
+	filterProp, err := expandPubsubSubscriptionFilter(d.Get("filter"), d, config)
+	if err != nil {
+		return err
+	} else if v, ok := d.GetOkExists("filter"); !isEmptyValue(reflect.ValueOf(filterProp)) && (ok || !reflect.DeepEqual(v, filterProp)) {
+		obj["filter"] = filterProp
+	}
 	deadLetterPolicyProp, err := expandPubsubSubscriptionDeadLetterPolicy(d.Get("dead_letter_policy"), d, config)
 	if err != nil {
 		return err
@@ -472,6 +487,9 @@ func resourcePubsubSubscriptionRead(d *schema.ResourceData, meta interface{}) er
 	if err := d.Set("expiration_policy", flattenPubsubSubscriptionExpirationPolicy(res["expirationPolicy"], d, config)); err != nil {
 		return fmt.Errorf("Error reading Subscription: %s", err)
 	}
+	if err := d.Set("filter", flattenPubsubSubscriptionFilter(res["filter"], d, config)); err != nil {
+		return fmt.Errorf("Error reading Subscription: %s", err)
+	}
 	if err := d.Set("dead_letter_policy", flattenPubsubSubscriptionDeadLetterPolicy(res["deadLetterPolicy"], d, config)); err != nil {
 		return fmt.Errorf("Error reading Subscription: %s", err)
 	}
@@ -738,6 +756,10 @@ func flattenPubsubSubscriptionExpirationPolicyTtl(v interface{}, d *schema.Resou
 	return v
 }
 
+func flattenPubsubSubscriptionFilter(v interface{}, d *schema.ResourceData, config *Config) interface{} {
+	return v
+}
+
 func flattenPubsubSubscriptionDeadLetterPolicy(v interface{}, d *schema.ResourceData, config *Config) interface{} {
 	if v == nil {
 		return nil
@@ -931,6 +953,10 @@ func expandPubsubSubscriptionExpirationPolicyTtl(v interface{}, d TerraformResou
 	return v, nil
 }
 
+func expandPubsubSubscriptionFilter(v interface{}, d TerraformResourceData, config *Config) (interface{}, error) {
+	return v, nil
+}
+
 func expandPubsubSubscriptionDeadLetterPolicy(v interface{}, d TerraformResourceData, config *Config) (interface{}, error) {
 	l := v.([]interface{})
 	if len(l) == 0 || l[0] == nil {

google/resource_pubsub_subscription_test.go

@@ -219,8 +219,9 @@ resource "google_pubsub_topic" "foo" {
 }
 
 resource "google_pubsub_subscription" "foo" {
-  name  = "%s"
-  topic = google_pubsub_topic.foo.id
+  name   = "%s"
+  topic  = google_pubsub_topic.foo.id
+  filter = "attributes.foo = \"bar\""
   labels = {
     foo = "%s"
   }

website/docs/r/pubsub_subscription.html.markdown

@@ -210,6 +210,13 @@ The following arguments are supported:
   is 1 day.
   Structure is documented below.
 
+* `filter` -
+  (Optional)
+  The subscription only delivers the messages that match the filter. 
+  Pub/Sub automatically acknowledges the messages that don't match the filter. You can filter messages
+  by their attributes. The maximum length of a filter is 256 bytes. After creating the subscription, 
+  you can't modify the filter.
+
 * `dead_letter_policy` -
   (Optional)
   A policy that specifies the conditions for dead lettering messages in