availability sli for SLO monitoring resource

products/monitoring/api.yaml

@@ -1144,7 +1144,9 @@ objects:
               name: latency
               description: |
                 Parameters for a latency threshold SLI.
-              required: true
+              exactly_one_of:
+                - service_level_indicator.0.basic_sli.0.latency
+                - service_level_indicator.0.basic_sli.0.availability  
               properties:
               - !ruby/object:Api::Type::String
                 required: true
@@ -1153,6 +1155,19 @@ objects:
                   A duration string, e.g. 10s.
                   Good service is defined to be the count of requests made to
                   this service that return in no more than threshold.
+            - !ruby/object:Api::Type::NestedObject
+              name: availability
+              description: |
+                Availability based SLI, dervied from count of requests made to this service that return successfully.
+              exactly_one_of:
+                - service_level_indicator.0.basic_sli.0.latency
+                - service_level_indicator.0.basic_sli.0.availability
+              properties:
+                - !ruby/object:Api::Type::Boolean
+                  name: enabled
+                  default_value: true
+                  description: |
+                    Enable availability sli
         - !ruby/object:Api::Type::NestedObject
           name: requestBasedSli
           api_name: 'requestBased'

products/monitoring/terraform.yaml

@@ -194,6 +194,9 @@ overrides: !ruby/object:Overrides::ResourceOverrides
         is_set: true
       serviceLevelIndicator.basicSli.version: !ruby/object:Overrides::Terraform::PropertyOverride
         is_set: true
+      serviceLevelIndicator.basicSli.availability: !ruby/object:Overrides::Terraform::PropertyOverride
+        custom_expand: 'templates/terraform/custom_expand/monitoring_slo_availability_sli.go.erb'
+        custom_flatten: 'templates/terraform/custom_flatten/monitoring_slo_availability_sli.go.erb'
       serviceLevelIndicator.requestBasedSli: !ruby/object:Overrides::Terraform::PropertyOverride
         # Force update all nested fields to allow for unsetting values.
         update_mask_fields:

templates/terraform/custom_expand/monitoring_slo_availability_sli.go.erb

@@ -0,0 +1,22 @@
+<%- # the license inside this block applies to this file
+	# Copyright 2020 Google Inc.
+	# Licensed under the Apache License, Version 2.0 (the "License");
+	# you may not use this file except in compliance with the License.
+	# You may obtain a copy of the License at
+	#
+	#     http://www.apache.org/licenses/LICENSE-2.0
+	#
+	# Unless required by applicable law or agreed to in writing, software
+	# distributed under the License is distributed on an "AS IS" BASIS,
+	# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+	# See the License for the specific language governing permissions and
+	# limitations under the License.
+-%>
+func expand<%= prefix -%><%= titlelize_property(property) -%>(v interface{}, d TerraformResourceData, config *Config) (interface{}, error) {
+	l := v.([]interface{})
+	if len(l) == 0 {
+		return nil, nil
+	}
+
+	return struct{}{}, nil
+}

templates/terraform/custom_flatten/monitoring_slo_availability_sli.go.erb

@@ -0,0 +1,33 @@
+<%# The license inside this block applies to this file.
+	# Copyright 2020 Google Inc.
+	# Licensed under the Apache License, Version 2.0 (the "License");
+	# you may not use this file except in compliance with the License.
+	# You may obtain a copy of the License at
+	#
+	#     http://www.apache.org/licenses/LICENSE-2.0
+	#
+	# Unless required by applicable law or agreed to in writing, software
+	# distributed under the License is distributed on an "AS IS" BASIS,
+	# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+	# See the License for the specific language governing permissions and
+	# limitations under the License.
+-%>
+func flatten<%= prefix -%><%= titlelize_property(property) -%>(v interface{}, d *schema.ResourceData, config *Config) interface{} {
+    if v == nil {
+		return nil
+	}
+	original := v.(map[string]interface{})
+	transformed := make(map[string]interface{})
+	transformed["enabled"] =
+		flattenMonitoringSloServiceLevelIndicatorBasicSliAvailabilityEnabled(original["enabled"], d, config)
+	return []interface{}{transformed}
+}
+
+
+func flattenMonitoringSloServiceLevelIndicatorBasicSliAvailabilityEnabled(v interface{}, d *schema.ResourceData, config *Config) interface{} {
+	if v == nil || isEmptyValue(reflect.ValueOf(v)) {
+		return true
+	}
+
+	return v
+}

third_party/terraform/tests/resource_monitoring_slo_test.go

@@ -104,6 +104,29 @@ func TestAccMonitoringSlo_basic(t *testing.T) {
 	})
 }
 
+func TestAccMonitoringSlo_availabilitySli(t *testing.T) {
+	t.Parallel()
+
+	var generatedId string
+	vcrTest(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckMonitoringSloDestroyProducer(t),
+		Steps: []resource.TestStep{
+			{
+				Config: testAccMonitoringSlo_availabilitySli(),
+				Check:  setTestCheckMonitoringSloId("google_monitoring_slo.primary", &generatedId),
+			},
+			{
+				ResourceName:      "google_monitoring_slo.primary",
+				ImportState:       true,
+				ImportStateVerify: true,
+				// Ignore input-only field for import
+				ImportStateVerifyIgnore: []string{"service"},
+			},
+		},
+	})
+}
 func TestAccMonitoringSlo_requestBased(t *testing.T) {
 	t.Parallel()
 
@@ -409,6 +432,25 @@ resource "google_monitoring_slo" "primary" {
 `
 }
 
+func testAccMonitoringSlo_availabilitySli() string {
+	return `
+data "google_monitoring_app_engine_service" "ae" {
+  module_id = "default"
+}
+
+resource "google_monitoring_slo" "primary" {
+  service = data.google_monitoring_app_engine_service.ae.service_id
+
+  goal = 0.9
+  rolling_period_days = 1
+
+  basic_sli {
+	availability {
+	}
+  }
+}
+`
+}
 func testAccMonitoringSloForSli(randSuffix, sliConfig string) string {
 	return fmt.Sprintf(`
 resource "google_monitoring_custom_service" "srv" {