Configure DNS refresh rate from DNS record TTL

charts/ambassador/crds/getambassador.io_mappings.yaml

@@ -371,6 +371,8 @@ spec:
               - type: array
             resolver:
               type: string
+            respect_dns_ttl:
+              type: boolean
             retry_policy:
               properties:
                 num_retries:

docs/yaml/ambassador/ambassador-crds.yaml

@@ -1078,6 +1078,8 @@ spec:
               - type: array
             resolver:
               type: string
+            respect_dns_ttl:
+              type: boolean
             retry_policy:
               properties:
                 num_retries:

docs/yaml/ambassador/ambassador-rbac-prometheus.yaml

@@ -1142,6 +1142,8 @@ spec:
               - type: array
             resolver:
               type: string
+            respect_dns_ttl:
+              type: boolean
             retry_policy:
               properties:
                 num_retries:

manifests/ambassador/ambassador-crds.yaml

@@ -1078,6 +1078,8 @@ spec:
               - type: array
             resolver:
               type: string
+            respect_dns_ttl:
+              type: boolean
             retry_policy:
               properties:
                 num_retries:

pkg/api/getambassador.io/v2/mapping_types.go

@@ -49,6 +49,7 @@ type MappingSpec struct {
 	KeepAlive          *KeepAlive             `json:"keepalive,omitempty"`
 	CORS               *CORS                  `json:"cors,omitempty"`
 	RetryPolicy        *RetryPolicy           `json:"retry_policy,omitempty"`
+	RespectDNSTTL      *bool                  `json:"respect_dns_ttl,omitempty"`
 	GRPC               *bool                  `json:"grpc,omitempty"`
 	HostRedirect       *bool                  `json:"host_redirect,omitempty"`
 	HostRewrite        string                 `json:"host_rewrite,omitempty"`

python/ambassador/envoy/v2/v2cluster.py

@@ -67,6 +67,9 @@ def __init__(self, config: 'V2Config', cluster: IRCluster) -> None:
             'dns_lookup_family': dns_lookup_family
         }
 
+        if cluster.respect_dns_ttl:
+            fields['respect_dns_ttl'] = cluster.respect_dns_ttl
+
         if ctype == 'EDS':
             fields['eds_cluster_config'] = { 'eds_config': {'ads': {}},
                                              'service_name': cmap_entry['endpoint_path']}

python/ambassador/envoy/v3/v3cluster.py

@@ -67,6 +67,9 @@ def __init__(self, config: 'V3Config', cluster: IRCluster) -> None:
             'dns_lookup_family': dns_lookup_family
         }
 
+        if cluster.respect_dns_ttl:
+            fields['respect_dns_ttl'] = cluster.respect_dns_ttl
+
         if ctype == 'EDS':
             fields['eds_cluster_config'] = {
                 'eds_config': {

python/ambassador/ir/ircluster.py

@@ -61,6 +61,7 @@ def __init__(self, ir: 'IR', aconf: Config, parent_ir_resource: 'IRResource',
                  load_balancer: Optional[dict] = None,
                  keepalive: Optional[dict] = None,
                  circuit_breakers: Optional[list] = None,
+                 respect_dns_ttl: Optional[bool] = False,
 
                  rkey: str="-override-",
                  kind: str="IRCluster",
@@ -284,6 +285,7 @@ def __init__(self, ir: 'IR', aconf: Config, parent_ir_resource: 'IRResource',
             'connect_timeout_ms': connect_timeout_ms,
             'cluster_idle_timeout_ms': cluster_idle_timeout_ms,
             'cluster_max_connection_lifetime_ms': cluster_max_connection_lifetime_ms,
+            'respect_dns_ttl': respect_dns_ttl,
         }
 
         if grpc:

python/ambassador/ir/irhttpmapping.py

@@ -117,6 +117,7 @@ class IRHTTPMapping (IRBaseMapping):
         "remove_request_headers": True,
         "remove_response_headers": True,
         "resolver": False,
+        "respect_dns_ttl": False,
         "retry_policy": False,
         # Do not include rewrite
         "service": False,       # See notes above

python/ambassador/ir/irhttpmappinggroup.py

@@ -250,7 +250,8 @@ def add_cluster_for_mapping(self, mapping: IRBaseMapping,
                                 cluster_idle_timeout_ms=mapping.get('cluster_idle_timeout_ms', None),
                                 cluster_max_connection_lifetime_ms=mapping.get('cluster_max_connection_lifetime_ms', None),
                                 circuit_breakers=mapping.get('circuit_breakers', None),
-                                marker=marker)
+                                marker=marker,
+                                respect_dns_ttl=mapping.get('respect_dns_ttl', False))
 
         # Make sure that the cluster is actually in our IR...
         stored = self.ir.add_cluster(cluster)

python/schemas/v2/Mapping.schema

@@ -207,6 +207,7 @@
         "host_regex": { "type": "boolean" },
         "headers": { "$ref": "#/definitions/mapStrStr" },
         "regex_headers": { "$ref": "#/definitions/mapStrStr" },
+        "respect_dns_ttl": { "type": "boolean" },
         "labels": {
             "type": "object"
         },

python/tests/kat/t_dns_type.py

@@ -54,3 +54,79 @@ def check(self):
         # Not getting a 400 bad request is confirmation that this setting works as long as the request can reach the upstream
         assert self.results[0].status == 200
 
+# Tests Respecting DNS TTL alone
+class DnsTtl(AmbassadorTest):
+    target: ServiceType
+
+    def init(self):
+        self.target = HTTP(name="target")
+
+    def config(self):
+        yield self, self.format("""
+---
+apiVersion: ambassador/v2
+kind:  Mapping
+name:  {self.target.path.k8s}-foo
+prefix: /foo/
+service: {self.target.path.fqdn}
+respect_dns_ttl: true
+""")
+
+    def queries(self):
+        yield Query(self.url("foo/"))
+
+    def check(self):
+        # Not getting a 400 bad request is confirmation that this setting works as long as the request can reach the upstream
+        assert self.results[0].status == 200
+
+# Tests the DNS TTL with the endpoint resolver
+class DnsTtlEndpoint(AmbassadorTest):
+    target: ServiceType
+
+    def init(self):
+        self.target = HTTP(name="target")
+
+    def config(self):
+        yield self, self.format("""
+---
+apiVersion: ambassador/v2
+kind:  Mapping
+name:  {self.target.path.k8s}-foo
+prefix: /foo/
+service: {self.target.path.fqdn}
+respect_dns_ttl: true
+resolver: endpoint
+""")
+
+    def queries(self):
+        yield Query(self.url("foo/"))
+
+    def check(self):
+        # Not getting a 400 bad request is confirmation that this setting works as long as the request can reach the upstream
+        assert self.results[0].status == 200
+
+# Tests the DNS TTL with Logical DNS type
+class DnsTtlDnsType(AmbassadorTest):
+    target: ServiceType
+
+    def init(self):
+        self.target = HTTP(name="target")
+
+    def config(self):
+        yield self, self.format("""
+---
+apiVersion: ambassador/v2
+kind:  Mapping
+name:  {self.target.path.k8s}-foo
+prefix: /foo/
+service: {self.target.path.fqdn}
+respect_dns_ttl: true
+dns_type: logical_dns
+""")
+
+    def queries(self):
+        yield Query(self.url("foo/"))
+
+    def check(self):
+        # Not getting a 400 bad request is confirmation that this setting works as long as the request can reach the upstream
+        assert self.results[0].status == 200

python/tests/test_cluster_options.py

@@ -69,3 +69,20 @@ def test_logical_dns_type_wrong():
         _test_cluster_setting(yaml, setting="type", 
             expected="EDS", exists=True, envoy_version=v)
 
+@pytest.mark.compilertest
+def test_dns_ttl():
+    # Test configuring the respect_dns_ttl generates an Envoy config
+    yaml = module_and_mapping_manifests(None, ["respect_dns_ttl: true"])
+    for v in SUPPORTED_ENVOY_VERSIONS:
+        # The dns type is listed as just "type"
+        _test_cluster_setting(yaml, setting="respect_dns_ttl", 
+            expected="true", exists=True, envoy_version=v)
+
+@pytest.mark.compilertest
+def test_dns_ttl():
+    # Test dns_ttl is not configured when not applied in the Mapping
+    yaml = module_and_mapping_manifests(None, None)
+    for v in SUPPORTED_ENVOY_VERSIONS:
+        # The dns type is listed as just "type"
+        _test_cluster_setting(yaml, setting="respect_dns_ttl", 
+            expected="false", exists=False, envoy_version=v)