Merge ~cjwatson/squid-reverseproxy-charm:services-only-from-config into squid-reverseproxy-charm:master

[Colin Watson]

Add services_only_from_config config setting

In some circumstances it is desirable for the charm to only re-export a subset of the services it consumes. This allows that.

I grabbed this from the snap store's fork of this charm: the store uses it as part of an arrangement to cache some names and search requests with different rate-limiting. I also need it for Launchpad in order to be able to write Apache virtual host configurations that send some requests through to haproxy via Squid but some requests directly to haproxy, for the same service (in our case we use this to selectively cache things based on whether the header indicate an attempt to authenticate). With two use cases, I think that makes it worth trying to get it into the mainline charm.

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[Tom Haddon (mthaddon)]

LGTM

review: Approve

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change successfully merged at revision d5133d08cae926fd89b9a7434fdbf6a66817004e

diff --git a/config.yaml b/config.yaml
index 99267bb..f0fea05 100644
--- a/config.yaml
+++ b/config.yaml
@@ -171,6 +171,10 @@ options:
           servers:
           - [foo.internal, 80]
           - [bar.internal, 80]
+  services_only_from_config:
+    default: false
+    type: boolean
+    description: Ignore services from relations unless configured in 'services'.
   enable_forward_proxy:
     default: false
     type: boolean
diff --git a/hooks/hooks.py b/hooks/hooks.py
index 73672a0..dad3b84 100755
--- a/hooks/hooks.py
+++ b/hooks/hooks.py
@@ -142,10 +142,14 @@ def get_reverse_sites():
     if len(all_sites) == 0:
         return
 
+    final_sites = {}
     for site, servers in all_sites.items():
-        servers.sort()
+        if (config_data.get("services_only_from_config")
+                and site not in server_options_by_site):
+            continue
+        final_sites[site] = sorted(servers)
 
-    return all_sites
+    return final_sites
 
 
 def get_auth_params():
diff --git a/hooks/tests/test_website_hooks.py b/hooks/tests/test_website_hooks.py
index 6f22bb7..e9a115f 100644
--- a/hooks/tests/test_website_hooks.py
+++ b/hooks/tests/test_website_hooks.py
@@ -266,3 +266,29 @@ class WebsiteRelationTest(TestCase):
         self.config_get.return_value = Serializable({
             "services": ""})
         self.assertEqual(None, hooks.get_reverse_sites())
+
+    def test_services_only_from_config(self):
+        self.relations_of_type.return_value = [
+            {"private-address": "1.2.3.4",
+             "__unit__": "foo/1",
+             "__relid__": "website:1",
+             "all_services": yaml.dump([
+                 {"service_name": "foo.internal",
+                  "service_port": 4242},
+                 {"service_name": "bar.internal",
+                  "service_port": 4243}
+                 ]),
+             },
+            ]
+        self.config_get.return_value = Serializable({
+            "services": yaml.dump([
+                {"service_name": "foo.internal", "servers": []},
+                ]),
+            "services_only_from_config": True,
+            })
+        expected = {
+            "foo.internal": [
+                ("foo_internal__website_1__foo_1", "1.2.3.4", 4242, ""),
+                ],
+            }
+        self.assertEqual(expected, hooks.get_reverse_sites())