Merge ~hloeung/charm-k8s-content-cache:master into charm-k8s-content-cache:master

[Haw Loeung]

Fixed to set correct 'Host' header for backend and allow overriding

Output from testing:

| https://paste.ubuntu.com/p/5dKg4VYM5j/

[Tom Haddon (mthaddon)]

One comment inline

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

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

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

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[Tom Haddon (mthaddon)]

LGTM, thx

review: Approve

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

Change successfully merged at revision 527b86c405c14cebee3d884e64d238ef2035da62

diff --git a/config.yaml b/config.yaml
index d7dcb7c..62c80f4 100644
--- a/config.yaml
+++ b/config.yaml
@@ -29,6 +29,12 @@ options:
       The backend to use for site, e.g. "http://mybackend.local:80"
 
       This setting is required.
+  backend_site_name:
+    type: string
+    description: >-
+      Backend site name, e.g. mybackend.local. If none given, will
+      work out from the configured 'backend' config above.
+    default: ""
   cache_inactive_time:
     type: string
     description: >-
diff --git a/docker/templates/nginx_cfg.tmpl b/docker/templates/nginx_cfg.tmpl
index 4e1ceb3..2e777e9 100644
--- a/docker/templates/nginx_cfg.tmpl
+++ b/docker/templates/nginx_cfg.tmpl
@@ -11,7 +11,7 @@ server {
 
     location / {
         proxy_pass \"${NGINX_BACKEND}\";
-        proxy_set_header Host \"${NGINX_SITE_NAME}\";
+        proxy_set_header Host \"${NGINX_BACKEND_SITE_NAME}\";
         # Removed the following headers to avoid cache poisoning.
         proxy_set_header Forwarded \"\";
         proxy_set_header X-Forwarded-Host \"\";
diff --git a/src/charm.py b/src/charm.py
index 171e521..e8decc4 100755
--- a/src/charm.py
+++ b/src/charm.py
@@ -5,6 +5,7 @@
 
 import hashlib
 import logging
+from urllib.parse import urlparse
 
 from ops.charm import CharmBase
 from ops.main import main
@@ -183,12 +184,18 @@ class ContentCacheCharm(CharmBase):
         """Return dict to be used as pod spec's envConfig."""
         config = self.model.config
 
+        backend = config['backend']
+        backend_site_name = config.get('backend_site_name')
+        if not backend_site_name:
+            backend_site_name = urlparse(backend).hostname
+
         client_max_body_size = '1m'
         if config.get('client_max_body_size'):
             client_max_body_size = config.get('client_max_body_size')
 
         pod_config = {
-            'NGINX_BACKEND': config['backend'],
+            'NGINX_BACKEND': backend,
+            'NGINX_BACKEND_SITE_NAME': backend_site_name,
             'NGINX_CACHE_INACTIVE_TIME': config.get('cache_inactive_time', '10m'),
             'NGINX_CACHE_MAX_SIZE': config.get('cache_max_size', '10G'),
             'NGINX_CACHE_PATH': CACHE_PATH,
diff --git a/tests/test_charm.py b/tests/test_charm.py
index 02466ed..bd918fd 100644
--- a/tests/test_charm.py
+++ b/tests/test_charm.py
@@ -340,6 +340,32 @@ class TestCharm(unittest.TestCase):
         harness.update_config(config)
         expected = {
             'NGINX_BACKEND': 'http://mybackend.local:80',
+            'NGINX_BACKEND_SITE_NAME': 'mybackend.local',
+            'NGINX_CACHE_INACTIVE_TIME': '10m',
+            'NGINX_CACHE_MAX_SIZE': '10G',
+            'NGINX_CACHE_PATH': CACHE_PATH,
+            'NGINX_CACHE_USE_STALE': 'error timeout updating http_500 http_502 http_503 http_504',
+            'NGINX_CACHE_VALID': '200 1h',
+            'NGINX_CLIENT_MAX_BODY_SIZE': '1m',
+            'NGINX_KEYS_ZONE': '39c631ffb52d-cache',
+            'NGINX_SITE_NAME': 'mysite.local',
+        }
+        expected.update(JUJU_ENV_CONFIG)
+        self.assertEqual(harness.charm._make_pod_config(), expected)
+
+    def test_make_pod_config_backend_site_name(self):
+        """Test make_pod_config with charm config backend_site_config, ensure envConfig returned is correct."""
+        harness = self.harness
+
+        harness.disable_hooks()
+        harness.begin()
+
+        config = copy.deepcopy(BASE_CONFIG)
+        config['backend_site_name'] = 'myoverridebackendsitename.local'
+        harness.update_config(config)
+        expected = {
+            'NGINX_BACKEND': 'http://mybackend.local:80',
+            'NGINX_BACKEND_SITE_NAME': 'myoverridebackendsitename.local',
             'NGINX_CACHE_INACTIVE_TIME': '10m',
             'NGINX_CACHE_MAX_SIZE': '10G',
             'NGINX_CACHE_PATH': CACHE_PATH,
@@ -364,6 +390,7 @@ class TestCharm(unittest.TestCase):
         harness.update_config(config)
         expected = {
             'NGINX_BACKEND': 'http://mybackend.local:80',
+            'NGINX_BACKEND_SITE_NAME': 'mybackend.local',
             'NGINX_CACHE_INACTIVE_TIME': '10m',
             'NGINX_CACHE_MAX_SIZE': '10G',
             'NGINX_CACHE_PATH': CACHE_PATH,