#73 implement --cluster-registry-url option

kube_ops_view/cluster_discovery.py

@@ -1,13 +1,30 @@
+import time
+from urllib.parse import urljoin
+
 import kubernetes.client
 import kubernetes.config
+import logging
+import re
+import requests
 import tokens
 from requests.auth import AuthBase
 
 DEFAULT_CLUSTERS = 'http://localhost:8001/'
+CLUSTER_ID_INVALID_CHARS = re.compile('[^a-z0-9:-]')
+
+logger = logging.getLogger(__name__)
 
 tokens.configure(from_file_only=True)
 
 
+def generate_cluster_id(url: str):
+    '''Generate some "cluster ID" from given API server URL'''
+    for prefix in ('https://', 'http://'):
+        if url.startswith(prefix):
+            url = url[len(prefix):]
+    return CLUSTER_ID_INVALID_CHARS.sub('-', url.lower()).strip('-')
+
+
 class StaticTokenAuth(AuthBase):
     def __init__(self, token):
         self.token = token
@@ -29,7 +46,8 @@ class OAuthTokenAuth(AuthBase):
 
 
 class Cluster:
-    def __init__(self, api_server_url, ssl_ca_cert=None, auth=None):
+    def __init__(self, id, api_server_url, ssl_ca_cert=None, auth=None):
+        self.id = id
         self.api_server_url = api_server_url
         self.ssl_ca_cert = ssl_ca_cert
         self.auth = auth
@@ -37,17 +55,20 @@ class Cluster:
 
 class StaticClusterDiscoverer:
 
-    def __init__(self, api_server_urls):
+    def __init__(self, api_server_urls: list):
         self._clusters = []
 
         if not api_server_urls:
             try:
                 kubernetes.config.load_incluster_config()
             except kubernetes.config.ConfigException:
-                cluster = Cluster('http://localhost:8001')
+                # we are not running inside a cluster
+                # => assume default kubectl proxy URL
+                cluster = Cluster(generate_cluster_id(DEFAULT_CLUSTERS), DEFAULT_CLUSTERS)
             else:
                 config = kubernetes.client.configuration
                 cluster = Cluster(
+                    generate_cluster_id(config.host),
                     config.host,
                     ssl_ca_cert=config.ssl_ca_cert,
                     auth=StaticTokenAuth(config.api_key['authorization'].split(' ', 1)[-1]))
@@ -60,7 +81,38 @@ class StaticClusterDiscoverer:
                     auth = OAuthTokenAuth('read-only')
                 else:
                     auth = None
-                self._clusters.append(Cluster(api_server_url, auth=auth))
+                self._clusters.append(Cluster(generate_cluster_id(api_server_url), api_server_url, auth=auth))
 
     def get_clusters(self):
         return self._clusters
+
+
+class ClusterRegistryDiscoverer:
+
+    def __init__(self, cluster_registry_url: str, cache_lifetime=60):
+        self._url = cluster_registry_url
+        self._cache_lifetime = cache_lifetime
+        self._last_cache_refresh = 0
+        self._clusters = []
+        self._session = requests.Session()
+        self._session.auth = OAuthTokenAuth('read-only')
+
+    def refresh(self):
+        try:
+            response = self._session.get(urljoin(self._url, '/kubernetes-clusters'), timeout=10)
+            response.raise_for_status()
+            clusters = []
+            for row in response.json()['items']:
+                # only consider "ready" clusters
+                if row.get('lifecycle_status', 'ready') == 'ready':
+                    clusters.append(Cluster(row['id'], row['api_server_url']))
+            self._clusters = clusters
+            self._last_cache_refresh = time.time()
+        except:
+            logger.exception('Failed to refresh from cluster registry {}'.format(self._url))
+
+    def get_clusters(self):
+        now = time.time()
+        if now - self._last_cache_refresh > self._cache_lifetime:
+            self.refresh()
+        return self._clusters