acmdns(host): expose and monitor health endpoint

resources/chaosknoten/acmedns/nginx/acmedns.hamburg.ccc.de.conf

@@ -77,6 +77,10 @@ server {
         proxy_pass http://127.0.0.1:8080/update;
     }
 
+    location = /health { # no auth by proxy required
+        proxy_pass http://127.0.0.1:8080/health;
+    }
+
     location @oauth2_signin {
         return 302 /oauth2/sign_in?rd=$scheme://$host$request_uri;
     }

resources/external/status/docker_compose/config/services-chaosknoten.yaml

@@ -19,6 +19,13 @@ endpoints:
       - "[CERTIFICATE_EXPIRATION] > 48h"
       - "[BODY] == pat(*OAuth2 Proxy*)"
 
+  - name: ACME DNS (health endpoint)
+    url: "https://acmedns.hamburg.ccc.de/health"
+    <<: *services_chaosknoten_defaults
+    conditions:
+      - "[STATUS] == 200"
+      - "[CERTIFICATE_EXPIRATION] > 48h"
+
   - name: ACME DNS (update endpoint)
     url: "https://acmedns.hamburg.ccc.de/update"
     <<: *services_chaosknoten_defaults