Remove custom proxy-metrics code.

The only reason we had a custom implementation for proxy-metrics was
because constellation used to start containers without any networking,
and would only attach to the network as a second step, which broke the
proxy's expectation. This issue was solved in
reside-ic/constellation#23.

Thanks to this we can simplify our setup and use the standard
declarative approach even for the proxy-metrics container.

src/montagu_deploy/cli.py

@@ -35,7 +35,7 @@ def main(argv=None):
         return about.__version__
     else:
         cfg = MontaguConfig(path, extra, options)
-        obj = MontaguConstellation(cfg)
+        obj = montagu_constellation(cfg)
         if args.action == "start":
             montagu_start(obj, args)
         elif args.action == "status":

src/montagu_deploy/montagu_constellation.py

@@ -9,44 +9,26 @@
 from montagu_deploy import database
 
 
-class MontaguConstellation:
-    def __init__(self, cfg):
-        api = api_container(cfg)
-        db = db_container(cfg)
-        admin = admin_container(cfg)
-        contrib = contrib_container(cfg)
-        proxy = proxy_container(cfg)
-        mq = mq_container(cfg)
-        flower = flower_container(cfg)
-        task_queue = task_queue_container(cfg)
-
-        containers = [api, db, admin, contrib, proxy, mq, flower, task_queue]
-
-        if cfg.fake_smtp_ref:
-            fake_smtp = fake_smtp_container(cfg)
-            containers.append(fake_smtp)
-
-        self.cfg = cfg
-        self.obj = constellation.Constellation(
-            "montagu", cfg.container_prefix, containers, cfg.network, cfg.volumes, data=cfg, vault_config=cfg.vault
-        )
-
-    def start(self, **kwargs):
-        self.obj.start(**kwargs)
-        # The proxy metrics container cannot be started via constellation, because
-        # it has to belong to the same network as the proxy as soon as it is started
-        # and constellation starts containers on the 'none' network. So we provide
-        # start/stop/status methods for the metrics container that mimic the
-        # constellation behaviour
-        start_proxy_metrics(self.cfg)
-
-    def stop(self, **kwargs):
-        stop_proxy_metrics(self.cfg)
-        self.obj.stop(**kwargs)
-
-    def status(self):
-        self.obj.status()
-        status_proxy_metrics(self.cfg)
+def montagu_constellation(cfg):
+    containers = [
+        api_container(cfg),
+        db_container(cfg),
+        admin_container(cfg),
+        contrib_container(cfg),
+        proxy_container(cfg),
+        proxy_metrics_container(cfg),
+        mq_container(cfg),
+        flower_container(cfg),
+        task_queue_container(cfg),
+    ]
+
+    if cfg.fake_smtp_ref:
+        fake_smtp = fake_smtp_container(cfg)
+        containers.append(fake_smtp)
+
+    return constellation.Constellation(
+        "montagu", cfg.container_prefix, containers, cfg.network, cfg.volumes, data=cfg, vault_config=cfg.vault
+    )
 
 
 def admin_container(cfg):
@@ -250,40 +232,14 @@ def proxy_configure(container, cfg):
         docker_util.string_into_container(cfg.dhparam, container, join(ssl_path, "dhparam.pem"))
 
 
-def start_proxy_metrics(cfg):
-    name = "{}-{}".format(cfg.container_prefix, cfg.containers["metrics"])
-    proxy_name = cfg.containers["proxy"]
-    image = str(cfg.proxy_metrics_ref)
-    print("Starting {} ({})".format(cfg.containers["metrics"], image))
-    docker.from_env().containers.run(
-        image,
-        restart_policy={"Name": "always"},
-        ports={"9113/tcp": 9113},
-        command=f'-nginx.scrape-uri "http://{proxy_name}/basic_status"',
-        network=cfg.network,
-        name=name,
-        detach=True,
-    )
-
-
-def stop_proxy_metrics(cfg):
-    name = "{}-{}".format(cfg.container_prefix, cfg.containers["metrics"])
-    container = get_container(name)
-    if container:
-        print(f"Killing '{name}'")
-        container.remove(force=True)
 
 
-def status_proxy_metrics(cfg):
-    name = "{}-{}".format(cfg.container_prefix, cfg.containers["metrics"])
-    container = get_container(name)
-    status = container.status if container else "missing"
-    print("    - {} ({}): {}".format(cfg.containers["metrics"], name, status))
 
-
-def get_container(name):
-    client = docker.client.from_env()
-    try:
-        return client.containers.get(name)
-    except docker.errors.NotFound:
-        return None
+def proxy_metrics_container(cfg):
+    proxy_name = cfg.containers["proxy"]
+    return constellation.ConstellationContainer(
+        cfg.containers["metrics"],
+        cfg.proxy_metrics_ref,
+        ports=[9113],
+        args=["-nginx.scrape-uri", f"http://{proxy_name}/basic_status"],
+    )