Add build info metric to pageserver, safekeeper and proxy (#2596)

* Test that we emit build info metric for pageserver, safekeeper and proxy with some non-zero length revision label

* Emit libmetrics_build_info on startup of pageserver, safekeeper and
proxy with label "revision" which tells the git revision.

test_runner/fixtures/neon_fixtures.py

@@ -1961,6 +1961,11 @@ class NeonProxy(PgProtocol):
     def _wait_until_ready(self):
         requests.get(f"http://{self.host}:{self.http_port}/v1/status")
 
+    def get_metrics(self) -> str:
+        request_result = requests.get(f"http://{self.host}:{self.http_port}/metrics")
+        request_result.raise_for_status()
+        return request_result.text
+
     def __enter__(self):
         return self
 

test_runner/regress/test_build_info_metric.py

@@ -0,0 +1,19 @@
+from fixtures.metrics import parse_metrics
+from fixtures.neon_fixtures import NeonEnvBuilder, NeonProxy
+
+
+def test_build_info_metric(neon_env_builder: NeonEnvBuilder, link_proxy: NeonProxy):
+    neon_env_builder.num_safekeepers = 1
+    env = neon_env_builder.init_start()
+
+    parsed_metrics = {}
+
+    parsed_metrics["pageserver"] = parse_metrics(env.pageserver.http_client().get_metrics())
+    parsed_metrics["safekeeper"] = parse_metrics(env.safekeepers[0].http_client().get_metrics_str())
+    parsed_metrics["proxy"] = parse_metrics(link_proxy.get_metrics())
+
+    for component, metrics in parsed_metrics.items():
+        sample = metrics.query_one("libmetrics_build_info")
+
+        assert "revision" in sample.labels
+        assert len(sample.labels["revision"]) > 0