Allow retry in query tests

sample-config/pgmon-metrics.yml

@@ -196,19 +196,6 @@ metrics:
                sync_state
         FROM pg_stat_replication
         WHERE client_addr || '_' || regexp_replace(application_name, '[ ,]', '_', 'g') = %(repid)s
-      90600: >
-        SELECT pid, usename,
-               EXTRACT(EPOCH FROM backend_start)::integer AS backend_start,
-               state,
-               pg_xlog_lsn_diff(pg_current_xlog_lsn(), sent_lsn) AS sent_lsn,
-               pg_xlog_lsn_diff(pg_current_xlog_lsn(), write_lsn) AS write_lsn,
-               pg_xlog_lsn_diff(pg_current_xlog_lsn(), flush_lsn) AS flush_lsn,
-               pg_xlog_lsn_diff(pg_current_xlog_lsn(), replay_lsn) AS replay_lsn,
-               COALESCE(EXTRACT(EPOCH FROM write_lag), 0)::integer AS write_lag,
-               COALESCE(EXTRACT(EPOCH FROM flush_lag), 0)::integer AS flush_lag,
-               COALESCE(EXTRACT(EPOCH FROM replay_lag), 0)::integer AS replay_lag,
-               sync_state
-        FROM pg_stat_replication WHERE client_addr || '_' || regexp_replace(application_name, '[ ,]', '_', 'g') = %(repid)s
       100000: >
         SELECT pid, usename,
                EXTRACT(EPOCH FROM backend_start)::integer AS backend_start,

src/pgmon.py

@@ -656,9 +656,12 @@ def test_queries():
         # If the metric has arguments to use while testing, grab those
         args = metric.get("test_args", {})
         print("Testing {} [{}]".format(name, ", ".join(["{}={}".format(key, value) for key, value in args.items()])))
-        # Run the query without the ability to retry.
+        # Run the query with the ability to retry, mostly because the PostgreSQL
+        # docker image restarts during its initialization phase.  If the health
+        # check passes during the first phase, the agent will start testing too
+        # early and will break when PostgreSQL restarts.
         try:
-            res = sample_metric(dbname, name, args, retry=False)
+            res = sample_metric(dbname, name, args, retry=True)
         except MetricVersionError:
             print("{} -> Unsupported for this version".format(name))
             continue