From e12628fe936769217dd28f537e834d10d5901289 Mon Sep 17 00:00:00 2001
From: Mikhail Kot <to@myrrc.dev>
Date: Fri, 15 Nov 2024 17:42:41 +0000
Subject: [PATCH] Collect max_connections metric (#9770)

This will further allow us to expose this metric to users
---
 compute/etc/neon_collector.jsonnet                     |  1 +
 .../etc/sql_exporter/compute_max_connections.libsonnet | 10 ++++++++++
 compute/etc/sql_exporter/compute_max_connections.sql   |  1 +
 3 files changed, 12 insertions(+)
 create mode 100644 compute/etc/sql_exporter/compute_max_connections.libsonnet
 create mode 100644 compute/etc/sql_exporter/compute_max_connections.sql

diff --git a/compute/etc/neon_collector.jsonnet b/compute/etc/neon_collector.jsonnet
index c6fa645b41..75d69c7b68 100644
--- a/compute/etc/neon_collector.jsonnet
+++ b/compute/etc/neon_collector.jsonnet
@@ -6,6 +6,7 @@
     import 'sql_exporter/compute_backpressure_throttling_seconds.libsonnet',
     import 'sql_exporter/compute_current_lsn.libsonnet',
     import 'sql_exporter/compute_logical_snapshot_files.libsonnet',
+    import 'sql_exporter/compute_max_connections.libsonnet',
     import 'sql_exporter/compute_receive_lsn.libsonnet',
     import 'sql_exporter/compute_subscriptions_count.libsonnet',
     import 'sql_exporter/connection_counts.libsonnet',
diff --git a/compute/etc/sql_exporter/compute_max_connections.libsonnet b/compute/etc/sql_exporter/compute_max_connections.libsonnet
new file mode 100644
index 0000000000..69cfa1f19c
--- /dev/null
+++ b/compute/etc/sql_exporter/compute_max_connections.libsonnet
@@ -0,0 +1,10 @@
+{
+  metric_name: 'compute_max_connections',
+  type: 'gauge',
+  help: 'Max connections allowed for Postgres',
+  key_labels: null,
+  values: [
+    'max_connections',
+  ],
+  query: importstr 'sql_exporter/compute_max_connections.sql',
+}
diff --git a/compute/etc/sql_exporter/compute_max_connections.sql b/compute/etc/sql_exporter/compute_max_connections.sql
new file mode 100644
index 0000000000..99a49483a6
--- /dev/null
+++ b/compute/etc/sql_exporter/compute_max_connections.sql
@@ -0,0 +1 @@
+SELECT current_setting('max_connections') as max_connections;