Extracted the postgresql monitor to its own monitor-type (#6443)

Co-authored-by: Dalton Pearson <dalton.pearson@praemo.com>
Co-authored-by: Frank Elsinga <frank@elsinga.de>

test/backend-test/test-postgres.js

@@ -0,0 +1,60 @@
+const { describe, test } = require("node:test");
+const assert = require("node:assert");
+const { PostgreSqlContainer } = require("@testcontainers/postgresql");
+const { PostgresMonitorType } = require("../../server/monitor-types/postgres");
+const { UP, PENDING } = require("../../src/util");
+
+describe(
+    "Postgres Single Node",
+    {
+        skip:
+            !!process.env.CI &&
+            (process.platform !== "linux" || process.arch !== "x64"),
+    },
+    () => {
+        test("Postgres is running", async () => {
+            // The default timeout of 30 seconds might not be enough for the container to start
+            const postgresContainer = await new PostgreSqlContainer(
+                "postgres:latest"
+            )
+                .withStartupTimeout(60000)
+                .start();
+            const postgresMonitor = new PostgresMonitorType();
+            const monitor = {
+                databaseConnectionString: postgresContainer.getConnectionUri(),
+            };
+
+            const heartbeat = {
+                msg: "",
+                status: PENDING,
+            };
+
+            try {
+                await postgresMonitor.check(monitor, heartbeat, {});
+                assert.strictEqual(heartbeat.status, UP);
+            } finally {
+                postgresContainer.stop();
+            }
+        });
+
+        test("Postgres is not running", async () => {
+            const postgresMonitor = new PostgresMonitorType();
+            const monitor = {
+                databaseConnectionString: "http://localhost:15432",
+            };
+
+            const heartbeat = {
+                msg: "",
+                status: PENDING,
+            };
+
+            // regex match any string
+            const regex = /.+/;
+
+            await assert.rejects(
+                postgresMonitor.check(monitor, heartbeat, {}),
+                regex
+            );
+        });
+    }
+);