Improved error log output for prometheus pushgateway requests (TryGho…

…st#21556)

ref
https://linear.app/ghost/issue/ENG-1746/enable-ghost-to-push-metrics-to-a-pushgateway

- Trying to get Ghost working with the prometheus pushgateway in
staging, but it's logging an error each time it tries to push the
metrics. The error output is pretty useless for debugging, so this
commit improves the error messages to make it easier to debug.

ghost/prometheus-metrics/package.json

@@ -32,6 +32,7 @@
     "typescript": "5.6.2"
   },
   "dependencies": {
+    "@tryghost/errors": "1.3.6",
     "@tryghost/logging": "2.4.19",
     "express": "4.21.1",
     "prom-client": "15.1.3",

ghost/prometheus-metrics/src/PrometheusClient.ts

@@ -1,6 +1,7 @@
 import {Request, Response} from 'express';
 import client from 'prom-client';
 import logging from '@tryghost/logging';
+import errors from '@tryghost/errors';
 
 type PrometheusClientConfig = {
     register?: client.Registry;
@@ -56,8 +57,14 @@ export class PrometheusClient {
             try {
                 await this.gateway.pushAdd({jobName});
                 logging.debug('Metrics pushed to pushgateway - jobName: ', jobName);
-            } catch (error) {
-                logging.error('Error pushing metrics to pushgateway - jobName: ', jobName);
+            } catch (err) {
+                let error;
+                if (typeof err === 'object' && err !== null && 'code' in err) {
+                    error = new errors.InternalServerError({message: 'Error pushing metrics to pushgateway: ' + err.code, code: err.code as string});
+                } else {
+                    error = new errors.InternalServerError({message: 'Error pushing metrics to pushgateway: Unknown error'});
+                }
+                logging.error(error);
             }
         }
     }

yarn.lock

@@ -7430,7 +7430,7 @@
     focus-trap "^6.7.2"
     postcss-preset-env "^7.3.1"
 
-"@tryghost/errors@1.3.1", "@tryghost/errors@1.3.5", "@tryghost/errors@^1.2.26", "@tryghost/errors@^1.2.3", "@tryghost/errors@^1.3.5", "@tryghost/errors@^1.3.6":
+"@tryghost/errors@1.3.1", "@tryghost/errors@1.3.5", "@tryghost/errors@1.3.6", "@tryghost/errors@^1.2.26", "@tryghost/errors@^1.2.3", "@tryghost/errors@^1.3.5", "@tryghost/errors@^1.3.6":
   version "1.3.5"
   resolved "https://registry.yarnpkg.com/@tryghost/errors/-/errors-1.3.5.tgz#f4ef8e5c41a8a37456f2285271124180685827ae"
   integrity sha512-iOkiHGnYFqSdFM9AVlgiL56Qcx6V9iQ3kbDKxyOAxrhMKq1OnOmOm7tr1CgGK1YDte9XYEZmR9hUZEg+ujn/jQ==