jobs: add osmocom-obs-check-builders

Add a job that checks if the amount of connected builders to the OBS
server matches what we expect. This should prevent what we had today,
that it only was noticed by chance several days after all builders
failed to connect and the packages were outdated since then.

I'm not sure if there is a proper api to do this check, but I don't
expect the string we check for to change often so this should work fine.

Change-Id: I6e7c1f206551722d6bfe1631b9c1da8d34d85ba8

jobs/osmocom-obs-check-builders.yml

@@ -0,0 +1,28 @@
+---
+- project:
+    name: Osmocom_OBS_check_builders
+    jobs:
+      - Osmocom_OBS_check_builders
+
+- job-template:
+    name: 'Osmocom_OBS_check_builders'
+    project-type: freestyle
+    defaults: global
+    description: |
+        Verify that the expected amount of builders are connected to
+        obs.osmocom.org.
+    builders:
+      - shell: |
+          scripts/obs/check_builders.sh
+    scm:
+      - git:
+          branches:
+            - 'origin/master'
+          url: https://gerrit.osmocom.org/osmo-ci
+    triggers:
+      - timed: "@hourly"
+    node: obs
+    publishers:
+       - email:
+          notify-every-unstable-build: true
+          recipients: 'jenkins-notifications@lists.osmocom.org'

scripts/obs/check_builders.sh

@@ -0,0 +1,11 @@
+#!/bin/sh -ex
+count=14
+wget -q https://obs.osmocom.org -O index.html
+
+if ! grep -q " of $count build hosts" index.html; then
+	grep "build hosts" index.html
+	set +x
+	echo
+	echo "ERROR: expected $count builders to be connected to OBS!"
+	echo
+fi