add a check for the running kernel version (#63481)

prometheus-entrouvert-exporter/prometheus-system-exporter.py

@@ -53,7 +53,7 @@ eo_rabbitmq = Gauge("eo_rabbitmq", "rabbitmq", ["ctn"], registry=registry)
 eo_threads = Gauge("eo_threads", "system threads", ["ctn"], registry=registry)
 eo_units = Gauge("eo_units", "systemd units", ["ctn", "name", "state"], registry=registry)
 eo_packages = Gauge("eo_packages", "packages", ["ctn", "state"], registry=registry)
-
+eo_kernel = Gauge("eo_kernel", "kernel update", ["ctn"], registry=registry)
 
 def run(cmd):
     m = shlex.split(cmd)
@@ -280,6 +280,31 @@ def run_in_machines(ctn):
                 metric.labels(**s.labels).set(s.value)
 
 
+def check_kernel_version(ctn):
+    # no check if no kernel installed (aka container)
+    if not os.path.exists("/vmlinuz"):
+        return
+
+    uname = os.uname()
+    current_version = uname.version
+    current_release = uname.release
+
+    # first check, simple : verify that the current release match /vmlinuz
+    next_boot_release = os.path.basename(os.readlink("/vmlinuz"))
+    if next_boot_release != "vmlinuz-%s" % current_release:
+        eo_kernel.labels(ctn).set(2)
+        return
+
+    # second check, a bit harder : verify that the current version matches the package
+    current_version_extract = current_version.split(" ")[3]
+    for line in subprocess.check_output(["dpkg", "--status", "linux-image-" + current_release]).split(b"\n"):
+        if line.startswith(b"Version: "):
+            if line != b"Version: " + current_version_extract.encode("ascii"):
+                eo_kernel.labels(ctn).set(1)
+                return
+            break    
+    eo_kernel.labels(ctn).set(0)
+
 if __name__ == "__main__":
     parser = argparse.ArgumentParser()
     parser.add_argument("--test", action="store_true", help="raise errors")
@@ -288,6 +313,7 @@ if __name__ == "__main__":
 
     for test in [
         certificates,
+        check_kernel_version,
         debian,
         etckeeper,
         exim,