Custom static metrics

README.rst

@@ -236,7 +236,7 @@ Proxmox VE Configuration
 For security reasons it is essential to add a user with read-only access
 (PVEAuditor role) for the purpose of metrics collection.
 
-Refer to the  `Proxmox Documentation`_ for the several ways of creating a user. 
+Refer to the  `Proxmox Documentation`_ for the several ways of creating a user.
 Once created, assign the user the `/` path permission.
 
 Prometheus Configuration
@@ -296,3 +296,36 @@ Grafana Dashboards
 .. _`supports Let's Encrypt`: https://pve.proxmox.com/pve-docs/pve-admin-guide.html#sysadmin_certificate_management
 .. _`Proxmox Documentation`: https://pve.proxmox.com/pve-docs/pve-admin-guide.html#pveum_permission_management
 .. _`Proxmox via Prometheus by Pietro Saccardi`: https://grafana.com/grafana/dashboards/10347-proxmox-via-prometheus/
+
+
+Custom Metrics
+--------------
+
+You can add custom (static) metrics into the Notes section of Proxmox. These will be exported by this exporter.
+
+Go to Proxmox - Datacenter - Notes and click the Edit button. Add a Markdown header that says exactly
+``Prometheus metrics`` and a backtick-delimited (\`\`\`) block with the actual metrics.
+
+For example:
+
+.. code:: markdown
+
+    ## Prometheus metrics
+    ```
+    # These metrics are parsed by our prometheus-pve-exporter which
+    # expects the exact heading above
+
+    # HELP my_metric_bytes Whatever
+    # TYPE my_metric_bytes gauge
+    my_metric_bytes 350e9
+    ```
+
+converts into
+
+.. code::
+
+    # HELP my_metric_bytes Whatever
+    # TYPE my_metric_bytes gauge
+    my_metric_bytes{__source="Datacenter > Notes"} 3.5e+011
+
+in the exporter output.

src/pve_exporter/collector.py

@@ -6,7 +6,10 @@
 import collections
 import itertools
 import logging
+import re
 
+from prometheus_client.samples import Sample
+from prometheus_client.parser import text_string_to_metric_families
 from prometheus_client.registry import Collector
 from proxmoxer import ProxmoxAPI
 from proxmoxer.core import ResourceException
@@ -359,12 +362,42 @@ def collect(self):  # pylint: disable=missing-docstring
         return [disk_size]
 
 
+class ClusterCustomMetricsCollector(Collector):
+    """
+    Collects custom labels defined in the Notes section
+    """
+    def __init__(self, pve):
+        self._pve = pve
+
+    def collect(self):
+        metrics = []
+        notes = self._pve.cluster.options.get().get('description', '')
+        if m := re.match(r'#+\s*Prometheus metrics\s*```(.*?)```', notes, re.MULTILINE | re.DOTALL):
+            custom_metrics_text = m.group(1)
+
+            for metric in text_string_to_metric_families(custom_metrics_text):
+                metric.name = f'pve_{metric.name}'
+                new_samples = [
+                    Sample(name=f'pve_{sample.name}', labels=sample.labels | {'__source': 'Datacenter > Notes'},
+                           exemplar=sample.exemplar, value=sample.value)
+                    for sample in metric.samples
+                ]
+                metric.samples = new_samples
+
+                metrics.append(metric)
+
+        return metrics
+
+
 def collect_pve(config, host, options: CollectorsOptions):
     """Scrape a host and return prometheus text format for it"""
 
     pve = ProxmoxAPI(host, **config)
 
     registry = CollectorRegistry()
+
+    registry.register(ClusterCustomMetricsCollector(pve))
+
     if options.status:
         registry.register(StatusCollector(pve))
     if options.resources: