Add basic openmetrics exposition

brian-brazil · brian-brazil · commit 682e5ecf5c15 · 2018-09-07T17:17:03.000+01:00
Signed-off-by: Brian Brazil &lt;brian.brazil@robustperception.io&gt;
diff --git a/prometheus_client/exposition.py b/prometheus_client/exposition.py
@@ -11,6 +11,7 @@
 from wsgiref.simple_server import make_server, WSGIRequestHandler
 
 from . import core
+import openmetrics.exposition
 try:
     from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer
     from SocketServer import ThreadingMixIn
@@ -36,12 +37,13 @@ def make_wsgi_app(registry=core.REGISTRY):
     def prometheus_app(environ, start_response):
         params = parse_qs(environ.get('QUERY_STRING', ''))
         r = registry
+        encoder, content_type = choose_encoder(environ.get['HTTP_ACCEPT'])
         if 'name[]' in params:
             r = r.restricted_registry(params['name[]'])
-        output = generate_latest(r)
+        output = encoder(r)
 
         status = str('200 OK')
-        headers = [(str('Content-type'), CONTENT_TYPE_LATEST)]
+        headers = [(str('Content-type'), content_type)]
         start_response(status, headers)
         return [output]
     return prometheus_app
@@ -87,22 +89,32 @@ def generate_latest(registry=core.REGISTRY):
     return ''.join(output).encode('utf-8')
 
 
+def choose_encoder(accept_header):
+    accept_header = accept_header or ''
+    for accepted in accept_header.split(','):
+        if accepted == 'text/openmetrics; version=0.0.1':
+            return (openmetrics.exposition.generate_latest, 
+                    openmetrics.exposition.CONTENT_TYPE_LATEST)
+    return (generate_latest, CONTENT_TYPE_LATEST)
+
+
 class MetricsHandler(BaseHTTPRequestHandler):
     """HTTP handler that gives metrics from ``core.REGISTRY``."""
     registry = core.REGISTRY
 
     def do_GET(self):
         registry = self.registry
         params = parse_qs(urlparse(self.path).query)
+        encoder, content_type = choose_encoder(self.headers.get('Accept'))
         if 'name[]' in params:
             registry = registry.restricted_registry(params['name[]'])
         try:
-            output = generate_latest(registry)
+            output = encoder(registry)
         except:
             self.send_error(500, 'error generating metric output')
             raise
         self.send_response(200)
-        self.send_header('Content-Type', CONTENT_TYPE_LATEST)
+        self.send_header('Content-Type', content_type)
         self.end_headers()
         self.wfile.write(output)
 
diff --git a/prometheus_client/openmetrics/__init__.py b/prometheus_client/openmetrics/__init__.py
diff --git a/prometheus_client/openmetrics/exposition.py b/prometheus_client/openmetrics/exposition.py
@@ -0,0 +1,29 @@
+#!/usr/bin/python
+
+from __future__ import unicode_literals
+
+from .. import core
+
+CONTENT_TYPE_LATEST = str('text/openmetrics; version=0.0.1; charset=utf-8')
+'''Content type of the latest OpenMetrics text format'''
+
+def generate_latest(registry):
+    '''Returns the metrics from the registry in latest text format as a string.'''
+    output = []
+    for metric in registry.collect():
+        mname = metric.name
+        output.append('# HELP {0} {1}'.format(
+            mname, metric.documentation.replace('\\', r'\\').replace('\n', r'\n').replace('"', r'\"')))
+        output.append('\n# TYPE {0} {1}\n'.format(mname, metric.type))
+        for name, labels, value in metric.samples:
+            if labels:
+                labelstr = '{{{0}}}'.format(','.join(
+                    ['{0}="{1}"'.format(
+                     k, v.replace('\\', r'\\').replace('\n', r'\n').replace('"', r'\"'))
+                     for k, v in sorted(labels.items())]))
+            else:
+                labelstr = ''
+            output.append('{0}{1} {2}\n'.format(name, labelstr, core._floatToGoString(value)))
+    output.append('# EOF\n')
+    return ''.join(output).encode('utf-8')
+
diff --git a/prometheus_client/twisted/_exposition.py b/prometheus_client/twisted/_exposition.py
@@ -1,5 +1,5 @@
 from __future__ import absolute_import, unicode_literals
-from .. import REGISTRY, generate_latest, CONTENT_TYPE_LATEST
+from .. import REGISTRY, exposition
 
 from twisted.web.resource import Resource
 
@@ -14,5 +14,6 @@ def __init__(self, registry=REGISTRY):
         self.registry = registry
 
     def render_GET(self, request):
-        request.setHeader(b'Content-Type', CONTENT_TYPE_LATEST.encode('ascii'))
-        return generate_latest(self.registry)
+        encoder, content_type = exposition.choose_encoder(request.getHeader('Accept'))
+        request.setHeader(b'Content-Type', content_type.encode('ascii'))
+        return encoder(self.registry)
