Add instrumentation (number of subscribers)

Also use flask.jsonify() instead of our custom function.

mailman_api/mailman.py

@@ -6,7 +6,8 @@ import ssl
 import subprocess
 import sys
 from functools import wraps
-from flask import Flask, request, abort, make_response, g
+from flask import Flask, request, abort, make_response, jsonify, g
+from flask_caching import Cache
 
 from .sso_api import sso_api_auth_required, init_sso
 from .tls_auth import tls_auth, init_tls_auth, PeerCertWSGIRequestHandler
@@ -14,6 +15,7 @@ from .tls_auth import tls_auth, init_tls_auth, PeerCertWSGIRequestHandler
 sys.path.insert(0, '/var/lib/mailman/bin')
 import paths
 from Mailman import MailList
+from Mailman import Utils
 
 
 app = Flask(__name__)
@@ -21,6 +23,8 @@ app.config['TLS_AUTH_ACLS'] = [
     ('/', 'client'),
 ]
 
+cache = Cache(config={'CACHE_TYPE': 'SimpleCache'})
+
 # Set up environment for Mailman processes: if we don't explicitly
 # control LANG, we're going to get locale setup errors.
 mm_env = dict(os.environ)
@@ -31,17 +35,6 @@ def _run(cmd):
     subprocess.check_call(cmd, env=mm_env)
 
 
-def to_json(fn):
-    """Encode response as JSON."""
-    @wraps(fn)
-    def _json_wrapper(*args, **kwargs):
-        result = fn(*args, **kwargs)
-        resp = make_response(json.dumps(result))
-        resp.headers['Content-Type'] = 'application/json'
-        return resp
-    return _json_wrapper
-
-
 def _random_password():
     return os.urandom(12).encode('base64').rstrip('=\n')
 
@@ -61,7 +54,6 @@ def _maybe_unicode(s):
 
 @app.route('/api/create_list', methods=('POST',))
 @tls_auth
-@to_json
 def create_list():
     list_addr = request.json['list']
     admin_addr = request.json['admin']
@@ -88,12 +80,11 @@ def create_list():
         ])
 
     app.logger.info('created new list %s', list_addr)
-    return {}
+    return jsonify({})
 
 
 @app.route('/api/get_list_attrs', methods=('POST',))
 @tls_auth
-@to_json
 def get_list_attrs():
     lists = request.json['lists']
     out = []
@@ -106,13 +97,12 @@ def get_list_attrs():
             'owners': list(set(m.owner[:])),
         }
         out.append(attrs)
-    return out
+    return jsonify(out)
 
 
 @app.route('/api/pwreset', methods=('POST',))
 @tls_auth
 @sso_api_auth_required
-@to_json
 def pwreset():
     list_addr = request.json['list']
     list_name = list_addr.split('@')[0]
@@ -125,12 +115,11 @@ def pwreset():
         '/var/lib/mailman/bin/change_pw', '-l',
         list_name,
     ])
-    return {}
+    return jsonify({})
 
 
 @app.route('/api/regenerate_archives', methods=('POST',))
 @tls_auth
-@to_json
 def regenerate_archives():
     list_addr = request.json['list']
     list_name = list_addr.split('@')[0]
@@ -139,7 +128,29 @@ def regenerate_archives():
         '/var/lib/mailman/bin/arch', '--wipe', '--quiet',
         list_name,
     ])
-    return {}
+    return jsonify({})
+
+
+### Instrumentation.
+
+@app.route('/metrics')
+@cache.cached(timeout=900)
+def metrics():
+    def _dump_metrics():
+        list_names = Utils.list_names()
+        for list_name in list_names:
+            try:
+                mlist = MailList.MailList(list_name, lock=False)
+            except Errors.MMUnknownListError:
+                # The list could have been deleted by another process.
+                continue
+
+            num_rmembers = len(mlist.getRegularMemberKeys())
+            num_dmembers = len(mlist.getDigestMemberKeys())
+            yield 'mailman_subscribers{list="%s"} %d\n' % (
+                list_name.lower(), num_rmembers + num_dmembers)
+
+    return app.response_class(_dump_metrics(), mimetype='text/plain')
 
 
 ### SSL server with the right parameters.
@@ -171,6 +182,7 @@ def main():
         parser.error('Too many arguments')
 
     app.config.from_pyfile(opts.config)
+    cache.init_app(app)
     init_sso(app)
     init_tls_auth(app)
     serve_ssl(app, host=opts.addr, port=opts.port)

requirements.txt

 git+https://git.autistici.org/ai/sso.git#egg=sso&subdirectory=src/python
 Flask
+Flask-Caching

setup.py

@@ -11,6 +11,7 @@ setup(
     author_email="info@autistici.org",
     url="https://git.autistici.org/ai3/python-mailman-api",
     install_requires=["Flask",
+                      "Flask-Caching",
                       "sso"],
     packages=find_packages(),
     entry_points={