Add support for Gunicorn execution

Modifies pvcapid to run under Gunicorn when in non-debug mode, instead
of the Flask development server. This is proper practice for one, and
also helps increase performance slightly in some workloads (file uploads
mainly).

api-daemon/pvcapid.py

@@ -19,6 +19,13 @@
 #
 ###############################################################################
 
+import sys
+from os import path
+
+# Ensure current directory (/usr/share/pvc) is in the system path for Gunicorn
+current_dir = path.dirname(path.abspath(__file__))
+sys.path.append(current_dir)
+
 import pvcapid.Daemon  # noqa: F401
 
 pvcapid.Daemon.entrypoint()

api-daemon/pvcapid/Daemon.py

@@ -19,15 +19,15 @@
 #
 ###############################################################################
 
-
+import sys
+import os
+import subprocess
 from ssl import SSLContext, TLSVersion
-
 from distutils.util import strtobool as dustrtobool
-
 import daemon_lib.config as cfg
 
 # Daemon version
-version = "0.9.100"
+version = "0.9.100~git-73c0834f"
 
 # API version
 API_VERSION = 1.0
@@ -37,7 +37,6 @@ API_VERSION = 1.0
 # Helper Functions
 ##########################################################
 
-
 def strtobool(stringv):
     if stringv is None:
         return False
@@ -53,7 +52,6 @@ def strtobool(stringv):
 # Configuration Parsing
 ##########################################################
 
-
 # Get our configuration
 config = cfg.get_configuration()
 config["daemon_name"] = "pvcapid"
@@ -61,22 +59,15 @@ config["daemon_version"] = version
 
 
 ##########################################################
-# Entrypoint
+# Flask App Creation for Gunicorn
 ##########################################################
 
-
-def entrypoint():
-    import pvcapid.flaskapi as pvc_api  # noqa: E402
-
-    if config["api_ssl_enabled"]:
-        context = SSLContext()
-        context.minimum_version = TLSVersion.TLSv1
-        context.get_ca_certs()
-        context.load_cert_chain(
-            config["api_ssl_cert_file"], keyfile=config["api_ssl_key_file"]
-        )
-    else:
-        context = None
+def create_app():
+    """
+    Create and return the Flask app and SSL context if necessary.
+    """
+    # Import the Flask app from pvcapid.flaskapi after adjusting the path
+    import pvcapid.flaskapi as pvc_api
 
     # Print our startup messages
     print("")
@@ -102,9 +93,59 @@ def entrypoint():
     print("")
 
     pvc_api.celery_startup()
-    pvc_api.app.run(
-        config["api_listen_address"],
-        config["api_listen_port"],
-        threaded=True,
-        ssl_context=context,
-    )
+
+    return pvc_api.app
+
+
+##########################################################
+# Entrypoint
+##########################################################
+
+def entrypoint():
+    if config['debug']:
+        app = create_app()
+
+        if config["api_ssl_enabled"]:
+            ssl_context = SSLContext()
+            ssl_context.minimum_version = TLSVersion.TLSv1
+            ssl_context.get_ca_certs()
+            ssl_context.load_cert_chain(
+                config["api_ssl_cert_file"], keyfile=config["api_ssl_key_file"]
+            )
+        else:
+            ssl_context = None
+
+        app.run(
+            config["api_listen_address"],
+            config["api_listen_port"],
+            threaded=True,
+            ssl_context=ssl_context,
+        )
+    else:
+        # Build the command to run Gunicorn
+        gunicorn_cmd = [
+            'gunicorn',
+            '--workers', '1',
+            '--threads', '8',
+            '--timeout', '86400',
+            '--bind', '{}:{}'.format(config["api_listen_address"], config["api_listen_port"]),
+            'pvcapid.Daemon:create_app()',
+            '--log-level', 'info',
+            '--access-logfile', '-',
+            '--error-logfile', '-',
+        ]
+
+        if config["api_ssl_enabled"]:
+            gunicorn_cmd += [
+                '--certfile', config["api_ssl_cert_file"],
+                '--keyfile', config["api_ssl_key_file"]
+            ]
+
+        # Run Gunicorn
+        try:
+            subprocess.run(gunicorn_cmd)
+        except KeyboardInterrupt:
+            exit(0)
+        except Exception as e:
+            print(e)
+            exit(1)

debian/control

@@ -32,7 +32,7 @@ Description: Parallel Virtual Cluster worker daemon
 
 Package: pvc-daemon-api
 Architecture: all
-Depends: systemd, pvc-daemon-common, python3-yaml, python3-flask, python3-flask-restful, python3-celery, python3-distutils, python3-redis, python3-lxml, python3-flask-migrate
+Depends: systemd, pvc-daemon-common, gunicorn, python3-gunicorn, python3-yaml, python3-flask, python3-flask-restful, python3-celery, python3-distutils, python3-redis, python3-lxml, python3-flask-migrate
 Description: Parallel Virtual Cluster API daemon
  A KVM/Zookeeper/Ceph-based VM and private cloud manager
  .