Neutron WSGI API server¶
Since OpenStack Epoxy (2025.1), the Neutron API server only runs using a uWSGI
server that loads the Neutron WSGI application. The configuration and modules
needed and how to execute the Neutron API using WSGI is described in
WSGI Usage with the Neutron API. The eventlet API server is no longer supported
and the code will be removed.
With the older implementation (eventlet API server) it was easy to create
an entry script to start the Neutron API, using the same code as in the
generated script defined in the [entry_points]console_script section.
That script started a python executable; it was possible to add break points
(using pdb) or create a profile for PyCharm, for example.
In the WSGI case this is a bit more complicated. It is not possible to attach a Python debugger to the running process because this is not a Python executable. The uWSGI server, when a request is received, uses the application entry point to route the request, but the root process is not a Python executable.
rpdb¶
An alternative to pdb is the use of
rpdb <https://pypi.org/project/rpdb/>. This library works the same as pdb
but opening a TCP port that can be accessed using telnet, netcat, etc. For
example:
import rpdb
debugger = rpdb.Rpdb(addr='0.0.0.0', port=12345)
debugger.set_trace()
To access to the remote PDB console, it is needed to execute the following command:
$ telnet localhost 12345
Executing the generated Neutron API script¶
The oslo-config-generator script can generate the script located in
[entry_points]wsgi_scripts, called neutron-api; this script will
receive the same name. This script can be executed locally and will spawn
a single process Neutron API server, running one single WSGI thread, regardless
of the Neutron [DEFAULT]api_workers parameter.
It is not possible to pass any configuration file to this executable but the
Neutron API will use the default ones /etc/neutron/neutron.conf and
/etc/neutron/plugins/ml2/ml2_conf.ini. Any parameter needed by the Neutron
API must be defined in these two files.
Because this script will run as a Python process, it is possible to attach a
debugger or add a break point using pdb. It is also possible to create a
PyCharm “configuration” (using its own term) to execute the Neutron API using
the PyCharm builtin debugger.
In order to run the Neutron API using this script, it is only needed to provide the listening port:
$ neutron-api --port 8000
Once running, it is needed to change the OpenStack endpoint for the networking service:
$ openstack endpoint list
+----------------------------------+-----------+--------------+----------------+---------+-----------+-------------------------------------------------+
| ID | Region | Service Name | Service Type | Enabled | Interface | URL |
+----------------------------------+-----------+--------------+----------------+---------+-----------+-------------------------------------------------+
| 3959198c9b3f457cbb03cf49cd278415 | RegionOne | neutron | network | True | public | http://192.168.10.100/networking |
| 5807512a0c344144a1bd4f3bda4d3316 | RegionOne | glance | image | True | public | http://192.168.10.100/image |
| 6954de6553c84cb19d2f3441411ca897 | RegionOne | nova_legacy | compute_legacy | True | public | http://192.168.10.100/compute/v2/$(project_id)s |
| 71fe40ea4e6e431cb800143b4349928c | RegionOne | keystone | identity | True | public | http://192.168.10.100/identity |
| 73b86abeaca14e7ba18a53b8357dddee | RegionOne | nova | compute | True | public | http://192.168.10.100/compute/v2.1 |
| 76f5c962173b419b994d86877070673e | RegionOne | placement | placement | True | public | http://192.168.10.100/placement |
| 841199dad0b54acbb1c781e0b881cbf3 | RegionOne | designate | dns | True | public | http://192.168.10.100/dns |
| f4b219c2287448e3add582204db7ac69 | RegionOne | cinder | block-storage | True | public | http://192.168.10.100/volume/v3 |
+----------------------------------+-----------+--------------+----------------+---------+-----------+-------------------------------------------------+
$ openstack endpoint set --url http://192.168.10.100:8000 3959198c9b3f457cbb03cf49cd278415
