Open Stack

On 09/25/2015 07:09 AM, Sergii Golovatiuk wrote:
> Hi,
>
> Morgan gave the perfect case why operators want to use uWSGI. Let's 
> imagine a future when all openstack services will work as mod_wsgi 
> processes under apache. It's like to put all eggs in one basket. If 
> you need to reconfigure one service on controller it may affect 
> another service. For instance, sometimes operators need to increase 
> number of Threads/Processes for wsgi or add new virtual host to 
> apache. That will require graceful or cold restart of apache. It 
> affects other services. Another case, internal problems in mod_wsgi 
> where it may lead to apache crash affecting all services.
>
> uWSGI/gunicorn model is safer as in this case apache is reverse_proxy 
> only. This  model gives flexibility for operators. They may use 
> apache/nginx as proxy or load balancer. Stop or crash of one service 
> won't lead to downtime of other services. The complexity of OpenStack 
> management will be easier and friendly.

There are some fallacies here:

1. OpenStack services should all be on the same machine.
2. OpenStack web services should run on ports other than 443.

I think both of these are ideas who's time have come and gone.

If you have a single machine, run them out of separate containers. That 
allows different services to work with different versions of the 
libraries. It lets you mix a newer Keystone with older everything else.

If everything is on port 443, you need a single web server at the front 
end to multiplex it;  uWSGI or any other one does not obviate that.


There are no good ports left in /etc/services;  stop trying to reserve 
new ones for the web.  If you need to run on a web service, you need to 
be able to get through firewalls.  You need to run on standard ports. 
Run on 443.

Keystone again is a great example of this: it has two ports: 5000 and 35357.

port 5000 in /etc/services is

commplex-main   5000/tcp

and  port 35357 is smack dab in the middle of the ephemeral range.


Again, so long as the web server supports the cryptographic secure 
mechanisms, I don't care what one you chose.  But The idea of use going 
to Keystone and getting a bearer token as the basis for security is 
immature;  we should be doing the following on every call:

1. TLS
2. Cryptographic authentication.


They can be together or split up.

So, lets get everything running inside Apache, and, at the same time, 
push our other favorite web servers to support the necessary pieces to 
make OpenStack and the Web secure.


>
>
>
> --
> Best regards,
> Sergii Golovatiuk,
> Skype #golserge
> IRC #holser
>
> On Fri, Sep 18, 2015 at 3:44 PM, Morgan Fainberg 
> <morgan.fainberg at gmail.com <mailto:morgan.fainberg at gmail.com>> wrote:
>
>     There is and has been desire to support uWSGI and other
>     alternatives to mod_wsgi. There are a variety of operational
>     reasons to consider uWSGI and/or gunicorn behind apache most
>     notably to facilitate easier management of the processes
>     independently of the webserver itself. With mod_wsgi the processes
>     are directly tied to the apache server where as with uWSGI and
>     gunicorn you can manage the various services independently and/or
>     with differing VENVs more easily.
>
>     There are potential other concerns that must be weighed when
>     considering which method of deployment to use. I hope we have
>     clear documentation within the next cycle (and possible choices
>     for the gate) for utilizing uWSGI and/or gunicorn.
>
>     --Morgan
>
>     Sent via mobile
>
>     On Sep 18, 2015, at 06:12, Adam Young <ayoung at redhat.com
>     <mailto:ayoung at redhat.com>> wrote:
>
>>     On 09/17/2015 10:04 PM, Jim Rollenhagen wrote:
>>>     On Thu, Sep 17, 2015 at 06:48:50PM -0400, Davanum Srinivas wrote:
>>>>     In the fuel project, we recently ran into a couple of issues with Apache2 +
>>>>     mod_wsgi as we switched Keystone to run . Please see [1] and [2].
>>>>
>>>>     Looking deep into Apache2 issues specifically around "apache2ctl graceful"
>>>>     and module loading/unloading and the hooks used by mod_wsgi [3]. I started
>>>>     wondering if Apache2 + mod_wsgi is the "right" solution and if there was
>>>>     something else better that people are already using.
>>>>
>>>>     One data point that keeps coming up is, all the CI jobs use Apache2 +
>>>>     mod_wsgi so it must be the best solution....Is it? If not, what is?
>>>     Disclaimer: it's been a while since I've cared about performance with a
>>>     web server in front of a Python app.
>>>
>>>     IIRC, mod_wsgi was abandoned for a while, but I think it's being worked
>>>     on again. In general, I seem to remember it being thought of as a bit
>>>     old and crusty, but mostly working.
>>
>>     I am not aware of that.  It has been the workhorse of the
>>     Python/wsgi world for a while, and we use it heavily.
>>
>>>     At a previous job, we switched from Apache2 + mod_wsgi to nginx + uwsgi[0]
>>>     and saw a significant performance increase. This was a Django app. uwsgi
>>>     is fairly straightforward to operate and comes loaded with a myriad of
>>>     options[1] to help folks make the most of it. I've played with Ironic
>>>     behind uwsgi and it seemed to work fine, though I haven't done any sort
>>>     of load testing. I'd encourage folks to give it a shot. :)
>>
>>     Again, switching web servers is as likely to introduce as to
>>     solve problems.  If there are performance issues:
>>
>>     1.  Idenitfy what causes them
>>     2.  Change configuration settings to deal with them
>>     3.  Fix upstream bugs in the underlying system.
>>
>>
>>     Keystone is not about performance.  Keystone is about security. 
>>     The cloud is designed to scale horizontally first.  Before
>>     advocating switching to a difference web server, make sure it
>>     supports the technologies required.
>>
>>
>>     1. TLS at the latest level
>>     2. Kerberos/GSSAPI/SPNEGO
>>     3. X509 Client cert validation
>>     4. SAML
>>
>>     OpenID connect would be a good one to add to the list;  Its been
>>     requested for a while.
>>
>>     If Keystone is having performance issues, it is most likely at
>>     the database layer, not the web server.
>>
>>
>>
>>     "Programmers waste enormous amounts of time thinking about, or
>>     worrying about, the speed of noncritical parts of their programs,
>>     and these attempts at efficiency actually have a strong negative
>>     impact when debugging and maintenance are considered. We /should/
>>     forget about small efficiencies, say about 97% of the time:
>>     *premature optimization is the root of all evil.* Yet we should
>>     not pass up our opportunities in that critical 3%."   --Donald Knuth
>>
>>
>>
>>>     Of course, uwsgi can also be ran behind Apache2, if you'd prefer.
>>>
>>>     gunicorn[2] is another good option that may be worth investigating; I
>>>     personally don't have any experience with it, but I seem to remember
>>>     hearing it has good eventlet support.
>>>
>>>     // jim
>>>
>>>     [0]https://uwsgi-docs.readthedocs.org/en/latest/
>>>     [1]https://uwsgi-docs.readthedocs.org/en/latest/Options.html
>>>     [2]http://gunicorn.org/
>>>
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