Re: CDN Test Results - Should We Continue Using a CDN?

[Maxim Cournoyer <maxim.cournoyer@gmail.com>]

Hello Chris!

Chris Marusich <cmmarusich@gmail.com> writes:

> Hi Guix!
>
> Recently, the Guix project experimented with using a CDN to improve
> substitute availability and performance.  This email summarizes the
> results of the test for your review.  I also hope this email will start
> a discussion about whether or not we should continue to use a CDN.
>
> First, I'll summarize what we did.  Starting on February 23rd, 2019 we
> conducted a test using Amazon CloudFront.  We configured ci.guix.info so
> that all requests for substitutes via that domain name would go through
> an Amazon CloudFront distribution that we set up for this purpose.  The
> test concluded on March 23rd, and the CDN is not currently being used.

I'm I living in the past, or did you mean another date than March 23rd?
:-)

> Amazon CloudFront provides us with billing information and aggregate
> usage statistics.  Here's the information for the duration of the test:
>
> Duration: 28 days (February 23rd - March 23rd)
> Expense: 156.88 US Dollars
> Requests received: 3,732,919
> Average request size: 490 KB
> Bytes transferred: 1,744.5724 GB
> Bytes from misses: 684.3992 GB
> Hits: 2.14 M (57.44%)
> Misses: 0.99 M (26.41%)
> Errors: 602.91 K (16.15%)
> 2xx: 2,983.24 K (79.92%)
> 3xx: 146.753 K (3.93%)
> 4xx: 593.159 K (15.89%)
> 5xx: 9.471 K (0.25%)
>

[...]

> Location                         Request Count  Request %  Bytes
> ---------------------------------------------------------------------
> United States                    933,448        25.01%     562.52  GB
> Germany                          687,548        18.42%     174.53  GB
> France                           341,573        9.15%      167.36  GB
> Canada                           179,630        4.81%      96.31   GB

[...]

> Since the test has concluded, we are not currently using a CDN.  Going
> forward, we need to decide if we want to continue to use a CDN.  Did you
> notice an improvement in download speed or substitute availability
> during the test period?  Do you have metrics of your own that you can
> share with us?  If so, please share the information so we can understand
> whether it's worth continuing to pay for a CDN.

I haven't noticed a big difference on ci.guix.info; but then my WiFi
link seems to saturate around 1 MiB or so at home, so I'm not a very
demanding user ;-). Things felt as zippy as usual.

> One of the reasons why we wanted to use a CDN in the first place was to
> free up resources so that the community could spend more time working on
> better solutions.

Pardon me for asking, but how does using a CDN frees up resources?
Aren't the usual infrastructure preserved (e.g., ci.guix.info)? It
seems it'd be an extra layer to maintain?

The heaviest bandwith usage appear to originate from areas already well
served by the current infrastructure (mirror.hydra.gnu.org -> North
America, ci.guix.info -> Europe), so I'm not sure spending resources on
a CDN is worthwhile in this context.

I'd rather see this (even modest) amount put into the hands of a
motivated hacker to work on a distributed solution instead of
encouraging a company which do not share our free software ideals.

I'm hoping this doesn't come across as too negative! Thanks for sharing
this interesting information with us.

Maxim