[erlang-questions] How do you go to production?

Tue Apr 16 21:54:03 CEST 2019

Hi Dieter,
Many thanks for sharing your experience.
Could you please outline your installation procedure?  Also, the size of your Docker application image (RAM footprint) ? I've been considering LXC containers, but I'd like to test with Docker.
All the best,
-----Original Message-----
From: "Dieter Schön" <dieter@REDACTED>
Sent: Tuesday, April 16, 2019 3:46pm
To: "Erlang-Questions Questions" <erlang-questions@REDACTED>
Subject: Re: [erlang-questions] How do you go to production?

here is a case from the other end of the spectrum. 
I developed a protocol converter for a satellite test system, it is installed on 2 (in words: two)  PCs.
For development, I used one application and rebar3. Production is just "rebar3 as prod tar" (From a labelled git commit).
Testing was done on the two PCs, where I used one as the system under test and the other as test harness/data generator.
 I was also using wireshark and other third party tools, to prevent incestuous behaviour.
To test the installation procedure I used docker, which was really nice. I had a blank machine in two seconds, 
where I could load and execute the installation script from the host. I had turnaround cycles from several seconds.
What else.. the application is quite small. It fits into one erlang application. Apart from it, the release only contains the observer and sasl.
Unit testing was done in EUnit.

This was my first project where I used erlang, and the learning curve was quite gentle. 
Kind regards,

Am So., Apr. 14, 2019 11:20 schrieb Max Lapshin [ <max.lapshin@REDACTED> ]( mailto:max.lapshin@REDACTED ):

I'm developing Flussonic for almost 10 years and we have some practices for packaging, deploying, running, maintainig that are not well known, however they are rather good for us.
It is interesting how do other people solve this.
At first, we do not use releases. It is because when we have started our long path, using of releases was not very easy.  Couple of days ago I've tested it with rebar3 and it is really easier to use. Perhaps we would use releases today.
Next: we use our own fpm script replacement for packaging. I can boast that it seems to be the only existing implementation of rpm outside of original library, however I'd better never pass this path again. I've written it in pre-docker era and frankly speaking it is a traumatic experience. However, we are using it for debian and it is really convenient:
[ https://github.com/flussonic/epm ]( https://github.com/flussonic/epm )
Some time ago we have switched to systemd. I personally consider systemd a very badly designed thing that was created without any discussions with existing system adminstrators. For example, systemd doesn't offer config validation before launch. Another brilliant idea is to offer libsystemd for linking into application. Unknown library with unknown quality. What can go wrong if you link it into your erlang or java application?
Sorry, but no. We have systemd.erl:  [ https://gist.github.com/maxlapshin/01773f0fca706acdcb4acb77d91d78bb ]( https://gist.github.com/maxlapshin/01773f0fca706acdcb4acb77d91d78bb )

Use Type=notify in  youdaemon.service
After you manage to launch your erlang daemon, you need to collect statistics. We had to add some more linux-related tools to fetch: cpu usage, disk I/O usage, system ram usage (swap, etc), per-interface network statistics, udp errors count, nvidia card usage, etc. 
If this is worthy outsource, I think we can extract it. 
Our os_stat library is linked with our in-erlang pulsedb library. We try to maintain as less dependencies as possible, so we collect all ticks from monitoring tools inside erlang library pulsedb:  [ https://github.com/pulsedb/pulsedb ]( https://github.com/pulsedb/pulsedb )   (maybe should update public branch)
It can save several thousands metrics with one tick per 1-3 seconds.
Support is an important part of our business, because customers cannot just launch software, they often need help.  We have many people in support staff and I do not want to manage their own public ssh keys on customer's servers. So we have written an ssh proxy: system that login to customer server with one private key and allow support guy to use his own key:  [ https://github.com/flussonic/ssh-proxy ]( https://github.com/flussonic/ssh-proxy )
All these things are rather useless for development and many of them are not required for in-house development, however it is hard to live without them when you sell software.
What is your experience with such things that standard erlang lacks?
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