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

[Dieter Schön]

Hi,

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,
Dieter

Am So., Apr. 14, 2019 11:20 schrieb Max Lapshin <max.lapshin@REDACTED>:

    Hi.

    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


    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

    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  (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



    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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