Re: [Caml-list] Create a deployable application unit from OPAM?

[Hans Ole Rafaelsen <hrafaelsen@gmail.com>]

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I managed to get it working.

First I tried to copy files from the lib folder (.cmxs etc), but did not
manage to solve all dependencies. It would probably have worked if I had
spent some more time figuring out what was still missing. So I installed
opam2 and installed the packages using the destdir folder (/opt/myapp)

for p in `opam2 list | cut -d ' ' -f 1`; do opam2 install --destdir
/opt/myapp/ $p ; done
(This is all, so I still have a job to do to figure out which I can do
without)

Also installed the Osigen app under /opt/myapp/

The whole folder was then copied a target node under /opt/myapp/
To solve paths I had to crate a new findlib.conf file and put it under
/opt/myapp/etc/
$ cat /opt/myapp/etc/findlib.conf
destdir="/opt/myapp/lib"
path="/opt/myapp/lib"
ocamlc="ocamlc.opt"
ocamlopt="ocamlopt.opt"
ocamldep="ocamldep.opt"
ocamldoc="ocamldoc.opt"

To run it, have have this script setting the environment
$ cat /opt/myapp/run.sh
#!/bin/bash

MYTOP=/opt/myapp/

CAML_LD_LIBRARY_PATH=$MYTOP/lib/stublibs
MANPATH=:$MYTOP/man
PERL5LIB=$MYTOP/lib/perl5:
OCAML_TOPLEVEL_PATH=/lib/toplevel
PATH=$MYTOP/bin:$PATH
OCAMLPATH=$MYTOP

export OCAMLFIND_CONF=$MYTOP/etc/findlib.conf

ocsigenserver.opt -c $MYTOP/etc/myapp/myapp.conf

Also, oscigenserver seems to use the ~/.opam2/4.06.1/ paths form extensions
loaded, so these have to be configured.
Got this kind of log messages
ocsigenserver.opt: ocsipersist:dbm: Launching a new Ocsidbm process:
/home/hans/.opam2/4.06.1/lib/ocsigenserver/extensions/ocsidbm.opt on
directory /opt/myapp/var/data/myapp/ocsipersist.

Needed to change the configuration of the module to use the right path for
the binary
vi /opt/myapp/etc/myapp/myapp.conf
...
    <extension findlib-package="ocsigenserver.ext.ocsipersist-dbm">
      <ocsidbm name="/opt/myapp/lib/ocsigenserver/extensions/ocsidbm.opt"/>
    </extension>
...
Still have a problem with mime-types, but it's probably a similar config
change.

So it's not totally smooth, but it seems to be doable.

Regards,

Hans Ole Rafaelsen




On Fri, Mar 30, 2018 at 4:11 PM, Louis Gesbert <louis.gesbert@ocamlpro.com>
wrote:

> There is no perfect solution at the moment, as there are still some
> hiccups with relocation of quite a few opam packages, but there are a few
> options:
>
> 1. Not precisely what you were asking for, since it involves re-compiling,
> but opam-bundle¹ can generate an all-in-one package that can easily be
> deployed to a different system and will bootstrap OCaml, opam, the packages
> and their dependencies, and can put wrappers for the binaries to your PATH.
> This takes a while, but avoids any relocation problems and is quite
> reliable.
> The bundle could also be used as base for a container, or even copied
> across similar hosts (to the same location), and just the wrappers
> reinstalled.
>
> 2. opam 2.0 has an `opam install --destdir` option, that you could use to
> copy the installed artefacts of the required packages to some prefix (be
> sure to reinstall all the dependencies, or start from an empty switch). You
> could then tar/gz that prefix, and copy it across hosts.
>
> 3. in a simpler way, you could just copy the opam switch across hosts.
> With opam 2, all metadata is gathered in <switch-prefix>/.opam-switch/, so
> omit that subdirectory and you just get a "normal" Linux prefix (i.e. with
> bin/, lib/, etc. subdirectories).
>
> Of course, 2. and 3. can hit relocation issues, depending on what the
> packages you are interested in use (e.g. ocsigenserver seems to have
> specific needs). As Gerd mentionned, specifying `CAML_LD_LIBRARY_PATH` and
> `OCAMLPATH` (and maybe a few others²) may help.
> And none of these reduce the end result to "just the binaries needed",
> although 2. might help a little by letting you choose which packages get
> into the dest-prefix. I am not aware of a way to do this automatically. A
> vast super-appoximation could be to just ignore opam build-dependencies:
> `opam reinstall --destdir SOME_TEMP_PREFIX $(opam list --installed --rec
> --required-by PACKAGES --nobuild --short)`, on the origin host, then
> package and ship SOME_TEMP_PREFIX, possibly with wrappers to set the
> required PATH variables.
>
> These are just a few clues, but hope this helps!
>
> Louis Gesbert — OCamlPro
>
>
>
> ¹ https://github.com/AltGr/opam-bundle
> ² https://github.com/ocaml/opam-repository/issues/10863#
> issuecomment-347174662
>
> > - Hans Ole Rafaelsen, 29/03/2018 18:31 -
> > Hi,
> >
> > I have small application written using Ocsigen. Ocaml and the rest of the
> > development environment is installed using OPAM.
> >
> > Now I want to install this application on a few other nodes, without
> having
> > to bring bring along the whole development process for deployment on each
> > node. What I want to end up with, is a single unit, e.g a tar-file, a
> > docker container or similar, that can be copied and deployed to the
> target
> > nodes. This unit should only contain the binaries needed to run the
> > application.
> >
> > I have tried to ask on the Ocsigen mailing-list how do do this for
> Ocsigen
> > applications, but without success. But I guess the problem is more
> related
> > to how to deploy applications built using OPAM. I did not find any way to
> > do this with OPAM, but I might have missed something. I have tried to
> copy
> > all the binary files (.so, .cmxa .cmxs, etc) from the OPAM directory and
> > setting the environment variables to point the this new location, but
> > without much success. When starting ocsigenserver it was not able to
> solve
> > all symbols. Looking more into the problem, it looks like binaries such
> as
> > ocsigenserver has hard coded the location of the OPAM development
> > environment. Might be possible to override this using environment
> > variables, but I'm not sure how. So I gave up on this track.
> >
> >
> > Is there a way to generate such a deployable unit from OPAM development
> > environment?
> >
> > Do anyone have some tips / best practice on how to deploy applications
> > built using OPAM?
> >
> > (I'm developing and want to deploy on Ubuntu 16.04.)
> >
> > Regards,
> >
> > Hans Ole Rafaelsen
> >
> >
>

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