How to deploy a binary with stack

[Matthias Kauer]

Hi,
I want to deploy a Haskell web application (gitit) on a small VPS and I'm not sure if the task is hard or I am going about it the wrong way.
The constraints are:
- The server has 512 MB RAM, so compiling there doesn't work.
- Docker will most likely not work either. I believe it requires extra config in OpenVZ and most hosters will not have done that.
- Locally, I have a VM (Virtualbox) with 4GB RAM and the same (similar) Ubuntu 14.04. environment.

After compiling with `stack install` and uploading, I cannot execute the binary because it complains about files missing that have the absolute path from the VM.

Is this actually a very difficult task? Or is it rather so mundane that people do not talk about it that much?
Can you offer some guidance on what I can do to achieve this?

Among other things, I have tried what is described here:
https://ro-che.info/articles/2015-10-26-static-linking-ghc (building with

stack build --ghc-options='-optl-static -optl-pthread' --force-dirty)
This ends up not linking gitit itself at the very end

```/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/4.8/crtbeginT.o: relocation R_X86_64_32 against `__TMC_END__' can not be used when making a shared object; recompile with -fPIC```
This might be fixable by installing the right system libraries, but is this even a good way to go about this?

Best regards,
Matthias

[Matthias Hörmann]

Hello

If you are using the same OS on both your compile and production
system and do have all the non-Haskell libraries you are linking
installed on both
you should be able to just copy the binary without any special options
during stack build.

I have done it for dozens of different projects.

Usually you need libgmp3c2, libpcre3 and zlib1g on Debian-based
systems and possibly a database C library if the Haskell library for
that you are using is
just a wrapper around the C version.

What kind of errors about missing files do you get?

Matthias Hörmann

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[Erik Hesselink]

This is due to the fact that gitit uses cabal's "data-files" section to make data files available at runtime. These are installed in the path mentioned in the error on the machine where you built, so they will be missing on the machine where you copied the binary. This was the reason we stopped using data-files, but obviously that won't work for you. I've looked briefly into getting stack to write these data files to a different (relative?) path so you could copy them over with the executable, but was unable to find anything. Maybe someone else with more stack knowledge can chime in on that?

Erik

On 1 September 2016 at 23:08, Matthias Kauer <ma.k...@gmail.com> wrote:

Thank you for the insight you provided. I'm having some trouble with the mailing list and retyping now.

I tried the straightforward approach again today.
Built gitit with `stack install` on 1 VM then copied it over to another. Both Ubuntu 14.04.

Running on the second VM yields:
```
vagrant@trusty:~$ ./gitit
gitit: /home/vagrant/gitit/.stack-work/install/x86_64-linux/lts-4.0/7.10.3/share/x86_64-linux-ghc-7.10.3/gitit-0.12.1.1/data/default.conf: openFile: inappropriate type (Not a directory)
```

Is this a gitit specific error? Or am I just missing some artifacts from the build process?

Kind regards,
Matthias Kauer

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[Matthias Kauer]

'data-files' and .stack-work were really good hints. Thank you, Erik.
I rsynced the whole .stack-work dir over now and this lets me successfully run gitit on the smaller VM. Ok, when I say "run", I mean "start", but it is something.
The folder in question has 500 MB, however, and I'd rather not transfer that much. After a bit of random action, it appears safe to delete files outside the gitit folder deeply nested within .stack-work, but I cannot be sure.
Do you have further input on that? Can I collect these files with stack (or cabal?) automatically?

Matthias

[Mark Fine]

There's an issue around adding a --prefix option to handle data-files location better:

https://github.com/commercialhaskell/stack/issues/848

Mark

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