OCaml-Core-OpenShift

OpenShift cartridge for OCaml with integrated building and running server.

This is a simple cartridge for creating applications based on OCaml ~~with Core~~ (well, unless you have larger gear at your disposal).

There is also another OCaml cartridge, you may want to check it out too. Originally I thought my cartridge would be different. However, during the development I gradually found out that they had done quite good job and I have converged to very similar design myself. (At least I have learned something.)

Comparing to the other one my cartridge implements also building, installation, and startup of packages (using OASIS and OPAM). This was loosely inspired by Haskell-Cloud.

Original idea was to create environment where it would be simple/possible to build applications based on Core+Async. However, it turned out to be quite hard to build Core under restrictions imposed by small gears of OpenShift.

To start with OCaml and Core read Real Wold OCaml.

HowTo

Example installation

repodir=~/ocamltest
rhc app create ocamltest --repo "${repodir}" "https://raw.githubusercontent.com/xkollar/ocaml-core-openshift/master/metadata/manifest.yml"
cd "${repodir}"

At this point only environment configuration is done. If you ssh to your gear you will not find any OCaml stuff there.

# do your changes and commit them into git
git push

When you push for the first time, OPAM will be downloaded and installed and then OCaml compiler and couple of auxiliary packages will be downloaded and/or built. (One might think that this should have been done during the application creation. However, compiler installation is rather lengthy process and it would have led to time-out thus causing inconsistent state.)

Next step is installation of your application (it should be OASIS and OPAM enabled) followed by execution of binary server. That can be vaguely described as follows:

# in application repo dir
oasis setup
opam pin add "${pkgname}" . -y
server -port "${OPENSHIFT_OCAML_CORE_PORT}" -address "${PENSHIFT_OCAML_CORE_ADDRESS}"

What needs to be done for your application

Your application must provide binary called server that uses values of environment variables OPENSHIFT_OCAML_CORE_PORT and OPENSHIFT_OCAML_CORE_ADDRESS as parameters for binding.