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The Hsansible Package

Ansible is a software for deploying, managing, and orchestrating computer systems over SSH. It has a modular design that allows users to create modules for various parts of the system.

This package provides simple framework for rapid development of Ansible modules in Haskell programming language. Haskell is flexible when it comes to being compiled or interpreted and so it's possible to use it either way, but each has it's own trade-offs.

Installation

Currently hsansible is not available on Hackage, hopefully soon it will be, and so the only way how to get it is from GitHub:

git clone git://github.com/trskop/hsansible.git

Installation: The Standard Cabal Way

Hsansible is a cabalized package, so using cabal-install in a cloned repository will work just fine:

cabal install

Standard Setup.hs way is also available:

runhaskell Setup.hs configure
runhaskell Setup.hs build
runhaskell Setup.hs install

See Cabal User Guide: Building and installing packages for details.

Installation: Sandboxing

It might be useful to create separate sandbox for packages that will be used by Ansbile modules. This can be done using cabal-dev, which its self can be installed using cabal-install. In such case it's a good idea to place the sandbox in a Ansible specific directory, in example:

cabal-dev install --sandbox=$HOME/.ansible/sandbox

Feel free to change $HOME/.ansible/sandbox to a directory of your choice. Since cabal-dev has it's own dependencies it might be useful to use only cabal-install and GHC tools to do the same thing:

INSTALL_DIR="$HOME/.ansible/sandbox"
PACKAGES_CONF="$INSTALL_DIR/packages-`ghc --numeric-version`.conf"
mkdir "$INSTALL_DIR"
ghc-pkg init "$PACKAGES_CONF"
cabal install --prefix="$INSTALL_DIR" --package-db="$PACKAGES_CONF"

You might also want to consider using option like --disable-documentation. Newer version of cabal-install should be able to work with sandboxes directly, but that functionality is currently in HEAD and I'm not familiar with it.

When hsansible is installed in sandbox, then interpreted Ansible modules written in Haskell have to know where to find it. To do so you need to modify #! line to look like this:

#!/usr/bin/runhaskell -package-conf=<path-to-packages-conf-goes-here>

Installation: Ansible Playbook

As expected, it's possible to use Ansible to install Hsansible. Following is an example of Ansible playbook that does that.

---
- hosts: debian ubuntu
  # ^ Setup does determine OS of targeted machine, but I sometimes found it
  # simpler to just have special groups for Debian and Ubuntu systems.
  # Operating system doesn't change that often and therefore it's possible to
  # get away with this and it really does simplify playbooks.

  sudo: no
  # ^ It's not necessary to install Hsansible via sudo since it may be
  # installed in user's home directory. Only the haskell-platform installation
  # requires sudo.

  vars:
    - hsansible_dir: /home/ansible/hsansible
    - haskell_sandbox: /home/ansible/haskell-sandbox

  tasks:
    # Tag "update-hsansible" is here to provide easy way to just update
    # Hsansible by installing newer version. You might want to also run ghc-pkg
    # unregister for older versions, but this playbook doesn't handle that.

    - name: Install Haskell Platform
      apt: pkg=haskell-platform state=installed update_cache=yes
      tags: [install-hsansible]
      # This is the only step that will always require sudo, others can work
      # without it, if the "hsansible_dir" and "haskell_sandbox" can be created by
      # the user Ansible uses for SSH login.
      sudo: yes

    - name: Clone/pull Hsansible repository
      # Depending on your firewall/proxy configuration you might want to swith to
      # "git:" protocol or create a tunel before doing this. Another possibility is
      # to have internal "Git Cache", a host that pulls Git repositories from the
      # internet and provides access to them from internal network. In such case
      # you need to provide correct repository URL.
      git: repo=https://github.com/trskop/hsansible.git dest=$hsansible_dir
      tags: [install-hsansible, update-hsansible]

    # This step is required if it wasn't ever executed before on target host under
    # the user you'll going to install Hsansible, particulary right after
    # first-time haskell-platform installation.
    - name: Update Cabal package cache
      command: /usr/bin/cabal update
      tags: [install-hsansible]

    # Relies on script provided by Hsansible in it's Git repository.
    - name: Install Hsansible in sandbox
      command: $hsansible_dir/tools/sandbox-install.sh --working-dir="$hsansible_dir" "$haskell_sandbox"
      tags: [install-hsansible, update-hsansible]

You can find it in examples/playbooks/install-hsansible-on-debian-and-ubuntu.yaml.