openhab.nix/README.mkd

A nix package for OpenHAB

No-frills, auto-updated high-quality package of OpenHAB for nix systems.

Many of the attempts to integrate OpenHAB with nix attempt to also create a declaratively-configured NixOS module at the same time. While an admirable goal, this approach has resulted in none of these projects working out of the box. With this flake the aim is to provide the barebones foundational stone for annybody looking to run OpenHAB either manually, or to enable integration to their systems in whatever other manner.

Usage

At the most basic level you can build the package like so:

$ nix build github:nagisa/nixpkg-openhab

However, more likely you will want to integrate this into a larger flake of some sort (such as the one building your system that is going to run OpenHAB):

inputs = {
    # ...;
    openhab.url = "github:nagisa/nixpkg-openhab";
    openhab.inputs = {
        # In case you alrady depend on `nixpkgs` in your flake, consider having `openhab`
        # “follow” it:
        nixpkgs.follows = "nixpkgs";
        # Similarly, for flake-utils:
        flake-utils.follows = "flake-utils";
    };
};

From there openhab.packages will contain a variety of packages, with openhab or its alias default being most interesting of them all. Among other things it also re-exports a copy of the jdk used for OpenHAB in case you need it for any reason.

Running OpenHAB

Running OpenHAB as-is is not going to work, however. You will need to set-up a directory with some configuration and user data storage, as well as some environment variables pointing OpenHAB (or rather Apache Karaf) at this directory.

In this example a basic openhab directory in current user’s home is created, however once you look at deploying a systemd service, this may get more complicated (though the general pattern will be similar…)

$ mkdir -p ~/openhab/userdata/etc
$ cp -rv $(nix build github:nagisa/nixpkg-openhab)/userdata/* ~/openhab/userdata
$ cp -rv $(nix build github:nagisa/nixpkg-openhab)/conf ~/openhab/
$ chmod -R +rw ~/openhab

Then, you can run OpenHAB with the appropriate environment variables.

env OPENHAB_USERDATA="$HOME"/openhab/userdata/ \
    OPENHAB_CONF="$HOME"/openhab/conf \
    $(nix build github:nagisa/nixpkg-openhab)/start.sh

At this point you should see openhab successfully launching and you should be able to access the web UI in your browser at localhost:8080.

Maintenance

This project is maintained automatically via GitHub Actions. It will periodically check the upstream openhab/openhab-distro repository for new releases and update the flake definition and the hash for the repository of dependencies here to the most recent proper release. Due to the way maven works (and mvn2nix does not work) the hash of the repository can change as OpenHAB's dependencies are upgraded, even without any changes to OpenHAB, so if you do happen to encounter a hash mismatch, it might get resolved on the next run of the maintenance action.

However, it is inevitable that things may break due to the upstream changes in the future. In that case, contributions and issues are welcome, of course.