docspell/website/site/content/docs/dev/development.md

+++
title = "Tips & Setup"
weight = 20
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# Starting Servers with `reStart`

When developing, it's very convenient to use the [revolver sbt
plugin](https://github.com/spray/sbt-revolver). Start the sbt console
and then run:

```
sbt:docspell-root> restserver/reStart
```

This starts a REST server. Once this started up, type:

```
sbt:docspell-root> joex/reStart
```

if also a joex component is required. Prefixing the commads with `~`,
results in recompile+restart once a source file is modified.

It is possible to start both in the root project:

```
sbt:docspell-root> reStart
```


# Custom config file

The sbt build is setup such that a file `dev.conf` in the directory
`local` (at root of the source tree) is picked up as config file, if
it exists. So you can create a custom config file for development. For
example, a custom database for development may be setup this way:

``` bash
#jdbcurl = "jdbc:h2:///home/dev/workspace/projects/docspell/local/docspell-demo.db;MODE=PostgreSQL;DATABASE_TO_LOWER=TRUE;AUTO_SERVER=TRUE"
jdbcurl = "jdbc:postgresql://localhost:5432/docspelldev"
#jdbcurl = "jdbc:mariadb://localhost:3306/docspelldev"

docspell.server {
  backend {
    jdbc {
      url = ${jdbcurl}
      user = "dev"
      password = "dev"
    }
  }
}

docspell.joex {
  jdbc {
    url = ${jdbcurl}
    user = "dev"
    password = "dev"
  }
  scheduler {
    pool-size = 1
  }
}
```

# Developing Frontend

The frontend is a SPA written in [Elm](https://elm-lang.org). The UI
framework in use is [tailwind](https://tailwindcss.com).

The frontend code is in the sub-project `webapp`. Running sbt's
`compile` task, compiles elm sources and creates the final CSS file.
Whenever the `restserver` module is build by sbt, the `webapp`
sub-project is built as well and the final files to deliver are
updated. So, when in sbt shell, "watch-compile" the project
`restserver`, (via `~ restserver/compile`), re-compiles elm-code on
change. However, it also re-creates the final css, which is a rather
long task.

To speed things up when only developing the frontend, a bash script is
provided in `project/dev-ui-build.sh`. Start the `restserver` once,
using `restserver/reStart` task as described above. Then run this
script in the source root. It will watch elm files and the css file
and re-compiles only on change writing the resulting files in the
correct locations so they get picked up by the restserver.

Now you can edit elm files and the `index.css` and then only refresh
the page. Elm compilation is *very* fast, it's difficult to reach the
refresh button before it is done compiling :). When editing the CSS,
it takes a little longer, but this is hardly necessary, thanks to
tailwind.

There is still a problem: the browser caches the js and css files by
default, so a page refresh is not enough, you need to clear the cache,
too. To avoid this annoyance, set a env variable `DOCSPELL_ENV` to the
value `dev`. Docspell then adds a response header, preventing the
browser to cache these files. This must be done, obviously, before
starting the restserver:

``` bash
$ export DOCSPELL_ENV=dev
$ sbt "restserver/reStart"
```

# Nix Expressions

The directory `/nix` contains nix expressions to install docspell via
the nix package manager and to integrate it into NixOS.

## Testing NixOS Modules

The modules can be build by building the `configuration-test.nix` file
together with some nixpkgs version. For example:

``` bash
nixos-rebuild build-vm -I nixos-config=./configuration-test.nix \
  -I nixpkgs=https://github.com/NixOS/nixpkgs-channels/archive/nixos-19.09.tar.gz
```

This will build all modules imported in `configuration-test.nix` and
create a virtual machine containing the system. After that completes,
the system configuration can be found behind the `./result/system`
symlink. So it is possible to look at the generated systemd config for
example:

``` bash
cat result/system/etc/systemd/system/docspell-joex.service
```

And with some more commands (there probably is an easier way…) the
config file can be checked:

``` bash
cat result/system/etc/systemd/system/docspell-joex.service | grep ExecStart | cut -d'=' -f2 | xargs cat | tail -n1 | awk '{print $NF}'| sed 's/.$//' | xargs cat | jq
```

To see the module in action, the vm can be started (the first line
sets more memory for the vm):

``` bash
export QEMU_OPTS="-m 2048"
./result/bin/run-docspelltest-vm
```


# Background Info

There is a list of [ADRs](@/docs/dev/adr/_index.md) containing
internal/background info for various topics.