add haze scripts

fixes #27

README.md

@@ -371,6 +371,62 @@ Additionally, the proxy allows access to the server containers trough either
 `rolling-bees-mail.haze.example.com` will give access to the smtp4dev web
 interface of the `rolling-bees` instance.
 
+## Haze scripts
+
+Haze scripts combine a set of instance options and a script to run in the
+instance.
+
+Haze scripts are intended to way to create automated ways of running more
+complex tests are setting up more complex instances.
+
+A script contains of 3 paths
+
+1. An optional shebang line setting `haze` as the interperter, e.g.
+   `#! /usr/bin/env haze`
+2. A shebang line setting the options for the instance creation as the
+   interperter, e.g. `#! haze shell pgsql s3`
+3. The rest that is ran as a script inside the created instace.
+
+For example, the following script will create an instance with `postgresql` and
+`s3` primary storage. Then creates a new file, gets the file id, read the object
+of the file from S3, validate that it contains the expected contents, and
+cleanup the instance.
+
+```bash
+#! /home/robin/Projects/haze/target/debug/haze script
+#! haze shell pgsql s3
+
+echo 'test' | occ file:put '-' /admin/files/test.txt
+FILE_ID=$(occ info:file /admin/files/test.txt | grep fileid: | grep -oE '[0-9]+')
+OBJECT_CONTENTS=$(occ file:object:get urn:oid:$FILE_ID -)
+if [ "$OBJECT_CONTENTS" == 'test' ]; then
+    echo "object contains expected contents"
+else
+    echo "object does not contains expected contents!"
+fi
+```
+
+### Script modes
+
+Scripts can be either `shell` or `start` scripts.
+
+`shell` scripts will automatically remove the created instance once the script
+is done, just like `haze shell` will. The intended use case for this is
+performing some tests in the created instance without leaving state behind.
+
+`start` scripts on the other hand will keep the instance, like `haze start`
+will. The intended use case for this is creating more complex instances without
+having to configure a dedicated preset.
+
+The script mode is determined based on the shebang line. The mode set in a
+script can be overriden by running the script with
+`haze script [shell|start] path-to-script.sh`.
+
+## Nushell scripts
+
+By default, the script contents are executed as a `bash` script, you can instead
+execute the script as a `nushell` script by using `.nu` as the file extention.
+
 ## Configuration
 
 Configuration is loaded from `~/.config/haze/haze.toml` and has the following