feat: startingpoint modules (#33)

* feat: add startingpoint modules
some modules authored by @gerblesh
original source: https://github.com/ublue-os/startingpoint/pull/135

* docs: better readme for modules dir

* docs: yafti deps

* docs: sp more information

* feat: startingpoint modules in container

* docs: sentence structure, check sidebar

modules/systemd/README.md

@@ -0,0 +1,41 @@
+# `systemd` Module for Startingpoint
+
+The `systemd` module streamlines the management of systemd units during image building. Units are divided into `system` and `user` categories, with `system` units managed directly using `systemctl` and `user` units using `systemctl --user`. You can specify which units to enable or disable under each category.
+
+## Example Configuration:
+
+```yaml
+type: systemd
+system:
+  enable:
+    - example.service
+  disable:
+    - example.target
+user:
+  enable:
+    - example.timer
+  disable:
+    - example.service
+```
+
+In this example:
+
+### System Units
+- `example.service`: Enabled (runs on system boot)
+- `example.target`: Disabled (does not run on system boot)
+
+### User Units
+- `example.timer`: Enabled (runs for the user)
+- `example.service`: Disabled (does not run for the user)
+
+This configuration achieves the same results as the following commands:
+
+```sh
+# System Units
+systemctl enable example.service
+systemctl disable example.target
+
+# User Units
+systemctl --user enable example.timer
+systemctl --user disable example.service
+```

modules/systemd/systemd.sh

@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+
+# Tell build process to exit if there are any errors.
+set -oue pipefail
+
+get_yaml_array ENABLED '.system.enabled[]' "$1"
+get_yaml_array DISABLED '.system.disabled[]' "$1"
+get_yaml_array USER_ENABLED '.user.enabled[]' "$1"
+get_yaml_array USER_DISABLED '.user.disabled[]' "$1"
+
+
+if [[ ${#ENABLED[@]} -gt 0 ]]; then
+    for unit in "${ENABLED[@]}"; do
+        unit=$(printf "$unit")
+        systemctl enable $unit
+    done
+fi
+if [[ ${#DISABLED[@]} -gt 0 ]]; then
+    for unit in "${DISABLED[@]}"; do
+        unit=$(printf "$unit")
+        systemctl disable $unit
+    done
+fi
+if [[ ${#USER_ENABLED[@]} -gt 0 ]]; then
+    for unit in "${ENABLED[@]}"; do
+        unit=$(printf "$unit")
+        systemctl --user enable $unit
+    done
+fi
+if [[ ${#USER_DISABLED[@]} -gt 0 ]]; then
+    for unit in "${DISABLED[@]}"; do
+        unit=$(printf "$unit")
+        systemctl --user disable $unit
+    done
+fi