feat(script): add snippet support for script module (#124)

modules/script/README.md

@@ -1,6 +1,8 @@
 # `script`
 
-The `script` module can be used to run arbitrary scripts at image build time that take no or minimal external configuration (in the form of command line arguments).
+The `script` module can be used to run arbitrary bash snippets and scripts at image build time. This is intended for running commands that need no YAML configuration.
+
+The snippets, which are run in a bash subshell, are declared under `snippets:`.   
 The scripts, which are run from the `config/scripts` directory, are declared under `scripts:`.
 
 ## Creating a Script

modules/script/module.yml

@@ -1,7 +1,10 @@
 name: script
-shortdesc: The script module can be used to run arbitrary scripts at image build time.
+shortdesc: The script module can be used to run arbitrary bash snippets and scripts at image build time.
 readme: https://raw.githubusercontent.com/blue-build/modules/main/modules/script/README.md
 example: |
   type: script
+  snippets:
+    - "curl https://example.com/examplebinary > /usr/bin/examplebinary" # example: download binary
+    - "ln -sf /usr/bin/ld.bfd /etc/alternatives/ld && ln -sf /etc/alternatives/ld /usr/bin/ld" # example: ld alternatives symlink workaround
   scripts:
-    - myscript.sh # will run config/scripts/myscript.sh
+    - myscript.sh # example: run config/scripts/myscript.sh

modules/script/script.sh

@@ -4,13 +4,17 @@
 set -euo pipefail
 
 get_yaml_array SCRIPTS '.scripts[]' "$1"
+get_yaml_array SNIPPETS '.snippets[]' "$1"
 
 cd "$CONFIG_DIRECTORY/scripts"
-
 # Make every script executable
 find "$PWD" -type f -exec chmod +x {} \;
-
 for SCRIPT in "${SCRIPTS[@]}"; do
     echo "Running script $SCRIPT"
-    eval "$PWD/$SCRIPT"
+    "$PWD/$SCRIPT"
 done
+
+for SNIPPET in "${SNIPPETS[@]}"; do
+    echo "Running snippet $SNIPPET"
+    bash -c "$SNIPPET"
+done