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/rpm-ostree/README.md

@@ -0,0 +1,33 @@
+# [`rpm-ostree`](https://coreos.github.io/rpm-ostree/) Module for Startingpoint
+
+The `rpm-ostree` module offers pseudo-declarative package and repository management using `rpm-ostree`.
+
+The module first downloads the repository files from repositories declared under `repos:` into `/etc/yum.repos.d/`. The magic string `%OS_VERSION%` is substituted with the current VERSION_ID (major Fedora version), which can be used, for example, for pulling correct versions of repositories from [Fedora's Copr](https://copr.fedorainfracloud.org/).
+
+Then the module installs the packages declared under `install:` using `rpm-ostree install`, it removes the packages declared under `remove:` using `rpm-ostree override remove`. If there are packages declared under both `install:` and `remove:` a hybrid command `rpm-ostree remove <packages> --install <packages>` is used, which should allow you to switch required packages for other ones.
+
+Additionally, the `rpm-ostree` module supports a temporary (waiting for `rpm-ostree` issue [#233](https://github.com/coreos/rpm-ostree/issues/233)) fix for packages that install into `/opt/`. Installation for packages that install into folder names declared under `optfix:` are fixed using some symlinks.
+
+## Example Configuration:
+
+```yml
+type: rpm-ostree
+repos:
+  - https://copr.fedorainfracloud.org/coprs/atim/starship/repo/fedora-%OS_VERSION%/atim-starship-fedora-%OS_VERSION%.repo
+install:
+  - python3-pip
+  - libadwaita
+remove:
+  - firefox
+  - firefox-langpacks
+```
+
+
+## Known issues
+
+When removing certain packages, some problem probably in upstream `rpm-ostree` causes a `depsolve` issue similar to below. [Removed packages are still present in the underlying ostree repository](https://coreos.github.io/rpm-ostree/administrator-handbook/#removing-a-base-package), what `remove` does is "hide" them from the system, it doesn't reclaim disk space.
+```
+Resolving dependencies...done
+error: Could not depsolve transaction; 1 problem detected:
+Problem: conflicting requests
+```

modules/rpm-ostree/rpm-ostree.sh

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+#!/usr/bin/env bash
+
+# Tell build process to exit if there are any errors.
+set -oue pipefail
+
+# Pull in repos
+get_yaml_array REPOS '.repos[]' "$1"
+if [[ ${#REPOS[@]} -gt 0 ]]; then
+    echo "Adding repositories"
+    for REPO in "${REPOS[@]}"; do
+        REPO="${REPO//%OS_VERSION%/${OS_VERSION}}"
+        wget "${REPO//[$'\t\r\n ']}" -P "/etc/yum.repos.d/"
+    done
+fi
+
+# Create symlinks to fix packages that create directories in /opt
+get_yaml_array OPTFIX '.optfix[]' "$1"
+if [[ ${#OPTFIX[@]} -gt 0 ]]; then
+    echo "Creating symlinks to fix packages that install to /opt"
+    # Create symlink for /opt to /var/opt since it is not created in the image yet
+    mkdir -p "/var/opt"
+    ln -s "/var/opt"  "/opt"
+    # Create symlinks for each directory specified in recipe.yml
+    for OPTPKG in "${OPTFIX[@]}"; do
+        OPTPKG="${OPTPKG%\"}"
+        OPTPKG="${OPTPKG#\"}"
+        OPTPKG=$(printf "$OPTPKG")
+        mkdir -p "/usr/lib/opt/${OPTPKG}"
+        ln -s "../../usr/lib/opt/${OPTPKG}" "/var/opt/${OPTPKG}"
+        echo "Created symlinks for ${OPTPKG}"
+    done
+fi
+
+get_yaml_array INSTALL '.install[]' "$1"
+get_yaml_array REMOVE '.remove[]' "$1"
+
+# The installation is done with some wordsplitting hacks
+# because of errors when doing array destructuring at the installation step.
+# This is different from other ublue projects and could be investigated further.
+INSTALL_STR=$(echo "${INSTALL[*]}" | tr -d '\n')
+REMOVE_STR=$(echo "${REMOVE[*]}" | tr -d '\n')
+
+# Install and remove RPM packages
+if [[ ${#INSTALL[@]} -gt 0 && ${#REMOVE[@]} -gt 0 ]]; then
+    echo "Installing & Removing RPMs"
+    echo "Installing: ${INSTALL_STR[*]}"
+    echo "Removing: ${REMOVE_STR[*]}"
+    # Doing both actions in one command allows for replacing required packages with alternatives
+    rpm-ostree override remove $REMOVE_STR $(printf -- "--install=%s " $INSTALL_STR)
+elif [[ ${#INSTALL[@]} -gt 0 ]]; then
+    echo "Installing RPMs"
+    echo "Installing: ${INSTALL_STR[*]}"
+    rpm-ostree install $INSTALL_STR
+elif [[ ${#INSTALL[@]} -gt 0 ]]; then
+    echo "Removing RPMs"
+    echo "Removing: ${REMOVE_STR[*]}"
+    rpm-ostree override remove $REMOVE_STR
+fi