refactor utils, nextcloud image, add fetch-docker script

Signed-off-by: ahuston-0 <aliceghuston@gmail.com>

utils/sops-mergetool.sh

@@ -0,0 +1,79 @@
+#!/usr/bin/env bash
+# Exit on first error and verify variables have been set/passed via CLI
+set -eu
+
+# Rename our variables to friendlier equivalents
+# https://git-scm.com/docs/gitattributes#_defining_a_custom_merge_driver
+base="$1"; local_="$2"; remote="$3"; merged="$4"
+
+# Resolve our default mergetool
+# https://github.com/git/git/blob/v2.8.2/git-mergetool--lib.sh#L3
+mergetool="$(git config --get merge.tool)"
+GIT_DIR="$(git --exec-path)"
+if test "$mergetool" = ""; then
+  echo "No default \`merge.tool\` was set for \`git\`. Please set one via \`git config --set merge.tool <tool>\`" 1>&2
+  exit 1
+fi
+
+# Create file names for our decrypted contents
+#   example_LOCAL_2823.yaml -> example_LOCAL_2823.decrypted.yaml
+extension=".${base##*.}"
+base_decrypted="${base/$extension/.decrypted$extension}"
+local_decrypted="${local_/$extension/.decrypted$extension}"
+remote_decrypted="${remote/$extension/.decrypted$extension}"
+merged_decrypted="${base_decrypted/_BASE_/_MERGED_}"
+backup_decrypted="${base_decrypted/_BASE_/_BACKUP_}"
+
+# If anything goes wrong, then delete our decrypted files
+handle_trap_exit () {
+  rm $base_decrypted || true
+  rm $local_decrypted || true
+  rm $remote_decrypted || true
+  rm $merged_decrypted || true
+  rm $backup_decrypted || true
+}
+trap handle_trap_exit EXIT
+
+# Decrypt our file contents
+sops --decrypt --show-master-keys "$base" > "$base_decrypted"
+sops --decrypt --show-master-keys "$local_" > "$local_decrypted"
+sops --decrypt --show-master-keys "$remote" > "$remote_decrypted"
+
+# Create a merge-diff to compare against
+set +e
+git merge-file -p "$local_decrypted" "$base_decrypted" "$remote_decrypted" > "$merged_decrypted"
+set -e
+cp "$merged_decrypted" "$backup_decrypted"
+
+# Set up variables for our mergetool
+# https://github.com/git/git/blob/v2.8.2/mergetools/meld
+# https://github.com/git/git/blob/v2.8.2/git-mergetool--lib.sh#L95-L111
+export LOCAL="$local_decrypted"
+export BASE="$base_decrypted"
+export REMOTE="$remote_decrypted"
+export MERGED="$merged_decrypted"
+export BACKUP="$backup_decrypted"
+
+# Load our mergetool scripts
+source "$GIT_DIR/git-mergetool--lib"
+source "$GIT_DIR/mergetools/$mergetool"
+
+# Override `check_unchanged` with a custom script
+check_unchanged () {
+  # If the contents haven't changed, then fail
+  if test "$MERGED" -nt "$BACKUP"; then
+    return 0
+  else
+    exit 1
+  fi
+}
+
+# Run our mergetool
+set +eu
+export merge_tool_path="$(get_merge_tool_path "$mergetool")"
+merge_cmd
+set -eu
+
+# Re-encrypt content
+sops --encrypt "$merged_decrypted" > "$merged"
+