Initial commit; base scripting and systemd user event code for borg based backup

etc/config.example

@@ -0,0 +1,44 @@
+# nextcloud-borg-backup configuration
+#
+# Copy to:
+#   ~/.config/nextcloud-borg-backup/config
+
+SOURCE_DIR="${HOME}/Nextcloud"
+REPO_DIR="/net/thor/volume1/NetBackup/Nextcloud/borg-repo"
+ARCHIVE_PREFIX="nextcloud"
+
+# Borg repository encryption. repokey-blake2 needs a passphrase file for
+# unattended systemd timer runs. The installer creates this file if missing.
+BORG_ENCRYPTION="repokey-blake2"
+BORG_PASSPHRASE_FILE="${HOME}/.config/nextcloud-borg-backup/passphrase"
+BORG_COMPRESSION="zstd,6"
+
+# Four weeks of restorable history. With the daily timer this keeps at least
+# one month of archives; manual extra runs inside the window are also retained.
+RETENTION_WITHIN="4w"
+
+# Safety checks.
+ALLOW_EMPTY_SOURCE="false"
+MIN_FREE_REPO_GB="5"
+PRECHECK_TIMEOUT_SECONDS="60"
+
+# Runtime paths.
+LOG_DIR="${HOME}/.local/state/nextcloud-borg-backup/logs"
+STATE_DIR="${HOME}/.local/state/nextcloud-borg-backup"
+RESTORE_DIR="${HOME}/Nextcloud-Restore"
+MOUNT_DIR="${XDG_RUNTIME_DIR:-/tmp}/nextcloud-borg-backup-mount"
+EXCLUDE_FILE="${HOME}/.config/nextcloud-borg-backup/excludes"
+LOCK_FILE="${HOME}/.local/state/nextcloud-borg-backup/nextcloud-borg-backup.lock"
+
+# Borg behavior.
+PRUNE_AFTER_BACKUP="true"
+COMPACT_AFTER_PRUNE="true"
+REPOSITORY_CHECK_AFTER_BACKUP="true"
+FULL_CHECK_INTERVAL_DAYS="7"
+FULL_CHECK_VERIFY_DATA="false"
+EXCLUDE_CACHES="true"
+ONE_FILE_SYSTEM="true"
+
+# Leave empty unless the rclone mount exposes unstable metadata and Borg rereads
+# too much. Conservative alternative: BORG_FILES_CACHE="mtime,size"
+BORG_FILES_CACHE=""