feat: add restore functionality (#12)

Reviewed-on: #12
Co-authored-by: Timo Behrendt <t.behrendt@t00n.de>
Co-committed-by: Timo Behrendt <t.behrendt@t00n.de>

src/backup.sh

@@ -15,6 +15,13 @@ log() {
     echo "$(date +"$LOG_DATE_FORMAT") - $*"
 }
 
+#######################################
+# Determine operation mode from the environment only.
+# Valid values: "backup" or "restore".
+# Default to "backup" if not provided.
+#######################################
+OPERATION_MODE="${OPERATION_MODE:-backup}"
+
 #######################################
 # Determine backup mode from the environment only.
 # Valid values: "directory" or "postgres".
@@ -27,7 +34,11 @@ BACKUP_MODE="${BACKUP_MODE:-directory}"
 #######################################
 REQUIRED_CMDS=(restic curl jq)
 if [ "$BACKUP_MODE" = "postgres" ]; then
-    REQUIRED_CMDS+=(pg_dump)
+    if [ "$OPERATION_MODE" = "backup" ]; then
+        REQUIRED_CMDS+=(pg_dump)
+    elif [ "$OPERATION_MODE" = "restore" ]; then
+        REQUIRED_CMDS+=(psql)
+    fi
 fi
 
 for cmd in "${REQUIRED_CMDS[@]}"; do
@@ -59,21 +70,41 @@ fi
 # Example: export RESTIC_REPOSITORY="rest:http://your-rest-server:8000/backup"
 : "${RESTIC_REPOSITORY:?Environment variable RESTIC_REPOSITORY is not set}"
 
+#######################################
+# Validate operation mode.
+#######################################
+case "$OPERATION_MODE" in
+    backup|restore)
+        ;;
+    *)
+        echo "Error: Unknown operation mode '$OPERATION_MODE'. Valid modes are 'backup' and 'restore'." >&2
+        exit 1
+        ;;
+esac
+
 #######################################
 # Validate mode-specific environment variables.
 #######################################
 case "$BACKUP_MODE" in
     directory)
-        : "${SOURCEDIR:?Environment variable SOURCEDIR is not set (required for directory backup mode)}"
+        if [ "$OPERATION_MODE" = "backup" ]; then
+            : "${SOURCEDIR:?Environment variable SOURCEDIR is not set (required for directory backup mode)}"
+        elif [ "$OPERATION_MODE" = "restore" ]; then
+            : "${RESTOREDIR:?Environment variable RESTOREDIR is not set (required for directory restore mode)}"
+        fi
         ;;
     postgres)
-        : "${PGHOST:?Environment variable PGHOST is not set (required for PostgreSQL backup mode)}"
-        : "${PGDATABASE:?Environment variable PGDATABASE is not set (required for PostgreSQL backup mode)}"
-        : "${PGUSER:?Environment variable PGUSER is not set (required for PostgreSQL backup mode)}"
+        : "${PGHOST:?Environment variable PGHOST is not set (required for PostgreSQL mode)}"
+        : "${PGDATABASE:?Environment variable PGDATABASE is not set (required for PostgreSQL mode)}"
+        : "${PGUSER:?Environment variable PGUSER is not set (required for PostgreSQL mode)}"
         # Optional: default PGPORT to 5432.
         : "${PGPORT:=5432}"
         if [ -z "${PGPASSWORD:-}" ]; then
-            echo "Warning: Environment variable PGPASSWORD is not set. pg_dump may fail if authentication is required."
+            if [ "$OPERATION_MODE" = "backup" ]; then
+                echo "Warning: Environment variable PGPASSWORD is not set. pg_dump may fail if authentication is required."
+            elif [ "$OPERATION_MODE" = "restore" ]; then
+                echo "Warning: Environment variable PGPASSWORD is not set. psql may fail if authentication is required."
+            fi
         fi
         ;;
     *)
@@ -173,6 +204,89 @@ backup_postgres() {
     run_restic_backup "${TEMP_BACKUP_DIR}"
 }
 
+#######################################
+# Run the restore using restic.
+# Arguments:
+#   $1 - The target directory to restore to.
+#   $2 - Optional snapshot ID to restore (defaults to latest).
+#######################################
+run_restic_restore() {
+    local target_dir="$1"
+    local snapshot_id="$2"
+    
+    log "Starting restore from repository ${RESTIC_REPOSITORY} to '${target_dir}'"
+    log "Using snapshot: ${snapshot_id}"
+    
+    # Create target directory if it doesn't exist
+    mkdir -p "${target_dir}"
+    
+    # Capture both stdout and stderr in a variable
+    restore_output=$(restic -r "${RESTIC_REPOSITORY}" restore "${snapshot_id}" --target "${target_dir}" --no-cache --json --verbose 2>&1)
+    # Optionally, also print the output to the console:
+    echo "$restore_output"
+    
+    # Parse the JSON lines output for the summary message
+    summary=$(echo "$restore_output" | jq -r 'select(.message_type=="summary") | "Restore completed: " + (.files_restored|tostring) + " files restored, " + (.bytes_restored|tostring) + " bytes in " + (.total_duration|tostring) + " sec"' 2>/dev/null || echo "Restore completed")
+    
+    # Check exit code of restic restore
+    if [ $? -eq 0 ]; then
+        msg="Restore successful. $summary"
+        log "$msg"
+        send_notification "$msg"
+    else
+        exit_code=$?
+        msg="Restore failed with error code ${exit_code}. $restore_output"
+        log "$msg"
+        send_notification "$msg"
+        exit "$exit_code"
+    fi
+}
+
+#######################################
+# Restore a directory (regular mode).
+#######################################
+restore_directory() {
+    local snapshot_id="${RESTORE_SNAPSHOT_ID:-latest}"
+    run_restic_restore "${RESTOREDIR}" "${snapshot_id}"
+}
+
+#######################################
+# Restore a PostgreSQL database.
+# Restores the database dump from the backup and applies it to the database.
+#######################################
+restore_postgres() {
+    local snapshot_id="${RESTORE_SNAPSHOT_ID:-latest}"
+    log "Starting PostgreSQL restore for database '${PGDATABASE}' on host '${PGHOST}'"
+    
+    # Create a temporary directory for the restore.
+    TEMP_RESTORE_DIR=$(mktemp -d)
+    log "Created temporary directory: ${TEMP_RESTORE_DIR}"
+
+    # Restore the backup to the temporary directory
+    run_restic_restore "${TEMP_RESTORE_DIR}" "${snapshot_id}"
+    
+    local dump_file="${TEMP_RESTORE_DIR}/dump.sql"
+    if [ ! -f "${dump_file}" ]; then
+        local msg="PostgreSQL restore failed. Database dump file not found at ${dump_file}"
+        log "$msg"
+        send_notification "$msg"
+        exit 1
+    fi
+    
+    log "Restoring PostgreSQL database from ${dump_file}..."
+    if psql -h "${PGHOST}" -p "${PGPORT}" -U "${PGUSER}" -d "${PGDATABASE}" ${PSQL_ARGS:-} < "${dump_file}"; then
+        local msg="PostgreSQL database restored successfully"
+        log "$msg"
+        send_notification "$msg"
+    else
+        local exit_code=$?
+        local msg="PostgreSQL restore failed with error code ${exit_code}"
+        log "$msg"
+        send_notification "$msg"
+        exit "$exit_code"
+    fi
+}
+
 #######################################
 # Cleanup temporary resources.
 #######################################
@@ -181,6 +295,10 @@ cleanup() {
         rm -rf "${TEMP_BACKUP_DIR}"
         log "Removed temporary directory ${TEMP_BACKUP_DIR}"
     fi
+    if [ -n "${TEMP_RESTORE_DIR:-}" ] && [ -d "${TEMP_RESTORE_DIR}" ]; then
+        rm -rf "${TEMP_RESTORE_DIR}"
+        log "Removed temporary directory ${TEMP_RESTORE_DIR}"
+    fi
 }
 trap cleanup EXIT
 
@@ -188,12 +306,26 @@ trap cleanup EXIT
 # Main routine.
 #######################################
 main() {
-    case "$BACKUP_MODE" in
-        directory)
-            backup_directory
+    case "$OPERATION_MODE" in
+        backup)
+            case "$BACKUP_MODE" in
+                directory)
+                    backup_directory
+                    ;;
+                postgres)
+                    backup_postgres
+                    ;;
+            esac
             ;;
-        postgres)
-            backup_postgres
+        restore)
+            case "$BACKUP_MODE" in
+                directory)
+                    restore_directory
+                    ;;
+                postgres)
+                    restore_postgres
+                    ;;
+            esac
             ;;
     esac
 }