# How to Rebuild and Reload Rust Services in Macro: Fast Development Workflow > Learn how to rebuild and reload Rust services instantly in Macro. This fast development workflow rebuilds only changed crates and reloads services without stopping the entire stack. - Repository: [Macro/macro](https://github.com/macro-inc/macro) - Tags: how-to-guide - Published: 2026-08-21 --- **Macro provides an interactive hot-key workflow and one-shot commands to rebuild only changed Rust crates and reload services instantly without stopping the entire stack.** The macro-inc/macro repository ships with a streamlined development environment that eliminates full-stack restarts when iterating on Rust microservices. Whether you prefer keyboard-driven hot-reloading or scripted automation, the **justfile**-based tooling detects changes, rebuilds only affected crates, and swaps containers in place. This guide covers both interactive and non-interactive methods to rebuild and reload Rust services in Macro with minimal disruption. ## Interactive Hot-Key Workflow Macro’s fastest feedback loop runs inside an attached terminal session where single keystrokes trigger incremental rebuilds. ### Starting the Development Stack Boot the local environment with the command that attaches your terminal for hot-key input: ```bash just run_local # Alternative: just stack up ``` This command initializes the **Docker Compose** infrastructure and begins listening for keyboard input. ### Triggering Rebuilds with the `r` Key While the stack is attached, press **`r`** to invoke the `just stack update` logic. According to [`docs/RUNNING_LOCALLY.md`](https://github.com/macro-inc/macro/blob/main/docs/RUNNING_LOCALLY.md), this hot-key executes three steps in sequence: 1. **Change detection** – The helper inspects the Cargo workspace to identify crates with modified source files. 2. **Compilation** – Changed crates are passed to `cargo build` using your active profile (debug or release). 3. **Container replacement** – Fresh binaries are copied into the service’s Dockerfile context, a new image is built, and the running container is swapped without dropping network or volume mounts. ### Clean Shutdown with `q` Press **`q`** to exit the hot-key loop gracefully. This action also removes the existing containers, ensuring the next `just run_local` invocation starts from a clean state. ## One-Shot Rebuild Commands If you prefer not to keep an attached terminal, achieve the same result via CLI. ### Basic Service Update Run the following command from the repository root to rebuild and reload only the changed services: ```bash just stack update ``` This executes the same change-detection and container-swap logic as the interactive `r` key. ### Including Frontend Assets To rebuild both Rust services and the frontend bundle after UI modifications, append the `--frontend` flag: ```bash just stack update --frontend ``` ## Change Detection and Build Process Understanding the internals helps debug build failures or optimize iteration speed. ### Cargo Workspace Inspection The `just` helper scans the workspace manifest to detect file changes. Only crates with modified source are submitted to the Rust compiler, keeping rebuild times minimal for large monorepos. ### Docker Image Reconstruction Compiled binaries from `target/` are copied into the service-specific Dockerfile context. For example, `services/document_storage_service/Dockerfile` consumes the freshly built binary during image reconstruction. ### Container Swapping Strategy **Docker Compose** stops the outdated container for the specific service and starts a fresh instance from the newly built image. The operation preserves the underlying network and volume configuration, maintaining database connections and state between reloads. ## Complete Development Workflow Examples The following patterns illustrate typical daily usage for Rust service development in Macro. ### Standard Iteration Loop ```bash # 1. Start the stack with hot-key support just run_local # 2. Edit Rust code, e.g., services/document_storage_service/src/lib.rs # 3. Press 'r' in the attached terminal to rebuild and reload ``` ### Non-Interactive CI or Scripting ```bash # Rebuild only what changed and reload services just stack update # Or include frontend rebuild just stack update --frontend ``` ### Working with Auxiliary Services For services excluded from the default build, launch with the auxiliary flag and then use standard reload triggers: ```bash just run_local --build-aux-services # Then press 'r' as needed, or run `just stack update` in another window ``` ## Summary - **Macro’s development tooling** resides in the `justfile` and is documented in [`docs/RUNNING_LOCALLY.md`](https://github.com/macro-inc/macro/blob/main/docs/RUNNING_LOCALLY.md). - **Interactive mode** uses `just run_local` plus the **`r`** key for instant reloads and **`q`** for clean exits. - **One-shot updates** use `just stack update`, with optional `--frontend` to include UI assets. - **Change detection** is workspace-aware, rebuilding only modified Rust crates and swapping Docker containers in place. - **Auxiliary services** require the `--build-aux-services` flag during startup but follow the same reload workflow. ## Frequently Asked Questions ### What is the fastest way to rebuild and reload Rust services in Macro during development? Run `just run_local` to attach your terminal, then press **`r`** whenever you modify Rust source code. This triggers a targeted rebuild and container swap without restarting the entire stack. ### How do I rebuild only the changed services without restarting the entire stack? Execute `just stack update` from any terminal window. The command detects which Cargo crates changed, recompiles them, rebuilds the Docker images, and reloads only the affected containers. ### Can I rebuild auxiliary services that are excluded from the default build? Yes. Start the stack with `just run_local --build-aux-services` to include additional services in the initial composition. Once running, use the same **`r`** hot-key or `just stack update` command to reload them after code changes. ### How do I include the frontend bundle in the rebuild process? Append the `--frontend` flag to your update command: `just stack update --frontend`. This rebuilds the Rust services and runs the frontend build pipeline in a single operation.