🛠 Builds

Custom Builds

Custom builds can be enabled by specifying a build command. You can also specify a path to run the build in, and a path to watch:

$ miniflare --build-command "npm run build"
$ miniflare --build-command "npm run build" --build-base-path "build"
$ miniflare --build-command "npm run build" --build-watch-path "source"
# wrangler.toml
command = "npm run build"
# Below options are optional
cwd = "build"
watch_dir = "source" # Defaults to "src" if command set
const mf = new Miniflare({
  buildCommand: "npm run build",
  // Below options are optional
  buildBasePath: "build",
  buildWatchPath: "source", // Defaults to "src" if command set

The build command will be executed once on initial worker load, then again every time something in the watched page changes. Note that scripts will only be reloaded when scriptPath's contents changes, so make sure that's set to your build output. You can either pass this explicitly, or set it in wrangler.toml:

dir = "" # Defaults to "dist"
main = "./output.js"


When using the CLI, if --build-watch-path is set, --watch is automatically assumed.

Wrangler Builds

Miniflare supports building webpack and rust type Wrangler projects too. This is done internally by automatically setting a default custom build configuration which calls wrangler build to do the actual building.


# wrangler.toml
type = "webpack"

Requires Wrangler to be installed.


If you can, use esbuild for much faster builds and reloads. See the ⚡️ Developing with esbuild recipe for an example.


# wrangler.toml
type = "rust"

Requires Wrangler and Rust to be installed.