Prettier

The Prettier module keeps formatting boring, consistent, and enforced before code review. It checks formatting locally, in CI, and in Dagger Cloud, and can rewrite source to match, always using your project's own Prettier config. Keep it alongside a linter so formatting policy stays separate from lint rules.

Official module: dagger/prettier

Add it to your workspace

dagger install github.com/dagger/prettier

Run the check

dagger check                 # run every check in the workspace
dagger check prettier:check  # just check formatting

prettier:check installs dependencies and runs prettier --check . across the workspace, failing if any file isn't formatted.

Fix formatting

Prettier also exposes a write function that runs prettier --write . across the workspace and returns the reformatted source as a changeset (everything except node_modules). Which files it touches is governed by your project's own Prettier configuration and ignore files. It's a regular function, not a check, so it doesn't run during dagger check. Call it directly:

dagger api call prettier write

Configure it

List the current settings with dagger settings prettier, then change one with dagger settings prettier <key> <value>. They live in dagger.toml under [modules.prettier.settings]:

• packageManager (default npm) is the package manager used to install dependencies before checking. Set it to yarn or pnpm to match the project.
• baseImageAddress (default node:25-alpine) is the Node base image Prettier runs in. Pin it to your project's Node version, e.g. node:22-alpine.

[modules.prettier.settings]
packageManager = "pnpm"
baseImageAddress = "node:22-alpine"

Working with other modules

Prettier pairs well with ESLint. ESLint checks code quality, Prettier owns formatting. If your project uses Biome for both, use the Biome module instead.