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 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): the package manager used to install dependencies before checking. Set it to yarn or pnpm to match the project.
• baseImageAddress (default node:25-alpine): 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.