Biome

The Biome module runs Biome over your JavaScript and TypeScript source and can return a fixed version when Biome can repair issues. Reach for it when a project uses Biome as its main code quality tool, so a single combined tool handles both lint and format rules instead of a separate ESLint and Prettier pair. Each root Biome config roots a project.

Add it to your workspace

dagger module install dagger.io/js/biome

The module is installed under the name biomejs.

Run the check

dagger check --biomejs                                   # check every project
dagger check --biomejs-biome-project=packages/ui         # check one project

The check is biomejs/projects/lint. It installs dependencies and runs the project's own Biome with biome check from the project directory. Biome's check covers both linting and formatting, which is why this single check replaces a separate ESLint and Prettier pair. A check over several projects reports every project that fails.

Projects

Flag	Collection	Key
--biomejs-biome-project	projects	Directory holding the root Biome config, relative to the workspace root. The root is .

List the keys with dagger list biomejs-biome-projects -a. Select collection items describes how to select items.

A project is a directory holding a root biome.json or biome.jsonc. A config with "root": false belongs to the nearest root config above it. Configs in directories ignored by .gitignore are left out.

Projects are found at or below the directory dagger runs from, plus the nearest project that encloses it.

The source is mounted without files ignored by .gitignore. Dependencies install at the nearest workspace root (a pnpm-workspace.yaml or a package.json with workspaces), else the nearest lockfile, else the nearest package.json.

Fix issues

Each project has a fix function that runs biome check --write and returns the repaired source as a changeset. Fixes are returned even when diagnostics Biome cannot fix remain. It is a regular function rather than a check, so it does not run during dagger check:

dagger -c 'biomejs | projects | get packages/ui | fix | export .'

fix takes files, to fix only some files, and fixFilter, patterns of the files to include in the changeset. Both are relative to the project root.

Configure it

List the current settings and their values with dagger module settings biomejs, then set one with dagger module settings biomejs <key> <value>. Settings are stored in dagger.toml under [modules.biomejs.settings] and apply to every project:

• packageManager (default empty) is the package manager that installs dependencies: npm, yarn, pnpm, or bun. Empty detects it from the packageManager field of package.json, then from the lockfile, then uses npm.
• baseImageAddress (default node:25-alpine, pinned by digest) is the Node base image Biome runs in. It must provide Node.js and npm. Pin it to the project's Node version, for example node:22-alpine.
• installFlags (default empty) are extra arguments for the install command, such as ["--ignore-scripts"].
• environment (default empty) sets environment variables for Biome, as KEY=VALUE.

[modules.biomejs.settings]
baseImageAddress = "node:22-alpine"

Working with other modules

Use Biome for projects that already have Biome config. If your project uses ESLint and Prettier separately, use those modules instead.

source code