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Configuration

Lerna's configuration is split into two files: lerna.json and nx.json.

Lerna.json

npmClient​

It is important to set this value if you are not using npm as your package manager (e.g. if you are using yarn or pnpm) so that lerna can adjust some of its internal logic when resolving configuration and packages. This is particularly true in the case of pnpm because it uses a separate pnpm-workspaces.yaml file to define its workspaces configuration.

packages​

By default, lerna will try and reuse any workspaces configuration you may have from your package manager of choice. If you prefer to specify a subset of your available packages for lerna to operate on, you can use the packages property which will tell Lerna where to look for package.json files.

lerna.json
{
  "packages": ["packages/*"]
}

version​

Lerna has two modes of publishing packages: fixed and independent. When using the fixed mode, all the affected packages will be published using the same version. The last published version is recorded in lerna.json as follows:

lerna.json
{
  "version": "1.2.0"
}

When using the independent mode, every package is versioned separately, and lerna.json will look as follows:

lerna.json
{
  "version": "independent"
}

See the version and publish docs for more details.

commands​

The lerna.json files can also encode options for each command like so:

{
  "command": {
    "version": {
      "allowBranch": "main",
      "conventionalCommits": true
    }
  }
}

Find the available options in the API docs.

Nx.json

NOTE: "{projectRoot}" and "{workspaceRoot}" are special syntax supported by the task-runner, which will be appropriately interpolated internally when the command runs. You should therefore not replace "{projectRoot}" or "{workspaceRoot}" with fixed paths as this makes your configuration less flexible.

nx.json
{
  "namedInputs": {
    "default": ["{projectRoot}/**/*"],
    "prod": ["!{projectRoot}/**/*.spec.tsx"]
  },
  "targetDefaults": {
    "build": {
      "dependsOn": ["prebuild", "^build"],
      "inputs": ["prod", "^prod"],
      "outputs": ["{projectRoot}/dist"],
      "cache": true
    },
    "test": {
      "inputs": ["default", "^prod", "{workspaceRoot}/jest.config.ts"],
      "cache": true
    }
  }
}

Target Defaults​

Targets are npm script names. You can add metadata associated with say the build script of each project in the repo in the targetDefaults section.

cache​

When set to true, tells Nx to cache the results of running the script. In most repos all non-long running tasks (i.e., not serve) should be cacheable.

dependsOn​

Targets can depend on other targets. A common scenario is having to build dependencies of a project first before building the project. The dependsOn property can be used to define the dependencies of an individual target.

"dependsOn": [ "prebuild", "^build"] tells Nx that every build script requires the prebuild script of the same project and the build script of all the dependencies to run first.

inputs & namedInputs​

The inputs array tells Nx what to consider to determine whether a particular invocation of a script should be a cache hit or not. There are three types of inputs:

Filesets

Examples:

  • {projectRoot}/**.*.ts
  • same as {fileset: "{projectRoot}/**/*.ts"}
  • {workspaceRoot}/jest.config.ts
  • same as {fileset: "{workspaceRoot}/jest.config.ts}

Runtime Inputs

Examples:

  • {runtime: "node -v"}

Node the result value is hashed, so it is never displayed.

Env Variables

Examples:

  • {env: "MY_ENV_VAR"}

Node the result value is hashed, so it is never displayed.

Named Inputs

Examples:

  • inputs: ["prod"]
  • same as inputs: [{input: "prod", projects: "self"}]

Often the same glob will appear in many places (e.g., prod fileset will exclude spec files for all projects).. Because keeping them in sync is error-prone, we recommend defining named inputs, which you can then reference in all of those places.

Using ^​

Examples:

  • inputs: ["^prod"]
  • same as inputs: [{input: "prod", projects: "dependencies"}]

Similar to dependsOn, the "^" symbols means "dependencies". This is a very important idea, so let's illustrate it with an example.

"test": {
  "inputs": [ "default", "^prod" ]
}

The configuration above means that the test target depends on all source files of a given project and only prod sources (non-test sources) of its dependencies. In other words, it treats test sources as private. If your remixapp project depends on the header library, changing the header tests will not have any effect on the remixapp test target.

outputs​

"outputs": ["{projectRoot}/dist"] tells Nx where the build script is going to create file artifacts. The provided value is actually the default, so we can omit it in this case. "outputs": [] tells Nx that the test target doesn't create any artifacts on disk. You can list as many outputs as you many. You can also use globs or individual files as outputs.

This configuration is usually not needed. Nx comes with reasonable defaults which implement the configuration above.

Project-Specific Configuration​

For a lot of workspaces, where projects are similar, nx.json will contain the whole Nx configuration. Sometimes, it's useful to have a project-specific configuration, which is placed in the project's package.json file.

package.json
{
  "name": "parent",
  "scripts": {
    "build": "...",
    "test": "..."
  },
  "dependencies": {...},
  "nx": {
    "namedInputs": {
      "prod": [
        "!{projectRoot}/**/*.test.tsx",
        "{workspaceRoot}/configs/webpack.conf.js"
      ]
    },
    "targets": {
      "build": {
        "dependsOn": [
          "^build"
        ],
        "inputs": [
          "prod",
          "^prod"
        ],
        "outputs": [
          "{workspaceRoot}/dist/parent"
        ]
      }
    }
    "implicitDependencies": ["projecta", "!projectb"]
  }
}

Note, the namedInputs and targetDefaults defined in nx.json are simply defaults. If you take that configuration and copy it into every project's package.json file, the results will be the same.

In other words, every project has a set of named inputs, and it's defined as: {...namedInputsFromNxJson, ...namedInputsFromProjectsPackageJson}. Every target/script's dependsOn is defined as dependsOnFromProjectsPackageJson || dependsOnFromNxJson. The same applies to inputs and outputs.

inputs & namedInputs​

Defining inputs for a given target would replace the set of inputs for that target name defined in nx.json. Using pseudocode inputs = packageJson.targets.build.inputs || nxJson.targetDefaults.build.inputs.

You can also define and redefine named inputs. This enables one key use case, where your nx.json can define things like this (which applies to every project):

"test": {
  "inputs": [
    "default",
    "^prod"
  ]
}

And projects can define their prod fileset, without having to redefine the inputs for the test target.

package.json
{
  "name": "parent",
  "scripts": {
    "build": "...",
    "test": "..."
  },
  "dependencies": {...},
  "nx": {
    "namedInputs": {
      "prod": [
        "!{projectRoot}/**/*.test.js",
        "{workspacRoot}/jest.config.js"
      ]
    }
  }
}

In this case Nx will use the right prod input for each project.

dependsOn​

Defining dependsOn for a given target would replace dependsOn for that target name defined in nx.json. Using pseudocode dependsOn = packageJson.targets.build.dependsOn || nxJson.targetDefaults.build.dependsOn.

outputs​

Defining outputs for a given target would replace outputs for that target name defined in nx.json. Using pseudocode outputs = packageJson.targets.build.outputs || nxJson.targetDefaults.build.outputs.

implicitDependencies​

The "implicitDependencies": ["projecta", "!projectb"] line tells Nx that the parent project depends on projecta even though there is no dependency in its package.json. Nx will treat such a dependency in the same way it treats explicit dependencies. It also tells Nx that even though there is an explicit dependency on projectb, it should be ignored.

Additional Configuration​

For additional ways to configure tasks and caching, see the relevant Nx documentation.