Configure Inputs for Task Caching

When Nx computes the hash for a given operation, it takes into account the inputs of the target. The inputs are a list of file sets, runtime inputs and environment variables that affect the output of the target. If any of the inputs change, the cache is invalidated and the target is re-run.

Nx errs on the side of caution when using inputs. Ideally, the "perfect" configuration of inputs will allow Nx to never re-run something when it does not need to. In practice though, it is better to play it safe and include more than strictly necessary in the inputs of a task. Forgetting to consider something during computation hash calculation may lead to negative consequences for end users. Start safe and fine-tune your inputs when there are clear opportunities to improve the cache hit rate.

For an overview of all the possible types of inputs and how to reuse sets of inputs as named inputs, see the reference documentation.

Throughout this recipe, the following project structure of a simple workspace will be used as an example to help understand inputs better.

View the Inputs of a Task

You can view the configuration for a task of a project by adding the --graph flag when running the command:

❯

nx build myreactapp --graph

This will show the task graph executed by Nx when running the command.

Clicking the task will open a tooltip which lists out all of the inputs of the task. A button within the tooltip will also reveal more details about the configuration for the project which the task belongs to.

Doing so will show a view such as the one below:

Nx Console has a button which will show a preview of this screen when a project level configuration file (project.json or package.json) is opened in the IDE.

Another way of accessing this information is to run nx show project myreactapp --web and the view above will be opened in a browser.

Use this tool to help understand what inputs are being used by Nx in your workspace.

Note

If no inputs are specified at all, Nx will default to looking at all files of a project and its dependencies. This is a rather cautious approach. This might cause Nx to re-run a task in some cases where the cache could have been used instead but it will always give you correct output.

Configure Inputs

The tasks you run in your workspace will likely already have inputs defined. Be sure to view the existing inputs and start from there.

Inputs of a task are configured in the inputs array on the target. This can be done in several different places:

As of Nx 18, Nx Plugins often infer inputs for tasks which run other tools.
- In doing so, they will also define some reasonable defaults for the inputs of those tasks.
The inputs array in the targetDefaults for a set of targets in nx.json.
The inputs array for a specific target in the project configuration file.

Copy the existing inputs before modifying inputs for a task

To override the inputs of a task, start by copying over the entire array shown when viewing the project details and then add/modify/remove inputs as needed.

As you configure inputs, keep the project details screen open and it will refresh as changes are made. Check to make sure that the intended configuration is shown.

Workspace Level Inputs

Target Defaults defined in nx.json apply to a set of targets. Defining inputs here one time will apply to a set of similar targets.

nx.json
{
  "targetDefaults": {
    "build": {
      "inputs": ["production", "^production"]
    }
  }
}

The above specifies that all targets with the name build will use the inputs specified. This configuration will override any inputs inferred by Nx Plugins as you have more direct control in your nx.json than the behavior of the Nx Plugin. The configuration defined here completely overwrites any inputs inferred by Nx Plugins and is not merged in any way. This configuration may be overridden by configuration in project-specific configuration files.

Project Level Inputs

Defining inputs of a target in project.json or package.json will apply only to tasks of the specific project.

apps/myreactapp/project.json
{
  "name": "myreactapp",
  "targets": {
    "build": {
      "inputs": ["production", "^production"]
    }
  }
}

The above specifies that the build target of the myreactapp project will use the inputs specified. This configuration will override any inputs inferred by Nx Plugins as well as any inputs defined in the Target Defaults in the nx.json file as this is more specific than those other methods of configuring inputs. The configuration defined here completely overwrites any inputs inferred by Nx Plugins or in target defaults and is not merged in any way.

Common Inputs

Test and Config Files

Often, projects include some files with runtime behavior and other files for unit testing. When running the build task, we do not want Nx to consider test files so updating the test files does not invalidate the cache for build tasks.

Plugins which define compile or bundling tasks such as @nx/webpack/plugin and @nx/vite/plugin will use the following inputs:

"inputs": [
  "production", // All files in a project including test files
  "^production" // Inputs of a dependencies which may affect behavior of projects which depend on them
]

Plugins which define testing tasks such as @nx/cypress/plugin, @nx/playwright/plugin, @nx/jest/plugin and @nx/vite/plugin will infer the following inputs for tasks:

"inputs": [
  "default", // All files in a project including test files
  "^production" // Inputs of a dependencies which may affect behavior of projects which depend on them
]

Given the above configurations, exclude the test and config files from the production named input:

nx.json
{
  "namedInputs": {
    "default": ["{projectRoot}/**/*", "sharedGlobals"],
    "production": [
      "default",
      "!{projectRoot}/jest.config.ts",
      "!{projectRoot}/**/?(*.)+(spec|test).ts"
    ]
  }
}

With the above named inputs, Nx will behave in the following way:

When only test files are changed, Nx will restore previous compilation results from the cache and re-run the tests for the projects containing the test files
When any production files are changed, Nx will re-run the tests for the project as well as any projects which depend on it

Consider the Version of a Language for all Tasks

Many times, the version of the programming language being used will affect the behavior of all tasks for the workspace. A runtime input can be added to the sharedGlobals named input to consider it for the hash of every task.

For example, to consider the version of Node.js in the hash of every task, add node --version as an input.

nx.json
{
  "namedInputs": {
    "default": ["{projectRoot}/**/*", "sharedGlobals"],
    "sharedGlobals": [{ "runtime": "node --version" }]
  }
}

Migration