Configure Outputs for Task Caching
Whenever Nx runs a cacheable task, it will store the results of that task in the cache. When Nx runs the task again, if the inputs for that task have not changed, it will restore the results from the cache instead of spending the time to run the task again.
Types of Outputs
Terminal Output
The terminal output of a task is replayed whenever a task is pulled from cache. Nx will always cache the terminal output of tasks which are cached.
Output Files
Targets can define which files are produced when a task is run. Nx will cache these files so that it can restore them when the task is pulled from cache.
These outputs files can be specified in several ways:
1"outputs": [
2 "{projectRoot}/dist/libs/mylib", // A directory
3 "{workspaceRoot}/dist/{projectRoot}", // A directory based on the project's root
4 "{workspaceRoot}/dist/{projectName}", // A directory based on the project's name
5 "{workspaceRoot}/test-results.xml", // A file
6 "{projectRoot}/dist/libs/mylib/**/*.js", // A glob pattern matching a set of files
7 "{options.outputPath}", // A path defined in the options of a task
8]
9All outputs explicitly specifying paths must be prefixed with either {projectRoot} or {workspaceRoot} to distinguish where the path is resolved from. {workspaceRoot} should only appear in the beginning of an output but {projectRoot} and {projectName} can be specified later in the output to interpolate the root or name of the a project into the output location.
Outputs can also be determined from the options of running a task via the {options.[propertyName]} syntax. This is useful when an option for the task determines the output location and could be modified when the task is run. This path is resolved from the root of the workspace.
If an output file or directory does not exist, it will be ignored.
View Outputs of a Task
The outputs of a task can be viewed by adding the --graph flag to the command:
❯
nx build myapp --graph
This will open the task graph in the browser. Clicking on a task in the graph will open a tooltip with a link to see details about the project. View the project's configuration to see a list of the outputs which are defined for each target.
Configure Outputs
The tasks you run in your workspace will likely already have outputs defined. Be sure to view the existing outputs and start from there.
As of Nx 18, Nx Plugins often infer outputs for tasks which run other tools. Nx Plugins will look at the configuration files and/or command-line-arguments of the tools in your workspace to understand the outputs of running those tools. In most cases, this inference will be inline with the outputs of the tool. Nx will reflect changes to the configuration or command-line arguments of your tools without any additional changes.
In some cases, Nx plugins may not infer the outputs of a task as you expect, they can be configured in the outputs array on the target. This can be done in several different places:
- The
outputsarray in thetargetDefaultsfor a set of targets innx.json. - The
outputsarray for a specific target in the project configuration file.
To override the outputs of a task, start by copying over the entire array shown when viewing the project details and then add/modify/remove outputs as needed.
As you configure outputs, 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 Outputs
Target Defaults defined in nx.json apply to a set of targets. Defining outputs here one time will apply to a set of similar targets.
1{
2 "targetDefaults": {
3 "build": {
4 "outputs": ["{projectRoot}/dist"]
5 }
6 }
7}
8The above specifies Nx will cache the dist directory under all project roots for all targets with the name build. This configuration will override any outputs 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 outputs inferred by Nx Plugins and is not merged in any way. This configuration may be overwritten by configuration in project-specific configuration files.
Specifying the same output location for multiple tasks often causes unintentional behavior. While sometimes this is intentional, try and ensure that a set of targets will yield unique output locations for the tasks belonging to different projects. Use the {projectRoot} and {projectName} notation to include unique characteristics of a project in the output.
Project Level Outputs
Defining outputs of a target in project.json or package.json will apply only to tasks of the specific project.
1{
2 "name": "myreactapp",
3 "targets": {
4 "build": {
5 "outputs": ["{projectRoot}/dist"]
6 }
7 }
8}
9The above specifies that the build target of the myreactapp project will use the outputs specified. This configuration will override any outputs inferred by Nx Plugins as well as any outputs defined in the Target Defaults in the nx.json file as this is more specific than those other methods of configuring outputs. The configuration defined here completely overwrites any outputs inferred by Nx Plugins or in target defaults and is not merged in any way.