97 lines
2.6 KiB
Markdown
97 lines
2.6 KiB
Markdown
# Task Pipeline Configuration
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Nx runs tasks in the most efficient way possible. The `nx.json` file is the place where you can configure how Nx does it.
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## Run Tasks in Parallel
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If you want to increase the number of processes running tasks to, say, 5 (by default, it is 3), pass the
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following:
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```shell
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npx nx build myapp --parallel=5
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```
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Note, you can also change the default in `nx.json`, like this:
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```json {% fileName="nx.json"%}
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{
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"tasksRunnerOptions": {
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"default": {
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"runner": "nx/tasks-runners/default",
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"options": {
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"cacheableOperations": [],
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"parallel": 5
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}
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}
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}
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}
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```
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## Define Task Dependencies (aka Task Pipelines)
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To ensure tasks run in the correct order, Nx needs to know how the tasks depend on each other. Add the following to `nx.json`:
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```jsonc {% fileName="nx.json"%}
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{
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...
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"targetDefaults": {
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"build": {
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"dependsOn": ["^build"]
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}
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}
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}
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```
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With this, Nx knows that before it can build a project, it needs to build all of its dependencies first. There are, however, no constraints on tests.
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This mechanism is very flexible. Let's look at this example:
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```jsonc {% fileName="nx.json"%}
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{
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...
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"targetDefaults": {
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"build": {
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"dependsOn": ["^build", "prebuild"]
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},
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"test": {
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"dependsOn": ["build"]
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}
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}
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}
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```
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> Note, older versions of Nx used targetDependencies instead of targetDefaults. `targetDependencies` was removed in version 16, with `targetDefaults` replacing its use case.
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When running `nx test myproj`, the above configuration would tell Nx to
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1. Run the `test` command for `myproj`
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2. But since there's a dependency defined from `test -> build` (see `test:["build"]`), Nx runs `build` for `myproj`
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first.
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3. `build` itself defines a dependency on `prebuild` (on the same project) as well as `build` of all the dependencies.
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Therefore, it will run the `prebuild` script and will run the `build` script for all the dependencies.
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Note, Nx doesn't have to run all builds before it starts running tests. The task orchestrator will run as many tasks
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in parallel as possible as long as the constraints are met.
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Situations like this are pretty common:
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Because we described the rules in `nx.json`, they will apply to all the projects in the repo. You can also define
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project-specific rules by adding them to the project's configuration ([learn more](/reference/project-configuration#dependson).
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```jsonc {% fileName="package.json"%}
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{
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...
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"nx": {
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"targets": {
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"test": {
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"dependsOn": [
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"build"
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]
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}
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}
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}
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}
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```
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