89 lines
3.3 KiB
Markdown
89 lines
3.3 KiB
Markdown
# Cache Task Results
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It's costly to rebuild and retest the same code over and over again. Nx uses a computation cache to never rebuild the
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same code twice.
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## Setup
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Nx has the most sophisticated and battle-tested computation caching system. It knows when the task you are
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about to run has been executed before, so it can use the cache to restore the results of running that task.
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To enable caching for `build` and `test`, edit the `cacheableOperations` property in `nx.json` to include the `build` and `test` tasks:
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```json title="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": ["build", "test"]
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}
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}
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}
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}
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```
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{% callout type="note" title="Cacheable operations need to be side effect free" %}
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This means that given the same input they should always result in
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the same output. As an example, e2e test runs that hit the backend API cannot be cached as the backend might influence
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the result of the test run.
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{% /callout %}
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Now, run the following command twice. The second time the operation will be instant:
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```bash
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nx test header
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```
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```bash title="Terminal Output"
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> nx run header:test [existing outputs match the cache, left as is]
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> header@0.0.0 test
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> jest
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PASS src/Header.spec.tsx
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✓ renders header (14 ms)
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Test Suites: 1 passed, 1 total
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Tests: 1 passed, 1 total
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Snapshots: 0 total
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Time: 0.528 s, estimated 2 s
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Ran all test suites.
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————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————
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> NX Successfully ran target test for project header (4ms)
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Nx read the output from the cache instead of running the command for 1 out of 1 tasks.
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```
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## Advanced Caching
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For a more in-depth understanding of the caching implementation and to fine-tune the caching for your repo, read [How Caching Works](/concepts/how-caching-works).
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## Local Computation Caching
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By default, Nx uses a local computation cache. Nx stores the cached values only for a week, after which they
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are deleted. To clear the cache run [`nx reset`](/nx/reset), and Nx will create a new one the next time it tries to access it.
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## Distributed Computation Caching
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The computation cache provided by Nx can be distributed across multiple machines. You can either build an implementation
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of the cache or use Nx Cloud. Nx Cloud is an app that provides a fast and zero-config implementation of distributed
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caching. It's completely free for OSS projects and for most closed-sourced
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projects ([read more here](https://dev.to/nrwl/more-time-saved-for-free-with-nx-cloud-4a2j)).
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You can connect your workspace to Nx Cloud by running:
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```bash
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npx nx connect-to-nx-cloud
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```
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## See Also:
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- [Nx Cloud Documentation](/nx-cloud/intro/what-is-nx-cloud)
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- [Nx Cloud Main Site](https://nx.app)
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- [--skip-nx-cache flag](/nx/affected#skip-nx-cache)
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- [tasks-runner-options property](/reference/nx-json#tasks-runner-options)
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