Cache Task Results
It's costly to rebuild and retest the same code over and over again. Nx uses a computation cache to never rebuild the same code twice.
Setup
Nx has the most sophisticated and battle-tested computation caching system. It knows when the task you are about to run has been executed before, so it can use the cache to restore the results of running that task.
To enable caching for build and test, edit the cacheableOperations property in nx.json to include the build and test tasks:
{
"tasksRunnerOptions": {
"default": {
"runner": "nx/tasks-runners/default",
"options": {
"cacheableOperations": ["build", "test"]
}
}
}
}
This means that given the same input they should always result in the same output. As an example, e2e test runs that hit the backend API cannot be cached as the backend might influence the result of the test run.
Now, run the following command twice. The second time the operation will be instant:
nx build header
~/workspace❯
nx build header
> nx run header:build [local cache]
> header@0.0.0 build
> rimraf dist && rollup --config
src/index.tsx → dist...
created dist in 858ms
—————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————
> NX Successfully ran target build for project header (13ms)
Nx read the output from the cache instead of running the command for 1 out of 1 tasks.
Replaying from Cache
When Nx determines that the inputs for a task have not changed, it recreates the outputs of that task as if it actually ran on your machine - but much faster. The outputs of a cached task include both the terminal output and the files created in the defined output directories for that task.
You can test this out by deleting the dist folder that the header:build task outputs to and then running nx build header again. The cached task will replay instantly and the correct files will be present in the dist folder.
header/
└── dist/ <-- this folder gets recreated
If your task creates output artifacts in a different location, you can change the output folder(s) that are cached. You can also customize which inputs will invalidate the cache if they are changed.
Advanced Caching
For a more in-depth understanding of the caching implementation and to fine-tune the caching for your repo, read How Caching Works.
Local Computation Caching
By default, Nx uses a local computation cache. Nx stores the cached values only for a week, after which they are deleted. To clear the cache run nx reset, and Nx will create a new one the next time it tries to access it.
Distributed Computation Caching
The computation cache provided by Nx can be distributed across multiple machines. You can either build an implementation of the cache or use Nx Cloud. Nx Cloud is an app that provides a fast and zero-config implementation of distributed caching. It's completely free for OSS projects and for most closed-sourced projects (read more here).
You can connect your workspace to Nx Cloud by running:
npx nx connect-to-nx-cloud
~/workspace❯
npx nx connect-to-nx-cloud
✔ Enable distributed caching to make your CI faster · Yes
> NX Generating @nrwl/nx-cloud:init
UPDATE nx.json
> NX Distributed caching via Nx Cloud has been enabled
In addition to the caching, Nx Cloud provides config-free distributed execution,
UI for viewing complex runs and GitHub integration. Learn more at https://nx.app
Your workspace is currently unclaimed. Run details from unclaimed workspaces can be viewed on cloud.nx.app by anyone
with the link. Claim your workspace at the following link to restrict access.
https://cloud.nx.app/orgs/workspace-setup?accessToken=YOURACCESSTOKEN
To see the remote cache in action, run:
nx build header && nx reset && nx build header
~/workspace❯
nx build header && nx reset && nx build header
> nx run header:build
> header@0.0.0 build
> rimraf dist && rollup --config
src/index.tsx → dist...
created dist in 786ms
—————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————
> NX Successfully ran target build for project header (2s)
See logs and investigate cache misses at https://cloud.nx.app/runs/k0HDHACpL8
> NX Resetting the Nx workspace cache and stopping the Nx Daemon.
This might take a few minutes.
> NX Daemon Server - Stopped
> NX Successfully reset the Nx workspace.
> nx run header:build [remote cache]
> header@0.0.0 build
> rimraf dist && rollup --config
src/index.tsx → dist...
created dist in 786ms
—————————————————————————————————————————————————————————————————————————————————————————————————————————————————————————
> NX Successfully ran target build for project header (664ms)
Nx read the output from the cache instead of running the command for 1 out of 1 tasks.
Nx Cloud made it possible to reuse header: https://nx.app/runs/P0X6ZGTkqZ