Caching Assets Between Jobs.md

Caching Assets Between Jobs

Let's start by using actions/cache@v3 to cache the npm cache between runs.

steps:
  - name: Checkout respository
    uses: actions/checkout@v3
  - name: Setup Node
    uses: actions/setup-node@v3
  - uses: actions/cache@v3 # 👀
    id: npm-cache # 👀
    with: # 👀
      path: ~/.npm # 👀
      key: npm-${{ hashFiles('**/package-lock.json') }} # 👀
  - run: npm ci
    name: Install modules from npm
  - run: npm test
    name: Run the tests

If we look at the Post Run for actions/cache@v3, we'll see that we wrote to the cache.

We can also navigate to it in the UI by going to the Actions tab and selecting Caches from the sidebar.

In my very silly example, we'll see that it cut the total time down by 4 seconds. This may not seem like a lot, but it's 33%.

Quick Exercise/Experiment

Go ahead and add it to the build job too and observe what happens.

Collapsing Our Code

As you can imagine, this is a pretty common task. So common that actions/setup-node@v3 has a little helper that will do this for you.

- name: Setup Node
  uses: actions/setup-node@v3
  with:
    node-version: 18
    cache: 'npm'

actions/setup-node@v3 names it a little differently, so you'll end up with a different cache, but that's okay.

But, like just because actions/setup-node@v3 does it for you, it does't mean that you won't want this functionality elsewhere. Here are some use cases off the top of my mind:

• You have a job or step that builds your assets and as long as something hasn't changed, then we want to just use whatever we had last time.
• For example, we have a script that install Temporal CLI along with the rest of our dependencies. I might choose to cache so that I'm not re-downloading it.