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Cache Intelligence

Modern continuous integration systems execute pipelines inside ephemeral environments that are provisioned solely for pipeline execution and are not reused from prior pipeline runs. As builds often require downloading and installing many library and software dependencies, caching these dependencies for quick retrieval at runtime can save a significant amount of time.

There are several ways to configure caching in Harness CI, such as Cache Intelligence, Save and Restore Cache steps, and mounting volumes. Save and Restore Cache steps and mounted volumes require you to manage the cache. With Cache Intelligence, Harness automatically caches and restores common dependencies. Cache Intelligence also doesn't require you to bring your own storage, because the cache is stored in the Harness-hosted environment, Harness Cloud.

Supported build infrastructures​

Currently, Cache Intelligence is only available for Linux and Windows platforms on Harness Cloud, the Harness-hosted build environment.

For other build infrastructures, you can use Save and Restore Cache steps, such as Save and Restore Cache from S3, to include caching in your CI pipelines.

Supported tools and paths​

Cache Intelligence fully supports Bazel, Maven, Gradle, Yarn, Go, and Node build tools, if the dependencies are stored in the default location for that tool.

For other build tools or non-default cache locations, you can leverage Harness Cloud's cache storage by enabling Cache Intelligence and providing custom cache paths.

Cache storage​

Harness Cloud allows up to 2GB of cache storage per account. All pipelines in the account use the same cache storage, and each build tool has a unique cache key that is used to restore the appropriate cache data at runtime.

The cache retention window is 15 days, which resets whenever the cache is updated.

Enable Cache Intelligence​

To enable Cache Intelligence in the YAML editor, add the following lines to the stage.spec:

          caching:
            enabled: true

For example:

    - stage:
        name: Build
        identifier: Build
        type: CI
        spec:
          caching:
            enabled: true
          cloneCodebase: true

If you're using an unsupported build tool, a non-default cache location, or a Windows platform, you must add custom cache paths. For a list of supported tools, go to Supported tools and paths.

Optionally, you can add a custom cache key.

Customize cache paths​

Cache Intelligence stores the data to be cached in the /harness directory by default. You can use paths to specify a list of locations to be cached. This is useful if:

  • Cache Intelligence is not supported for your build tool.
  • You have customized cache locations, such as with yarn config set cache-folder.
  • You're using a Windows platform.

In the YAML editor, add a list of paths to cache under stage.spec.caching, for example:

    - stage:
        name: Build
        identifier: Build
        type: CI
        spec:
          caching:
            enabled: true
            paths:
              - /harness/node_modules ## On a Windows platform, the path would be 'C:\harness\node_modules'.
          cloneCodebase: true
...

If a cache path is outside the /harness directory, you must also specify this as a shared path. In the YAML editor, add a list of sharedPaths under stage.spec, for example:

    - stage:
        name: Build
        identifier: Build
        type: CI
        spec:
          caching:
            enabled: true
            paths:
              - /harness/node_modules
              - /my_cache_directory/module_cache1
          cloneCodebase: true
...
          platform:
            os: Linux
            arch: Amd64
          runtime:
            type: Cloud
            spec: {}
          sharedPaths:
            - /my_cache_directory/module_cache1

Customize cache keys​

Harness generates a cache key from a hash of the build lock file (such as pom.xml, build.gradle, or package.json) that Harness detects. If Harness detects multiple tools or multiple lock files, Harness combines the hashes to create the cache key.

To customize the cache key in the YAML editor, add key: CUSTOM_KEY_VALUE under stage.spec.caching. You can use fixed values, runtime inputs, and expressions for the key value.

The following YAML example uses <+input>, which prompts the user to supply a cache key value at runtime.

    - stage:
        name: Build
        identifier: Build
        type: CI
        spec:
          caching:
            enabled: true
            key: <+input>
          cloneCodebase: true
...

Cache Intelligence API​

You can use the Cache Intelligence API to get information about the cache or delete the cache.

To invoke these APIs, you must have an API key with core_account_edit permissions. For information about API keys, go to Manage API keys.

Get cache metadata​

Get metadata about the cache, such as the size and path.

curl --location --request GET 'https://app.harness.io/gateway/ci/cache/info?accountIdentifier=$HARNESS_ACCOUNT_ID' \
--header 'Accept: application/json' \
--header 'Authorization: Bearer $AUTH_TOKEN'

Delete cache​

Delete the cache. You can include an optional path parameter to delete a specific sub-directory in the cache.

curl --location --request DELETE 'https://app.harness.io/gateway/ci/cache/info?accountIdentifier=$HARNESS_ACCOUNT_ID&path=/path/to/deleted/directory' \
--header 'Accept: application/json' \
--header 'Authorization: Bearer $AUTH_TOKEN'