Creating Functions

You can create a new function definition in the OCI Functions server in different ways, depending on how you want to provide the function source:

• Using the Console, a CLI command, or an API operation to create a new image-based function based on an existing Docker image that has already been pushed to the Docker registry (as described in this topic).
• Using the Console, a CLI command, or an API operation to create a code-only function from an archive containing function code and dependencies (see Creating Functions from Archives (Code-only Functions)).
• Using the single Fn Project CLI command fn deploy to build a new Docker image, push the image to the Docker registry, and create a new image-based function from the image in one step (as described in Creating and Deploying Image-Based Functions Using the Fn Project CLI).
• Using Code Editor (see Creating Image-Based Functions Using Code Editor).
• Using pre-built functions (see Creating Functions Using Pre-Built Functions).

When creating an image-based function from an existing Docker image, you specify function metadata to store in the OCI Functions server. For example, the maximum length of time the function is allowed to execute for.

The existing image on which you base a new image-based function must be suitable for use with OCI Functions. Typically, to build and push a suitable image, you or somebody else will use Fn Project CLI commands and/or Docker CLI commands. For example, having written your function code and a func.yaml file containing function metadata (perhaps based on the template helloworld function and func.yaml created using fn init), you can:

• Use fn build to build a new Docker image from the function.
• Use docker push to push the image to the Docker registry.

With the image in the Docker registry, you can then use the Console, a CLI command, or an API operation to create an image-based function from the image, as described in this topic.