Function Definition
Function
Function
is the control plane of Build
and Serving
and it’s also the interface for users to use OpenFunction. Users needn’t to create the Build
or Serving
separately because Function
is the only place to define a function’s Build
and Serving
.
Once a function is created, it will controll the lifecycle of Build
and Serving
without user intervention:
If
Build
is defined in a function, a builder custom resource will be created to build function’s container image once a function is deployed.If
Serving
is defined in a function, a serving custom resource will be created to control a function’s serving and autoscalling.Build
andServing
can be defined together which means the function image will be built first and then it will be used in serving.Build
can be defined withoutServing
, the function is used to build image only in this case.Serving
can be defined withoutBuild
, the function will use a previously built function image for serving.
Build
OpenFunction uses Shipwright and Cloud Native Buildpacks to build the function source code into container images.
Once a function is created with Build
spec in it, a builder
custom resource will be created which will use Shipwright to manage the build tools and strategy. The Shipwright will then use Tekton to control the process of building container images including fetching source code, generating image artifacts, and publishing images.
Serving
Once a function is created with Serving
spec, a Serving
custom resource will be created to control a function’s serving phase. Currently OpenFunction Serving supports two runtimes: the Knative sync runtime and the OpenFunction async runtime.
The sync runtime
For sync functions, OpenFunction currently supports using Knative Serving as runtime. And we’re planning to add another sync function runtime powered by the KEDA http-addon.
The async runtime
OpenFunction’s asyn runtime is an event-driven runtime which is implemented based on KEDA and Dapr. Async functions can be triggered by various event types like message queue, cronjob, and MQTT etc.
Reference
For more information, see Function Specifications.
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