GraalVM Native Image-based function init-images

You can create a set of function init-images (boilerplate generators) for supported GraalVM releases by either running the build.sh script with no arguments (Fn will be read from fnfdk.version) or by defining the Fn FDK in the FNFDK_VERSION environment variable before running.

The generated function projects use mostly static linking which allows compiled function executables to be deployed on any container image with glibc available. Users of the init-image can easily edit the generated Dockerfile to specify the deployment image. The default deployment base image is slim Oracle Linux but Distoless Base (gcr.io/distroless/base), and Alpine with glibc (frolvlad/alpine-glibc) also work.

The fully qualified tag of each generated init-images is of the format: <INIT IMAGE NAME>:jdk<JAVA VERSION>-ol<ORACLE LINUX VERSION>-fdk<FDK VERSION>. For example a tag could be jdk17-ol8-fdk1.0.175. The same image will be tagged with just the JDK number for ease of use, e.g., jdk17.

Using init-images

Once built, you can generate a starter function using the fn CLI. The syntax is:

fn init --init-image <INIT IMAGE NAME>:jdk<JAVA VERSION> <FUNCTION NAME>

e.g.,

fn init --init-image fnproject/fn-java-graalvm-init:jdk17 myfunc

This will generate a function named myfunc in folder of the same name. To build the function you invoke fn build as you would for any Fn function. The build instructions for the function are defined in a Dockerfile which can be customized as needed.

Function Names

A Java class will be generated for the function with a legal Java name derived from the provided function name. Snake case with underscores (e.g., my_func) and kebab case with dashes (e.g, my-func) are supported and will result in a camel case function class name (e.g., MyFunc).

Credits

Forked and extracted from github.com/fnproject/fdk-project to prototype updates to GraalVM container image structure changes.