The Konnex Engine Framework

OpenFaaS Language Template for the D Programming Language (DLang)

NOTE: This is a full language template with project generator. It includes a working build, push and deploy template for dlang functions initally based on the official Dockerfile language template.

This template contains a basic Hello World function that builds to a statically linked binary executable from inside an Alpine 3.13 Docker container.

The resulting binary is containerized using a Docker FROM scratch image for deployment to OpenFaaS.

Works with the faas-cli command line tool as you would expect.

Usage

New or Existing OpenFaaS Deployment

Add or modify the templates configuration section in your /stack.yml file to include the Konnex Engine DLang language template.

For example:

configuration:
  templates:
    - name: dlang
      source: https://github.com/konnex-engine-io/dlang-template.git
    - name: node12
    - name: python3
    - name: go

From the root folder of your FaaS project (the folder where stack.yml is located), pull the template with the command:

faas-cli template pull stack --overwrite

This will pull the Konnex Engine DLang language template along with any templates available in the official OpenFaaS Template Store. The --overwrite flag ensures that any existing templates are overwritten with the newly downloaded templates.

Next, create a new function from the newly downloaded Konnex Engine DLang language template and append it to the function stack with the command:

faas-cli new myfunc --lang dlang --append ./stack.yml

This creates a new folder named myfunc and generates a basic hello world function project inside of that folder. The folder structure is as follows:

myfunc
  |- source
  |     |- function
  |     |     |-hello.d
  |     |- handler.d
  |- Dockerfile
  |- dub.json

Modify the source folder as required to create your functionality.

NOTE: It is recommended to create your functionality in a separate file and import it into the handler as per the hello.d example. This will allow you to deploy your functions without further modification to either the function-scoped Dockerfile or the global-scoped stack.yml file.

This way, you may name your files and folders as you choose, they need not be called function or any other specific name to match the above example.

Then either:

• Deploy to local OpenFaaS Cluster (faasd or full OpenFaas on localhost Kubernetes):

  faas-cli up -f ./stack.yml

• Deploy to production OpenFaaS cluster:

  faas-cli up -f ./stack.yml --gateway=https://openfaas.yourdomain.com

As per the Dockerfile, This will pull the of-watchdog binary from the official OpenFaas image, create a build container to build your statically linked executable, build the deployment container FROM scratch for you executable, and deploy your function to OpenFaaS.

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