The Hello Forge Service

The hello forge service is a simple flask application that reports its uptime. This is useful for illustrating the principles of building a service with forge.

Key Files

Forge looks at these files to build and deploy the edge service:

• service.yaml

  This identifies this directory as a service. It also contains parameters that are supplied to the deployment templates. In this case that consists of the service name, the port the container exposes, and the minimum memory and cpu required by the application.

  Any additional configuration information supplied in this file is made available to the deployment templates. This is useful if you want to develop fancier custom deployment templates and make them easily configurable via parameters in service.yaml.

• Dockerfile

  This tells forge how to build the service. You can replace this with a different Dockerfile if you want to use a different application framework, or replace this edge service with a prepackaged API gateway like ambassador.

• k8s/*

  This directory contains the templates forge uses to produce the kubernetes yaml necessary to deploy a service. They can be customized on a per service basis as needed. The templates are also jinja templates. Please refer to the jinja documentation for the full syntax.

  When these templates are instantiated, they are supplied with all the parameters in service.yaml as well as all the metadata from the build. This currently consists of the built image names corresponding with each Dockerfile the service uses.

  The service parameters are supplied to the deployment templates under the service variable name. The build metadata is supplied under the build variable name, and the docker images are available in the build.images map. This map is keyed by path relative to the directory containing the service.yaml file.