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Using hln

What is hln?​

hln is a command-line interface (CLI) that you can use to create your application from a particular stack.

hln CLI has the ability of searching and downloading stacks from stackhub, creating application from a particular stack, and managing lifecycle of an application.

How does hln work?​

With the help of hln CLI, all you need to do is to choose a stack and specify inputs such as your application name, the kubeconfig of your cluster, etc. Then you can spin up your application with a single command hln up -i.

Under the hood, hln relies on two core concepts, stack and dagger. Stack is the sketch of your application architecture. Dagger is the execution engine of our stack.

Stack input from hln​

1. Input from Env​

Inputs can be directly set via environment variables. hln will pass the inputs to the stack execution.

hln will set two env by default:

  • KUBECONFIG: If this env is not set, it will set to ~/.kube/config by default.
  • APP_NAME: This is automaticaly set to the <app> from the arguments. For example, hln up my-app, APP_NAME=my-app.

2. Interactive input​

hln up -i will parse stack input schema and prompt for interactive input. The inputs will be set as env to pass to the stack execution.

If a input is set from the env, then hln up -i won't prompt this field for interative input.