Your First Package

Your First Package

Build a minimal Brane package, test it locally, and run it on an instance.

1. Write the Code

mkdir hello-world && cd hello-world

Create hello_world.sh:

#!/bin/bash
echo 'output: "Hello from Brane!"'

Brane reads output from stdout as YAML key-value pairs.

2. Define the Package Interface

Create container.yml:

name: hello_world
version: 1.0.0
kind: ecu

files:
  - hello_world.sh

entrypoint:
  kind: task
  exec: hello_world.sh

actions:
  'hello_world':
    command:
    input:
    output:
    - name: output
      type: string

3. Build and Test

brane package build ./container.yml
brane package list
brane package test hello_world

4. Push and Run

brane login http://<CENTRAL_NODE_ADDRESS> --username <YOUR_NAME>
brane package push hello_world
brane workflow repl --remote http://<CENTRAL_NODE_ADDRESS>:50053

In the REPL:

import hello_world;
println(hello_world());

Python Example

Create analyze.py:

#!/usr/bin/env python3
import yaml

def main():
    result = {"output": "Hello from Python!"}
    print(yaml.dump(result, default_flow_style=True).strip())

if __name__ == "__main__":
    main()

And container.yml:

name: python_hello
version: 1.0.0
kind: ecu

dependencies:
  - python3
  - python3-yaml

files:
  - analyze.py

entrypoint:
  kind: task
  exec: analyze.py

actions:
  'hello':
    command:
    input:
    output:
    - name: output
      type: string

The dependencies field installs system packages via apt in the container.

How Inputs Work

When Brane calls a function, it passes inputs via environment variables (variable name = parameter name) and the function name as sys.argv[1].

Output must be printed to stdout as YAML with keys matching the declared output names.

Supported Input Types

Type	BraneScript	Description
string	"text"	Text values
integer	42	Whole numbers
real	3.14	Floating-point numbers
boolean	true / false	Boolean values
Array[T]	[1, 2, 3]	Arrays of a single type

Next Steps

• Write workflows with BraneScript
• See the CLI reference for all package commands