Netstack mode allows you to access resources in a NetBird network from an Azure Function. This mode is helpful if you want to access a database or other resource not exposed to the public internet from a limited environment like Azure functions.

How it works

The function_app.py contains the testing code. It uses socks and socket libraries to connect to the Postgres database. NetBird provides the socks proxy. The Postgres driver uses the socket connection to connect to the remote database.

Besides the Python code and Azure function specifics. We've added two custom files:

Dockerfile: This file is used to build the docker image for the Azure function with NetBird installed.
command.sh: This file is used as a docker command for the image; it starts NetBird in the background and then starts the Azure function server.

Prerequisites

An existing Azure function. You can follow the steps here: https://learn.microsoft.com/en-us/azure/azure-functions/functions-deploy-container?tabs=docker%2Cbash%2Cazure-cli&pivots=programming-language-python
Docker for local build
An internal Postgres database with netbird enabled

Create the database table

Access the Postgres database and create the table using the following statement:

CREATE TABLE visits (
        id SERIAL PRIMARY KEY,
        ip_address VARCHAR(255),
        visit_time TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

Create the function image

Build the function image using the following command:

docker build -t <your docker hub username>/azure-functions-python-db-access .

Push the image to docker hub

Push the image to the docker hub using the following command:

docker push <your docker hub username>/azure-functions-python-db-access

Set the environment variables

You need to configure the following environment variables in your Azure function's application settings page:

POSTGRES_HOST: The hostname of your Postgres database
POSTGRES_USER: The username of your Postgres database
POSTGRES_PASSWORD: The password of your Postgres database
POSTGRES_DB: The name of your Postgres database
NB_SETUP_KEY: The setup key of your NetBird network (We recommend using an ephemeral setup key. See https://netbird.dev/docs/setup-key for more details)

Deploy the function

Replace the docker image in your Azure functions deployment plan with the image you just pushed to the docker hub.