This page is a supplementary document for Google Developer Group Hong Kong (GGDHK) Flutter Study Group, link to the event is provided in this note.

Google Developer Group HK: Flutter Study Group #01


Link to the sample `docker-compose.yml` files can be found <OutLink href="https://github.com/nbean452/google-dev-fest-2025-workshop">here</OutLink>

Description: This is a hands-on workshop on the steps required to run open-source docker applications on a Compute Engine instance in Google Cloud Platform and serve the apps via https.

When you read this, it's safe to assume that you have met the pre-requisites:

- Created a Compute Engine instance from GCP
- Able to SSH into the Compute Engine instance
- Own a subdomain (e.g., domain.com) and have access to its DNS settings
- Have API token key for the domain registrar (e.g., Cloudflare, Namecheap, etc) to authorize issuance of SSL certificates

Note: If you are experienced, some of these steps are interchangeable if you want to host apps from your own personal computer.

So, what are the next steps?

- [Git Clone this repository](#git-clone-this-repository)
- [Docker Installation](#docker-installation)
- [Setup Docker Network](#setup-docker-network)
- [Setup the env files](#setup-the-env-files)
- [Run the applications](#run-the-applications)
- [Configure Nginx Proxy Manager](#configure-nginx-proxy-manager)

## Git Clone this repository

First, we need to clone this repository into our Compute Engine instance. So SSH into your Compute Engine instance and run the following command:

```sh
sudo apt install git -y && git clone https://github.com/nbean452/google-dev-fest-2025-workshop.git
```

## Docker Installation

Now that we've SSH-ed into our Compute Engine instance, we need to install Docker before we can run the apps that we want. So we need to run the following commands

Note: installation command taken from official Docker installation instructions for Linux Debian 12 <OutLink href="https://docs.docker.com/engine/install/debian/">here</OutLink>

```sh
# Remove pre-existing docker installation from the machine
for pkg in docker.io docker-doc docker-compose podman-docker containerd runc; do sudo apt-get remove $pkg; done &&

# Add Docker's official GPG key:
sudo apt-get update
sudo apt-get install ca-certificates curl -y
sudo install -m 0755 -d /etc/apt/keyrings
sudo curl -fsSL https://download.docker.com/linux/debian/gpg -o /etc/apt/keyrings/docker.asc
sudo chmod a+r /etc/apt/keyrings/docker.asc

# Add the repository to Apt sources:
echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/debian \
  $(. /etc/os-release && echo "$VERSION_CODENAME") stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
sudo apt-get update

sudo apt-get install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin -y

# Give our user permission to run `docker` without sudo privileges
sudo groupadd docker
sudo usermod -aG docker $USER

# Ensure docker always run when compute instance is turned on
sudo systemctl enable docker.service
sudo systemctl enable containerd.service

exec $SHELL
```

If everything went well, you should be able to verify if the installation went well with this command:

```sh
docker run hello-world
```

## Setup Docker Network

To achieve our goal of having our docker apps accessible by our web server (`nginx-proxy-manager`) when there's an incoming request, we need to create a docker network and put all our docker containers within the same network

```sh
docker network create --driver bridge services-network
```

## Setup the env files

To make it easier to manage our own apps, let's create `.env` files from the given `.env.example` files in each app subdirectories

## Run the applications

Now that we have everything set up, we can now run our applications. For each subdirectory, run the following commands (except nginx-proxy-manager, which we will run last):

```sh
cd <app-directory>
docker compose up -d
```

## Configure Nginx Proxy Manager

First thing, we need to do `docker compose up -d` in the `nginx-proxy-manager` subdirectory to start the NGINX Proxy Manager app. But here's the difference, first run, we're going to route port 81 within the docker into the host machine's port 80 (to access nginx proxy manager dashboard from browser). From there, we can set up the SSL certificates and proxy hosts.

- Proxy hosts (helps NGINX understand which app to forward the incoming request to)
- SSL Certificates (helps secure the connection between the user and the NGINX server) using the Cloudflare API token (we're using Cloudflare for this demo)

Once these are set up, we can now change back the port mapping to "80:80" and "443:443" in the `docker-compose.yml` file within the `nginx-proxy-manager` subdirectory and restart the container.

# Conclusion

You have reached the end of this README, meaning that you have successfully hosted your own open-source applications on a Compute Engine instance in Google Cloud Platform and served the apps via https using NGINX Proxy Manager. Congratulations!


This is a hands-on workshop on the steps required to run open-source docker applications on a Compute Engine instance in Google Cloud Platform and serve the apps via https.

Notes

Google Developer Group HK: Flutter Study Group #01

Google DevFest 2025 Notes: Host Open-source Applications on Compute Engine