Yejun Su
🪷 BUDDING

Kamal

Table of Contents

Deploy Rails applications 

I recently deployed a Rails application to Hetzner and AWS China1. Deploying on Hetzner is simple, requiring just two steps: launching a server and deploying. In contrast, deploying on AWS China involves extra steps because Docker Hub is not accessible from servers located in China.

The steps are:

  1. Launch an Amazon EC2 instance
  2. Create Amazon ECR repositories to store Docker Hub images
  3. Create an IAM user and assign only the “AmazonEC2ContainerRegistryFullAccess” permission
  4. Push Docker Hub images to Amazon ECR on local machine
  5. Pull images from Amazon ECR on Amazon EC2
  6. Deploy

Push Docker Hub images to Amazon ECR on local machine 

  1. Login ECR

    aws configure
aws ecr get-login-password | docker login --username AWS --password-stdin <aws-ecr-domain>

  2. Push basecamp/kamal-proxy image

    docker pull basecamp/kamal-proxy:v0.9.0 --platform linux/amd64
docker tag basecamp/kamal-proxy:v0.9.0 <aws-ecr-domain>/basecamp/kamal-proxy:v0.9.0
docker push <aws-ecr-domain>/basecamp/kamal-proxy:v0.9.0

  3. Push pgvector/pgvector image

    docker pull pgvector/pgvector:pg17 --platform linux/amd64
docker tag pgvector/pgvector:pg17 <aws-ecr-domain>/pgvector/pgvector:pg17
docker push <aws-ecr-domain>/pgvector/pgvector:pg17

Pull images from Amazon ECR on Amazon EC2 

  1. Install Docker

    sudo apt update
sudo apt install -y docker.io
sudo usermod -aG docker $USER

  2. Install AWS CLI

    curl "https://awscli.amazonaws.com/awscli-exe-linux-x86_64.zip" -o "awscliv2.zip"
sudo apt install -y unzip
unzip awscliv2.zip
sudo ./aws/install

  3. Login ECR

    aws configure
aws ecr get-login-password | docker login --username AWS --password-stdin <aws-ecr-domain>

  4. Pull basecamp/kamal-proxy image

    docker pull <aws-ecr-domain>/basecamp/kamal-proxy:v0.9.0
docker tag <aws-ecr-domain>/basecamp/kamal-proxy:v0.9.0 basecamp/kamal-proxy:v0.9.0

  5. Pull pgvector/pgvector image

    docker pull <aws-ecr-domain>/pgvector/pgvector:pg17

Deploy 

  1. Run kamal setup the first time to setup everything.
  2. Run kamal deploy for subsequent deployments.

Deploy public images 

I use Atuin2 for shell history. It supports syncing shell history through a sync server, which can be self-hosted using Docker. Kamal accessories are good at deploying such Docker images. The idea is to transform its Docker Compose example to Kamal accessories:

service: atuin
image: atuin
accessories:
  db:
    image: postgres:14
    host: &host hetzner
    env:
      clear:
        POSTGRES_DB: atuin
        POSTGRES_USER: atuin
      secret:
        - POSTGRES_PASSWORD
    directories:
      - ./data:/var/lib/postgresql/data/
  server:
    image: ghcr.io/atuinsh/atuin:v18.10.0
    host: *host
    cmd: server start
    env:
      clear:
        ATUIN_HOST: 0.0.0.0
        ATUIN_OPEN_REGISTRATION: false
        RUST_LOG: info,atuin_server=debug
      secret:
        - ATUIN_DB_URI
    proxy:
      host: atuin.yejun.dev
      app_port: 8888
      ssl: true
      healthcheck:
        interval: 1
        timeout: 1
        path: "/"

See https://github.com/goofansu/kamal-services for details.

  1. The config is taken from my application for your reference. ↩︎

  2. Atuin is a command-line tool to sync, search and backup shell history. ↩︎

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