# Using Docker with NubesGen

Docker is the default option with NubesGen, and allows to run any kind of application supporting Docker.

It comes with two options: "Docker with a Dockerfile" and "Docker with Spring Boot".

# Tutorial: running a Docker image with NubesGen

We're going to deploy https://github.com/jdubois/golang-sample-app (opens new window), which is a sample application written in Go. We'll use NubesGen's GitOps support to automatically build and deploy the application.

Prerequisites:

Tip: You can go to https://aka.ms/nubesgen-azure-shell (opens new window) to have those prerequisites installed, and run the script from a Web browser.

Steps:

  1. Fork the project on your GitHub account.
  2. Clone the fork on your computer. Change <your-github-account> by the name of your GitHub account:
    git clone https://github.com/<your-github-account>/golang-sample-app.git
    
  3. In the cloned project (cd golang-sample-app), set up GitOps with NubesGen by using the NubesGen CLI (more information here):
     ./nubesgen-cli-linux gitops
    
  4. Use the command-line with NubesGen (more information here) to generate a NubesGen configuration:
    curl "https://nubesgen.com/demo.tgz?application=app_service.standard&gitops=true" | tar -xzvf -
    
  5. Create a new branch called env-dev, and push your code:
    git checkout -b env-dev
    git add .
    git commit -m 'Configure GitOps with NubesGen'
    git push --set-upstream origin env-dev
    
  6. Go to your GitHub project, and check that the GitHub Action is running.
  7. You can go to the Azure Portal (opens new window) to check the created resources.
  8. The application should be deployed on your App Service instance. Its URL should be in the form https://app-demo-XXXX-XXXX-XXXX-XXXX-dev-001.azurewebsites.net/, and you can also find it in the GitHub Action workflow (Job: "manage-infrastructure", step "Apply Terraform"), or in the Azure portal. As it is a simple application, it should print by default Hello, world.
  9. Once you have finished, you should clean up your resources:
  10. Delete the resource group that was created by NubesGen to host your resources, which is named rg-demo-XXXX-XXXX-XXXX-XXXX-001.
  11. Delete the storage account used to store your Terraform state, in the rg-terraform-001 resource group.

# Which Azure resources are created

NubesGen will generate:

# Configuration options

In the generated terraform/modules/app-service/main.tf file, NubesGen will configure some environment variables for your application.

# Important options

  • WEBSITES_PORT is the port that will be exposed by your Docker image. By default it is set to 8080, but if your Docker image uses port 1337 instead, you will need to reconfigure this accordingly.
  • DOCKER_REGISTRY_SERVER_URL, DOCKER_REGISTRY_SERVER_USERNAME and DOCKER_REGISTRY_SERVER_PASSWORD are used to access the Docker container registry. If you want to use another registry, you need to modify those variables accordingly.

# Other options

  • DATABASE_URL: the URL to your database
  • DATABASE_USERNAME: the database user name
  • DATABASE_PASSWORD: the database password
  • REDIS_HOST: the Redis host name
  • REDIS_PASSWORD: the Redis password
  • REDIS_PORT: the Redis port (by default 6380)
  • AZURE_STORAGE_ACCOUNT_NAME: the storage account name
  • AZURE_STORAGE_ACCOUNT_KEY: the storage account key
  • AZURE_STORAGE_BLOB_ENDPOINT: the blob storage endpoint
  • MONGODB_DATABASE: the MongoDB database name
  • MONGODB_URI: the MongoDB database URL

# Using a Dockerfile vs using Spring Boot

Using a Dockerfile is the default way to use Docker, so this will work in most situations. NubesGen will build your project using the standard docker build command.

Spring Boot is a Java framework that can use a Dockerfile, but which uses by default a Maven plugin: this is supported by NubesGen if you select that option, in which case the Docker image will be built using the mvn spring-boot:build-image command.

If you have selected Spring Boot, NubesGen will also configure the same configuration properties as the ones described in Spring Boot with NubesGen. For example, your database should be automatically configured.