Spring Boot DigitalOcean App Platform Demo

This repository showcases an opinionated deployment of a sample Spring boot application right from GitHub source to DigitalOcean App Platform using:

Maven - Build and package the sample Spring Boot application into a fat jar
GitHub Actions - Trigger a build on code commit which in turn builds, test and creates a docker image using the Dockerfile. The image is pushed to DigitalOcean container registry and finally deployed to App Platform using Terraform.
Terraform - Manage infrastructure on DigitalOcean

Overview

The following diagram depicts the opinionated pipeline built using Github Actions

Run ./mvnw clean package is used to test and build the Spring Boot fat JAR
Run docker build creates a docker image of the fat JAR using the Dockerfile in the repo
Run doctl CLI is used to push the built image to DigitalOcean Container Registry. A secret is created in GitHub Actions as DO_TOKEN which holds the DigitalOcean API token. The image is tagged using the first 7 characters of the GitHub SHA
Run terraform apply is run targeting the App platform instance to deploy the app using the docker image built in the previous step

Spring Boot App

The Spring boot app is a very simply app that uses Spring Data JPA to implement JPA repositories. There are two endpoints GET /api/customer and POST /api/customer to get all customers stored in the database and create a customer respectively

To run the app locally

Run the app
```
./mvnw spring-boot:run  
```

Note: The application uses H2 memory database and creates the table during startup

Terraform

The terraform directory includes the script to manage the following infrastructure

Service	Usage
DigitalOcean App Platform	PaaS platform to run the Spring Boot application as a service
DigitalOcean Managed Database	PostgresSQL Database for the application
DigitalOcean Container Registry	Store build images of the application.

Note: A DigitalOcean spaces bucket has to be created manually as a pre-requisite to store the Terraform state information. Also generate the Spaces key and secret as described here Open the Digital Ocean web console and navigate to 'Spaces' and create a bucket with the name demo-terraform-state-config. The region should be sgp1 (Singapore)

Considerations

Get the Digital Ocean API token from the console as described here
Use Terraform workspaces to manage multiple environments like dev,qa,prod. Each of these environments have different requirements of resource capacity such as CPU, memory which are configured in Terraform
Use the DigitalOcean 'Development database' in the Development environment. The ' Development database' is a low resource instance and is not suitable for production workloads
Database cluster only accepts connection from the app platform for each environment ( Trusted Sources). Firewall rules are place to block all other traffic

Execution

All commands to be run from inside the terraform folder

Export the Digital Ocean API token as

export DO_TOKEN=<>
export DO_SPACES_ACCESS_KEY=<>
export DO_SPACES_SECRET=<>

Run Terraform initialization

terraform init \
  -backend-config="access_key=$DO_SPACES_ACCESS_KEY" \
  -backend-config="secret_key=$DO_SPACES_SECRET"

Create a new workspace dev
```
terraform workspace new dev
```
Terraform should automatically select the dev environment. All commands will now be executed in the dev workspace
Create the Docker registry only once. Note the Docker registry must be created before running the CI pipeline as the pipeline uploads the docker images to this registry
```
terraform apply -target=digitalocean_container_registry.demo-docr -var="do_token=$DO_TOKEN" 
```
To verify the changes do the infrastructure. Ensure you are in the right workspace
```
terraform plan -var="do_token=$DO_TOKEN" 
```
To commit the infrastructure changes on the dev workspace. Ensure you are in the right workspace
```
terraform apply -var="do_token=$DO_TOKEN" 
```

Access

Once the application has been successfully deployed onto the App platform, navigate to the App Platform section in DigitalOcean to get the live url. Note that we do create a custom domain as dev.demo.com as a sample to showcase custom domains. Sample screenshot attached below