Java Demo App

The App

This is a simple Sales Manager Java App that stores sales items in a table presented in a web app.

This demo repo is designed to help understand some of CI/CD (Continuous Integration/Continuous Delivery) principles and best practices.

The Setting

Java (Spring Boot framework) with MVC (Model View Controller) and OOP (Object Oriented Programming) design patterns. Backend Database is PostreSQL 10.4 (but can be used with other versions).

CI/CD Pipeline GitHub Actions as the main CI/CD pipeline orchestrator

Tools used to optimize the pipeline (See the .github/workflows/ci.yml .github/workflows/cd.yml for more detailed configuration).

CI - Continuous Integration

• Caching Dependencies to Speed Up Workflows
• Reusing Docker Layer Caching from pervious docker builds with action-docker-layer-caching or build-push-action actions.
• Using the Metrix Strategy to run unit tests in parallel to scale-out resources and reduce significant testing time.
• Using the Split Test Action to help splitting tests by previous testing time runs or line count (or other strategies) across multiple runners.
• GitHub Advanced Security - Code Scanning using the CodeQL analysis to scan for vulnerabilities.
• Liquibase Quality Checks - To help enforce Database schema changes best practices set by your DBA team, including naming conventions, grants & revokes, rollback scripts and security risks.

CD - Continuous Delivery/Deployment

• Using Environments with an approval step review prior to deployments
• Using the azure/login action to leverage the OIDC (OpenID Connect) functionality for the benefit of to exchange short-lived tokens directly with Azure cloud provider prior to deployment
• Running a Canary or Blue-Green deployments in an AKS (Azure Kubernetes) Cluster.

CI/CD Diagram

stateDiagram
    state Developer-Workflow {
    Commits --> PR: Developers Commit new changes in a Pull Request
    PR --> Build: Security Scans, Build & Unit Test Suite
    }
    
    state Continuous-Integration {
        state GitHub-Advanced-Security {
        Build --> PR: Feedback of failed tests - back to dev
        Build --> JunitTests: Storing Artifacts
        JunitTests --> Publish: If CI passes, \nmerging to main branch \nand publishing Containerised\n App to GitHub\n Container Registry
        state Parallel-Testing {
        JunitTests --> JunitTest1: Each test runs in \na containerized environment
        JunitTests --> JunitTest2
        JunitTests --> JunitTest3
        JunitTests --> JunitTest4
        JunitTests --> JunitTest5
        JunitTests --> JunitTest..N
        }
      }
    }

    state Continuous-Delivery {
    Publish --> SystemTesting: Pulling Image from GHCR
    SystemTesting --> IntegrationTesting: [staging]
    IntegrationTesting --> AccepetanceTesting: [staging]
    }
    AccepetanceTesting --> Deploy: Login with OpenID Connect and \nDeploy the app to K8s
    Deploy --> [ProdInstance1]: Blue
    Deploy --> [ProdInstance2]: Green

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Building and Testing

Maven is used as the project management for Building and Testing the application. To build the application, you can run:

mvn clean package

It will generate a JAR file in the target folder with the following format salesmanager-x.x.x-SNAPSHOT.jar.
To run the application, you can deploy the JAR file. For example:

java -jar target/salesmanager-0.0.6-SNAPSHOT.jar

How to Demo

For easy demos without the need to stand up a Postgres database, a lightweight local H2 database (PostgreSQL Mode) is setup by default in the src/main/resources/application.properties file.
You can run the ./build_and_run_app.sh helper shell script and interact with the web app on localhost:8086.

You can easily use a GitHub codespaces with this repository. To set up your codespace, simply go to this repo main page --> Click Code --> Codespaces '+'.

Running the CI workflow

1. In order to run the workflow, you will need to fork this repo.
   
2. Then, make sure to save the following environment variables in your repository secrets so you can successfully run the Database schema mirgations scripts (using Liquibase as the schema migration tool) on application startup and when running the tests.
   

Repository Secrets LIQUIBASE_COMMAND_URL LIQUIBASE_COMMAND_USERNAME LIQUIBASE_COMMAND_PASSWORD

If you are going to use the same dockerised service container in the CI job for dev, then the default values should be:

LIQUIBASE_COMMAND_URL = jdbc:postgresql://postgres:5432/postgres
LIQUIBASE_COMMAND_USERNAME = postgres
LIQUIBASE_COMMAND_PASSWORD = postgres

Gitgraph Diagram - Developer Workflow

%%{init: { 'logLevel': 'debug', 'theme': 'base', 'gitGraph': {'showBranches': true}} }%%
      gitGraph
        commit
        branch hotfix
        checkout hotfix
        commit
        branch develop
        checkout develop
        commit id:"ash" tag:"abc"
        branch featureB
        checkout featureB
        commit type:HIGHLIGHT
        checkout main
        checkout hotfix
        commit type:NORMAL
        checkout develop
        commit type:REVERSE
        checkout featureB
        commit
        checkout main
        merge hotfix
        checkout featureB
        commit
        checkout develop
        branch featureA
        commit
        checkout develop
        merge hotfix
        checkout featureA
        commit
        checkout featureB
        commit
        checkout develop
        merge featureA
        branch release
        checkout release
        commit
        checkout main
        commit
        checkout release
        merge main
        checkout develop
        merge release

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