Project setup with SpringBoot, Git and Maven

Tools

The recommended toolchain for this course is:

Resources

Guides for using Spring Boot: https://spring.io/guides
A REST service example: https://spring.io/guides/gs/rest-service/
Quickstart guide that covers project setup and a simple hello world program: https://spring.io/quickstart
Spring Initializr, a tool to quickly configure your project: https://start.spring.io/
This is a video guide to setting up a hello world example in spring:

These instructions are also available in video format:

Git

Once you have familiarized yourself a bit with Spring, you should set up version control. There are lots of options, but the recommended approach is to use Git and host your project at the DSV Gitea instance.

In order to be able to deploy your code using an external tool like Jenkins, you will need to create a local git repository, add your code to it, and regularly push the updates in your local repository to a server-based mirror that Jenkins can pull the code from.

Setting up gitea remote

In order to set up the remote mirror, start by logging in at Gitea. Once logged in, do the following:

Click the "+" icon in the upper right of the window and choose "New Repository"
Enter a repository name. The name can't contain whitespace since it will be part of the git URL.
If you want the repository to not be publically viewable, check the box marked "Make Repository Private"
All the other fields can be left blank
Click the green button labeled "Create Repository"

You now have an empty repository prepared on the server, where you will be pushing your code. Under the heading "Clone this repository" you should see the git URL to this repository. In order to minimize authentication-related confusion, you should always be using the "SSH" variant of the git URL.

Keep this page open, you will need the git URL later.

Adding a public key for pushing your code

In order to push code from your computer to the gitea remote, you will need to configure public key authentication for gitea. If you don't already have a public key to use, you will need to create one now:

Open a terminal (linux/mac) or git bash (widows)
Run the command ssh-keygen
Press enter through the prompts except if it asks to overwrite an existing key, in which case you should answer no and use your existing key instead

Now you have a key pair that you can use for pushing your code. You now need to add the public part of that key to your gitea user.

In order to find your public key, run cat ~/.ssh/id_*.pub in your terminal/git bash. A long string of alphanumeric characters should be printed in the terminal. Keep the window around, you will need it later.
Open gitea in your web browser
Click your avatar in the upper right of the screen and choose "Settings"
Click the "SSH/GPG Keys" heading
Under "Manage SSH keys", click "Add key"
Go back to the window with the public key in it, highlight the output and copy it (right-click -> copy)
Paste the public key in the "Content" box in gitea. Do NOT use the keys from the keys page here!
Click the green button labeled "Add Key"

Setting up your local repository and connecting it to the remote

This is how to set up your repository using the command-line git tools:

Open a terminal (on linux/mac) or git bash (windows) and navigate to the directory where you keep your source code for this project.
Initialize an empty repository in the current directory: git init
Add the gitea remote using the SSH URL from when you created your repository on gitea: git remote add origin [your git URL]
Instruct git to track all existing files in this directory and any subdirectories: git add .
Make the initial commit of the files you just staged: git commit -m "First commit"
Push your code to the remote: git push -u origin master

Your code should now be browseable in the gitea web UI.

The core git commands you will be needing when developing are:

git add [file] - Add a new file to be tracked by git, or stage new changes to an already tracked file
git commit - Commit your currently staged changes
git push - Push local commits to the remote
git pull - Pull commits fro mthe remote to your local copy
git status - View the current state of your repository; both any local changes and how your local copy differs from the remote

You will need to find out a number of things yourself in order for the group to be able to share a single repository with a reasonable workflow:

Granting other users write access to a repository you own
Resolving merge conflicts
Using git integrations in IDEs

Preparing your project for deployment to tomcat

If you usually run your project in SpringBoot's embedded tomcat server, your pom.xml will need to be updated to be buildable by jenkins and produce a deployable artifact.

Make sure maven produces a war package:
```
<packaging>war</packaging>
```

Add a dependency to jenkins core libraries:

<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-core</artifactId>
</dependency>

Add a maven extension for git integration:

<build>
  ...
  <extensions>
    ...
    <extension>
      <groupId>ar.com.synergian</groupId>
      <artifactId>wagon-git</artifactId>
      <version>0.2.5</version>
    </extension>
  </extensions>
</build>

Add the source repositories for the new dependencies:

<repositories>
  <repository>
    <id>spring-releases</id>
    <url>https://repo.spring.io/libs-release</url>
  </repository>
</repositories>
<pluginRepositories>
  <pluginRepository>
    <id>spring-releases</id>
    <url>https://repo.spring.io/libs-release</url>
  </pluginRepository>
  <pluginRepository>
    <id>synergian-repo</id>
    <url>https://raw.github.com/synergian/wagon-git/releases</url>
  </pluginRepository>
</pluginRepositories>

Add the URL to your gitea remote:

<distributionManagement>
  <repository>
    <id>internal.repo</id>
    <name>Internal repo</name>
    <url>git@gitea.dsv.su.se/[auser]/[arepo].git</url>
  </repository>
</distributionManagement>

Now your pom.xml should be all set. The remaining thing to be done is to modify your main application to extend SpringBootServletInitializer:

Once these changes have all been made, commit and push your code to the remote as usual. Once the updates have been pushed to the remote, you should be able to build and deploy yor project using Jenkins.