This is a contribution to the SUSE Cloud Native Foundations Scholarship Program which I received and some of the peers want a CI online demo. So here I will share on my knowledge and experience on continuous integration using a public repository and public runner. I will start with a sample project creation, GitHub project setup and end with GitHub action setup and runner.
What is CI?
In software engineering, continuous integration (CI) is the practice of merging all developers' working copies to a shared mainline several times a day.[1]
So essentially, it is a routine where every developer has to go through after they made code changes. Example, syntax check, linting, code compiling, multiple tests, package building, perhaps also support different runtime versions and/or operating systems.
There are many CI software available, please choose the one which match your requirements. I particularly like Jenkins a lot but Jenkins would require you to setup the runner on your machine. Since the objective of this blog is all public, hence, I picked GitHub action.
Let's begin with initial project setup. Reference if you want to know more.
https://maven.apache.org/guides/getting-started/maven-in-five-minutes.html
https://docs.github.com/en/actions/guides/building-and-testing-java-with-maven
```
$ export JAVA_HOME=/usr/lib/jvm/jdk-11.0.5/
$ mvn --version
Apache Maven 3.6.3
Maven home: /usr/share/maven
Java version: 11.0.5, vendor: Oracle Corporation, runtime: /usr/lib/jvm/jdk-11.0.5
Default locale: en_US, platform encoding: UTF-8
OS name: "linux", version: "5.10.0-7-amd64", arch: "amd64", family: "unix"
$ mvn archetype:generate -DgroupId=ch.weetech.app -DartifactId=demo_ci -DarchetypeArtifactId=maven-archetype-quickstart -DarchetypeVersion=1.4 -DinteractiveMode=false
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------< org.apache.maven:standalone-pom >-------------------
[INFO] Building Maven Stub Project (No POM) 1
[INFO] --------------------------------[ pom ]---------------------------------
...
...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 5.555 s
[INFO] Finished at: 2021-06-20T14:53:50+08:00
[INFO] ------------------------------------------------------------------------
$ cd demo_ci
$ tree .
.
├── pom.xml
└── src
├── main
│ └── java
│ └── ch
│ └── weetech
│ └── app
│ └── App.java
└── test
└── java
└── ch
└── weetech
└── app
└── AppTest.java
11 directories, 3 files
$ mvn package
[INFO] Scanning for projects...
[INFO]
[INFO] -----------------------< ch.weetech.app:demo_ci >-----------------------
[INFO] Building demo_ci 1.0-SNAPSHOT
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- maven-resources-plugin:3.0.2:resources (default-resources) @ demo_ci ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
...
...
...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.221 s
[INFO] Finished at: 2021-06-20T14:56:41+08:00
[INFO] ------------------------------------------------------------------------
$ java -cp target/demo_ci-1.0-SNAPSHOT.jar ch.weetech.app.App
Hello World!
```
Once we have the sample project setup, test and compile code locally okay. Then it is time that we initialize git repository locally and push to GitHub. But before we do of the following, you need to create a new repository on your GitHub.
```
$ mvn clean
[INFO] Scanning for projects...
[INFO]
[INFO] -----------------------< ch.weetech.app:demo_ci >-----------------------
[INFO] Building demo_ci 1.0-SNAPSHOT
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.079 s
[INFO] Finished at: 2021-06-20T15:24:46+08:00
[INFO] ------------------------------------------------------------------------
$ git init
hint: Using 'master' as the name for the initial branch. This default branch name
hint: is subject to change. To configure the initial branch name to use in all
hint: of your new repositories, which will suppress this warning, call:
hint:
hint: git config --global init.defaultBranch <name>
hint:
hint: Names commonly chosen instead of 'master' are 'main', 'trunk' and
hint: 'development'. The just-created branch can be renamed via this command:
hint:
hint: git branch -m <name>
$ git status -m master
$ git status .
On branch master
No commits yet
Untracked files:
(use "git add <file>..." to include in what will be committed)
pom.xml
src/
nothing added to commit but untracked files present (use "git add" to track)
$ git add pom.xml src/
$ git commit -m "initial"
[master (root-commit) 2cd8641] initial
3 files changed, 108 insertions(+)
create mode 100644 pom.xml
create mode 100644 src/main/java/ch/weetech/app/App.java
create mode 100644 src/test/java/ch/weetech/app/AppTest.java
$ git remote add origin https://github.com/jasonwee/demo_ci.git
$ git branch -M main
$ git push -u origin main
Enumerating objects: 16, done.
Counting objects: 100% (16/16), done.
Delta compression using up to 16 threads
Compressing objects: 100% (6/6), done.
Writing objects: 100% (16/16), 1.76 KiB | 899.00 KiB/s, done.
Total 16 (delta 0), reused 0 (delta 0), pack-reused 0
To https://github.com/jasonwee/demo_ci.git
* [new branch] main -> main
Branch 'main' set up to track remote branch 'main' from 'origin'.
$ git status .
On branch main
Your branch is up to date with 'origin/main'.
nothing to commit, working tree clean
```
Now that you pushed everything to GitHub, next is to setup GitHub Actions.
1. Locate Actions from the project tab.
2. Picked 'Java with Maven' as this best match the current requirement.
3. Check action configurations are okay and commit it.
4. once you commit, the action will kickstart the first run.
Congratulation! This is the first CI that you setup. The rest, as you may have already guessed will be the same as every developer will do, i.e. making code changes.
```
$ vim README.md
$ cat README.md
a contribution to https://www.udacity.com/scholarships/suse-cloud-native-foundations-scholarship
$ git status .
On branch main
Your branch is up to date with 'origin/main'.
Untracked files:
(use "git add <file>..." to include in what will be committed)
README.md
nothing added to commit but untracked files present (use "git add" to track)
$ git add README.md
$ git commit -m "added readme" README.md
[main a966f09] added readme
1 file changed, 1 insertion(+)
create mode 100644 README.md
$ git push
Enumerating objects: 4, done.
Counting objects: 100% (4/4), done.
Delta compression using up to 16 threads
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 410 bytes | 410.00 KiB/s, done.
Total 3 (delta 0), reused 0 (delta 0), pack-reused 0
To https://github.com/jasonwee/demo_ci.git
a273126..a966f09 main -> main
```
