v-lai / git-tutorial

git-tutorial

Login to the AWS EC2 node as user devops:

$ ssh devops@IP-ADDRESS

Once logged in you will be in /home/devops.

Clone the Git repo docker-java-sample there:

$ git clone https://github.com/kurianinc/docker-java-sample.git

This will clone the repository under the directory docker-java-sample. If needed, default directory name can be changed.

Under docker-java-sample directory, build the Java app:

$ cd docker-java-sample
$ mvn package
$ mvn exec:java

You will see Hello World! printed among the deluge of build output.

Now try to make some change to the source code file where the above message printed.

Prior to making the change create a feature branch for the changes that you plan.

Check active branches locally:

$ git branch
* master

Create a new branch YOUR-BRANCH-NAME (example: tk-change-message) off the current branch master, and, make that current:

$ git branch YOUR-BRANCH-NAME
$ git checkout YOUR-BRANCH-NAME

Edit the source file to make changes:

$ vi src/main/java/org/examples/java/App.java

Make sure that your change is error free and working before a commit:

$ mvn package
$ mvn exec:java

Commit the change to Git locally:

$ git commit src/main/java/org/examples/java/App.java -m "Updated message"

Push the committed changes to Git server:

$ git push --set-upstream origin YOUR-BRANCH-NAME # First time after the branch is created
$ git push # Subsequent code pushes to remote server

The user credentials to access Git server can be cached locally so you won't be prompted for those when code is pushed.

$ git config --global credential.helper 'store --file ~/.git-creds'

On the browser, see your branch listed at https://github.com/kurianinc/docker-java-sample/branches.

Create a new PR by clicking on the New pull request button against your branch.

A PR is essenatially a merge between two branches, usually a merge of feature branch into the parent branch it based on. In this sample case, merging YOUR-BRANCH-NAME (example: tk-change-message) into master.

A PR is reviewed and approved by team members prior to merging.

Common practices, usually called Git Flow:

• A repo will have branches master and 'develop, masterrepresenting code in production anddevelop` representing ongoing development work.
• Feature branches are created off develop and those will be merged into develop after testing.
• Prior to pushing code to production, develop is merged into master.
• For hot-fixes in production branches are created off master and merge such changes into both develop and master.