git-recipes-and-commands.md

Git Recipes and Commands

• Git Recipes and Commands
• Commands
• Recipes
  • Creating a new branch from command line
  • Downloading a newly created branch of your fork
  • Syncing a fork: Merging commits from main repo master into your fork's master
  • Rebasing a branch of your fork to the your fork's master
  • Pulling all changes
  • Merging a PR to a branch locally to test out the changes
  • Updating an Exisiting Branch on Your Fork with Latest Code From Master on Main Repo
  • Updating a New Branch on Your Fork with Latest Code From Master on Main Repo
  • Targeting a PR to a branch other than Master
  • Undoing changes made to fork's master by mistake
  • Reverting your last change
  • Using the same Pravega Version as the Hadoop Connector
  • Disabling push to upstream
  • Cherry-Picking a PR for merge from master to a branch
  • Resolving Merge Conflicts on a Branch of Your Fork
  • Stashing and Unstashing

Table of contents generated with markdown-toc

Assumptions:

• Remote upstream is pravega/pravega.git
• Remote origin is youracount/pravega.git

Commands

• Display commit logs

  $ git log
  $ git log --oneline
  
  # See more options at https://git-scm.com/docs/git-log

• Checkout

  # git checkout <commit-id>
  
  # Revert changes since last commit
  $ git checkout .
  
  # Revert changes since last commit on a file
  $ git checkout <file-name>
  
  # Checkout an existing branch
  $ git checkout <branch-name>
  
  # Create a new branch and and check it out 
  $ git checkout -b <branch-name>
  
  # See more options here: https://guide.freecodecamp.org/git/git-checkout/
  

Further Reading:

• https://guide.freecodecamp.org/git

Recipes

Creating a new branch from command line

$ git clone https://github.com/ravisharda/pravega.git
$ git checkout -b issue-3227-auth-logic
(verify using 'git branch')
$ git push origin issue-3227-auth-logic

Downloading a newly created branch of your fork

Pravega:

$ git clone https://github.com/ravisharda/pravega.git
$ cd pravega
$ git branch
$ git checkout -b <branch-name>
$ git branch

Pravega Samples: Note: In Samples, PRs are against develop branch, not against master (please, check https://github.com/pravega/pravega-samples/wiki/How-to-release#about-this-repository).

$ git clone https://github.com/ravisharda/pravega-samples.git
$ cd pravega-samples
$ git branch
$ git checkout -b issue-181-security-samples
$ git branch

Syncing a fork: Merging commits from main repo master into your fork's master

(Alternatively, you can sync a fork's branch from the main repo's branch: just replace master with the branch name in the commands below, and in step 1, do a git clone -b <branch-name> ...

S.No.	Command	Description	Verification (if any)
1	git clone https://github.com/ravisharda/pravega.git	Download the forked copy from Github	-
2	cd pravega	-	-
3	git remote add upstream https://github.com/pravega/pravega.git	Add an upstream remote branch, which will facilitate pulling down new commits from the main repo	git remote -v or git remote show upstream
5	git remote set-url --push upstream no-pushing	Prevent pushes to upstream	-
6	git fetch upstream	Fetch the branches and their respective commits from the upstream repository. Commits to master will be stored in a local branch, upstream/master.	-
7	git checkout master	Check out your fork's local master branch	git branch
8	git merge upstream/master	Merge the changes from upstream/master into your local master branch. This brings your fork's master branch into sync with the upstream repository, without losing your local changes.	-
9	git push origin master	Syncing your fork only updates your local copy of the repository. To update your fork on GitHub, you must push your changes.	-
10	Go to https://github.com/ravisharda/pravega/ and inspect the message	Verify that your fork's master is even with upstream.

Source: GitHub Help - Syncing a Fork

Rebasing a branch of your fork to the your fork's master

$ git clone https://github.com/<youraccount>/pravega.git
$ cd pravega
$ git checkout <branch-name>
$ git rebase master
$ git log
$ git push origin <branch-name>

Pulling all changes

• Pulling all changes...
  • git pull
  • ... in the remote repo to master: git pull origin master
  • ... in the remote repo to a branch: git pull origin <branch-name>

(Will fail if there are merge conflicts)

Merging a PR to a branch locally to test out the changes

# git fetch origin pull/ID/head:BRANCHNAME
# Assumptions:
# PR no. = 3356, branch that you want to test out is: r0.4
#
$ git clone https://github.com/pravega/pravega.git
$ git fetch origin pull/3356/head:r0.4
$ git checkout r0.4

See more at https://help.github.com/en/articles/checking-out-pull-requests-locally

Similar experience, when trying out a colleague's PR (PR 217 vijikarthi:issue-pravega-security):

Forked the repo
$ git clone https://github.com/ravisharda/flink-connectors.git
$ git remote add upstream https://github.com/pravega/flink-connectors.git
$ git fetch upstream pull/217/head:issue-pravega-security

Yet another way - actually a much simpler one:

# Recursive is necessary for flink-connections project
$ git clone --recursive -b issue-pravega-security https://github.com/vijikarthi/flink-connectors

Updating an Exisiting Branch on Your Fork with Latest Code From Master on Main Repo

1. Download the branch from your fork: git clone -b <branch_name> https://github.com/ravisharda/pravega.git
2. Add an upstream remote branch, which will facilitate pulling down new commits from the main repo:

   $ git remote add upstream https://github.com/pravega/pravega.git
   $ git remote -v
   $ git remote set-url --push upstream no-pushing
   $ git remote -v
   

3. Perform the rebase:
   1. First make sure you are currently in the feature branch: git branch
   2. Fetch all the new changes from the main repo/upstream: git pull --rebase upstream master
   3. Fix any mrge conflicts that might arise.
   4. Continue rebasing: git rebase --continue
   5. Verify the code.
   6. Now, push all the changes you have made to the branch to the master of your forked repo:

      $ git push --force origin <pull-request-branch-name>
      
      # In some cases you might have to force push.
      $ git push --force origin <pull-request-branch-name>
      

Updating a New Branch on Your Fork with Latest Code From Master on Main Repo

1. Download the forked copy from GitHub: git clone https://github.com/ravisharda/pravega.git
2. Add an upstream remote branch, which will facilitate pulling down new commits from the main repo: git remote add upstream https://github.com/pravega/pravega.git. (Verify using git remote -v)
3. Make a new branch: git checkout -b <branch_name>
4. Make changes to the code as needed.
5. Commit the changes you have made.
6. Push up to your GitHub fork:
   1. First make sure you are currently in the feature branch: git branch
   2. Fetch all the new changes from the main repo/upstream: git pull --rebase upstream master
   3. Fix any mrge conflicts that might arise.
   4. Continue rebasing: git rebase --continue
   5. Verify the code.
   6. Now, push all the changes you have made to the branch to the master of your forked repo: git push --force origin <pull-request-branch-name>

In this case your forked repo/branch will be ahead of forked repo/master. Not something you often want to do. It might be useful when you want to forked branch to track a branch on the main repo.

Targeting a PR to a branch other than Master

I used these steps for one of the PRs in pravega-samples repo:

1. git clone https://github.com/ravisharda/pravega.git
2. Creates issue-181-security-samples-dev branch off develop: git checkout -b issue-181-security-samples-dev develop
3. Checkout the new branch: git checkout issue-181-security-samples
4. Made changes.
5. Committed and pushed as usual.

Undoing changes made to fork's master by mistake

Use git reset approach described here.

1. Identify the commit you want to revert to: git log --oneline
2. git reset --hard d9a15c2b6
3. git push --force

Reverting your last change

git reset HEAD~1 // this undo the last commit //git add -u (optionally, add some changes) git commit -s git push --force

Using the same Pravega Version as the Hadoop Connector

1. cd $hadoop-connector/pravega
2. git log to get the commit point.
3. Checkout Pravega to that commit point.

   git clone https://github.com/pravega/pravega.git
   git checkout <COMMIT>
   

Disabling push to upstream

This'd be useful when you have commit access to main and want to prevent any inadvertant push to main's master:

$ git remote -v
origin  https://github.com/ravisharda/pravega.git (fetch)
origin  https://github.com/ravisharda/pravega.git (push)
upstream        https://github.com/pravega/pravega.git (fetch)
upstream        https://github.com/pravega/pravega.git (push)

# Update/override the push URL to be something other than the pull URL
$ git remote set-url --push upstream no-pushing

$ git remote -v
origin  https://github.com/ravisharda/pravega.git (fetch)
origin  https://github.com/ravisharda/pravega.git (push)
upstream        https://github.com/pravega/pravega.git (fetch)
upstream        no-pushing (push)

Cherry-Picking a PR for merge from master to a branch

Say, source = master, target = r0.6

First, make sure the target branch in your form is up-to-date. Follow the steps mentioned under "Syncing a fork..", replacing the master branch with the target branch.

Now, perform the cherry pick.

Create a branch in your form, say `issue-3696-cherrypick-pr-4420-to-r0.6` from the target branch (`r0.6` in this case). 

# git clone https://github.com/ravisharda/pravega.git

$ git checkout issue-3696-cherrypick-pr-4420-to-r0.6

# Verify you are on the right branch. 
$ git branch

# Identify the commit id of the PR that you are trying to cherry pick. Use that one below.
$ git cherry-pick b8911f8f4c0b452d18cb34e3d6ce23a13d6eccee

$ git status --oneline

$ git push origin

# Now, navigate to Github repo online and create a PR keeping source as `ravisharda/issue-3696-cherrypick-pr-4420-to-r0.6` and target as say, `pravega/r0.6`.

Cherry-Picking commits made in fork/branch for a branch based out of another branch

Say, source: ravisharda/src-branch (created out of master), target = ravisharda/target-branch (created based on r0.6)

git clone ...

Create a branch "target-branch" based out of r0.6 branch

git checkout master

git fetch

git checkout target-branch

git status

Note the commits (from... to)
git cherry-pick d32d46ac4b71d581ea58f53c3a1a36b05e5f619c..86b239c71b4ccfdf7ce527d4239bcae54a07fa7f

If the previous step doesn't work
git cherry-pick -abort

git cherry-pick commit-id-4
git cherry-pick commit-id-3
git cherry-pick commit-id-2
git cherry-pick commit-id-1

git commit

Push the commits 

Resolving Merge Conflicts on a Branch of Your Fork

When working on a recent PR, I encountered an issue where my branch had merge conflicts. Here are the steps I followed to resolve them:

1. Ensure remote upstream for fetch operation is set. Check it is by running: git remote -v. Expect to see an output like the following:

   origin  https://github.com/ravisharda/pravega.git (fetch)
   origin  https://github.com/ravisharda/pravega.git (push)
   upstream        https://github.com/pravega/pravega.git (fetch)
   upstream        no-pushing (push)
   

2. git fetch upstream
3. Perform the merge.

   $ git branch
   * issue-3728-batch-client-auth
   master
   
   $ git stash
   
   $ git checkout master
   Switched to branch 'master'
   Your branch is up to date with 'origin/master'.
   
   $ git status
   on branch master
   Your branch is up to date with 'origin/master'.
   
   nothing to commit, working tree clean
   
   # Merge upstream's master to local master. We are already on local master.
   $ git merge upstream/master
   
   $ git status
   n branch master
   Your branch is ahead of 'origin/master' by 19 commits.
   (use "git push" to publish your local commits)
   
   nothing to commit, working tree clean
   
   $ git checkout issue-3728-batch-client-auth
   Switched to branch 'issue-3728-batch-client-auth'
   
   $ git merge master
   Auto-merging controller/src/main/java/io/pravega/controller/server/rpc/grpc/v1/ControllerServiceImpl.java
   CONFLICT (content): Merge conflict in controller/src/main/java/io/pravega/controller/server/rpc/grpc/v1/ControllerServiceImpl.java
   Automatic merge failed; fix conflicts and then commit the result.
   
   # Now, used IntelliJ resolve conflicts feature to perform a merge. 
   
   $ git status
   git status
   On branch issue-3728-batch-client-auth
   All conflicts fixed but you are still merging.
     (use "git commit" to conclude merge)
   
   Changes to be committed:
   
        modified:   build.gradle
        modified:   client/src/main/java/io/praveg..
        ...
   
   $ git commit -s
   [issue-3728-batch-client-auth b10a1635f] Merge branch 'master' into issue-3728-batch-client-auth
   
   $ git status
   On branch issue-3728-batch-client-auth
   nothing to commit, working tree clean
   

4. Push the changes. I did it via IntelliJ.

Stashing and Unstashing

Say you were in a branch and had some deltas. Now you want to work in another branch.

> 3669-tls-material/pravega$ git branch -v
* issue-3669-improve-default-tls-material fac451837 Use the new PKI/TLS material.
  master                                  cb253c8c7 Issue #3624: Fix backward compatibility issue with WireCommands. (#3640)

> 3669-tls-material/pravega$ git remote -v
origin  https://github.com/ravisharda/pravega.git (fetch)
origin  https://github.com/ravisharda/pravega.git (push)

> 3669-tls-material/pravega$ git stash
Saved working directory and index state WIP on issue-3669-improve-default-tls-material: fac451837 Use the new PKI/TLS material.

> 3669-tls-material/pravega$ git checkout master
Switched to branch 'master'
Your branch is up to date with 'origin/master'.

> 3669-tls-material/pravega$ git remote -v
origin  https://github.com/ravisharda/pravega.git (fetch)
origin  https://github.com/ravisharda/pravega.git (push)

> 3669-tls-material/pravega$ git checkout issue-3669-improve-default-tls-material
Switched to branch 'issue-3669-improve-default-tls-material'

> 3669-tls-material/pravega$ git stash pop
On branch issue-3669-improve-default-tls-material
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

        modified:   config/logback.xml
        modified:   standalone/src/main/java/io/pravega/local/LocalPravegaEmulator.java

Untracked files:
  (use "git add <file>..." to include in what will be committed)

        config/.cleanup_pki.sh.swp
        config/bak/
        config/ca-cert.srl
        config/cleanup_pki.sh
        config/custom-csr.conf
        config/junk/
        config/server.csr
        config/server.keystore.p12

no changes added to commit (use "git add" and/or "git commit -a")
Dropped refs/stash@{0} (86b7ac7e7689c7d258e899e066a18307d79eb83e)

> 3669-tls-material/pravega$