Lecture 6: Working with remotes

Introduction to Git --- Fall 2021 # Lecture 6: Working with remotes   ![](https://www.hpc2n.umu.se/sites/default/files/umu-logo-left-se.png =250x) ![](https://www.hpc2n.umu.se/sites/default/files/hpc2n-logo-text5.png =250x) ![](https://www.hpc2n.umu.se/sites/default/files/images/SNIC_logo_autocrop.png =250x) <small>Slides: https://hackmd.io/@hpc2n-git-2021/L6-remotes#/</small> ---  <style type="text/css"> .reveal p { text-align: left; } .reveal ul { display: block; } .reveal ol { display: block; } </style> ## Concepts A remote repository is a version of the project which can be hosted in your local machine, some network, or over the internet (Pro Git, 2nd. Ed., Scott Chacon and Ben Straub) where you and your collaborators can push or pull code modifications. In addition to this, a remote is a way to backup your repository. ---  ![](https://i.imgur.com/z2FesR1.jpg) ---  ## Basic concepts cont. The command ```java $ git remote -v origin git@bitbucket.org:arm2011/gitcourse.git (fetch) origin git@bitbucket.org:arm2011/gitcourse.git (push) ``` displays the remotes that are already set up where you can *fetch* and *pull* changes. In this case there is only a single remoted called **origin**. ---  ```java $git graph * 2e56d0a (HEAD -> main, origin/main, origin/HEAD) text of exercise git diff usage * 22a7316 Adding yet more lectures * 0ddb791 Adding some more of the lectures * 3ff9f8f Adding some of the lectures ``` ---  ## Adding remotes A remote repository can be added manually with the command ```java $ git remote add remote_name location $ git remote add origin https://github.com/aliceuser2020/my-first-project.git $ git remote -v origin https://github.com/aliceuser2020/my-first-project.git (fetch) origin https://github.com/aliceuser2020/my-first-project.git (push) ``` where the location of the remote can be an URL or the path if that is in your local machine. ---  Protocols: - local -> git clone /opt/git/project.git - SSH -> git clone ssh://user@server:project.git - HTTP -> git clone http://example.com/gitproject.git - Git ---  Why do we need more than one remote? ```graphviz digraph { rankdir=TD S [style=invis] "Bob repo" [shape=diamond] "Alice fork" [fixedsize=circle] "Alice fork" -> "Alice local" "Bob repo" -> "Alice fork" "Alice local" -> "Bob repo" [style=dashed] orig [label="origin" shape=plaintext fontcolor=red] orig -> "Alice fork" [style=dashed color=red] ups [label="upstream" shape=plaintext fontcolor=red] ups -> "Bob repo" [style=dashed color=red] } ``` ---  ```java $ git remote add upstream git@bitbucket.org:bob/gitcourse.git $ git remote -v origin https://github.com/aliceuser2020/my-first-project.git (fetch) origin https://github.com/aliceuser2020/my-first-project.git (push) upstream https://github.com/bobuser2020/my-first-project.git (fetch) upstream https://github.com/bobuser2020/my-first-project.git (push) ``` ---  ```java $git graph * 2e56d0a (HEAD -> main, upstream/main, origin/main, origin/HEAD) text of exercise git diff usage * 22a7316 Adding yet more lectures * 0ddb791 Adding some more of the lectures * 3ff9f8f Adding some of the lectures ``` ---  ## Working with remotes One can push or fetch/pull to or from remotes by ```shell $ git push remote_name branch_name $ git fetch remote_name branch_name $ git pull remote_name branch_name ``` ---  In case you obtained the repository by cloning an existing one you will have the **origin** remote. You can do push/fetch/pull for this remote with ```shell $ git push origin master $ git fetch origin master $ git pull origin master ``` ---  or ```shell $ git push $ git fetch $ git pull ``` because the remote *origin* and the *master* branch are configured for pushing and pulling by default upon cloning. ---  The command: ```shell $ git pull ``` brings all the changes (branches) that are in the remote and tries to merge them with your local repo. The default behavior of *git pull* is in the *$GIT_DIR/config* file: ```shell [remote "origin"] fetch = +refs/heads/*:refs/remotes/origin/* ``` ---  In fact, *git pull* is a combination of two commands: ```shell $ git fetch remote_name branch_name $ git merge remote_name/branch_name ``` or ```shell $ git fetch $ git merge ``` ---  The command ```shell $ git push ``` will send all the changes (branches) to the remote by default. This can be changed by applying: ```shell git config --global push.default matching(default), current, ... ``` ---  If you have a brand-new branch called **new**, then it is recommended to push it the first time with the command: ```shell git push -u origin new ``` which is equivalent to ```shell git push origin new git branch --set-upstream new origin/new ``` ---  then, you will be able to push/pull the changes in the branch by simply typing **git push/pull** ---  ### Displaying remote information ```console $ git remote show origin * remote origin Fetch URL: git@bitbucket.org:arm2011/gitcourse.git Push URL: git@bitbucket.org:arm2011/gitcourse.git HEAD branch: master Remote branches: experiment tracked feature tracked less-salt tracked master tracked nested-feature tracked Local branches configured for 'git pull': feature merges with remote feature master merges with remote master nested-feature merges with remote nested-feature Local refs configured for 'git push': feature pushes to feature (fast-forwardable) master pushes to master (up to date) nested-feature pushes to nested-feature (up to date) ``` ---  ### Renaming remotes ```shell $ git remote rename initial_name new_name ``` ### Deleting remotes ```shell $ git remote remove remote_name ``` ---  ## Bare repositories ![](https://i.imgur.com/OzGOuAt.jpg) A bare repository is a repository with no working directory. ---  ### Creating a bare repository ```shell $ mkdir bare.git && cd bare.git $ git init --bare ``` ### Cloning a bare repository cont. ```shell $ git clone --bare location ``` ---  ## Using GitHub ![](https://i.imgur.com/kj3WDWT.jpg) ---  Upon login into your GitHub account you will see the following option to create a new repository ![](https://i.imgur.com/E8lMrMi.jpg) ---  Here, you can choose the type of repository that is appropriate to your needs (public/private), if you want to add *README* and *.gitignore* files and also the type of license for your project, ![](https://i.imgur.com/un2NdHE.jpg) ---  GitHub will suggest some steps that you can take for your brand-new repository: ![](https://i.imgur.com/9egKoEv.jpg) ---  ![](https://i.imgur.com/qlUQxq3.jpg) ---  ## Setting ssh-keys 1. ssh-keygen -t rsa -b 4096 -C "pedro@gemail.com" 2. eval $(ssh-agent -s) 3. ssh-add ~/.ssh/id_rsa 4. clip < ~/.ssh/id_rsa.pub (it copies the ssh key that has got generated) ---  5. Go to your remote repository on github.com and then **Settings** -> **SSH and GPG keys** ->new SSH key -> write a title and paste the copied SSH key and save it 6. check if the key was properly set on github/bitbucket ``` $ ssh -T git@bitbucket.org $ ssh -T git@github.com ``` ---  ![](https://i.imgur.com/j1PivRS.jpg) ---  ## Network visualization ![](https://i.imgur.com/q9f0ZFH.jpg) ---  ## Pull requests In the following scenario, a developer, Bob, has its repo on GitHub. Another developer, Alice, finds it useful and forks it. After doing some changes, Alice push them and do a "pull request" ```graphviz digraph { rankdir=LR S [style=invis] "Bob repo" [shape=diamond] "Alice fork" [fixedsize=circle] "Alice fork" -> "Alice local" "Bob repo" -> "Alice fork" "Alice local" -> "Bob repo" [style=dashed] orig [label="origin" shape=plaintext fontcolor=red] orig -> "Alice fork" [style=dashed color=red] ups [label="upstream" shape=plaintext fontcolor=red] ups -> "Bob repo" [style=dashed color=red] } ``` ---  ![](https://i.imgur.com/9SGeaEk.jpg) ---  Then, Bob receives an email with the pull request information about Alice modifications. On the GitHub site he sees the request: ![](https://i.imgur.com/JZ73bMu.jpg) ---  Because Bob find the changes from Alice useful and there are no conflicts he can merge them straight away, ![](https://i.imgur.com/5yiTuCC.jpg) ---  ## Issues If you find some issues in the files/code you can open an "Issue" on GitHub ![](https://i.imgur.com/mJ9NfvF.jpg) ---  ![](https://i.imgur.com/1M4f1Nr.jpg) ---  You may also assign people to the issues that are more related to that topic. In future commits you may refer to this issue by using the issue number, <span style="color:blue">#2</span> in this case. This will allow you to track the evolution of the issue on GitHub. ---  ## Best practices - Talk with your colleagues. - Some commands such as **git rebase** change the history. It wouldn't be a good idea to use them on public branches. - Don't accept pull requests right away.