Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Git Intermediate Workshop slides v1.3

1,409 views

Published on

Slide del workshop di livello medio

Published in: Software
  • Be the first to comment

Git Intermediate Workshop slides v1.3

  1. 1. OptionFactory Git, beyond the basics intermediate level workshop
  2. 2. About OptionFactory Main activities ● Software development & consultancy ● Continuous Integration & Delivery ● Training & coaching Key competences ● Java, Javascript, C++, Go, Erlang and more ● Secure Software Development Lifecycle ● Lean Software Development ● Re-engineering Core domains ● High Availability and High Performance systems ● Application security ● Telcos, finance, insurance and security sensitive domains ● Startups, new markets and high uncertainty domains
  3. 3. Goals If that doesn’t fix it, git.txt contains the phone number of a friend of mine who understands git. Just wait through a few minutes of “It’s really pretty simple, just think of branches as…” and eventually you’ll learn the commands that will fix everything. HTTP://XKCD.COM/1597/ “
  4. 4. Goals (II) No, improvising is wonderful. But, the thing is that you cannot improvise unless you know exactly what you're doing. Christopher Walken “ ”
  5. 5. Establishing a common base ● Participants’ ○ background ○ VCS tools known ○ level of experience ○ expectations
  6. 6. Version control in 4 steps ● Do some work ● Checkin a “unit of work” (aka: transaction). Think “savegame” ● Repeat as much as you want ● Go back “in time” when something happens. Think “reload and try again”
  7. 7. Version control landscape Git Mercurial (HG) SVN ClearCase Model Distributed (clone) Distributed (clone) Centralized (checkout) Centralized (checkout) Transaction unit Commit Commit Commit File Storage model Snapshot Delta Delta ? Transaction id Hash Hash (local sequence) Global sequence Path + per-branch sequence Concurrency model Merge/Rebase (graph) Merge (graph) Merge on commit (linear) Pessimistic locking + merge (linear) Rename / move tracking No (heuristic) Yes Yes Yes*
  8. 8. Centralized vs distributed (I)
  9. 9. Centralized vs Distributed (II) Centralized Distributed Instances Single, mandatory Every istance is equal. “Central authority” is a convention, not a necessity Transaction id Centrally assigned Anyone must be able to assign it The Truth™ One and only “Luke, you're going to find that many of the truths we cling to depend greatly on our own point of view.” _ Obi-Wan Kenobi
  10. 10. Centralized vs Distributed (III) Centralized Distributed Isolation None, each transaction is “public” Many Sandboxes environments Speed per commit Low, every transaction required network communication Fast, changes are on the local filesystem. Conflicts Pain Manageable pain
  11. 11. Version control landscape Git Mercurial (HG) SVN ClearCase Model Distributed (clone) Distributed (clone) Centralized (checkout) Centralized (checkout) Transaction unit Commit Commit Commit File Storage model Snapshot Delta Delta ? Transaction id Hash Hash (local sequence) Global sequence Path + per-branch sequence Concurrency model Merge/Rebase (graph) Merge (graph) Merge on commit (linear) Pessimistic locking + merge (linear) Rename / move tracking No (heuristic) Yes Yes Yes*
  12. 12. Delta storage
  13. 13. Snapshot storage
  14. 14. Starting up ● setup your global git environment git config --global user.name “Mario Rossi” git config --global user.email “mrossi@example.com” ● initialize (i.e. create) your first repository mkdir myfirstrepo cd myfirstrepo git init
  15. 15. Inside a commit ● parent id(s) ● timestamp ● author (& committer) ● content ○ filesystem state NOT part of a commit (more on that later) ● branch ● tags
  16. 16. Creating a commit ● Create / edit files on your working copy (your local filesystem) ● Mark your changes for inclusion by copying them in the staging area ● Create a new commit, providing the missing (meta) data ● What goes in the commit comes from: ○ whatever you put in the staging area ○ your global git configuration (e.g. your name, email) ○ the git environment (e.g. the current date, the commit you started working from) ○ the commit message you specify
  17. 17. Files lifecycle
  18. 18. checkout/reset (file) Checkout <file> Checkout <ref> -- <file> Reset <file> Effect on graph shape None None None Effect on Staging Area None Overwritten with version from graph Overwritten with version from graph Effect on working copy Overwrite with version from staging area Overwritten with version from graph None Staging area Working Copy Graph add <file> com m it reset<file> checkout <ref> -- <file> checkout <file>
  19. 19. Alternate (time)lines ● Creating alternate lines of work ○ branch ● Navigating the graph ○ checkout ○ reset ● “Crossing the streams” and other weird stuff ○ merging ○ rebasing ○ cherry-picking
  20. 20. References & reachability ● A reference is just a named pointer to a commit in the graph ● Every commit, to be reachable, must be referenced: ○ directly (by a ref) ○ indirectly (by a reachable descendant, pointing to its parent) ● Bad parenting advisory: ○ Parent commits do not know about their children ○ You can’t navigate forward in time through the graph
  21. 21. references: Branches ● a “branch” identifies a sequence of commits, tracing a workflow ● “master” is by convention the project main line ● A branch points to a commit in the graph, and represents a pointer to such commit. It is not directly related to working copy or staging area ● Any number of branches can point to the same commit, they are all independent
  22. 22. references: HEAD ● HEAD is a special reference. It can either point to a commit or a branch, and represents where we are in the graph ● The commit it points to (directly or indirectly) is used for comparison against the staging area ● When HEAD points to a Branch reference, that branch is “current”, and will move ahead on commit ● When HEAD points directly to a commit, we are in the “detached HEAD” state ○ this is true even if there are branches referencing that same commit
  23. 23. references: Tags ● Lightweight Tags are similar to branches (a name attached to a specific commit), but they are not meant to move ● Annotated Tags also contain an id, timestamp, author and a message on top of that ● Therefore, annotated tags can be signed
  24. 24. Checkout/Reset/Revert (ref) Checkout <ref> Reset <ref> Revert <ref> Moves HEAD only “current” Branch “current” Branch Effect on graph shape None potentially leaves back “dead” nodes Creates new node Effect on Staging Area Fails if dirty* overwritten with --mixed (default) or --hard Fails if dirty Effect on working Copy Fails if dirty overwritten only with --hard Attempts merge, fail if not possible
  25. 25. Remotes, refs, tracking branches ● remotes: names pointer to a remote repository ○ origin is the one you cloned from (just another convention) ● remote branches ○ Remote references differ from branches (refs/heads references) mainly in that they’re considered read-only. You can git checkout to one, but Git won’t point HEAD at one, so you’ll never update it with a commit command. Git manages them as bookmarks to the last known state of where those branches were on those servers. ● tracking branches ○ created once you checkout a remote branch ○ tracks your work on that branch to allow sync
  26. 26. Synchronization & collaboration ● clone ● push ● fetch ● pull (fetch+merge o fetch+rebase)
  27. 27. Collaborative workflow ● commit message ● approach ○ merge-based ○ rebase-based ○ not exclusive
  28. 28. http://zeroturnaround.com/wp-content/uploads/2016/02/Git-Cheat-Sheet.png
  29. 29. Version control landscape Git Mercurial (HG) SVN ClearCase Model Distributed (clone) Distributed (clone) Centralized (checkout) Centralized (checkout) Transaction unit Commit Commit Commit File Storage model Snapshot Delta Delta ? Transaction id Hash Hash (local sequence) Global sequence Path + per-branch sequence Concurrency model Merge/Rebase (graph) Merge (graph) Merge on commit (linear) Pessimistic locking + merge (linear) Rename / move tracking No (heuristic) Yes Yes Yes*
  30. 30. git as a service ● github, gitlab, bitbucket ● basic concepts mapping ● Authorization models ● “Fork” and “Pull Request” implementations ○ pull request ■ What’s that? “Please, take my changes”
  31. 31. security and workflow considerations ● Certificates ● Credentials storage
  32. 32. Plumbing
  33. 33. Resources ■ Good base: http://www.learnenough.com/git-tutorial ■ Visualizing Git Concepts with D3: https://onlywei.github.io/explain-git-with-d3/ ■ Think like a git: http://think-like-a-git.net/epic.html ■ Cache your passwords: https://help.github.com/articles/caching-your-github-password-in-git/ ■ Git-csm book, in particular: ● https://git-scm.com/book/en/v2/Git-Basics-Recording-Changes-to-the-Repository ● https://git-scm.com/book/en/v2/Git-Tools-Reset-Demystified ● https://git-scm.com/book/en/v2/Git-Basics-Git-Aliases ■ Some open source projects to visualize git graphs: ● https://github.com/FredrikNoren/ungit/blob/master/README.md ● https://github.com/Readify/GitViz ● https://github.com/Haacked/SeeGit ■ Always funny to watch: http://gource.io/ ■ Git cheat sheet: http://zeroturnaround.com/rebellabs/git-commands-and-best-practices-cheat-sheet/ ■ Interesting videos: ● Git For Ages 4 And Up: https://www.youtube.com/watch?v=1ffBJ4sVUb4 ● Introduction to Git with Scott Chacon of GitHub: https://www.youtube.com/watch?v=ZDR433b0HJY

×