Discover what “distributed” VCS (Version Control system) actually means.

1. Git: a “Distributed” VCS?
Discover what “distributed” VCS (Version Control system)
actually means.

2. Daniel CHAFFIOL
Softeam Cadextan
(1999)
BNP-Paribas
Société Générale
HSBC

3. VonC
Stack Overflow
(2008)
Git - Hg – SVN - ClearCase
Golang - Docker
Eclipse - Jenkins

6. Git: Distributed Version Control System

7. Git: Distributed Version Control System
2005, Linus torvalds

8. Git: Distributed Version Control System
2005, Linus torvalds
“I’m an egotistical bastard, and I
name all my project after myself.
First Linux, now git[1]
”
[1]: git (n): British slang for a stupid or unpleasant person

9. Distributed:
○ Local repo
○ Upstream vs. Downstream
○ Full repo clone

10. Local repository
Your “local” is not “my local”

11. Git: Local repository
Distributed
Local file manager:
Local repo

12. Git: Local repository
No setup
Just unzip an archive
Local repo
git init
git commit
...

13. No authentication
Just a declaration (user.name/user.email)
Git: Local repository
Local repo
git config:
user.name
user.email

14. No global hooks/settings
Local hooks are locals
Git: Local repository
Local repo
.git/hooks

15. No permission
644 (rw-r--r--) or 755 (rwxr-xr-x) only
Git: Local repository
Local repo
umask 022

16. No timestamp
git checkout even used to reset timestamps
Git: Local repository
Local repo
git commit
git checkout
...

17. Recap:
Local repository:
No authentication
Basic permission record
Basic timestamp record

18. Upstream vs.
Downstream
You know one,
not the other

19. Git: Upstream vs. Downstream
VCS: Version Control System
Upstream is remote:
Remote repo

20. Git: Upstream vs. Downstream
VCS: Version Control System
Downstream is local:
Remote repoLocal repo
UPSTREAMDownstream

21. Git: Upstream vs. Downstream
“No git server” or “git client”:
Direct access through shared filesystem:
UPSTREAM repo
sharedpath

22. Git: Upstream vs. Downstream
“No git server” or “git client”:
Remote access through listeners:
Remote repo
query

23. Git: Upstream vs. Downstream
Multiple upstream:
All known:
Downstream
repo
UPSTREAM
repos
git fetch
git fetch

24. Git: Upstream vs. Downstream
Multiple upstream:
Example: GitHub fork
Downstream
repo
DOWNSTREAM
UPSTREAM
repos
git fetch
original repo
forked repo
git push

25. Git: Upstream vs. Downstream
Multiple downstream repos:
All unknown:
Local
repo
UPSTREAM
repos
git fetch
git fetch
Downstreams
repos

26. Git: Upstream vs. Downstream
Multiple workflows (merge vs. publication):
Merge workflow:

27. Git: Upstream vs. Downstream
Multiple workflows (merge vs. publication):
Publication workflows:

28. Recap:
Local repository:
No authentication
Basic permission record
Basic timestamp record
Upstream vs. Downstream:
No Listeners
Downstreams unknown
Publication workflow

29. Full repository
clone
If you can access it,
you can clone it

30. Git: Full repository clone
You clone (almost) everything
All branches, all tags, all notes:
git clone
git fetch
Remote repoLocal repo

31. Git: Full repository clone
You clone (almost) everything
Not hooks or config though:
Remote repoLocal repo
git clone/fetch/pull
config
hooks

32. Git: Full repository clone
You clone what you need
Not “one giant unique repo”:
Remote repoLocal repo
git clone
git clone

33. Git: Full repository clone
You do clone *all* the remote repo.
*All*: no authorization when reading:
git clone
git fetch
Remote repoLocal repo

34. Git: Full repository clone
You can put authorization when accessing the upstream repo.
I.E, add a “guardian” like gitolite:
Remote repoLocal repo
git push
gitolite
(perl)
git fetch

35. Git: Full repository clone
You can have audit when accessing the upstream repo.
I.E, gitolite can record git operations:
Remote repoLocal repo
git push
gitolitegit fetch

36. Recap:
Local repository:
No authentication
Basic permission record
Basic timestamp record
Upstream vs. Downstream:
No Listeners
Downstreams unknown
Publication workflow
Full repository clone:
No authorization
Gitolite for authorization and audit
Smaller-size git repos

37. Conclusion:
Local repository:
No authentication
Basic permission record
Basic timestamp record
Upstream vs. Downstream:
No Listeners
Downstreams unknown
Publication workflow
Full repository clone:
No authorization
Smaller-size git repos
Gitolite for authorization and audit

38. Distributed VCS:
Local: No authentication
Upstream: No Listeners
Clone: No authorization/audit