Git::Hooks, plenv and Carton. How to set up Git hooks using Git::Hooks Perl package and minimizing touching to Perl module namespace.

1. Safe Git::Hooks Installation
Git Hooks with Plenv and Carton
Mikko Koivunalho
NORDIC PERL WORKSHOP 2014
Nov 17th, 2014 / Helsinki

2. Outline
Introduction
Our Problem
Solution
Our Tools
Last
Questions
SubGit

3. Git and Perl
Git and Perl go hand-in-hand.
I some parts of Git are made with Perl.

4. Git Hooks
I Common to many Version Control Systems, also Git has a way to

5. re o custom scripts when certain important actions occur. These
are called hooks.
I There are two groups of these hooks: client-side and server-side.
Client-side hooks are triggered by operations such as committing
and merging, while server-side hooks run on network operations such
as receiving pushed commits.
I We want to use the hooks mechanism to some actions!
I De

6. ne our needs:
1. Only client side hooks.
2. Must be expandable.
3. Must not touch the client's system (speci

7. cally, system Perl).

8. Solution?
I We need a solution which is:
expandable Easy to develop further and easy to deploy improments to it.
friendly Easy for user to take into use.
maintainable Automatically install new versions into client's system.
invisible Cover our tracks, i.e. hide Perl away.

9. Go on. . .
Let's build that!

10. Git::Hooks
Framework for Git Hooks
I CPAN: Git::Hooks
I Framework for implementing Git (and Gerrit) hooks
I Author: Gustavo L. de M. Chaves gnustavo@cpan.org
I https://metacpan.org/release/Git-Hooks
I Git::Hooks provides several hooks out-of-the-package. We just need
to get Git::Hooks running.

11. Plenv
I Plenv
I Perl binary manager. (Create virtual Perl environments: Installs any
Perl version and keeps the Perls and their corresponding CPAN
installations from getting mixed.)
I Author: Tokuhiro Matsuno
I https://github.com/tokuhirom/plenv/
I Installation: Clone the Git repository and set global path.
I Alternative installation: Use anyenv from
https://github.com/riywo/anyenv.git. Get Ruby, Python,
Java, Lua, Go environments in the bargain.

12. Carton
I Carton
I Perl module dependency manager. Download and install CPAN
modules locally in directory 'local'. Isolate the installation so you
always run the same versions.
I Author: Tatsuhiko Miyagawa
I https://metacpan.org/pod/Carton
I Installation: Install via plenv.
I Alternative installation: Use anyenv from
https://github.com/riywo/anyenv.git. Get Ruby, Python,
Java, Lua, Go environments in the bargain.

13. Repo Layout
Our empty repository contains:
/
.git
.git-repo-admin
.perl-version........................................17
cpanfile.............................................246
cpanfile.snapshot................................58165
local...................| ../.git/git-hooks-carton-local/

14. Starting Files
.perl-version (the name of the perl to install with plenv.):
5.18.4 g i thooks
cpan

15. le (Carton seed

16. le):
# At l e a s t t h i s Pe r l v e r s i o n ( can be h i g h e r ) :
r e q u i r e s ' p e r l ' , ' 5 . 1 8 . 4 ' ;
# The o n l y package we r e a l l y need .
r e q u i r e s ' Gi t : : Hooks ' , ' 1 . 3 . 0 ' ;
# P e r l C r i t i c f o r c h e c k i n g the Pe r l code (most r e l a t e d to Gi t
hooks ) .
r e q u i r e s ' Pe r l : : C r i t i c ' , ' 1.122 ' ;
Install:
cd . . # Step out o f the . p e r l v e r s i o n c o n t r o l l e d ' space '
p l e n v i n s t a l l 5 . 1 8 . 4 as=5.18.4 g i thooks
p l e n v i n s t a l l cpanm ; p l e n v r e h a s h
cpanm Car ton ; c a r t o n i n s t a l l

17. Carton at work
I Running
carton install
I

18. lls the directory 'local' with installed CPAN modules.
I It also creates a new

19. le: 'cpan

20. le.snapshot'.
I This

21. le contains a snapshot of the whole 'local' directory: modules,
their dependencies, the exact versions.
I Commit both

22. les 'cpan

23. le' and 'cpan

24. le.snapshot' to the repository.
I When installing to a virgin environment, run
carton install {deployment
I and Carton will not use the seed

25. le 'cpan

26. le' but instead the
snapshot

27. le to restore the exact same environment.

28. An Isolated Perl
I An isolated Perl environment maintained by

29. les '.perl-version'
(plenv) and directory 'local' (carton).
I Uses only plenv installed modules.
I You can even limit yourself to Carton installed modules:
I Run
carton exec perl-program.pl
I Carton has already installed Git::Hooks. Now let's set it up.

30. Hooking into Git
I The actual Git hooks are located in the '.git/hooks' subdirectory in
the repo root. Create a symbolic link from every hook you want to
activate to the '.git-repo-admin' directory. E.g.
ln -s .git-repo-admin/git-hooks.sh .git/hooks/commit-msg
I Link the Git con

31. guration

32. le '.git/con

33. g' to

34. le
'.git-repo-admin/con

35. g hooks.local':
I Add the following rows to

36. le '.git/con

37. g':
[include]
path = con

38. g hooks
I and create a symbolic link from the

39. le 'con

40. g hooks' to the
corresponding

41. le '.git-repo-admin/con

42. g hooks.local':
ln -s .git-repo-admin/con

43. g hooks.local .git/con

44. g hooks
I Use the

45. le '.git-repo-admin/con

46. g hooks.local' like a normal Git
con

47. g

48. le. Add it to the version control and thereby make it every
client's con

49. g

50. le for Git::Hooks con

51. guration.

52. git-hooks.sh: Bash Part
#! / u s r / b i n / env bash
REPO DIR=$ (pwd)
HOOK NAME=$fBASH SOURCEg # Ac t u a l l y hooks/hook name
SOURCE=$fBASH SOURCE[ 0 ] g
wh i l e [ h $SOURCE ] ; do # r e s o l v e $SOURCE u n t i l the f i l e
i s no l o n g e r a s yml i n k
DIR=$ ( cd P $ ( di rname $SOURCE ) pwd )
SOURCE=$ ( r e a d l i n k $SOURCE )
[ [ $SOURCE != / ] ] SOURCE=$DIR/$SOURCE # i f $SOURCE
was a r e l a t i v e s yml ink , we need to r e s o l v e i t r e l a t i v e
to the path where the s yml i n k f i l e was l o c a t e d
done
THIS SCRIPT=$fSOURCEg
DIR=$ ( cd P $ ( di rname $SOURCE ) pwd )
cd $fDIRg
i f [ e g i thookshook . sh ] ; then s o u r c e . / g i thookshook .
sh ; f i
CMD= e x e c c a r t o n e x e c p e r l x $fTHIS SCRIPTg $fREPO DIRg $f
HOOK NAMEg $@
i f [ $VERBOSE = 1 ] ; then echo CMD=$fCMDg ; f i
$fCMDg
# End o f Bash s c r i p t

53. git-hooks.sh: Perl Part
# S t a r t o f Pe r l s c r i p t
#! / u s r / b i n / env p e r l
us e s t r i c t ; us e wa rning s ;
my $ v e r b o s e = 0 ;
$ v e r b o s e = $ENVf 'VERBOSE ' g i f d e f i n e d $ENVf 'VERBOSE ' g ;
my $ r e p o d i r = s h i f t @ARGV;
my $hook name = s h i f t @ARGV;
c h d i r $ r e p o d i r ;
p r i n t g i thooks . sh ( p l ) now i n d i r ' $ r e p o d i r ' . n n i f (
$ v e r b o s e ) ;
my $ s u b g i t c h a n g e = $hook name =~ s /n/( us e r ) ( [ ^ n / ]+) /n/ $2/
msx ;
i f ( $ s u b g i t c h a n g e ) f p r i n t Thi s i s SubGi t repo , removed '
us e r ' f rom hooks name . n n i f $ v e r b o s e ; g
us e Gi t : : Hooks ;
p r i n t Ex e c u t i n g : run hook ( $hook name , @ARGV) nn i f (
$ v e r b o s e ) ;
run hook ( $hook name , @ARGV) ;

54. Small Things left
I If you think it is not good to have the directory
'.git-repo-admin/local'
oating freely in the repository, turn it into a
symbolic link and move the directory itself under '.git' directory.
I Set up additional hooks into directory
'.git-repo-admin/hooks.d.local'.

55. con

56. g hooks.local
[githooks]
plugin = CheckLog
plugin = CheckFile
hooks = hooks.d
[githooks checklog]
title-required = 1
title-max-widt = 50
title-period = allow
spelling = 1
spelling-lang = EN
[githooks check

57. le]
name = *.p[lm] cd .git-repo-admin; carton exec perlcritic {harsh fg

58. What we Have in Repo.
/
.gitignore
config hooks ....| ../.git-repo-admin/con

59. g hooks.local
hooks/commit-msg.....| ../.git-repo-admin/git-hooks.sh
.git
.git-repo-admin
.perl-version........................................17
cpanfile.............................................246
cpanfile.snapshot................................58165
git-hooks.sh*......................................1736
config hooks.local..................................943
initialize-hooks.sh*..............................3240
InitializeHooks.pm...............................18593
local...................| ../.git/git-hooks-carton-local/
hooks.d.local
commit-msg, post-merge, [...]

60. Download All the Code for .git-repo-admin
I .git-repo-admin
I
I Author: Mikko Koivunalho
I https://github.com/mikkoi/.git-repo-admin
I Installation: Clone the Git repository and copy the '.git-repo-admin'
directory to your own repositories.

61. Questions
Questions?
And maybe answers

62. SubGit
For People Who Need to Hide Their Liking of Git. . .
SubGit
http://www.subgit.com
I SubGit is a tool for a smooth, stress-free Svn to Git migration.
I Create a writable Git mirror of a local or remote Subversion
repository and use both Subversion and Git.
I Bidirectional Subversion to Git replication!
I When using remote synchronization Subversion is not even aware of
it being synchronized with a Git repository.