This document summarizes a presentation about migrating from Subversion to Git version control. It discusses performing an inception to determine suitability, converting repositories from SVN to Git format using git-svn, and adopting the new workflow. Key benefits of Git mentioned include flexible branching/merging, speed, and enabling new collaboration workflows. The document also addresses infrastructure changes, potential workflows using forks, and concludes that Git adoption is increasing while migration tools have improved.

2. True Git
THE GREAT MIGRATION
STEFAN SAASEN • STASH DEVELOPMENT MANAGER
• ATLASSIAN • @stefansaasen

3. TODO Show of hands
Picture with hands/lighter/concert

4. Source Control Management
SVN
Git

5. Source Control Management
2011
2013 (projected)
SVN
2013
Git
2015 (projected)

6. Source Control Management
78
20
2011
2013 (projected)
SVN
2013
Git
2015 (projected)

7. Source Control Management
78
68
41
20
2011
2013 (projected)
SVN
2013
Git
2015 (projected)

8. Source Control Management
78
70
68
49
41
20
2011
2013 (projected)
SVN
2013
Git
2015 (projected)

9. Source Control Management
78
70
68
68
49
41
55
20
2011
2013 (projected)
SVN
2013
Git
2015 (projected)

10. Why am I passionate about this?

11. Why am I passionate about this?

12. Why Git?

13. Branching & Merging

14. Branching & Merging
fast, cheap and simple

15. first class concept
Branching & Merging
fast, cheap and simple

16. first class concept
Branching & Merging
fast, cheap and simple

17. Foundation for new
workflows

18. Speed

19. Speed
git log
git status
git diff

20. git bisect
Speed
git log
git status
git diff

21. git bisect

22. Bad
git bisect

23. Good (v2.7)
Bad
git bisect

24. Test
Bad
git bisect

25. Test
Bad
git bisect

26. Regression!
Bad
git bisect

27. Regression!
git bisect
Fast graph traversal
Fast checkout

28. git bisect
Speed
git log
git status
git diff

29. Enables new features
Improves basic features

30. Local commits

31. Edit & Publish
Local commits

32. Edit & Publish
Local commits
Rewrite History

33. Edit & Publish
Local commits
Rewrite History

34. Flexibility

35. Git does what you are
doing today, only better

36. SVN

37. GIT
SVN
LABEL TITLE

38. GIT
SVN
LABEL TITLE
Existing
workflows

39. GIT
SVN
LABEL TITLE
Existing
workflows
New ways of
collaborating

40. GIT
SVN
LABEL TITLE
Existing
workflows
New branch
workflows
New ways of
collaborating

41. GIT
SVN
LABEL TITLE
Existing
workflows
New branch
workflows
New ways of
collaborating

42. GIT
SVN
LABEL TITLE
Existing
workflows
New branch
workflows
New ways of
collaborating

43. GIT
SVN
LABEL TITLE
Existing
workflows
New branch
workflows
New ways of
collaborating

44. Release branching
master
2.8
2.7

45. Release branching
master
2.8
2.7
Bugfix

46. Release branching
master
2.8
2.7
Bugfix


47. Release branching
master
2.8
2.7
Bugfix


48. Release branching
master
2.8
2.7
Bugfix


49. Release branching
master
2.8
2.7
Bugfix


50. Git Workflows
a-la-carte
Rapid Agile
Delivery
Nicola Paolucci
Thursday - 11:15 am
Matthew Watson
Thursday - 1:15 pm

52. So you’ve decided to
migrate!

53. The process
Adoption
2
1
3
Inception
Conversion

54. Inception
1

55. Inception
• Is git suitable?
1

56. Inception
• Is git suitable?
• Test the conversion
1

57. Inception
• Is git suitable?
• Test the conversion
• Identify the repositories that need to be converted
1

58. Inception
• Is git suitable?
• Test the conversion
• Identify the repositories that need to be converted
• Identify the tools that need to be updated. CI, issue
tracking, IDE, scripts and build tools, deployment
tools
1

59. 1

60. The process
Adoption
2
1
3
Inception
Conversion

61. Adoption
2

62. Adoption
• You need to answer: “What’s in it for me”
2

63. Adoption
• You need to answer: “What’s in it for me”
• Make sure tooling is ready and can be used by
everyone
2

64. Adoption
• You need to answer: “What’s in it for me”
• Make sure tooling is ready and can be used by
everyone
• Identify the git champions - they will be thrilled to
help
2

65. Adoption
• You need to answer: “What’s in it for me”
• Make sure tooling is ready and can be used by
everyone
• Identify the git champions - they will be thrilled to
help
• Don’t expect to win everyone over immediately
2

66. 2

67. 2
Just text by itself, for
impact.

68. The process
Adoption
2
1
3
Inception
Conversion

69. We’ve got you covered!
&
Scripts
Tutorial & Documentation

70. We’ve got you covered!
&
Scripts
Tutorial & Documentation
bit.ly/go-dvcs

71. 3
git-svn

72. Conversion - Preparation
3

73. Conversion - Preparation
3
Map Authors
jdeveloper = John Developer <jd@example.com>

74. Conversion - Preparation
3
Map Authors
jdeveloper = John Developer <jd@example.com>
/tags
/trunk
/branches
Identify SVN
repository layout

75. Conversion - Initial Clone
3
git svn clone
--authors-file=/authors.txt
--trunk=/trunk
--tags=/tags
--branches=/branches

76. Conversion - Initial Clone
?
3
git svn clone
--authors-file=/authors.txt
--trunk=/trunk
--tags=/tags
--branches=/branches

77. Conversion - Sync
3

78. Conversion - Sync
3

79. Conversion - Sync
git svn fetch
3

80. Infrastructure first
CI
Issues
IDE
3

81. Infrastructure first
read-only
CI
Issues
IDE
3

82. Infrastructure first
read-only
CI
Issues
IDE
3

83. Infrastructure first
read-only
Sync every minute
CI
Issues
IDE
3

84. Conversion - Cleanup
• Cleanup branches
• Remove unused files
• Create git tags
• Remove commit
metadata
3

85. Conversion - Cleanup
• Cleanup branches
• Remove unused files
• Create git tags
• Remove commit
metadata
3

86. 3
read-only
CI
Issues
IDE

87. 3
Then your team
read-only
CI
Issues
IDE

88. 3
Then your team
read-only
CI
Issues
IDE

89. 3
Then your team
read-only
CI
Issues
IDE

90. Other Tools?

91. SubGit

92. The process
Adoption
2
1
3
Inception
Conversion

93. Or are you?

94. Collaboration model?
Branching model?
Just text by itself, for
impact.

95. +
Enterprise

96. +
Enterprise
= Centralized

97. Metrics
Issues
Builds
Deployments
+
Enterprise
= Centralized

98. Workflows will change

99. for the better
Workflows will change

100. for the better
Workflows will change
but they don’t have to change on day one!

101. This happened in both
Confluence and JIRA...

102. From SVN like
confluence-project-4.0
CONF-1234
master

103. From SVN like
git cherry-pick bae6251
confluence-project-4.0
CONF-1234
master

104. From SVN like
git cherry-pick bae6251
confluence-project-4.0
CONF-1234
master

105. From SVN like
confluence-project-4.0
CONF-1234
master

106. From SVN like
confluence-project-4.0
CONF-1234
master

107. To git branch based workflow
confluence-project-4.1
master

108. To git branch based workflow
confluence-project-4.1
master

109. To git branch based workflow
confluence-project-4.1
CONF-2345
master

110. To git branch based workflow
git merge confluence-project-4.1
confluence-project-4.1
CONF-2345
master

111. To git branch based workflow
confluence-project-4.1
CONF-2345
master

112. To git branch based workflow
git merge confluence-project-4.1
confluence-project-4.1
CONF-2345
master

113. Forks can be
useful!

114. Forks can be
useful!
Sub-Teams

115. Forks can be
useful!
Sub-Teams

116. Forks can be
useful!
Contributions from
outside of the team
Sub-Teams

117. Conclusion

118. 80
78
70
68
60
20
0
49
41
40
68
55
20
2011
2013 (projected)
SVN
2013
Git
2015 (projected)

119. 80
78
70
68
60
20
0
49
41
40
68
55
20
2011
2013 (projected)
SVN
2013
Git
2015 (projected)

120. “
Subversion (58%) is being
threatened by Git (47%) for de
facto leadership of the Version
Control space.
”
ZEROTURNAROUND DEVELOPER PRODUCTIVITY REPORT 2013

121. is here to stay

122. expands

123. migration is a
solved problem

124. Thank you!
STEFAN SAASEN • STASH DEVELOPMENT MANAGER
• ATLASSIAN • @stefansaasen