Dealing with large code bases. cd ams meetup

viktor@jv-ration.com | @sadovnikov
Dealing with
Large Code Bases
Continuous Delivery Amsterdam
August 2016

Viktor Sadovnikov
● 1985 - first keyboard touch
● 1988 - first line of code
● 1993 - first computer at home
● 1994 - first paid line of code
● 2001 - first code to test another code
● 2005 - first build server run
● 2007 - first automated deployments
2
@sadovnikov

Common
Build Project
3

Common Build Project
Initial Scope
4
Source Repository From CVS to SVN
Build Tool From mix of Maven, Ant and Eclipse to Maven;
Dependencies from Nexus
Artifacts Repository From “something” to Nexus; deployable from Jenkins only;
Build Server From “something” to Jenkins;
Automate creation of builds jobs
Migration Done by projects themselves or (mainly stale) by us;
Extensive migration checklist

“Bonus” Scope
5
Platform Moving builds from Windows to Linux
Upgrades Upgrading JDK during migration
Packaging 2 tailored packaging types
Deployment Number of applications shared dependencies at runtime

Volumes
6
Maven modules
(artifacts)
3.500 (trunks only): 1.760 jars, 250 wars
External dependencies 2.200 libraries
Build jobs +/- 4.000 jobs (including branches)
Jenkins installations 12 instances;
later moved to 4 masters with pool of slaves

Challenges
and Lack of
Tooling
7
Tooling for
Software
Development

#1. Finding the Code
● Finding code of a dependency in SVN to check available tags (versions), to
find out correct group and artifact IDs, to contact developers;
● Enquiries about existing projects
8
● FishEye from Atlassian… works only on SVN
● SonarQube from SonarSource… finds everything
Solutions:

#2. Changing Shared Libraries
● Can I stop compiling for JDK 5?
● How much effort will my change cause?
● Do they use correct (after migration) and recent versions?
● What is used? How is used?
9
● NoneSolutions:

#3. Conflicts of Versions
● Direct dependency does not match transitive dependency
● What needs to be released before I can use changed shared library?
● Why do I get “entire world” as my compile dependency?
● (WRONG) Why do my builds pick-up old SNAPSHOT?
10
● Manual execution of Maven Dependency plugin (-Dverbose)
● Parsing the results
● On level of modules, not projects
Solutions:

#4. Finding the Builds
● 12 Jenkins instances and 4.000 build jobs
● Hard requirement of every project migration
11
● grep on build job configuration files… on all 12 servers
● Ctrl+F on Jenkins “all” page… unless the builds are renamed
● Referencing builds in pom.xml… gets obsolete quickly
Solutions:

development
environment
Cross
examiner
12

Evolution of deCrex
deCrex - Development Environment Cross Examiner - scanner and analyzer of
source repositories and build servers
13
main() to
generate
JSON.
Running from
IntelliJ
Daily triggered
from Jenkins to
publish JSON
An intranet
application,
running
internally
Publically
available
installation to
scan OSS
Started simple... ...and could not stop
https://ossa.jv-ration.com

#1. Finding the Code
● Search for Maven
Modules and builds
● Based on IDs, names,
descriptions
14

#2. Changing Shared Libraries
● List of direct dependees
● Versions direct
dependees depend on
● Quick access to details
of dependees
15

#3. Conflicts of Versions
● Build Jobs you project
depends on
● 7 Releases to push
changes in “Spring Data
Build” to “Spring Boot
Build”
● There are cycle
dependencies among
builds
16

#4. Finding the Builds
● From modules to builds
● From builds to modules
17

Dealing with Code:
OSS approach in
Enterprises
18

Dealing with Code:
many vs. mono
19

Two Approaches
20
OSS Approach. Many-repos
● Every logically complete unit
(project) is in its own repo with
its own release cycle
● Build tools resolve
dependencies using artifact
repositories
● Most familiar approach, heavily
used in OSS projects
Monolithic Repos. Monorepos
● Single repository with all code
● No version constraints for
internal code
● All internal code is a part of the
build
● Used by companies like
Google, Facebook, Deis.io,
Twitter, Salesforce...

Many-repos Approach
● Clean boundaries between
projects
● Easier reusable in other contexts
code
● Fine-tuned access control
● Lighter, faster builds
21
● Refactoring becomes an
incompatible change
● Diamond dependencies and
interdependencies in internal code
● Loss of atomicity of commits
● Temptation to pick a version and
“stabilize” - stagnate
● Not fixing bugs in “not my code”
● Growth of obsolete and deprecated
code

Monorepos Approach
● Refactoring enabler: changing
APIs, removing obsolete code
● Atomic commits for large changes
● No switching between repos
● Collaboration among teams
● Less management (CI and repo)
● Code Management: search,
moving files around
22
● Ownership of the code is
detached from repo authorization
● Implementation problems: pulling
too much, mixed commit logs, etc
● Fully distributed SCM is
problematic
● Latency and requirements of
builds

Recognitions of Many-Repos Shortcomings
● Semantic Versioning
contract between me and you: since I can't know what you're doing, I promise not to do certain
things with my library so that you can use it with some confidence
● GIT Submodules and Subtrees
“you want to be able to treat the two projects as separate yet still be able to use one from within the
other”
● GitLab
Issues, Milestones and Merge Requests combined on group level
● @depricated
● Spring Boot
79 modules under one aggregator
23

deCrex - Wrapper for Many-repos
Enables use of many-repos with clean project boundaries and code ownership,
lighter builds and distributed SCM by adding
● insights on dependees of every project,
● reporting on
○ stagnated dependencies and interdependencies in internal code,
○ projects without dependees - either a “delivery” or an obsolete code,
● Build Plan to ease CI setup,
● searching through “monorepo”
24

Upcoming Changes
● Ease of installation on premises
● UI improvements
● Extending support for build tools (Gradle) and servers
(Travis CI), SCM (puur GIT)
25
● Configuring “Monorepo members”
● Managing “ownership” of the code
● Notifying code owners about stagnated dependencies
● Interested in scanning your code?

Q&A
https://ossa.jv-ration.com
26
@sadovnikov

Dealing with large code bases. cd ams meetup

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