Move from Subversion to Git

Several Apache projects (e.g. ServiceMix, Karaf, Camel) moved from Subversion to Git. Is it time for Sling to move also?

see discussion on dev@

Can Sling (committers and contributors) benefit from moving to Git?

Pros

offline support
cherry picking
easy to move projects (e.g. between bundles, contrib, whiteboard...)
...

Cons

not eating our own dog food
slow for big repositories (many modules)
tagging is global
...

What needs to be prepared for moving to Git?

repository layout
release process
...

Git at Apache

http://wiki.apache.org/general/GitAtApache
http://www.apache.org/dev/git.html

Repository Layout and Projects (Modules)

There are currently over 280 projects (modules) in our repository and only few are reactor/builder (sling, *reactor, *builder) projects:

adapter-annotations
apache-sling-jar-resource-bundle
inplace-integration-test
installing-dependencies-sample
maven-jcrocm-plugin
maven-jspc-plugin
maven-launchpad-plugin
maven-sling-plugin
org.apache.sling.adapter
org.apache.sling.api
org.apache.sling.atom.taglib
org.apache.sling.auth.core
org.apache.sling.auth.form
org.apache.sling.auth.openid
org.apache.sling.auth.selector
org.apache.sling.auth.xing.api
org.apache.sling.auth.xing.login
org.apache.sling.auth.xing.oauth
org.apache.sling.bgservlets
org.apache.sling.bundleresource.impl
org.apache.sling.cassandra
org.apache.sling.commons.cache
org.apache.sling.commons.cache.api
org.apache.sling.commons.cache.container-test
org.apache.sling.commons.cache.ehcache
org.apache.sling.commons.cache.impl
org.apache.sling.commons.cache.infinispan
org.apache.sling.commons.cache.portal
org.apache.sling.commons.classloader
org.apache.sling.commons.compiler
org.apache.sling.commons.fsclassloader
org.apache.sling.commons.html
org.apache.sling.commons.js.nodetypes
org.apache.sling.commons.json
org.apache.sling.commons.log
org.apache.sling.commons.logservice
org.apache.sling.commons.mime
org.apache.sling.commons.osgi
org.apache.sling.commons.scheduler
org.apache.sling.commons.testing
org.apache.sling.commons.threaddump
org.apache.sling.commons.threads
org.apache.sling.crankstart.api
org.apache.sling.crankstart.api.fragment
org.apache.sling.crankstart.core
org.apache.sling.crankstart.launcher
org.apache.sling.crankstart.reactor
org.apache.sling.crankstart.sling.extensions
org.apache.sling.crankstart.test.services
org.apache.sling.datasource
org.apache.sling.discovery.api
org.apache.sling.discovery.impl
org.apache.sling.discovery.standalone
org.apache.sling.discovery.support
org.apache.sling.distribution.api
org.apache.sling.distribution.core
org.apache.sling.distribution.it
org.apache.sling.distribution.sample
org.apache.sling.engine
org.apache.sling.event
org.apache.sling.event.dea
org.apache.sling.extensions.apt.parser
org.apache.sling.extensions.apt.servlet
org.apache.sling.extensions.classloader-leak-detector
org.apache.sling.extensions.dojo
org.apache.sling.extensions.dojo.sling
org.apache.sling.extensions.explorer
org.apache.sling.extensions.gwt.explorer
org.apache.sling.extensions.gwt.sample
org.apache.sling.extensions.gwt.servlet
org.apache.sling.extensions.logback-groovy-fragment
org.apache.sling.extensions.slf4j.mdc
org.apache.sling.extensions.webconsolebranding
org.apache.sling.extensions.webconsolesecurityprovider
org.apache.sling.featureflags
org.apache.sling.fragment.activation
org.apache.sling.fragment.transaction
org.apache.sling.fragment.ws
org.apache.sling.fragment.xml
org.apache.sling.fsresource
org.apache.sling.ftpserver
org.apache.sling.hc.annotations
org.apache.sling.hc.core
org.apache.sling.hc.it
org.apache.sling.hc.junit.bridge
org.apache.sling.hc.reactor
org.apache.sling.hc.samples
org.apache.sling.hc.support
org.apache.sling.hc.webconsole
org.apache.sling.i18n
org.apache.sling.ide.api
org.apache.sling.ide.api-test
org.apache.sling.ide.artifacts
org.apache.sling.ide.eclipse-core
org.apache.sling.ide.eclipse-m2e-test
org.apache.sling.ide.eclipse-m2e-ui
org.apache.sling.ide.eclipse-test
org.apache.sling.ide.eclipse-ui
org.apache.sling.ide.feature
org.apache.sling.ide.impl-resource
org.apache.sling.ide.impl-resource-test
org.apache.sling.ide.impl-vlt
org.apache.sling.ide.impl-vlt-test
org.apache.sling.ide.m2e-feature
org.apache.sling.ide.p2update
org.apache.sling.ide.source-bundle
org.apache.sling.ide.vlt-wrapper
org.apache.sling.installer.console
org.apache.sling.installer.core
org.apache.sling.installer.factory.configuration
org.apache.sling.installer.factory.deploymentpackage
org.apache.sling.installer.factory.subsystems
org.apache.sling.installer.it
org.apache.sling.installer.provider.file
org.apache.sling.installer.provider.jcr
org.apache.sling.javax.activation
org.apache.sling.jcr.api
org.apache.sling.jcr.base
org.apache.sling.jcr.classloader
org.apache.sling.jcr.compiler
org.apache.sling.jcr.contentloader
org.apache.sling.jcr.davex
org.apache.sling.jcr.jackrabbit.accessmanager
org.apache.sling.jcr.jackrabbit.base
org.apache.sling.jcr.jackrabbit.client
org.apache.sling.jcr.jackrabbit.server
org.apache.sling.jcr.jackrabbit.usermanager
org.apache.sling.jcr.jcr-wrapper
org.apache.sling.jcr.oak.server
org.apache.sling.jcr.ocm
org.apache.sling.jcr.prefs
org.apache.sling.jcr.registration
org.apache.sling.jcr.repository.it-jackrabbit-oak
org.apache.sling.jcr.repository.it-resource-versioning
org.apache.sling.jcr.resource
org.apache.sling.jcr.resourcesecurity
org.apache.sling.jcr.webconsole
org.apache.sling.jcr.webdav
org.apache.sling.jcr.workspacepicker
org.apache.sling.jmx.jolokia
org.apache.sling.jmx.provider
org.apache.sling.junit.core
org.apache.sling.junit.healthcheck
org.apache.sling.junit.performance
org.apache.sling.junit.remote
org.apache.sling.junit.scriptable
org.apache.sling.launchpad
org.apache.sling.launchpad.api
org.apache.sling.launchpad.base
org.apache.sling.launchpad.content
org.apache.sling.launchpad.contrib-testing
org.apache.sling.launchpad.installer
org.apache.sling.launchpad.integration-tests
org.apache.sling.launchpad.karaf
org.apache.sling.launchpad.karaf-features
org.apache.sling.launchpad.karaf-integration-tests
org.apache.sling.launchpad.karaf-launchpad-integration-tests
org.apache.sling.launchpad.test-bundles
org.apache.sling.launchpad.test-fragment
org.apache.sling.launchpad.test-services
org.apache.sling.launchpad.test-services-war
org.apache.sling.launchpad.testing
org.apache.sling.launchpad.testing-war
org.apache.sling.mailarchive.james.wrapper
org.apache.sling.mailarchive.reactor
org.apache.sling.mailarchive.server
org.apache.sling.mailarchive.stats
org.apache.sling.mailarchive.ui
org.apache.sling.models.api
org.apache.sling.models.impl
org.apache.sling.models.integration-tests
org.apache.sling.mongodb
org.apache.sling.oak-s3
org.apache.sling.osgi.obr
org.apache.sling.paxexam.util
org.apache.sling.performance.base
org.apache.sling.performance.jcr.resource-2.0.10
org.apache.sling.performance.jcr.resource-2.1.0
org.apache.sling.performance.jcr.resource-2.2.0
org.apache.sling.performance.jcr.resource-2.2.10
org.apache.sling.performance.reactor
org.apache.sling.performance.tests
org.apache.sling.provisioning.model
org.apache.sling.query
org.apache.sling.reqanalyzer
org.apache.sling.resource-editor
org.apache.sling.resource.inventory
org.apache.sling.resourceaccesssecurity
org.apache.sling.resourceaccesssecurity.it
org.apache.sling.resourcecollection
org.apache.sling.resourcemerger
org.apache.sling.resourceresolver
org.apache.sling.rewriter
org.apache.sling.sample.slingshot
org.apache.sling.samples.accessmanager.ui
org.apache.sling.samples.custom-login-form
org.apache.sling.samples.custom-selector-login-form
org.apache.sling.samples.espblog
org.apache.sling.samples.fling
org.apache.sling.samples.frameworkfragment
org.apache.sling.samples.javashell
org.apache.sling.samples.jcr.contentloader
org.apache.sling.samples.path-based.rtp
org.apache.sling.samples.post-servlet-extensions
org.apache.sling.samples.slingbucks
org.apache.sling.samples.urlfilter
org.apache.sling.samples.usermanager.ui
org.apache.sling.samples.webloader.service
org.apache.sling.samples.webloader.ui
org.apache.sling.scripting.api
org.apache.sling.scripting.console
org.apache.sling.scripting.core
org.apache.sling.scripting.freemarker
org.apache.sling.scripting.groovy
org.apache.sling.scripting.java
org.apache.sling.scripting.javascript
org.apache.sling.scripting.jsp
org.apache.sling.scripting.jsp.jstl
org.apache.sling.scripting.jsp.taglib
org.apache.sling.scripting.jst
org.apache.sling.scripting.python
org.apache.sling.scripting.ruby
org.apache.sling.scripting.scala.config
org.apache.sling.scripting.scala.forum
org.apache.sling.scripting.scala.hello-world
org.apache.sling.scripting.scala.script
org.apache.sling.scripting.sightly
org.apache.sling.scripting.sightly.js.provider
org.apache.sling.scripting.sightly.reactor
org.apache.sling.scripting.sightly.repl
org.apache.sling.scripting.sightly.testing
org.apache.sling.scripting.sightly.testing-content
org.apache.sling.scripting.thymeleaf
org.apache.sling.scripting.velocity
org.apache.sling.scripting.xproc
org.apache.sling.security
org.apache.sling.serviceusermapper
org.apache.sling.servlets.compat
org.apache.sling.servlets.get
org.apache.sling.servlets.post
org.apache.sling.servlets.resolver
org.apache.sling.settings
org.apache.sling.slingstart
org.apache.sling.startupfilter
org.apache.sling.startupfilter.disabler
org.apache.sling.superimposing
org.apache.sling.tenant
org.apache.sling.testing.jcr-mock
org.apache.sling.testing.osgi-mock
org.apache.sling.testing.reactor
org.apache.sling.testing.resourceresolver-mock
org.apache.sling.testing.samples.failingtests
org.apache.sling.testing.samples.integrationtests
org.apache.sling.testing.samples.sampletests
org.apache.sling.testing.sling-mock
org.apache.sling.testing.sling-mock-jackrabbit
org.apache.sling.testing.tools
org.apache.sling.tooling.support.install
org.apache.sling.urlrewriter
org.apache.sling.validation.api
org.apache.sling.validation.core
org.apache.sling.validation.examples
org.apache.sling.validation.it-http
org.apache.sling.validation.reactor
org.apache.sling.validation.test-services
org.apache.sling.xss
reactor
sample-war
sling
sling-archetype-parent
sling-builder
sling-bundle-archetype
sling-contrib-builder
sling-initial-content-archetype
sling-jcrinstall-bundle-archetype
sling-lauchpad
sling-launchpad-karaf-builder
sling-launchpad-standalone-archetype
sling-launchpad-webapp-archetype
sling-samples-builder
sling-servlet-archetype
sling-taglib-archetype
slingstart-maven-plugin

Idea

one Git repository per project/module (we should keep it that simple - is launchpad really different, a release unit, Justin Edelson?)
grouping repositories with Google repo, e.g. core (bundles), launchpad, testing, samples, tooling as needed
using artifactId as repository name for artifacts (bundles, plugins, jars, ...) and simple names for grouping (builder/reactor) repositories
using Google repo allows developers to set up their own grouping repositories - even non Sling committers

Grouping repositories (projects/modules)

There are some tools for grouping repositories (projects/modules):

After playing around with some and reading about pros and cons, it seems that Google repo fits best for Sling.

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