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Overview

In a corporate environment it makes sense to have some control over the setup of Maven.
For example:

  • restricting dependencies to approved versions of artifacts
  • reducing network bandwidth by having a maven repository proxied
  • sharing corporate assets by deploying them centrally

These scenarios can be realized by using internal Maven repositoriesand a Maven proxy. Be very careful not to confuse these two concepts as both services are often located on the same physical machine and it is easy to get them mixed up.

This guide will recommend installing both the Maven internal repositories and the Maven proxy on a single machine and to make this guide a bit more readable this machine will be called NUCLEUS.

To get an overview of repositories please read http://maven.apache.org/guides/introduction/introduction-to-repositories.html

For another example of repository setup with diagrams showing this configuration see http://cvs.peopleware.be/training/maven/maven2/repositories.html

Definitions of Repositories

A repository holds Maven artifacts in a well defined directory structure.

The purpose of the repository influences the types of resources that are stored in that repository.

The following list attempts to define the different terms used when discussing different repository types.

local repository

The directory structure on your local machine which stores all the artifacts required by all the projects on your system.

It is a cache of artifacts from remote repositories for any mvn command you have run.

remote repository

A remote repository is where the user may get artifacts from. A remote repository can be located anywhere and accessed by any protocol supported by Wagon (ftp/scp/http/file/...)

intranet repository

A remote repository inside your firewall, i.e. a repository not on your machine but in the confines of your organization.

You might have internal release/snapshot repositories as well.

private repository

Same as #internal repository.

central repository

A special remote repository which is situated at http://www.ibiblio.org/maven2/.

This remote repository is where most open source software artifacts are located.

release repository

A release repository is a remote repository specifically for housing released code.

No snapshots should be stored in this repository.

snapshot repository

A snapshot repository is a remote repository specifically for housing non-release code as snapshots should not be stored with released artifacts.

Creating the repositories

Creating a Maven proxy

A Maven proxy can be thought of as a Maven mirror that aggregates one or more Maven repositories.

This document will walk through the setup of maven-proxy http://maven-proxy.codehaus.org/. At least one other alternative exists called Proximity https://is-micro.myip.hu/projects/ismicro-commons/proximity/projects-overview.html however I found the documentation to be sparse or non existant as of 2006-01-13.

Additional installation instructions can be found at http://docs.codehaus.org/display/MAVEN/MAVEN-PROXY

Prerequisites

Shell access to NUCLEUS

Shell access is needed to exectute commands and to configure the maven proxy. This may be done in conjunction with a sysadmin if you do not have the required privileges.

Build 0.2 of maven-proxy

See http://maven-proxy.codehaus.org/Downloads for access to http://dist.codehaus.org/maven-proxy/distributions/maven-proxy-standalone-0.2.zip

maven-proxy.properties configuration file.

Up to date configuration properties file can be found at http://maven-proxy.codehaus.org/Configuration.

An already configured instance of the maven-proxy.properties for maven-proxy 0.2 configuration file is as below.
The only changes needed are:

  • replace WEB_ROOT with the correct path details
  • decide whether to allow non-local access to web configuration pages. If yes, then change serverName to the host details of the machine instead of localhost.
################
# This file IS NOT DOCUMENTED, it is taken from
# maven-proxy/core/src/test/resources/org/apache/maven/proxy/config/PropertyLoaderTest1.properties
# and configured to match http://docs.codehaus.org/display/MAVENUSER/Using+Maven+in+a+corporate+environment
#
# You will need to globally replace WEB_ROOT to be the full path to where
# the maven2 repositories are located.  As per the above document these directories
# live under the web server root directory.
#
# If you want remote browsing of the maven-proxy repository then you must
# configure serverName to be something other than localhost.
################

################ GLOBAL SETTINGS
# This is where maven-proxy stores files it has downloaded
repo.local.store=WEB_ROOT/maven2_repositories/maven_proxy

#The port to listen on - not used if loaded as a webapp
port=9999

#This is the base area that all files are loaded from. While it is possible to leave this blank, this behaviour
#is deprecated and will be disabled in version 2.0.  There are too many namespace conflicts caused by not using
#a prefix.
#The repository will be shown at http://localhost:9999/repository/
#for the .war loaded into a webapp server, the default prefix is "repository" (edit the web.xml to change)
# As maven doesn't like a trailing slash, this address shouldn't have one either.
prefix=repository

#This is the simple date format used to display the last modified date while browsing the repository.
lastModifiedDateFormat=yyyy/MM/dd HH:mm:ss

################ SNAPSHOT HANDLING
#If you want the proxy to look for newer snapshots, set to true
snapshot.update=true

################ M2 METADATA HANDLING
#If you want the proxy to prevent looking for newer metadata, set to false (default is true)
#metadata.update=false

################ M2 POM HANDLING
#If you want the proxy to look for newer POMs, set to true (default is false)
pom.update=true

################ PROMOTION HANDLING
# ***** NOT CURRENTLY IMPLEMENTED *****
#Promotion describes the process by which new artifacts are loaded to global maven-proxy repository.  It
# is designed to be used by "higher security installations" that do not want to acquire artifacts from
# remote repositories without approval.
#
#If promotion handling is enabled, then the proxy will not download remote artifacts without permission
# (local repositories with copy=false are considered to be local)
#
#Permission to download is granted via the Promotion menu which will be enabled
#  when promotion handling is enabled.
#
#If promotion is false, artifacts are sourced from any repository as per normal.
#
#Promotion and snapshots:  If promotion is enabled, snapshots are not downloadable.  The concept of using
# a snapshot in a production build (which is primarily what promotion is for) is counterintuitive.
##
promotion=false

################ WEB INTERFACE
# This defines the absolute URL the server should use to identify itself.
# This can often be determined automatically, but we recommend you specify
# it explicitly to prevent problems during startup.
# The prefix will be added to this for the actual repository
# i.e. proxy available at http://localhost:9999/, repository at http://localhost:9999/repository
serverName=http://localhost:9999

#If true, the repository can be browsed
browsable=true

#If true, the repository can be searched
searchable=true

#Not currently implemented. Will allow webdav access to the repository at some point.
webdav=true

#Stylesheet - if configured, will override the default stylesheet shipped with maven-proxy - absolute URLs only
#eg.  /maven-proxy/style.css, http://www.example.com/style.css
stylesheet=/maven-proxy/style.css

#bgColor / bgColorHighlight are replaced in the built in stylesheet to produce a simple color scheme.
#If a stylesheet is set, these are not used.
bgColor=#14B
bgColorHighlight=#94B

#rowColor / rowColorHighlight are replaced in the built in stylesheet to produce a simple color scheme.
#If a stylesheet is set, these are not used.
rowColor=#CCF
rowColorHighlight=#DDF


################ PROXIES
#Note: Proxies are only needed for external repositories.
#If you need to use a proxy to get Internet access to an external repository
#then in the repository definition section you must also specify which proxy that repository should use.
#e.g. repo.www-ibiblio-org.proxy=one

#This is just a hack, it should auto discover them (but it currently doesn't)
#proxy.list=one,two,three

#Unauthenticated proxy
#proxy.one.host=proxy1.example.com
#proxy.one.port=3128

#Authenticated proxy
#proxy.two.host=proxy2.example.org
#proxy.two.port=80
#proxy.two.username=username2
#proxy.two.password=password2

#Authenticated proxy
#proxy.three.host=proxy3.example.net
#proxy.three.port=3129
#proxy.three.username=username3
#proxy.three.password=password3


################# REPOSITORIES
#This is not just a hack, it specifies the order repositories should be checked
#Note that the proxy adds a "/" which is why the urls aren't suffixed with a "/"
repo.list=inhouse,inhouse_snapshot,external_free,external_non_free,www-ibiblio-org,dist-codehaus-org

#inhouse
repo.inhouse.url=file:///WEB_ROOT/maven2_repositories/inhouse
repo.inhouse.description=inhouse released artifacts
#If copy is true, jars are copied from the store to the proxy-repo. Only configurable for file:/// repos
repo.inhouse.copy=false
#If hardfail is true, any unexpected errors from the repository will cause
#the client download to fail (typically with a 500 error)
repo.inhouse.hardfail=true
#Don't cache a file repository
repo.inhouse.cache.period=0

#inhouse_snapshot
repo.inhouse_snapshot.url=file:///WEB_ROOT/maven2_repositories/inhouse_snapshot
repo.inhouse_snapshot.description=inhouse snapshot artifacts
#If copy is true, jars are copied from the store to the proxy-repo. Only configurable for file:/// repos
repo.inhouse_snapshot.copy=false
#If hardfail is true, any unexpected errors from the repository will cause
#the client download to fail (typically with a 500 error)
repo.inhouse_snapshot.hardfail=true
#Don't cache a file repository
repo.inhouse_snapshot.cache.period=0

#external_free
repo.external_free.url=file:///WEB_ROOT/maven2_repositories/external_free
repo.external_free.description=external free artifacts, but with annoying license restrictions so they can not be housed on ibiblio.
#If copy is true, jars are copied from the store to the proxy-repo. Only configurable for file:/// repos
repo.external_free.copy=false
#If hardfail is true, any unexpected errors from the repository will cause
#the client download to fail (typically with a 500 error)
repo.external_free.hardfail=true
#Don't cache a file repository
repo.external_free.cache.period=0

#external_non_free
repo.external_non_free.url=file:///WEB_ROOT/maven2_repositories/external_non_free
repo.external_non_free.description=external non free artfiacts
#If copy is true, jars are copied from the store to the proxy-repo. Only configurable for file:/// repos
repo.external_non_free.copy=false
#If hardfail is true, any unexpected errors from the repository will cause
#the client download to fail (typically with a 500 error)
repo.external_non_free.hardfail=true
#Don't cache a file repository
repo.external_non_free.cache.period=0

#www.ibiblio.org
#Maven1 Repository
#repo.www-ibiblio-org.url=http://www.ibiblio.org/maven
#Maven2 Repository
repo.www-ibiblio-org.url=http://www.ibiblio.org/maven2
repo.www-ibiblio-org.description=www.ibiblio.org
#If hardfail is true, any unexpected errors from the repository will cause
#the client download to fail (typically with a 500 error)
repo.www-ibiblio-org.hardfail=true
#Cache this repository for 1 hour
repo.www-ibiblio-org.cache.period=3600
repo.www-ibiblio-org.cache.failures=true
#If a Proxy is needed, which one?
#repo.www-ibiblio-org.proxy=one

#dist.codehaus.org
repo.dist-codehaus-org.url=http://dist.codehaus.org
#If hardfail is true, any unexpected errors from the repository will cause
#the client download to fail (typically with a 500 error)
repo.dist-codehaus-org.hardfail=false
#Cache this repository for 1 hour
repo.dist-codehaus-org.cache.period=3600
repo.dist-codehaus-org.cache.failures=true
#If a Proxy is needed, which one?
#repo.dist-codehaus-org.proxy=one

 

Install maven-proxy on NUCLEUS

Get your systems administrator to install maven-proxy.
See http://docs.codehaus.org/display/MAVEN/MAVEN-PROXY for additional instructions on how to do this.

Run maven-proxy

Run maven proxy with your maven-proxy.properties file specified.

Update settings.xml

<mirrors>
        ...
        <mirror>
            <id>maven-proxy</id>
            <name>Maven-Proxy Mirror</name>
            <url>http://NUCLEUS:9999/repository/</url>
            <mirrorOf>central</mirrorOf>
        </mirror>
    </mirrors>

 

Run maven

Maven should now connect to your installed maven-proxy to download artificats.
Remember on the first run the proxy's cache will be empty so the first run will be slower than usual.

Why proxy internal repositories?

People who do not deploy to the internal repositories do not need those repositories defined in settings.xml. They can use maven-proxy to retrieve those artifacts for them. The repositories external_free and external_non_free are internal repositories that only a few people need to deploy to, the rest can access via maven-proxy.

An oustanding uncertainty is the <mirrorOf> section defines "central". So if a person does not have all the repositories defined in settings.xml will they still contact maven-proxy for external_free?? Need to check this.

Continuous Integration

TODO: Placeholder

Errata

repositories in settings.xml

Defining repositories in settings.xml does not appear to be the ideal way to do this.

Internal repositories should be defined in pom.xml. If this is done in the parent pom it will be inherited for all modules.

I originally put it into settings.xml so that each project would not have to define the internal repositories but it makes more sense for the project to authoratively declare where the repositories are and this has the benefit of reducing the duplication for every developer into their settings.xml.

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