I have a dependency in pom on some library.
I want to make some changes in it, test it locally and if it will work fine - deploy it to remote repo.
So I have locally made some changes in this library, installed it as a jar, and want to replace in my main project remote library with the local one.
What is proper way to do it?
You can override default maven repository in project's pom:
<repositories>
<repository>
<id>central</id>
<url>file://d:/repo</url>
</repository>
</repositories>
When resolving dependencies, Maven looks in your local repository ($HOME/.m2/repository). So if you have installed your modified dependency into your local repository (e.g. through mvn install) then when you build your main project, it will be used.
To make this more obvious, you may want to change the versions being used in both the library and your main project POM, so that you can be sure your version is being used for testing.
You may also find this question/answer useful: How do I force Maven to use my local repository rather than going out to remote repos to retrieve artifacts?
Maven first looks in your local repository in
C:\Users\User\.m2\repository
and if it can't find the library, then it looks in remote repos. If I understand your question correctly, this should be happening automatically as long as you point the correct version in the POM.
It's possible to set the maven local repository in settings.xml:
<localRepository>${user.home}/.m2/repository</localRepository>
And it's possible to set the maven local repository on the command line:
mvn clean install -Dmaven.repo.local=repository
Is it possible to specify within the pom.xml itself?
Note: I'd like a way to specify, in the pom.xml, where maven initially searches for artifacts (by default, ~/.m2/repository) and where maven installs artifacts via mvn install (by default, ~/.m2/repository).
According to the Maven POM Reference and the Guide to using multiple repositories, you can specify repositories in pom.xml too.
There are two different ways that you can specify the use of multiple repositories. The first way is to specify in a POM which repositories you want to use
And according to Introduction to repositories, you can use the file:// protocol in <url>.
Remote repositories refer to any other type of repository, accessed by a variety of protocols such as file:// and http://.
So the following works:
<project>
...
<repositories>
<repository>
<id>example-repo</id>
<name>Example Repository</name>
<url>file://path/to/your/local/repository</url>
</repository>
</repositories>
</project>
Edit:
Based on your comment and edit, you need to override the default repository and Maven home directory in pom.xml.
I've found a topic about disabling central repository, and tried out the answers, but Maven still uses the values from settings.xml. This answer in another thread explains why:
settings.xml allows you to override definitions in pom.xml, not the other way round.
So it's seems it is not possible to override the default mechanism from pom.xml, Maven will search for dependencies in repositories configured in settings.xml and will install to Maven home specified in that file.
If the problem is having to write the options every time when running maven, you can use a feature available since version 3.3.1 that allows you to set command line options in your project (or parent project of your module). Read #Brice's answer: https://stackoverflow.com/a/48583079
So with this feature in mind, you can achieve a similar result by setting up a new settings.xml with the <localRepository> pointing to the location you desire and use maven.config in your project to make maven use the new settings.xml, which by the way can be anywhere you want.
I have a maven project running perfectly using the pom.xml file to get the needed jar files. Unfortunately the database I connect to doesn't have any jar files out on mvnrepository. Right now they're sitting in the Referenced Libraries folder.
Since these files are proprietary I need to keep them local. I've set up Apache Archiva and have added the files.
Can I get my project pom file to reference both a remote repository and a local repository?
Yes you can, something like this:
<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0
https://maven.apache.org/xsd/settings-1.0.0.xsd">
<localRepository/>
<interactiveMode/>
<usePluginRegistry/>
<offline/>
<pluginGroups/>
<servers/>
<mirrors/>
<proxies/>
<profiles/>
<activeProfiles/>
</settings>
For more details on this you can look over here.
You can also look at this article.
With the following configuration you can achieve it:
<localRepository>/dev/m2repo</localRepository>
Can I get my project pom file to reference both a remote repository and a local repository?
That's how Maven already works. Dependencies are first looked up in your local repository and if not present, they are downloaded from the remote repository to the local repository. In this case, your third-party Jars need to be either installed in your local repository, or better yet deployed to the remote repository so that other developers can use them.
Ideally you would deploy these third party libraries to a remote repository using a repository manager like Sonatype Nexus. If you are using a Nexus repository manager, see https://books.sonatype.com/nexus-book/reference/using-sect-uploading.html for how to do this. This would apply to your exact scenario, as the linked page describes:
When your build makes use of proprietary or custom dependencies that are not available from public repositories, you will often need to find a way to make them available to developers in a custom Maven repository. Nexus Repository Manager Pro and Nexus Repository Manager OSS ship with a preconfigured third-party repository that was designed to hold third-party dependencies that are used in your builds.
This can also be done using the maven-deploy-plugin but requires you to configure in the pom.xml the target repository as described in the documentation.
EDIT:
You mention using Apache Archiva which is also a repository manager that allows you to deploy the artifacts to its repository. https://archiva.apache.org/docs/2.2.1/userguide/deploy.html explains how to do it. https://archiva.apache.org/docs/2.2.1/userguide/using-repository.html explains how to configure Maven to get dependencies from an Archiva repository.
You can also install the libraries only to your local repository by running the maven-install-plugin:
mvn install:install-file -Dfile=<path-to-file> -DgroupId=<group-id> \
-DartifactId=<artifact-id> -Dversion=<version> -Dpackaging=<packaging>
See https://maven.apache.org/guides/mini/guide-3rd-party-jars-local.html. The drawback is that other developers have to do this step in order to build their projects.
Does maven require a connection to the internet at some point to be able to use it? Meaning specifically getting the internal maven plugins for compiling, cleaning, packaging, etc?
You can run Maven in "offline" mode using the -o or -offline option (e.g. mvn -o install). Of course any artifacts not available in your local repository will fail. Maven is not predicated on distributed repositories, but they certainly make things more seamless. It's for this reason that many shops use internal mirrors that are incrementally synced with the central repos.
In addition, the mvn dependency:go-offline can be used to ensure you have all of your dependencies installed locally before you begin to work offline.
If you have a PC with internet access in your LAN, you should install a local Maven repository.
I recommend Artifactory Open Source. This is what we use in our organization, it is really easy to setup.
Artifactory acts as a proxy between your build tool (Maven, Ant, Ivy, Gradle etc.) and the outside world.
It caches remote artifacts so that you don’t have to download them over and over again.
It blocks unwanted (and sometimes security-sensitive) external requests for internal artifacts and controls how and where artifacts are deployed, and by whom.
After setting up Artifactory you just need to change Maven's settings.xml in the development machines:
<?xml version="1.0" encoding="UTF-8"?>
<settings xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 http://maven.apache.org/xsd/settings-1.0.0.xsd" xmlns="http://maven.apache.org/SETTINGS/1.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<mirrors>
<mirror>
<mirrorOf>*</mirrorOf>
<name>repo</name>
<url>http://maven.yourorganization.com:8081/artifactory/repo</url>
<id>repo</id>
</mirror>
</mirrors>
<profiles>
<profile>
<repositories>
<repository>
<snapshots>
<enabled>false</enabled>
</snapshots>
<id>central</id>
<name>libs-release</name>
<url>http://maven.yourorganization.com:8081/artifactory/libs-release</url>
</repository>
<repository>
<snapshots />
<id>snapshots</id>
<name>libs-snapshot</name>
<url>http://maven.yourorganization.com:8081/artifactory/libs-snapshot</url>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<snapshots>
<enabled>false</enabled>
</snapshots>
<id>central</id>
<name>plugins-release</name>
<url>http://maven.yourorganization.com:8081/artifactory/plugins-release</url>
</pluginRepository>
<pluginRepository>
<snapshots />
<id>snapshots</id>
<name>plugins-snapshot</name>
<url>http://maven.yourorganization.com:8081/artifactory/plugins-snapshot</url>
</pluginRepository>
</pluginRepositories>
<id>artifactory</id>
</profile>
</profiles>
<activeProfiles>
<activeProfile>artifactory</activeProfile>
</activeProfiles>
</settings>
We used this solution because we had problems with internet access in our development machines and some artifacts downloaded corrupted files or didn't download at all. We haven't had problems since.
You have two options for this:
1.) make changes in the settings.xml add this in first tag
<localRepository>C:/Users/admin/.m2/repository</localRepository>
2.) use the -o tag for offline command.
mvn -o clean install -DskipTests=true
mvn -o jetty:run
Maven needs the dependencies in your local repository. The easiest way to get them is with internet access (or harder using other solutions provided here).
So assumed that you can get temporarily internet access you can prepare to go offline using the maven-dependency-plugin with its dependency:go-offline goal. This will download all your project dependencies to your local repository (of course changes in the dependencies / plugins will require new internet / central repository access).
Sadly dependency:go-offline hasn't worked for me as it didn't cached
everything, ie. POMs files and other implicitly mention dependencies.
The workaround has been to specify a local repository location, either within settings.xml file with <localRepository>...</localRepository> or by running mvn with -Dmaven.repo.local=... parameter.
After initial project build, all necessary artifacts should be cached, and then you can reference repository location the same ways, while running Maven build in offline mode (mvn -o ...).
Before going offline you have to make sure that everything is in your local repo, which is required while working offline. Running "mvn dependency:go-offline" for the project(s)/pom(s), you intend to work on, will reduce the efforts to achieve this.
But it´s usually not the whole story, because dependency:go-offline will only download the "bare build" plugins (go-offline / resolve-plugins does not resolve all plugin dependencies). So you have to find a way to download deploy / test / site plugins (and maybe others) and their dependencies into your repo.
Furthermore dependency:go-offline does not download the pom´s artifact itself, so you have to dependency:copy it if required.
Sometimes - as MaDa wrote - you do not know, what you will need, while being offline, which makes it pretty impossible to have a "sufficient" repo.
Anyway having a properly filled repo you only have to add "<offline>true</offline>" to Maven´s settings.xml to go offline.
Do not change the Maven profile (id) you used to fill your repo, while being offline. Maven recognizes the downloaded artifacts in its metadata with an "identity", which is bound to the profile id.
If you're using IntelliJ, you can simply go to Preferences -> Build, Execution, Deployment -> Build Tools -> Maven and check/uncheck Work offline.
Does this work for you?
http://jojovedder.blogspot.com/2009/04/running-maven-offline-using-local.html
Don't forget to add it to your plugin repository and point the url to wherever your repository is.
<repositories>
<repository>
<id>local</id>
<url>file://D:\mavenrepo</url>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>local</id>
<url>file://D:\mavenrepo</url>
</pluginRepository>
</pluginRepositories>
If not, you may need to run a local server, e.g. apache, on your machines.
(source: jfrog.com)
or
Just use Maven repository servers like Sonatype Nexus http://www.sonatype.org/nexus/ or JFrog Artifactory https://www.jfrog.com/artifactory/.
After one developer builds a project, build by next developers or Jenkins CI will not require Internet access.
Maven repository server also can have proxies configured to access Maven Central (or more needed public repositories), and they can have cynch'ed list of artifacts in remote repositories.
My experience shows that the -o option doesn't work properly and that the go-offline goal is far from sufficient to allow a full offline build:
The solution I could validate includes the use of the --legacy-local-repository maven option rather than the -o (offline) one and
the use of the local repository in place of the distribution repository
In addition, I had to copy every maven-metadata-maven2_central.xml files of the local-repo into the maven-metadata.xml form expected by maven.
See the solution I found here.
A new plugin has appeared to fix shortcomings of mvn dependency:go-offline:
https://github.com/qaware/go-offline-maven-plugin
Add it in your pom, then run mvn -T1C de.qaware.maven:go-offline-maven-plugin:resolve-dependencies. Once you've setup all dynamic dependencies, maven won't try to download anything again (until you update versions).
Answering your question directly: it does not require an internet connection, but access to a repository, on LAN or local disk (use hints from other people who posted here).
If your project is not in a mature phase, that means when POMs are changed quite often, offline mode will be very impractical, as you'll have to update your repository quite often, too. Unless you can get a copy of a repository that has everything you need, but how would you know? Usually you start a repository from scratch and it gets cloned gradually during development (on a computer connected to another repository). A copy of the repo1.maven.org public repository weighs hundreds of gigabytes, so I wouldn't recommend brute force, either.
Here's a clear, straightforward way to cache Maven dependencies for offline development (based on #luka5z and others' comments):
While you have internet access, cache dependencies locally:
mvn -Dmaven.repo.local=dependencies install
Disconnect from the internet, verify that offline mode compilation succeeds:
mvn clean
mvn -o -Dmaven.repo.local=dependencies package
Continue developing offline as long as needed.
In preparation before working offline just run
mvn dependency:go-offline
<offline> false </offline>
<localRepository>${user.home}/.m2/repository</localRepository>
to
<offline> true <offline>
<localRepository>${user.home}/.m2/repository</localRepository>
Change the offline tag from false to true .
will download from repo online
I want to limit maven to use only private/not public maven repository, do these two settings have the same effect ?
1.Setting mirror in settings.xml
<mirrors>
<mirror>
<id>my-internal-site</id>
<mirrorOf>*</mirrorOf>
<name>our maven repository</name>
<url>http://myserver/repository</url>
</mirror>
</mirrors>
2.Setting repository in pom.xml
<repositories>
<repository>
<id>my-internal-site</id>
<name>our maven repository</name>
<url>http://myserver/repo</url>
</repository>
</repositories>
Again the requirement is that maven never goes out to public repositories even if some dependencies are not there on the internal repository. thank you
No they don't have the same effect.
The second setting add a new repository as a "complement" to central but doesn't prevent Maven to check central by itself.
The first one forces Maven to use a single repository by having it mirror all repository requests (by setting mirrorOf to *). This is the way to use a single repository.
What you're looking for is thus the first setting and need to be defined in the settings.xml.
Now, adding your corporate repository in the ~/.m2/settings.xml file of each machine can be a bit painful and what I like to do in a corporate environment is to distribute and install a "customized" version of Maven containing the mirror predefined in conf/settings.xml. This way, people just have to install the "corporate" version and they are ready to go.
No, they mean different things:
In the first example, you said that the given repository is a mirror of all repositories, including the official one.
In the second example, you simply add a new repository. In case a dependency is not found in the local repository, Maven will then look in this repository after having searched in the official repository.
Thus, to force the usage of an internal repository, you must configure the mirror in your settings.xml file.
This is explained in the official documentation of Maven.