How do I configure Maven for offline development?

Does maven require a connection to the internet at some point 开发者_如何学JAVAto 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.

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):

1. While you have internet access, cache dependencies locally:

mvn -Dmaven.repo.local=dependencies install

2. 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