How do I use Maven through a proxy?

I want to share my experience of using maven through a proxy.

You would most likely face exceptions and messages like:

repository metadata for: 'org.apache.maven.plugins' could not be retrieved from 
repository: central due to an error: Error transferring file: Connection refused: connect

[WARNING] Failed to retrieve plugin descriptor for org.apache.maven.plugins:maven-clean-
plugin:2.5: Plugin org.apache.maven.plugins:maven-clean-plugin:2.5 or one of its 
dependencies could not be resolved: Failed to read artifact descriptor for 
org.apache.maven.plugins:maven-clean-plugin:jar:2.5

How to configure Maven to use proxy server?

Solution 1:

For details of setting up a proxy for Maven, see the mini guide.

Essentially you need to ensure the proxies section in either the global settings ([maven install]/conf/settings.xml), or user settings (${user.home}/.m2/settings.xml) is configured correctly. It is better to do this in your user settings to avoid storing the password in plain text in a public location.

Maven 2.1 introduced password encryption, but I've not got round to checking if the encryption applies for the proxy settings as well as repository passwords (don't see why it wouldn't though).

For info, there is a commented-out proxy configuration in your settings.xml and instructions on how to modify it.

From the mini-guide, your settings should look 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
                  http://maven.apache.org/xsd/settings-1.0.0.xsd">
[...]
  <proxies>
    <proxy>
      <active>true</active>
      <protocol>http</protocol>
      <host>proxy.somewhere.com</host>
      <port>8080</port>
      <username>proxyuser</username>
      <password>somepassword</password>
      <nonProxyHosts>www.google.com|*.somewhere.com</nonProxyHosts>
    </proxy>
  </proxies>
[...]
</settings>

Solution 2:

How to use a socks proxy?

Set up a SSH tunnel to a server somewhere:

ssh -D $PORT $USER@$SERVER

Linux (bash):

export MAVEN_OPTS="-DsocksProxyHost=127.0.0.1 -DsocksProxyPort=$PORT"

Windows:

set MAVEN_OPTS="-DsocksProxyHost=127.0.0.1 -DsocksProxyPort=$PORT"

Solution 3:

I also had this problem, and I solved it by editing the settings.xml file in my .m2 folder. My settings.xml is like this now:

<settings>
  <proxies>
    <proxy>
      <id>genproxy</id>
      <active>true</active>
      <protocol>http</protocol>
      <host>proxyHost</host>
      <port>3128</port>
      <username>username</username>
      <password>password</password>
    </proxy>
 </proxies>
</settings>

Solution 4:

Also note that some plugins (remote-resources comes to mind) use a really old library that only accepts proxy configuration through MAVEN_OPTS;

-Dhttp.proxyHost=<host> -Dhttp.proxyPort=<port> -Dhttps.proxyHost=<host> -Dhttps.proxyPort=<port>

You might be stuck on auth for this one.

Solution 5:

To set Maven Proxy :

Edit the proxies session in your ~/.m2/settings.xml file. If you cant find the file, create one.

<settings>
<proxies>
    <proxy>
        <id>httpproxy</id>
        <active>true</active>
        <protocol>http</protocol>
        <host>your-proxy-host</host>
        <port>your-proxy-port</port>
        <nonProxyHosts>local.net|some.host.com</nonProxyHosts>
    </proxy>
<proxy>
        <id>httpsproxy</id>
        <active>true</active>
        <protocol>https</protocol>
        <host>your-proxy-host</host>
        <port>your-proxy-port</port>
        <nonProxyHosts>local.net|some.host.com</nonProxyHosts>
    </proxy>

</proxies>
</settings>

Edit the proxies session in your {M2_HOME}/conf/settings.xml