.travis.yml

language: java

env:
  global:
    - SONATYPE_USERNAME=yourusername
    - secure: "your encrypted SONATYPE_PASSWORD=pass"
    
after_success:
  - python addServer.py
  - mvn clean deploy --settings ~/.m2/mySettings.xml

README.md

1. encrypt your sonatype oss password with travis encrypt -r user/repo SONATYPE_PASSWORD=pass
2. put addServer.py somewhere in your repository
3. add the relevant lines to your .travis.yml

Deployment will only happen when the build was successful and the encrypted variables are available (= no deployment for pull requests etc.). If the deployment itself was unsuccessful, then the build still passes.

If you only want to deploy for certain branches, use shell scripting like:

after_success:
  - "[[ $TRAVIS_BRANCH == \"master\" ]] && { python travis/addServer.py; mvn clean deploy --settings ~/.m2/mySettings.xml; };"

Warning: This will deploy multiple times if you use the matrix functionality, see the issue.

addServer.py

#!/usr/bin/env python
import sys
import os
import os.path
import xml.dom.minidom

if os.environ["TRAVIS_SECURE_ENV_VARS"] == "false":
  print "no secure env vars available, skipping deployment"
  sys.exit()

homedir = os.path.expanduser("~")

m2 = xml.dom.minidom.parse(homedir + '/.m2/settings.xml')
settings = m2.getElementsByTagName("settings")[0]

serversNodes = settings.getElementsByTagName("servers")
if not serversNodes:
  serversNode = m2.createElement("servers")
  settings.appendChild(serversNode)
else:
  serversNode = serversNodes[0]
  
sonatypeServerNode = m2.createElement("server")
sonatypeServerId = m2.createElement("id")
sonatypeServerUser = m2.createElement("username")
sonatypeServerPass = m2.createElement("password")

idNode = m2.createTextNode("sonatype-nexus-snapshots")
userNode = m2.createTextNode(os.environ["SONATYPE_USERNAME"])
passNode = m2.createTextNode(os.environ["SONATYPE_PASSWORD"])

sonatypeServerId.appendChild(idNode)
sonatypeServerUser.appendChild(userNode)
sonatypeServerPass.appendChild(passNode)

sonatypeServerNode.appendChild(sonatypeServerId)
sonatypeServerNode.appendChild(sonatypeServerUser)
sonatypeServerNode.appendChild(sonatypeServerPass)

serversNode.appendChild(sonatypeServerNode)
  
m2Str = m2.toxml()
f = open(homedir + '/.m2/mySettings.xml', 'w')
f.write(m2Str)
f.close()