Use a different set of API keys and do it the same way. Your travis box gets setup for your build run and then completely torn down again after your build has finished. You have root access to your box during the build, so you can do whatever you want with it.
Travis has a feature to encrypt environment variables ("Encrypting environment variables"). This can be used to protect your secret API keys. I've successfully used this for my Heroku API key.
All you have to do is install the travis gem, encrypt the string you want and add the encrypted string in your .travis.yml. The encryption is only valid for one repository. The travis command gets your public key for your repo and can then decrypt the string during the build.
Please add the following to your .travis.yml file:
secure: "OrEeqU0z6GJdC6Sx/XI7AMiQ8NM9GwPpZkVDq6cBHcD6OlSppkSwm6JvopTR\newLDTdtbk/dxKurUzwTeRbplIEe9DiyVDCzEiJGfgfq7woh+GRo+q6+UIWLE\n3nowpI9AzXt7iBhoKhV9lJ1MROrnn4DnlKxAEUlHTDi4Wk8Ei/g="
Variables defined in repository settings are the same for all builds, and when you restart an old build, it uses the latest values. These variables are not automatically available to forks.
Define variables in the Repository Settings that:
differ per repository.
contain sensitive data, such as third-party credentials.
To define variables in Repository Settings, make sure you’re logged in, navigate to the repository in question, choose “Settings” from the cog menu, and click on “Add new variable” in the “Environment Variables” section.
according to this in travis ci documentation it's said that :
If you have both the Heroku and Travis CI command line clients installed, you can get your key, encrypt it and add it to your .travis.yml by running the following command from your project directory: