Storing credentials in a Google App Engine Java server
<p>I have a Java Server running on Google App Engine, with integrations with third-party services (eg. SendGrid).</p>

<p>What's the best way to store credentials (usernames/passwords, API keys) for these third-party services? In the Java code, or through a configuration file such as web.xml or appengine-web.xml, or elsewhere? How would I access the credentials through code?</p>