EC2 Metadata Client

[davidmankin]

Since all access to EC2MetadataUtils is static, the class is very difficult to use in a properly tested application. It can't be mocked; you can't give canned answers when running in a non-EC2 environment.

If there were an EC2Metadata interface or abstract class of which there were a default implementation, then it would be easier to use.

A contrived example:

public class Application {
    EC2Metadata metadata;
    public static void main(String args[]) {
        new Application(EC2MetadataUtils.getDefaultInstance());
    }
    public Application(EC2Metadata metadata) {
        this.metadata = metadata;
        LOG.info("We're running on " + metadata.getInstanceId());
    }
}

public class ApplicationTest {
    @Mock EC2Metadata metadata;
    @Test public testApp() {
        when(metadata.getDefaultInstance()).then(return "i-fakeinstance");
        new Application(metadata);
        verifyLoggedLine("We're running on i-fakeinstance");
    }
}

As it stands today, I need to run a whole HTTP process that mimics the metadata server and somehow get the system property to point to it; and even that is a global setting for the whole JVM: parallel tests can interfere with each other. Or I can write my own EC2Metadata interface and use it throughout my app, but it's not something each developer should have to do.

[millems]

Using this issue to track building a public-facing EC2 Metadata Client.

[PyvesB]

I'm surprised that this has not yet been implemented, especially as someone volunteered to contribute this last year. Why was he ignored?

[dagnir]

Sorry for the delay in our response. We aim to respond to all comments, feedback and pull requests our customers make and we apologize that we failed to do so in this instance.

We have been working with the EC2 team to figure out the best possible customer experience for exposing this information, and in the meantime we welcome all suggestions and will use them to help us in that decision making process.

We will keep updating this issue as we move towards delivery.

Thank you for your patience!

[injeniero]

@dagnir Any update on this?

[spender0]

any progress? It turned out that we need to change metadata_service_timeout as the connection in our case takes more than 1 second. But it is hardcoded in the SDK

[sanjeeb26]

@dagnir do you have timeline when this will be available in the SDK?

[dFarras]

@millems @dagnir is there any new about this issue?

Thanks in advance