public String readResource(String resourcePath) throws IOException, SdkClientException {
        URL url = getEc2MetadataServiceUrlForResource(resourcePath);
        log.debug("Connecting to EC2 instance metadata service at URL: " + url.toString());

        HttpURLConnection connection = (HttpURLConnection)url.openConnection();
        connection.setConnectTimeout(1000 * 2);
        connection.setReadTimeout(1000 * 5);
        connection.setRequestMethod("GET");
        connection.setDoOutput(true);
        connection.addRequestProperty("User-Agent", USER_AGENT);
        connection.connect();

        return readResponse(connection);
    }
Connects to the metadata service to read the specified resource and
returns the text contents.

@param resourcePath
           The resource

@return The text payload returned from the Amazon EC2 Instance Metadata
        service for the specified resource path.

@throws IOException
            If any problems were encountered while connecting to metadata
            service for the requested resource path.
@throws SdkClientException
            If the requested metadata service is not found.
aws-java-sdk-core/src/main/java/com/amazonaws/internal/EC2MetadataClient.java