Original, we are calling getContainerReport to AMContainer information (such as container log url, nm address, startTime, etc). It works fine when the Application is running, and the container is running. But when the application is finished, we will not keep finished container info. In that case, we could not get any finished container report from RM. That is why we see the AM logs link in web ui as "N/A" as well as other related attempt information.
In this patch, instead of querying from container Report, we directly get attempt(AM Container) information from AttemptInfo which is from RMAttempt. So, no matter the application is running or is finished, we could get related information and show them in the web ui