[HDFS-12294] Let distcp to bypass external attribute provider when calling getFileStatus etc at source cluster

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Component/s: hdfs
• Assignee: Yongjun Zhang
• Reporter: Yongjun Zhang
• Created: 12/Aug/17 23:49
• Updated: 08/Sep/17 14:53
• Resolved: 08/Sep/17 14:51

Description

This is an alternative solution for HDFS-12202, which proposed introducing a new set of API, with an additional boolean parameter bypassExtAttrProvider, so to let NN bypass external attribute provider when getFileStatus. The goal is to avoid distcp from copying attributes from one cluster's external attribute provider and save to another cluster's fsimage.

The solution here is, instead of having an additional parameter, encode this parameter to the path itself, when calling getFileStatus (and some other calls), NN will parse the path, and figure out that whether external attribute provider need to be bypassed. The suggested encoding is to have a prefix to the path before calling getFileStatus, e.g. /ab/c becomes /.reserved/bypassExtAttr/a/b/c. NN will parse the path at the very beginning.

Thanks much to andrew.wang for this suggestion. The scope of change is smaller and we don't have to change the FileSystem APIs.

Issue Links

• is related to: HDFS-12357 Let NameNode to bypass external attribute provider for special user
• is related to: HDFS-12202 Provide new set of FileSystem API to bypass external attribute provider

Sub-Tasks

• NameNode to support file path prefix /.reserved/bypassExtAttr: Resolved
• Add a field to FsServerDefaults to tell if external attribute provider is enabled: Resolved