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Stephen J Day 33a1f4ef7d Address server errors received during layer upload ... This changeset addresses intermittent internal server errors encountered during pushes. The root cause has been isolated to layers that result in identical, empty filesystems but may have some path declarations (imaginge "./"), resulting in different tarsums. The main error message reported during these upload problems was a 500 error, which was not correct. Further investigation showed the errors to be rooted in digest verification when finishing uploads. Inspection of the surrounding code also identified a few issues. PutLayerChunk was slightly refactered into PutLayerUploadComplete. Helper methods were avoided to make handler less confusing. This simplification leveraged an earlier change in the spec that moved non-complete chunk uploads to the PATCH method. Simple logging was also added in the unknown error case that should help to avoid mysterious 500 errors in the future. At the same time, the glaring omission of a proper layer upload cancel method was rectified. This has been added in this change so it is not missed in the future. In the future, we may want to refactor the handler code to be more straightforward, hopefully letting us avoid these problems in the future. Added test cases that reproduce these errors and drove these changes include the following: 1. Push a layer with an empty body results in invalid blob upload. 2. Push a layer with a different tarsum (in this case, empty tar) 3. Deleting a layer upload works. 4. Getting status on a deleted layer upload returns 404. Common functionality was grouped into shared functions to remove repitition. The API tests will still require future love. Signed-off-by: Stephen J Day <stephen.day@docker.com>		2015-01-29 21:26:35 -08:00
docs	Address server errors received during layer upload	2015-01-29 21:26:35 -08:00