Preserve ETag case for S3 compatibility

[harshavardhana]

Description

Preserve ETag case for S3 compatibility

Motivation and Context

Most hadoop distributions hortonworks, cloudera all
depend on aws-sdk-java 1.7.x to 1.10.x - the releases
which have bugs related case sensitive check for
ETag header. Go changes the case of the headers set
to be canonical but only preserves them when set
through a direct map.

This fixes most compatibility issues we have had
in the past supporting older hadoop distributions.

Regression

No

How Has This Been Tested?

Using hortonworks HDP 2.6.5 with hadoop 2.7.3 and aws-sdk-java 1.10.6

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added unit tests to cover my changes.
• I have added/updated functional tests in mint. (If yes, add mint PR # here: )
• All new and existing tests passed.

[poornas]

For consistency, can you also make this change in checkCopyObjectPreconditions and checkPreconditions

[harshavardhana]

For consistency, can you also make this change in checkCopyObjectPreconditions and checkPreconditions

Done @poornas

[poornas]

LGTM

[kannappanr]

@harshavardhana Please fix unit tests. Travis is failing.

[harshavardhana]

@harshavardhana Please fix unit tests. Travis is failing.

Done @kannappanr

[kannappanr]

ping @poornas @donatello

[codecov]

Codecov Report

Merging #7498 into master will decrease coverage by 0.49%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master    #7498     +/-   ##
=========================================
- Coverage   48.02%   47.53%   -0.5%     
=========================================
  Files         296      281     -15     
  Lines       46797    46465    -332     
=========================================
- Hits        22476    22086    -390     
- Misses      22236    22306     +70     
+ Partials     2085     2073     -12

Impacted Files	Coverage Δ
cmd/object-handlers.go	54.42% <100%> (ø)	⬆️
cmd/bucket-handlers.go	57.16% <100%> (ø)	⬆️
cmd/api-headers.go	73.33% <100%> (ø)	⬆️
cmd/object-handlers-common.go	64.9% <100%> (ø)	⬆️
cmd/disk-usage.go	0% <0%> (-78.95%)	⬇️
cmd/update-notifier.go	55.35% <0%> (-25%)	⬇️
cmd/server-rlimit.go	37.5% <0%> (-16.67%)	⬇️
cmd/namespace-lock.go	58.62% <0%> (-12.32%)	⬇️
cmd/posix-errors.go	40% <0%> (-9.34%)	⬇️
cmd/retry.go	82.14% <0%> (-5.36%)	⬇️
... and 26 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 10a6071...f79072f. Read the comment docs.

[minio-ops]

Mint Automation

Test	Result
mint-compression-xl.sh	✔️
mint-xl.sh	✔️
mint-large-bucket.sh	✔️
mint-compression-dist-xl.sh	✔️
mint-compression-fs.sh	✔️
mint-fs.sh	✔️
mint-dist-xl.sh	✔️
mint-worm.sh	❌ more...
mint-gateway-nas.sh	❌ more...

7498-f79072f/mint-worm.sh.log:

Running with
SERVER_ENDPOINT:      72.28.97.57:31090
ACCESS_KEY:           minio
SECRET_KEY:           ***REDACTED***
ENABLE_HTTPS:         0
SERVER_REGION:        us-east-1
MINT_DATA_DIR:        /mint/data
MINT_MODE:            worm
ENABLE_VIRTUAL_STYLE: 0

To get logs, run 'docker cp 6180b73d3233:/mint/log /tmp/mint-logs'

(1/1) Running worm tests ... FAILED in 3 seconds
{
  "alert": "",
  "args": {
    "bucketName": "bucket-gvkrovcvrewgpfz2h82p4t8a1qvubccbesde8v01widcfz74mj823vr",
    "expiry": 60000000000,
    "objectName": "testObject"
  },
  "duration": 3068,
  "error": "RequestError: send request failed\ncaused by: Put http://72.28.97.57:31090/bucket-gvkrovcvrewgpfz2h82p4t8a1qvubccbesde8v01widcfz74mj823vr: dial tcp 72.28.97.57:31090: connect: no route to host",
  "function": "PutAndDelete",
  "message": "WORM_MODE ON  - CreateBucket Failed",
  "name": "test worm mode",
  "status": "FAIL"
}

Executed 0 out of 1 tests successfully.

7498-f79072f/mint-gateway-nas.sh.log:

Running with
SERVER_ENDPOINT:      72.28.97.57:32503
ACCESS_KEY:           minio
SECRET_KEY:           ***REDACTED***
ENABLE_HTTPS:         0
SERVER_REGION:        us-east-1
MINT_DATA_DIR:        /mint/data
MINT_MODE:            full
ENABLE_VIRTUAL_STYLE: 0

To get logs, run 'docker cp af229612f000:/mint/log /tmp/mint-logs'

(1/14) Running aws-sdk-go tests ... FAILED in 3 seconds
{
  "alert": "",
  "args": {
    "bucketName": "aws-sdk-go-test-ck6n3vgomiuyff",
    "expiry": 60000000000,
    "objectName": "presignedTest"
  },
  "duration": 2722,
  "error": "RequestError: send request failed\ncaused by: Put http://72.28.97.57:32503/aws-sdk-go-test-ck6n3vgomiuyff: dial tcp 72.28.97.57:32503: connect: no route to host",
  "function": "PresignedPut",
  "message": "AWS SDK Go CreateBucket Failed",
  "name": "aws-sdk-go",
  "status": "FAIL"
}

Executed 0 out of 14 tests successfully.