- do not fail the healthcheck if heal status
was not obtained from one of the nodes,
if many nodes fail then report this as a
catastrophic error.
- add "x-minio-write-quorum" value to match
the write tolerance supported by server.
- admin info now states if a drive is healing
where madmin.Disk.Healing is set to true
and madmin.Disk.State is "ok"
This commit addresses a maintenance / automation problem when MinIO-KES
is deployed on bare-metal. In orchestrated env. the orchestrator (K8S)
will make sure that `n` KES servers (IPs) are available via the same DNS
name. There it is sufficient to provide just one endpoint.
If DiskInfo calls failed the information returned was used anyway
resulting in no endpoint being set.
This would make the drive be attributed to the local system since
`disk.Endpoint == disk.DrivePath` in that case.
Instead, if the call fails record the endpoint and the error only.
newDynamicTimeout should be allocated once, in-case
of temporary locks in config and IAM we should
have allocated timeout once before the `for loop`
This PR doesn't fix any issue as such, but provides
enough dynamism for the timeout as per expectation.
- admin info node offline check is now quicker
- admin info now doesn't duplicate the code
across doing the same checks for disks
- rely on StorageInfo to return appropriate errors
instead of calling locally.
- diskID checks now return proper errors when
disk not found v/s format.json missing.
- add more disk states for more clarity on the
underlying disk errors.
This commit adds a new admin API for creating master keys.
An admin client can send a POST request to:
```
/minio/admin/v3/kms/key/create?key-id=<keyID>
```
The name / ID of the new key is specified as request
query parameter `key-id=<ID>`.
Creating new master keys requires KES - it does not work with
the native Vault KMS (deprecated) nor with a static master key
(deprecated).
Further, this commit removes the `UpdateKey` method from the `KMS`
interface. This method is not needed and not used anymore.
object KMS is configured with auto-encryption,
there were issues when using docker registry -
this has been left unnoticed for a while.
This PR fixes an issue with compatibility.
Additionally also fix the continuation-token implementation
infinite loop issue which was missed as part of #9939
Also fix the heal token to be generated as a client
facing value instead of what is remembered by the
server, this allows for the server to be stateless
regarding the token's behavior.
When manual healing is triggered, one node in a cluster will
become the authority to heal. mc regularly sends new requests
to fetch the status of the ongoing healing process, but a load
balancer could land the healing request to a node that is not
doing the healing request.
This PR will redirect a request to the node based on the node
index found described as part of the client token. A similar
technique is also used to proxy ListObjectsV2 requests
by encoding this information in continuation-token
Bonus fix during versioning merge one of the PR was missing
the offline/online disk count fix from #9801 port it correctly
over to the master branch from release.
Additionally, add versionID support for MRF
Fixes#9910Fixes#9931
- Implement a new xl.json 2.0.0 format to support,
this moves the entire marshaling logic to POSIX
layer, top layer always consumes a common FileInfo
construct which simplifies the metadata reads.
- Implement list object versions
- Migrate to siphash from crchash for new deployments
for object placements.
Fixes#2111
Bonus fixes in quota enforcement to use the
new datastructure and use timedValue to cache
a value/reload automatically avoids one less
global variable.
this is a major overhaul by migrating off all
bucket metadata related configs into a single
object '.metadata.bin' this allows us for faster
bootups across 1000's of buckets and as well
as keeps the code simple enough for future
work and additions.
Additionally also fixes#9396, #9394
enable linter using golangci-lint across
codebase to run a bunch of linters together,
we shall enable new linters as we fix more
things the codebase.
This PR fixes the first stage of this
cleanup.
- elasticsearch client should rely on the SDK helpers
instead of pure HTTP calls.
- webhook shouldn't need to check for IsActive() for
all notifications, failure should be delayed.
- Remove DialHTTP as its never used properly
Fixes#9460
This PR fixes couple of behaviors with service accounts
- not need to have session token for service accounts
- service accounts can be generated by any user for themselves
implicitly, with a valid signature.
- policy input for AddNewServiceAccount API is not fully typed
allowing for validation before it is sent to the server.
- also bring in additional context for admin API errors if any
when replying back to client.
- deprecate GetServiceAccount API as we do not need to reply
back session tokens
- Introduced a function `FetchRegisteredTargets` which will return
a complete set of registered targets irrespective to their states,
if the `returnOnTargetError` flag is set to `False`
- Refactor NewTarget functions to return non-nil targets
- Refactor GetARNList() to return a complete list of configured targets
- Removes PerfInfo admin API as its not OBDInfo
- Keep the drive path without the metaBucket in OBD
global latency map.
- Remove all the unused code related to PerfInfo API
- Do not redefined global mib,gib constants use
humanize.MiByte and humanize.GiByte instead always
- Implement a graph algorithm to test network bandwidth from every
node to every other node
- Saturate any network bandwidth adaptively, accounting for slow
and fast network capacity
- Implement parallel drive OBD tests
- Implement a paging mechanism for OBD test to provide periodic updates to client
- Implement Sys, Process, Host, Mem OBD Infos
- Add conservative timeouts upto 3 minutes
for internode communication
- Add aggressive timeouts of 30 seconds
for gateway communication
Fixes#9105Fixes#8732Fixes#8881Fixes#8376Fixes#9028
This is to improve responsiveness for all
admin API operations and allowing callers
to cancel any on-going admin operations,
if they happen to be waiting too long.
- avoid setting last heal activity when starting self-healing
This can be confusing to users thinking that the self healing
cycle was already performed.
- add info about the next background healing round
Metrics used to have its own code to calculate offline disks.
StorageInfo() was avoided because it is an expensive operation
by sending calls to all nodes.
To make metrics & server info share the same code, a new
argument `local` is added to StorageInfo() so it will only
query local disks when needed.
Metrics now calls StorageInfo() as server info handler does
but with the local flag set to false.
Co-authored-by: Praveen raj Mani <praveen@minio.io>
Co-authored-by: Harshavardhana <harsha@minio.io>
This commit fixes typos in the displayed server info
w.r.t. the KMS and removes the update status.
For more information about why the update status
is removed see: PR #8943
This commit removes the `Update` functionality
from the admin API. While this is technically
a breaking change I think this will not cause
any harm because:
- The KMS admin API is not complete, yet.
At the moment only the status can be fetched.
- The `mc` integration hasn't been merged yet.
So no `mc` client could have used this API
in the past.
The `Update`/`Rewrap` status is not useful anymore.
It provided a way to migrate from one master key version
to another. However, KES does not support the concept of
key versions. Instead, key migration should be implemented
as migration from one master key to another.
Basically, the `Update` functionality has been implemented just
for Vault.
The server info handler makes a http connection to other
nodes to check if they are up but does not load the custom
CAs in ~/.minio/certs/CAs.
This commit fix it.
Co-authored-by: Harshavardhana <harsha@minio.io>
On every restart of the server, usage was being
calculated which is not useful instead wait for
sufficient time to start the crawling routine.
This PR also avoids lots of double allocations
through strings, optimizes usage of string builders
and also avoids crawling through symbolic links.
Fixes#8844
- Stop spawning store replay routines when testing the notification targets
- Properly honor the target.Close() to clean the resources used
Fixes#8707
Co-authored-by: Harshavardhana <harsha@minio.io>
In existing functionality we simply return a generic
error such as "MalformedPolicy" which indicates just
a generic string "invalid resource" which is not very
meaningful when there might be multiple types of errors
during policy parsing. This PR ensures that we send
these errors back to client to indicate the actual
error, brings in two concrete types such as
- iampolicy.Error
- policy.Error
Refer #8202
Admin data usage info API returns the following
(Only FS & XL, for now)
- Number of buckets
- Number of objects
- The total size of objects
- Objects histogram
- Bucket sizes
This PR adds support below metrics
- Cache Hit Count
- Cache Miss Count
- Data served from Cache (in Bytes)
- Bytes received from AWS S3
- Bytes sent to AWS S3
- Number of requests sent to AWS S3
Fixes#8549
This PR implements locking from a global entity into
a more localized set level entity, allowing for locks
to be held only on the resources which are writing
to a collection of disks rather than a global level.
In this process this PR also removes the top-level
limit of 32 nodes to an unlimited number of nodes. This
is a precursor change before bring in bucket expansion.
This PR refactors object layer handling such
that upon failure in sub-system initialization
server reaches a stage of safe-mode operation
wherein only certain API operations are enabled
and available.
This allows for fixing many scenarios such as
- incorrect configuration in vault, etcd,
notification targets
- missing files, incomplete config migrations
unable to read encrypted content etc
- any other issues related to notification,
policies, lifecycle etc
This PR adds code to appropriately handle versioning issues
that come up quite constantly across our API changes. Currently
we were also routing our requests wrong which sort of made it
harder to write a consistent error handling code to appropriately
reject or honor requests.
This PR potentially fixes issues
- old mc is used against new minio release which is incompatible
returns an appropriate for client action.
- any older servers talking to each other, report appropriate error
- incompatible peer servers should report error and reject the calls
with appropriate error
This commit replaces the returned error message by
the hardware info handler from `Method-Not-Allowed`
to `Bad-Request` since the current HTTP error is not
correct according to the HTTP spec.
In particular:
```
The origin server MUST generate an Allow header field
in a 405 response containing a list of the target
resource's currently supported methods.
```
From: https://tools.ietf.org/html/rfc7231#section-6.5.5
- This PR allows config KVS to be validated properly
without being affected by ENV overrides, rejects
invalid values during set operation
- Expands unit tests and refactors the error handling
for notification targets, returns error instead of
ignoring targets for invalid KVS
- Does all the prep-work for implementing safe-mode
style operation for MinIO server, introduces a new
global variable to toggle safe mode based operations
NOTE: this PR itself doesn't provide safe mode operations
- adding oauth support to MinIO browser (#8400) by @kanagaraj
- supports multi-line get/set/del for all config fields
- add support for comments, allow toggle
- add extensive validation of config before saving
- support MinIO browser to support proper claims, using STS tokens
- env support for all config parameters, legacy envs are also
supported with all documentation now pointing to latest ENVs
- preserve accessKey/secretKey from FS mode setups
- add history support implements three APIs
- ClearHistory
- RestoreHistory
- ListHistory
- add help command support for each config parameters
- all the bug fixes after migration to KV, and other bug
fixes encountered during testing.
The measures are consolidated to the following metrics
- `disk_storage_used` : Disk space used by the disk.
- `disk_storage_available`: Available disk space left on the disk.
- `disk_storage_total`: Total disk space on the disk.
- `disks_offline`: Total number of offline disks in current MinIO instance.
- `disks_total`: Total number of disks in current MinIO instance.
- `s3_requests_total`: Total number of s3 requests in current MinIO instance.
- `s3_errors_total`: Total number of errors in s3 requests in current MinIO instance.
- `s3_requests_current`: Total number of active s3 requests in current MinIO instance.
- `internode_rx_bytes_total`: Total number of internode bytes received by current MinIO server instance.
- `internode_tx_bytes_total`: Total number of bytes sent to the other nodes by current MinIO server instance.
- `s3_rx_bytes_total`: Total number of s3 bytes received by current MinIO server instance.
- `s3_tx_bytes_total`: Total number of s3 bytes sent by current MinIO server instance.
- `minio_version_info`: Current MinIO version with commit-id.
- `s3_ttfb_seconds_bucket`: Histogram that holds the latency information of the requests.
And this PR also modifies the current StorageInfo queries
- Decouples StorageInfo from ServerInfo .
- StorageInfo is enhanced to give endpoint information.
NOTE: ADMIN API VERSION IS BUMPED UP IN THIS PR
Fixes#7873
specific errors, `application` errors or `all` by default.
console logging on server by default lists all logs -
enhance admin console API to accept `type` as query parameter to
subscribe to application/minio logs.
endpoint.IsLocal will not have .Host entries so
using them to skip double entries will never work.
change the code such that we look for endpoint.Host
outside of endpoint.IsLocal logic to skip double
hosts appropriately.
Move these functions to their appropriate file.
Add LDAP based users-groups system
This change adds support to integrate an LDAP server for user
authentication. This works via a custom STS API for LDAP. Each user
accessing the MinIO who can be authenticated via LDAP receives
temporary credentials to access the MinIO server.
LDAP is enabled only over TLS.
User groups are also supported via LDAP. The administrator may
configure an LDAP search query to find the group attribute of a user -
this may correspond to any attribute in the LDAP tree (that the user
has access to view). One or more groups may be returned by such a
query.
A group is mapped to an IAM policy in the usual way, and the server
enforces a policy corresponding to all the groups and the user's own
mapped policy.
When LDAP is configured, the internal MinIO users system is disabled.
It looks like from implementation point of view fastjson
parser pool doesn't behave the same way as expected
when dealing many `xl.json` from multiple disks.
The fastjson parser pool usage ends up returning incorrect
xl.json entries for checksums, with references pointing
to older entries. This led to the subtle bug where checksum
info is duplicated from a previous xl.json read of a different
file from different disk.
This commit adds an admin API route and handler for
requesting status information about a KMS key.
Therefore, the client specifies the KMS key ID (when
empty / not set the server takes the currently configured
default key-ID) and the server tries to perform a dummy encryption,
re-wrap and decryption operation. If all three succeed we know that
the server can access the KMS and has permissions to generate, re-wrap
and decrypt data keys (policy is set correctly).
The change now is to ensure that we take custom URL as
well for updating the deployment, this is required for
hotfix deliveries for certain deployments - other than
the community release.
This commit changes the previous work d65a2c6725
with newer set of requirements.
Also deprecates PeerUptime()
Add API to set policy mapping for a user or group
Contains a breaking Admin APIs change.
- Also enforce all applicable policies
- Removes the previous /set-user-policy API
Bump up peerRESTVersion
Add get user info API to show groups of a user
This change adds admin APIs and IAM subsystem APIs to:
- add or remove members to a group (group addition and deletion is
implicit on add and remove)
- enable/disable a group
- list and fetch group info
This PR fixes relying on r.Context().Done()
by setting
```
Connection: "close"
```
HTTP Header, this has detrimental issues for
client side connection pooling. Since this
header explicitly tells clients to turn-off
connection pooling. This causing pro-active
connections to be closed leaving many conn's
in TIME_WAIT state. This can be observed with
`mc admin trace -a` when running distributed
setup.
This PR also fixes tracing filtering issue
when bucket names have `minio` as prefixes,
trace was erroneously ignoring them.
- Policy mapping is now at `config/iam/policydb/users/myuser1.json`
and includes version.
- User identity file is now versioned.
- Migrate old data to the new format.
When MinIO is behind a proxy, proxies end up killing
clients when no data is seen on the connection, adding
the right content-type ensures that proxies do not come
in the way.
This allows for canonicalization of the strings
throughout our code and provides a common space
for all these constants to reside.
This list is rather non-exhaustive but captures
all the headers used in AWS S3 API operations
This API returns the information related to the self healing routine.
For the moment, it returns:
- The total number of objects that are scanned
- The last time when an item was scanned
This commit fixes a privilege escalation issue against
the S3 and web handlers. An authenticated IAM user
can:
- Read from or write to the internal '.minio.sys'
bucket by simply sending a properly signed
S3 GET or PUT request. Further, the user can
- Read from or write to the internal '.minio.sys'
bucket using the 'Upload'/'Download'/'DownloadZIP'
API by sending a "browser" request authenticated
with its JWT token.
It is required to set the environment variable in the case of distributed
minio. LoadCredentials is used to notify peers of the change and will not work if
environment variable is set. so, this function will never be called.
Different gateway implementations due to different backend
API errors, might return different unsupported errors at
our handler layer. Current code posed a problem for us because
this information was lost and we would convert it to InternalError
in this situation all S3 clients end up retrying the request.
To avoid this unexpected situation implement a way to support
this cleanly such that the underlying information is not lost
which is returned by gateway.
Collect historic cpu and mem stats. Also, use actual values
instead of formatted strings while returning to the client. The string
formatting prevents values from being processed by the server or
by the client without parsing it.
This change will allow the values to be processed (eg.
compute rolling-average over the lifetime of the minio server)
and offloads the formatting to the client.
Deprecate the use of Admin Peers concept and migrate all peer
communication to Notification subsystem. This finally allows
for a common subsystem for all peer notification in case of
distributed server deployments.
This is part of implementation for mc admin health command. The
ServerDrivesPerfInfo() admin API returns read and write speed
information for all the drives (local and remote) in a given Minio
server deployment.
Part of minio/mc#2606
In many situations, while testing we encounter
ErrInternalError, to reduce logging we have
removed logging from quite a few places which
is acceptable but when ErrInternalError occurs
we should have a facility to log the corresponding
error, this helps to debug Minio server.
This PR introduces two new features
- AWS STS compatible STS API named AssumeRoleWithClientGrants
```
POST /?Action=AssumeRoleWithClientGrants&Token=<jwt>
```
This API endpoint returns temporary access credentials, access
tokens signature types supported by this API
- RSA keys
- ECDSA keys
Fetches the required public key from the JWKS endpoints, provides
them as rsa or ecdsa public keys.
- External policy engine support, in this case OPA policy engine
- Credentials are stored on disks
When download profiling data API fails to gather profiling data
from all nodes for any reason (including profiler not enabled),
return 400 http code with the appropriate json message.
Two handlers are added to admin API to enable profiling and disable
profiling of a server in a standalone mode, or all nodes in the
distributed mode.
/minio/admin/profiling/start/{cpu,block,mem}:
- Start profiling and return starting JSON results, e.g. one
node is offline.
/minio/admin/profiling/download:
- Stop the on-going profiling task
- Stream a zip file which contains all profiling files that can
be later inspected by go tool pprof
This PR adds two new admin APIs in Minio server and madmin package:
- GetConfigKeys(keys []string) ([]byte, error)
- SetConfigKeys(params map[string]string) (err error)
A key is a path in Minio configuration file, (e.g. notify.webhook.1)
The user will always send a string value when setting it in the config file,
the API will know how to convert the value to the appropriate type. The user
is also able to set a raw json.
Before setting a new config, Minio will validate all fields and try to connect
to notification targets if available.
This PR is the first set of changes to move the config
to the backend, the changes use the existing `config.json`
allows it to be migrated such that we can save it in on
backend disks.
In future releases, we will slowly migrate out of the
current architecture.
Fixes#6182
No locks are ever left in memory, we also
have a periodic interval of clearing stale locks
anyways. The lock instrumentation was not complete
and was seldom used.
Deprecate this for now and bring it back later if
it is really needed. This also in-turn seems to improve
performance slightly.
Currently, requestid field in logEntry is not populated, as the
requestid field gets set at the very end.
It is now set before regular handler functions. This is also
useful in setting it as part of the XML error response.
Travis build for ppc64le has been quite inconsistent and stays queued
for most of the time. Removing this build as part of Travis.yml for
the time being.
Added support for new RPC support using HTTP POST. RPC's
arguments and reply are Gob encoded and sent as HTTP
request/response body.
This patch also removes Go RPC based implementation.
This commit ensures that all tickers are stopped using defer ticker.Stop()
style. This will also fix one bug seen when a client starts to listen to
event notifications and that case will result a leak in tickers.
As we move to multiple config backends like local disk and etcd,
config file should not be read from the disk, instead the quick
package should load and verify for duplicate entries.
This PR implements an object layer which
combines input erasure sets of XL layers
into a unified namespace.
This object layer extends the existing
erasure coded implementation, it is assumed
in this design that providing > 16 disks is
a static configuration as well i.e if you started
the setup with 32 disks with 4 sets 8 disks per
pack then you would need to provide 4 sets always.
Some design details and restrictions:
- Objects are distributed using consistent ordering
to a unique erasure coded layer.
- Each pack has its own dsync so locks are synchronized
properly at pack (erasure layer).
- Each pack still has a maximum of 16 disks
requirement, you can start with multiple
such sets statically.
- Static sets set of disks and cannot be
changed, there is no elastic expansion allowed.
- Static sets set of disks and cannot be
changed, there is no elastic removal allowed.
- ListObjects() across sets can be noticeably
slower since List happens on all servers,
and is merged at this sets layer.
Fixes#5465Fixes#5464Fixes#5461Fixes#5460Fixes#5459Fixes#5458Fixes#5460Fixes#5488Fixes#5489Fixes#5497Fixes#5496
* Update the GetConfig admin API to use the latest version of
configuration, along with fixes to the corresponding RPCs.
* Remove mutex inside the configuration struct, and inside
notification struct.
* Use global config mutex where needed.
* Add `serverConfig.ConfigDiff()` that provides a more granular diff
of what is different between two configurations.
- Changes related to moving admin APIs
- admin APIs now have an endpoint under /minio/admin
- admin APIs are now versioned - a new API to server the version is
added at "GET /minio/admin/version" and all API operations have the
path prefix /minio/admin/v1/<operation>
- new service stop API added
- credentials change API is moved to /minio/admin/v1/config/credential
- credentials change API and configuration get/set API now require TLS
so that credentials are protected
- all API requests now receive JSON
- heal APIs are disabled as they will be changed substantially
- Heal API changes
Heal API is now provided at a single endpoint with the ability for a
client to start a heal sequence on all the data in the server, a
single bucket, or under a prefix within a bucket.
When a heal sequence is started, the server returns a unique token
that needs to be used for subsequent 'status' requests to fetch heal
results.
On each status request from the client, the server returns heal result
records that it has accumulated since the previous status request. The
server accumulates upto 1000 records and pauses healing further
objects until the client requests for status. If the client does not
request any further records for a long time, the server aborts the
heal sequence automatically.
A heal result record is returned for each entity healed on the server,
such as system metadata, object metadata, buckets and objects, and has
information about the before and after states on each disk.
A client may request to force restart a heal sequence - this causes
the running heal sequence to be aborted at the next safe spot and
starts a new heal sequence.
This change fixes an authentication bypass attack against the
minio Admin-API. Therefore the Admin-API rejects now all types of
requests except valid signature V2 and signature V4 requests - this
includes signature V2/V4 pre-signed requests.
Fixes#5411
Since the server performs automatic clean-up of multipart uploads that
have not been resumed for more than a couple of weeks, it was decided
to remove functionality to heal multipart uploads.
- Return error when the config JSON has duplicate keys (fixes#5286)
- Limit size of configuration file provided to 256KiB - this prevents
another form of DoS
This change introduces following simplified steps to follow
during config migration.
```
// Steps to move from version N to version N+1
// 1. Add new struct serverConfigVN+1 in config-versions.go
// 2. Set configCurrentVersion to "N+1"
// 3. Set serverConfigCurrent to serverConfigVN+1
// 4. Add new migration function (ex. func migrateVNToVN+1()) in config-migrate.go
// 5. Call migrateVNToVN+1() from migrateConfig() in config-migrate.go
// 6. Make changes in config-current_test.go for any test change
```
`disksUnavailable` healStatus constant indicates that a given object
needs healing but one or more of disks requiring heal are offline. This
can be used by admin heal API consumers to distinguish between a
successful heal and a no-op since the outdated disks were offline.
This API is meant for administrative tools like mc-admin to heal an
ongoing multipart upload on a Minio server. N B This set of admin
APIs apply only for Minio servers.
`github.com/minio/minio/pkg/madmin` provides a go SDK for this (and
other admin) operations. Specifically,
func HealUpload(bucket, object, uploadID string, dryRun bool) error
Sample admin API request:
POST
/?heal&bucket=mybucket&object=myobject&upload-id=myuploadID&dry-run
- Header(s): ["x-minio-operation"] = "upload"
Notes:
- bucket, object and upload-id are mandatory query parameters
- if dry-run is set, API returns success if all parameters passed are
valid.
Also changes the behavior of `secretKeyHash` which is
not necessary to be sent over the network, each node
has its own secretKeyHash to validate.
Fixes#3696
Partial(fix) #3700 (More changes needed with some code cleanup)
Following is a sample list lock API request schematic,
/?lock&bucket=mybucket&prefix=myprefix&duration=holdDuration
x-minio-operation: list
The response would contain the list of locks held on mybucket matching
myprefix for a duration longer than holdDuration.
Creds don't require secretKeyHash to be calculated
everytime, cache it instead and re-use.
This is an optimization for bcrypt.
Relevant results from the benchmark done locally, negative
value means improvement in this scenario.
```
benchmark old ns/op new ns/op delta
BenchmarkAuthenticateNode-4 160590992 80125647 -50.11%
BenchmarkAuthenticateWeb-4 160556692 80432144 -49.90%
benchmark old allocs new allocs delta
BenchmarkAuthenticateNode-4 87 75 -13.79%
BenchmarkAuthenticateWeb-4 87 75 -13.79%
benchmark old bytes new bytes delta
BenchmarkAuthenticateNode-4 15222 9785 -35.72%
BenchmarkAuthenticateWeb-4 15222 9785 -35.72%
```
* Implement heal format REST API handler
* Implement admin peer rpc handler to re-initialize storage
* Implement HealFormat API in pkg/madmin
* Update pkg/madmin API.md to incl. HealFormat
* Added unit tests for ReInitDisks rpc handler and HealFormatHandler
Golang HTTP client automatically detects content-type but
for S3 clients this content-type might be incorrect or
might misbehave.
For example:
```
Content-Type: text/xml; charset=utf-8
```
Should be
```
Content-Type: application/xml
```
Allow this to be set properly.
* Filter lock info based on bucket, prefix and time since lock was held
* Implement list and clear locks REST API
* madmin: Add list and clear locks API
* locks: Clear locks matching bucket, prefix, relTime.
* Gather lock information across nodes for both list and clear locks admin REST API.
* docs: Add lock API to management APIs
