minio/minio

S3 API

MinIO implements the S3 REST API. The router is cmd/api-router.go; verbs are dispatched to handlers across several files. This page is an inventory, not a spec — refer to AWS S3 docs for argument details.

Object operations

Operation	Handler file
`PutObject`	`cmd/object-handlers.go`
`GetObject` / `HeadObject`	`cmd/object-handlers.go`
`DeleteObject` / `DeleteObjects`	`cmd/object-handlers.go`
`CopyObject`	`cmd/object-handlers.go`
`PutObjectTagging` / `GetObjectTagging` / `DeleteObjectTagging`	`cmd/object-handlers.go`
`PutObjectAcl` / `GetObjectAcl`	`cmd/acl-handlers.go`
`PutObjectRetention` / `PutObjectLegalHold`	`cmd/object-handlers.go`
`RestoreObject`	`cmd/object-handlers.go`
`SelectObjectContent`	`cmd/object-handlers.go` (delegates to `internal/s3select/`)

Multipart upload

Operation	Handler file
`CreateMultipartUpload`	`cmd/object-multipart-handlers.go`
`UploadPart` / `UploadPartCopy`	`cmd/object-multipart-handlers.go`
`CompleteMultipartUpload`	`cmd/object-multipart-handlers.go`
`AbortMultipartUpload`	`cmd/object-multipart-handlers.go`
`ListParts`	`cmd/object-multipart-handlers.go`
`ListMultipartUploads`	`cmd/object-multipart-handlers.go`

Bucket operations

Operation	Handler file
`CreateBucket`, `DeleteBucket`	`cmd/bucket-handlers.go`
`ListBuckets`	`cmd/bucket-handlers.go`
`HeadBucket`	`cmd/bucket-handlers.go`
`ListObjects` (V1, V2)	`cmd/bucket-listobjects-handlers.go`
`ListObjectVersions`	`cmd/bucket-listobjects-handlers.go`
`Put/Get/Delete BucketPolicy`	`cmd/bucket-policy-handlers.go`
`Put/Get BucketVersioning`	`cmd/bucket-versioning-handler.go`
`Put/Get BucketLifecycleConfiguration`	`cmd/bucket-lifecycle-handlers.go`
`Put/Get BucketReplication`	`cmd/bucket-replication-handlers.go`
`Put/Get BucketEncryption`	`cmd/bucket-encryption-handlers.go`
`Put/Get BucketNotificationConfiguration`	`cmd/bucket-notification-handlers.go`
`Put/Get BucketTagging`	`cmd/bucket-handlers.go`
`Put/Get BucketObjectLockConfiguration`	`cmd/bucket-object-lock.go`
`Get/Put BucketCors`	`cmd/bucket-handlers.go`
`Get BucketLocation`	`cmd/bucket-handlers.go`
`Get/Put BucketACL`	`cmd/acl-handlers.go`

Streaming and signed URLs

Streaming SigV4 (AWS-Chunked) is implemented in cmd/streaming-signature-v4.go.
Unsigned trailer mode is in cmd/streaming-v4-unsigned.go.
Pre-signed URL validation is in cmd/signature-v4.go.
POST policy uploads are in cmd/postpolicyform.go and cmd/post-policy-fan-out.go.

Rejected / not-implemented

cmd/api-router.go explicitly rejects a few S3 features (?torrent, ?accelerate, ?requestPayment, ...) with NotImplemented. The list is in the file's rejectedObjAPIs and rejectedBucketAPIs.

CORS

Standard AWS CORS rules with default-on per-bucket configuration support. Implemented in cmd/bucket-handlers.go and middleware in cmd/api-router.go (uses github.com/rs/cors).

CompleteMultipartUpload tweaks

MinIO supports a few non-standard tweaks the AWS spec doesn't cover:

"Fan-out" upload: a single uploaded object can be replicated into multiple keys via the x-minio-fan-out header (cmd/post-policy-fan-out.go).
Implicit checksums: when a client doesn't include x-amz-checksum-*, MinIO computes one anyway and surfaces it in the response.

Errors

Every S3 error code maps to an entry in cmd/api-errors.go (95 KB of switch + descriptors). The string table is generated by stringer (apierrorcode_string.go). Custom MinIO-only codes start with MinIO.