restic/vendor/github.com/minio/minio-go/docs/API.md

Minio Go Client API Reference

Initialize Minio Client object.

Minio

package main

import (
    "fmt"

    "github.com/minio/minio-go"
)

func main() {
        // Use a secure connection.
        ssl := true

        // Initialize minio client object.
        minioClient, err := minio.New("play.minio.io:9000", "Q3AM3UQ867SPQQA43P2F", "zuf+tfteSlswRu7BJ86wekitnifILbZam1KYY3TG", ssl)
        if err != nil {
                fmt.Println(err)
                return
        }
}

AWS S3

package main

import (
    "fmt"

    "github.com/minio/minio-go"
)

func main() {
        // Use a secure connection.
        ssl := true

        // Initialize minio client object.
        s3Client, err := minio.New("s3.amazonaws.com", "YOUR-ACCESSKEYID", "YOUR-SECRETACCESSKEY", ssl)
        if err != nil {
                fmt.Println(err)
                return
        }
}

Bucket operations	Object operations	Encrypted Object operations	Presigned operations	Bucket Policy/Notification Operations	Client custom settings
MakeBucket	GetObject	NewSymmetricKey	PresignedGetObject	SetBucketPolicy	SetAppInfo
ListBuckets	PutObject	NewAsymmetricKey	PresignedPutObject	GetBucketPolicy	SetCustomTransport
BucketExists	PutObjectStreaming	GetEncryptedObject	PresignedPostPolicy	ListBucketPolicies	TraceOn
RemoveBucket	CopyObject	PutEncryptedObject		SetBucketNotification	TraceOff
ListObjects	StatObject	NewSSEInfo		GetBucketNotification	SetS3TransferAccelerate
ListObjectsV2	RemoveObject			RemoveAllBucketNotification
ListIncompleteUploads	RemoveObjects			ListenBucketNotification
	RemoveIncompleteUpload
	FPutObject
	FGetObject
	ComposeObject
	NewSourceInfo
	NewDestinationInfo

1. Constructor

New(endpoint, accessKeyID, secretAccessKey string, ssl bool) (*Client, error)

Initializes a new client object.

Parameters

Param	Type	Description
endpoint	string	S3 compatible object storage endpoint
accessKeyID	string	Access key for the object storage
secretAccessKey	string	Secret key for the object storage
ssl	bool	If 'true' API requests will be secure (HTTPS), and insecure (HTTP) otherwise

NewWithRegion(endpoint, accessKeyID, secretAccessKey string, ssl bool, region string) (*Client, error)

Initializes minio client, with region configured. Unlike New(), NewWithRegion avoids bucket-location lookup operations and it is slightly faster. Use this function when if your application deals with single region.

Parameters

Param	Type	Description
endpoint	string	S3 compatible object storage endpoint
accessKeyID	string	Access key for the object storage
secretAccessKey	string	Secret key for the object storage
ssl	bool	If 'true' API requests will be secure (HTTPS), and insecure (HTTP) otherwise
region	string	Region for the object storage

2. Bucket operations

MakeBucket(bucketName, location string) error

Creates a new bucket.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
location	string	Region where the bucket is to be created. Default value is us-east-1. Other valid values are listed below. Note: When used with minio server, use the region specified in its config file (defaults to us-east-1).
		us-east-1
		us-west-1
		us-west-2
		eu-west-1
		eu-central-1
		ap-southeast-1
		ap-northeast-1
		ap-southeast-2
		sa-east-1

Example

err := minioClient.MakeBucket("mybucket", "us-east-1")
if err != nil {
    fmt.Println(err)
    return
}
fmt.Println("Successfully created mybucket.")

ListBuckets() ([]BucketInfo, error)

Lists all buckets.

Param	Type	Description
bucketList	[]BucketInfo	Lists of all buckets

Param	Type	Description
bucket.Name	string	Name of the bucket
bucket.CreationDate	time.Time	Date of bucket creation

Example

buckets, err := minioClient.ListBuckets()
    if err != nil {
    fmt.Println(err)
    return
}
for _, bucket := range buckets {
    fmt.Println(bucket)
}

BucketExists(bucketName string) (found bool, err error)

Checks if a bucket exists.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket

Return Values

Param	Type	Description
found	bool	Indicates whether bucket exists or not
err	error	Standard Error

Example

found, err := minioClient.BucketExists("mybucket")
if err != nil {
    fmt.Println(err)
    return
}
if found {
    fmt.Println("Bucket found")
}

RemoveBucket(bucketName string) error

Removes a bucket.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket

Example

err := minioClient.RemoveBucket("mybucket")
if err != nil {
    fmt.Println(err)
    return
}

ListObjects(bucketName, prefix string, recursive bool, doneCh chan struct{}) <-chan ObjectInfo

Lists objects in a bucket.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectPrefix	string	Prefix of objects to be listed
recursive	bool	true indicates recursive style listing and false indicates directory style listing delimited by '/'.
doneCh	chan struct{}	A message on this channel ends the ListObjects iterator.

Return Value

Param	Type	Description
chan ObjectInfo	chan ObjectInfo	Read channel for all objects in the bucket, the object is of the format listed below:

Param	Type	Description
objectInfo.Key	string	Name of the object
objectInfo.Size	int64	Size of the object
objectInfo.ETag	string	MD5 checksum of the object
objectInfo.LastModified	time.Time	Time when object was last modified

// Create a done channel to control 'ListObjects' go routine.
doneCh := make(chan struct{})

// Indicate to our routine to exit cleanly upon return.
defer close(doneCh)

isRecursive := true
objectCh := minioClient.ListObjects("mybucket", "myprefix", isRecursive, doneCh)
for object := range objectCh {
    if object.Err != nil {
        fmt.Println(object.Err)
        return
    }
    fmt.Println(object)
}

ListObjectsV2(bucketName, prefix string, recursive bool, doneCh chan struct{}) <-chan ObjectInfo

Lists objects in a bucket using the recommended listing API v2

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectPrefix	string	Prefix of objects to be listed
recursive	bool	true indicates recursive style listing and false indicates directory style listing delimited by '/'.
doneCh	chan struct{}	A message on this channel ends the ListObjectsV2 iterator.

Return Value

Param	Type	Description
chan ObjectInfo	chan ObjectInfo	Read channel for all the objects in the bucket, the object is of the format listed below:

Param	Type	Description
objectInfo.Key	string	Name of the object
objectInfo.Size	int64	Size of the object
objectInfo.ETag	string	MD5 checksum of the object
objectInfo.LastModified	time.Time	Time when object was last modified

// Create a done channel to control 'ListObjectsV2' go routine.
doneCh := make(chan struct{})

// Indicate to our routine to exit cleanly upon return.
defer close(doneCh)

isRecursive := true
objectCh := minioClient.ListObjectsV2("mybucket", "myprefix", isRecursive, doneCh)
for object := range objectCh {
    if object.Err != nil {
        fmt.Println(object.Err)
        return
    }
    fmt.Println(object)
}

ListIncompleteUploads(bucketName, prefix string, recursive bool, doneCh chan struct{}) <- chan ObjectMultipartInfo

Lists partially uploaded objects in a bucket.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
prefix	string	Prefix of objects that are partially uploaded
recursive	bool	true indicates recursive style listing and false indicates directory style listing delimited by '/'.
doneCh	chan struct{}	A message on this channel ends the ListenIncompleteUploads iterator.

Return Value

Param	Type	Description
chan ObjectMultipartInfo	chan ObjectMultipartInfo	Emits multipart objects of the format listed below:

Return Value

Param	Type	Description
multiPartObjInfo.Key	string	Name of incompletely uploaded object
multiPartObjInfo.UploadID	string	Upload ID of incompletely uploaded object
multiPartObjInfo.Size	int64	Size of incompletely uploaded object

Example

// Create a done channel to control 'ListObjects' go routine.
doneCh := make(chan struct{})

// Indicate to our routine to exit cleanly upon return.
defer close(doneCh)

isRecursive := true // Recursively list everything at 'myprefix'
multiPartObjectCh := minioClient.ListIncompleteUploads("mybucket", "myprefix", isRecursive, doneCh)
for multiPartObject := range multiPartObjectCh {
    if multiPartObject.Err != nil {
        fmt.Println(multiPartObject.Err)
        return
    }
    fmt.Println(multiPartObject)
}

3. Object operations

GetObject(bucketName, objectName string) (*Object, error)

Returns a stream of the object data. Most of the common errors occur when reading the stream.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectName	string	Name of the object

Return Value

Param	Type	Description
object	*minio.Object	minio.Object represents object reader. It implements io.Reader, io.Seeker, io.ReaderAt and io.Closer interfaces.

Example

object, err := minioClient.GetObject("mybucket", "photo.jpg")
if err != nil {
    fmt.Println(err)
    return
}
localFile, err := os.Create("/tmp/local-file.jpg")
if err != nil {
    fmt.Println(err)
    return
}
if _, err = io.Copy(localFile, object); err != nil {
    fmt.Println(err)
    return
}

FGetObject(bucketName, objectName, filePath string) error

Downloads and saves the object as a file in the local filesystem.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectName	string	Name of the object
filePath	string	Path to download object to

Example

err := minioClient.FGetObject("mybucket", "photo.jpg", "/tmp/photo.jpg")
if err != nil {
    fmt.Println(err)
    return
}

PutObject(bucketName, objectName string, reader io.Reader, contentType string) (n int, err error)

Uploads objects that are less than 64MiB in a single PUT operation. For objects that are greater than 64MiB in size, PutObject seamlessly uploads the object as parts of 64MiB or more depending on the actual file size. The max upload size for an object is 5TB.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectName	string	Name of the object
reader	io.Reader	Any Go type that implements io.Reader
contentType	string	Content type of the object

Example

file, err := os.Open("my-testfile")
if err != nil {
    fmt.Println(err)
    return
}
defer file.Close()

n, err := minioClient.PutObject("mybucket", "myobject", file, "application/octet-stream")
if err != nil {
    fmt.Println(err)
    return
}

PutObjectStreaming(bucketName, objectName string, reader io.Reader) (n int, err error)

Uploads an object as multiple chunks keeping memory consumption constant. It is similar to PutObject in how objects are broken into multiple parts. Each part in turn is transferred as multiple chunks with constant memory usage. However resuming previously failed uploads from where it was left is not supported.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectName	string	Name of the object
reader	io.Reader	Any Go type that implements io.Reader

Example

file, err := os.Open("my-testfile")
if err != nil {
    fmt.Println(err)
    return
}
defer file.Close()

n, err := minioClient.PutObjectStreaming("mybucket", "myobject", file)
if err != nil {
    fmt.Println(err)
    return
}

CopyObject(dst DestinationInfo, src SourceInfo) error

Create or replace an object through server-side copying of an existing object. It supports conditional copying, copying a part of an object and server-side encryption of destination and decryption of source. See the SourceInfo and DestinationInfo types for further details.

To copy multiple source objects into a single destination object see the ComposeObject API.

Parameters

Param	Type	Description
dst	DestinationInfo	Argument describing the destination object
src	SourceInfo	Argument describing the source object

Example

// Use-case 1: Simple copy object with no conditions, etc
// Source object
src := minio.NewSourceInfo("my-sourcebucketname", "my-sourceobjectname", nil)

// Destination object
dst, err := minio.NewDestinationInfo("my-bucketname", "my-objectname", nil, nil)
if err != nil {
    fmt.Println(err)
    return
}

// Copy object call
err = s3Client.CopyObject(dst, src)
if err != nil {
    fmt.Println(err)
    return
}

// Use-case 2: Copy object with copy-conditions, and copying only part of the source object.
// 1. that matches a given ETag
// 2. and modified after 1st April 2014
// 3. but unmodified since 23rd April 2014
// 4. copy only first 1MiB of object.

// Source object
src := minio.NewSourceInfo("my-sourcebucketname", "my-sourceobjectname", nil)

// Set matching ETag condition, copy object which matches the following ETag.
src.SetMatchETagCond("31624deb84149d2f8ef9c385918b653a")

// Set modified condition, copy object modified since 2014 April 1.
src.SetModifiedSinceCond(time.Date(2014, time.April, 1, 0, 0, 0, 0, time.UTC))

// Set unmodified condition, copy object unmodified since 2014 April 23.
src.SetUnmodifiedSinceCond(time.Date(2014, time.April, 23, 0, 0, 0, 0, time.UTC))

// Set copy-range of only first 1MiB of file.
src.SetRange(0, 1024*1024-1)

// Destination object
dst, err := minio.NewDestinationInfo("my-bucketname", "my-objectname", nil, nil)
if err != nil {
    fmt.Println(err)
    return
}

// Copy object call
err = s3Client.CopyObject(dst, src)
if err != nil {
    fmt.Println(err)
    return
}

ComposeObject(dst DestinationInfo, srcs []SourceInfo) error

Create an object by concatenating a list of source objects using server-side copying.

Parameters

Param	Type	Description
dst	minio.DestinationInfo	Struct with info about the object to be created.
srcs	[]minio.SourceInfo	Slice of struct with info about source objects to be concatenated in order.

Example

// Prepare source decryption key (here we assume same key to
// decrypt all source objects.)
decKey := minio.NewSSEInfo([]byte{1, 2, 3}, "")

// Source objects to concatenate. We also specify decryption
// key for each
src1 := minio.NewSourceInfo("bucket1", "object1", decKey)
src1.SetMatchETag("31624deb84149d2f8ef9c385918b653a")

src2 := minio.NewSourceInfo("bucket2", "object2", decKey)
src2.SetMatchETag("f8ef9c385918b653a31624deb84149d2")

src3 := minio.NewSourceInfo("bucket3", "object3", decKey)
src3.SetMatchETag("5918b653a31624deb84149d2f8ef9c38")

// Create slice of sources.
srcs := []minio.SourceInfo{src1, src2, src3}

// Prepare destination encryption key
encKey := minio.NewSSEInfo([]byte{8, 9, 0}, "")

// Create destination info
dst := minio.NewDestinationInfo("bucket", "object", encKey, nil)
err = s3Client.ComposeObject(dst, srcs)
if err != nil {
	log.Println(err)
	return
}

log.Println("Composed object successfully.")

NewSourceInfo(bucket, object string, decryptSSEC *SSEInfo) SourceInfo

Construct a SourceInfo object that can be used as the source for server-side copying operations like CopyObject and ComposeObject. This object can be used to set copy-conditions on the source.

Parameters

Param	Type	Description
bucket	string	Name of the source bucket
object	string	Name of the source object
decryptSSEC	*minio.SSEInfo	Decryption info for the source object (nil without encryption)

Example

// No decryption parameter.
src := NewSourceInfo("bucket", "object", nil)

// With decryption parameter.
decKey := NewSSEKey([]byte{1,2,3}, "")
src := NewSourceInfo("bucket", "object", decKey)

NewDestinationInfo(bucket, object string, encryptSSEC *SSEInfo, userMeta map[string]string) (DestinationInfo, error)

Construct a DestinationInfo object that can be used as the destination object for server-side copying operations like CopyObject and ComposeObject.

Parameters

Param	Type	Description
bucket	string	Name of the destination bucket
object	string	Name of the destination object
encryptSSEC	*minio.SSEInfo	Encryption info for the source object (nil without encryption)
userMeta	map[string]string	User metadata to be set on the destination. If nil, with only one source, user-metadata is copied from source.

Example

// No encryption parameter.
dst, err := NewDestinationInfo("bucket", "object", nil, nil)

// With encryption parameter.
encKey := NewSSEKey([]byte{1,2,3}, "")
dst, err := NewDecryptionInfo("bucket", "object", encKey, nil)

FPutObject(bucketName, objectName, filePath, contentType string) (length int64, err error)

Uploads contents from a file to objectName.

FPutObject uploads objects that are less than 64MiB in a single PUT operation. For objects that are greater than the 64MiB in size, FPutObject seamlessly uploads the object in chunks of 64MiB or more depending on the actual file size. The max upload size for an object is 5TB.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectName	string	Name of the object
filePath	string	Path to file to be uploaded
contentType	string	Content type of the object

Example

n, err := minioClient.FPutObject("mybucket", "myobject.csv", "/tmp/otherobject.csv", "application/csv")
if err != nil {
    fmt.Println(err)
    return
}

StatObject(bucketName, objectName string) (ObjectInfo, error)

Gets metadata of an object.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectName	string	Name of the object

Return Value

Param	Type	Description
objInfo	ObjectInfo	Object stat information

Param	Type	Description
objInfo.LastModified	time.Time	Time when object was last modified
objInfo.ETag	string	MD5 checksum of the object
objInfo.ContentType	string	Content type of the object
objInfo.Size	int64	Size of the object

Example

objInfo, err := minioClient.StatObject("mybucket", "photo.jpg")
if err != nil {
    fmt.Println(err)
    return
}
fmt.Println(objInfo)

RemoveObject(bucketName, objectName string) error

Removes an object.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectName	string	Name of the object

err := minioClient.RemoveObject("mybucket", "photo.jpg")
if err != nil {
    fmt.Println(err)
    return
}

RemoveObjects(bucketName string, objectsCh chan string) errorCh chan minio.RemoveObjectError

Removes a list of objects obtained from an input channel. The call sends a delete request to the server up to 1000 objects at a time. The errors observed are sent over the error channel.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectsCh	chan string	Prefix of objects to be removed

Return Values

Param	Type	Description
errorCh	_chan minio.RemoveObjectError	Channel of errors observed during deletion.

errorCh := minioClient.RemoveObjects("mybucket", objectsCh)
for e := range errorCh {
    fmt.Println("Error detected during deletion: " + e.Err.Error())
}

RemoveIncompleteUpload(bucketName, objectName string) error

Removes a partially uploaded object.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectName	string	Name of the object

Example

err := minioClient.RemoveIncompleteUpload("mybucket", "photo.jpg")
if err != nil {
    fmt.Println(err)
    return
}

4. Encrypted object operations

NewSymmetricKey(key []byte) *minio.SymmetricKey

Parameters

Param	Type	Description
key	string	Name of the bucket

Return Value

Param	Type	Description
symmetricKey	*minio.SymmetricKey	minio.SymmetricKey represents a symmetric key structure which can be used to encrypt and decrypt data.

symKey := minio.NewSymmetricKey([]byte("my-secret-key-00"))

NewAsymmetricKey(privateKey []byte, publicKey[]byte) (*minio.AsymmetricKey, error)

Parameters

Param	Type	Description
privateKey	[]byte	Private key data
publicKey	[]byte	Public key data

Return Value

Param	Type	Description
asymmetricKey	*minio.AsymmetricKey	represents an asymmetric key structure which can be used to encrypt and decrypt data.
err	error	encountered errors.

privateKey, err := ioutil.ReadFile("private.key")
if err != nil {
    log.Fatal(err)
}

publicKey, err := ioutil.ReadFile("public.key")
if err != nil {
    log.Fatal(err)
}

// Initialize the asymmetric key
asymmetricKey, err := minio.NewAsymmetricKey(privateKey, publicKey)
if err != nil {
    log.Fatal(err)
}

GetEncryptedObject(bucketName, objectName string, encryptMaterials minio.EncryptionMaterials) (io.ReadCloser, error)

Returns the decrypted stream of the object data based of the given encryption materiels. Most of the common errors occur when reading the stream.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectName	string	Name of the object
encryptMaterials	minio.EncryptionMaterials	The module to decrypt the object data

Return Value

Param	Type	Description
stream	io.ReadCloser	Returns the deciphered object reader, caller should close after reading.
err	_error	Returns errors.

Example

// Generate a master symmetric key
key := minio.NewSymmetricKey("my-secret-key-00")

// Build the CBC encryption material
cbcMaterials, err := NewCBCSecureMaterials(key)
if err != nil {
    t.Fatal(err)
}

object, err := minioClient.GetEncryptedObject("mybucket", "photo.jpg", cbcMaterials)
if err != nil {
    fmt.Println(err)
    return
}
defer object.Close()

localFile, err := os.Create("/tmp/local-file.jpg")
if err != nil {
    fmt.Println(err)
    return
}

if _, err = io.Copy(localFile, object); err != nil {
    fmt.Println(err)
    return
}

PutEncryptedObject(bucketName, objectName string, reader io.Reader, encryptMaterials minio.EncryptionMaterials, metadata map[string][]string, progress io.Reader) (n int, err error)

Encrypt and upload an object.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectName	string	Name of the object
reader	io.Reader	Any Go type that implements io.Reader
encryptMaterials	minio.EncryptionMaterials	The module that encrypts data
metadata	map[string][]string	Object metadata to be stored
progress	io.Reader	A reader to update the upload progress

Example

// Load a private key
privateKey, err := ioutil.ReadFile("private.key")
if err != nil {
    log.Fatal(err)
}

// Load a public key
publicKey, err := ioutil.ReadFile("public.key")
if err != nil {
    log.Fatal(err)
}

// Build an asymmetric key
key, err := NewAssymetricKey(privateKey, publicKey)
if err != nil {
    log.Fatal(err)
}

// Build the CBC encryption module
cbcMaterials, err := NewCBCSecureMaterials(key)
if err != nil {
    t.Fatal(err)
}

// Open a file to upload
file, err := os.Open("my-testfile")
if err != nil {
    fmt.Println(err)
    return
}
defer file.Close()

// Upload the encrypted form of the file
n, err := minioClient.PutEncryptedObject("mybucket", "myobject", file, encryptMaterials, nil, nil)
if err != nil {
    fmt.Println(err)
    return
}

NewSSEInfo(key []byte, algo string) SSEInfo

Create a key object for use as encryption or decryption parameter in operations involving server-side-encryption with customer provided key (SSE-C).

Parameters

Param	Type	Description
key	[]byte	Byte-slice of the raw, un-encoded binary key
algo	string	Algorithm to use in encryption or decryption with the given key. Can be empty (defaults to AES256)

Example

// Key for use in encryption/decryption
keyInfo := NewSSEInfo([]byte{1,2,3}, "")

5. Presigned operations

PresignedGetObject(bucketName, objectName string, expiry time.Duration, reqParams url.Values) (*url.URL, error)

Generates a presigned URL for HTTP GET operations. Browsers/Mobile clients may point to this URL to directly download objects even if the bucket is private. This presigned URL can have an associated expiration time in seconds after which it is no longer operational. The default expiry is set to 7 days.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectName	string	Name of the object
expiry	time.Duration	Expiry of presigned URL in seconds
reqParams	url.Values	Additional response header overrides supports response-expires, response-content-type, response-cache-control, response-content-disposition.

Example

// Set request parameters for content-disposition.
reqParams := make(url.Values)
reqParams.Set("response-content-disposition", "attachment; filename=\"your-filename.txt\"")

// Generates a presigned url which expires in a day.
presignedURL, err := minioClient.PresignedGetObject("mybucket", "myobject", time.Second * 24 * 60 * 60, reqParams)
if err != nil {
    fmt.Println(err)
    return
}

PresignedPutObject(bucketName, objectName string, expiry time.Duration) (*url.URL, error)

Generates a presigned URL for HTTP PUT operations. Browsers/Mobile clients may point to this URL to upload objects directly to a bucket even if it is private. This presigned URL can have an associated expiration time in seconds after which it is no longer operational. The default expiry is set to 7 days.

NOTE: you can upload to S3 only with specified object name.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectName	string	Name of the object
expiry	time.Duration	Expiry of presigned URL in seconds

Example

// Generates a url which expires in a day.
expiry := time.Second * 24 * 60 * 60 // 1 day.
presignedURL, err := minioClient.PresignedPutObject("mybucket", "myobject", expiry)
if err != nil {
    fmt.Println(err)
    return
}
fmt.Println(presignedURL)

PresignedHeadObject(bucketName, objectName string, expiry time.Duration, reqParams url.Values) (*url.URL, error)

Generates a presigned URL for HTTP HEAD operations. Browsers/Mobile clients may point to this URL to directly get metadata from objects even if the bucket is private. This presigned URL can have an associated expiration time in seconds after which it is no longer operational. The default expiry is set to 7 days.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectName	string	Name of the object
expiry	time.Duration	Expiry of presigned URL in seconds
reqParams	url.Values	Additional response header overrides supports response-expires, response-content-type, response-cache-control, response-content-disposition.

Example

// Set request parameters for content-disposition.
reqParams := make(url.Values)
reqParams.Set("response-content-disposition", "attachment; filename=\"your-filename.txt\"")

// Generates a presigned url which expires in a day.
presignedURL, err := minioClient.PresignedHeadObject("mybucket", "myobject", time.Second * 24 * 60 * 60, reqParams)
if err != nil {
    fmt.Println(err)
    return
}

PresignedPostPolicy(PostPolicy) (*url.URL, map[string]string, error)

Allows setting policy conditions to a presigned URL for POST operations. Policies such as bucket name to receive object uploads, key name prefixes, expiry policy may be set.

Create policy :

policy := minio.NewPostPolicy()

Apply upload policy restrictions:

policy.SetBucket("mybucket")
policy.SetKey("myobject")
policy.SetExpires(time.Now().UTC().AddDate(0, 0, 10)) // expires in 10 days

// Only allow 'png' images.
policy.SetContentType("image/png")

// Only allow content size in range 1KB to 1MB.
policy.SetContentLengthRange(1024, 1024*1024)

// Get the POST form key/value object:

url, formData, err := minioClient.PresignedPostPolicy(policy)
if err != nil {
    fmt.Println(err)
    return
}

POST your content from the command line using curl:

fmt.Printf("curl ")
for k, v := range formData {
    fmt.Printf("-F %s=%s ", k, v)
}
fmt.Printf("-F file=@/etc/bash.bashrc ")
fmt.Printf("%s\n", url)

6. Bucket policy/notification operations

SetBucketPolicy(bucketname, objectPrefix string, policy policy.BucketPolicy) error

Set access permissions on bucket or an object prefix.

Importing github.com/minio/minio-go/pkg/policy package is needed.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectPrefix	string	Name of the object prefix
policy	policy.BucketPolicy	Policy can be one of the following,
		policy.BucketPolicyNone
		policy.BucketPolicyReadOnly
		policy.BucketPolicyReadWrite
		policy.BucketPolicyWriteOnly

Return Values

Param	Type	Description
err	error	Standard Error

Example

err := minioClient.SetBucketPolicy("mybucket", "myprefix", policy.BucketPolicyReadWrite)
if err != nil {
    fmt.Println(err)
    return
}

GetBucketPolicy(bucketName, objectPrefix string) (policy.BucketPolicy, error)

Get access permissions on a bucket or a prefix.

Importing github.com/minio/minio-go/pkg/policy package is needed.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectPrefix	string	Prefix matching objects under the bucket

Return Values

Param	Type	Description
bucketPolicy	policy.BucketPolicy	string that contains: none, readonly, readwrite, or writeonly
err	error	Standard Error

Example

bucketPolicy, err := minioClient.GetBucketPolicy("mybucket", "")
if err != nil {
    fmt.Println(err)
    return
}
fmt.Println("Access permissions for mybucket is", bucketPolicy)

ListBucketPolicies(bucketName, objectPrefix string) (map[string]BucketPolicy, error)

Get access permissions rules associated to the specified bucket and prefix.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
objectPrefix	string	Prefix matching objects under the bucket

Return Values

Param	Type	Description
bucketPolicies	map[string]BucketPolicy	Map of object resource paths and their permissions
err	error	Standard Error

Example

bucketPolicies, err := minioClient.ListBucketPolicies("mybucket", "")
if err != nil {
    fmt.Println(err)
    return
}
for resource, permission := range bucketPolicies {
    fmt.Println(resource, " => ", permission)
}

GetBucketNotification(bucketName string) (BucketNotification, error)

Get all notification configurations related to the specified bucket.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket

Return Values

Param	Type	Description
bucketNotification	BucketNotification	structure which holds all notification configurations
err	error	Standard Error

Example

bucketNotification, err := minioClient.GetBucketNotification("mybucket")
if err != nil {
    log.Fatalf("Failed to get bucket notification configurations for mybucket - %v", err)
}
for _, topicConfig := range bucketNotification.TopicConfigs {
    for _, e := range topicConfig.Events {
        fmt.Println(e + " event is enabled")
    }
}

SetBucketNotification(bucketName string, bucketNotification BucketNotification) error

Set a new bucket notification on a bucket.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket
bucketNotification	BucketNotification	Represents the XML to be sent to the configured web service

Return Values

Param	Type	Description
err	error	Standard Error

Example

topicArn := NewArn("aws", "sns", "us-east-1", "804605494417", "PhotoUpdate")

topicConfig := NewNotificationConfig(topicArn)
topicConfig.AddEvents(minio.ObjectCreatedAll, minio.ObjectRemovedAll)
lambdaConfig.AddFilterPrefix("photos/")
lambdaConfig.AddFilterSuffix(".jpg")

bucketNotification := BucketNotification{}
bucketNotification.AddTopic(topicConfig)
err := c.SetBucketNotification(bucketName, bucketNotification)
if err != nil {
    fmt.Println("Unable to set the bucket notification: " + err)
}

RemoveAllBucketNotification(bucketName string) error

Remove all configured bucket notifications on a bucket.

Parameters

Param	Type	Description
bucketName	string	Name of the bucket

Return Values

Param	Type	Description
err	error	Standard Error

Example

err := c.RemoveAllBucketNotification(bucketName)
if err != nil {
    fmt.Println("Unable to remove bucket notifications.", err)
}

ListenBucketNotification(bucketName, prefix, suffix string, events []string, doneCh <-chan struct{}) <-chan NotificationInfo

ListenBucketNotification API receives bucket notification events through the notification channel. The returned notification channel has two fields 'Records' and 'Err'.

• 'Records' holds the notifications received from the server.
• 'Err' indicates any error while processing the received notifications.

NOTE: Notification channel is closed at the first occurrence of an error.

Parameters

Param	Type	Description
bucketName	string	Bucket to listen notifications on
prefix	string	Object key prefix to filter notifications for
suffix	string	Object key suffix to filter notifications for
events	[]string	Enables notifications for specific event types
doneCh	chan struct{}	A message on this channel ends the ListenBucketNotification iterator

Return Values

Param	Type	Description
chan NotificationInfo	chan	Read channel for all notifications on bucket
NotificationInfo	object	Notification object represents events info
notificationInfo.Records	[]NotificationEvent	Collection of notification events
notificationInfo.Err	error	Carries any error occurred during the operation

Example

// Create a done channel to control 'ListenBucketNotification' go routine.
doneCh := make(chan struct{})

// Indicate a background go-routine to exit cleanly upon return.
defer close(doneCh)

// Listen for bucket notifications on "mybucket" filtered by prefix, suffix and events.
for notificationInfo := range minioClient.ListenBucketNotification("YOUR-BUCKET", "PREFIX", "SUFFIX", []string{
    "s3:ObjectCreated:*",
    "s3:ObjectAccessed:*",
    "s3:ObjectRemoved:*",
    }, doneCh) {
    if notificationInfo.Err != nil {
        log.Fatalln(notificationInfo.Err)
    }
    log.Println(notificationInfo)
}

7. Client custom settings

SetAppInfo(appName, appVersion string)

Adds application details to User-Agent.

Parameters

Param	Type	Description
appName	string	Name of the application performing the API requests.
appVersion	string	Version of the application performing the API requests.

Example

// Set Application name and version to be used in subsequent API requests.
minioClient.SetAppInfo("myCloudApp", "1.0.0")

SetCustomTransport(customHTTPTransport http.RoundTripper)

Overrides default HTTP transport. This is usually needed for debugging or for adding custom TLS certificates.

Parameters

Param	Type	Description
customHTTPTransport	http.RoundTripper	Custom transport e.g, to trace API requests and responses for debugging purposes.

TraceOn(outputStream io.Writer)

Enables HTTP tracing. The trace is written to the io.Writer provided. If outputStream is nil, trace is written to os.Stdout.

Parameters

Param	Type	Description
outputStream	io.Writer	HTTP trace is written into outputStream.

TraceOff()

Disables HTTP tracing.

SetS3TransferAccelerate(acceleratedEndpoint string)

Set AWS S3 transfer acceleration endpoint for all API requests hereafter. NOTE: This API applies only to AWS S3 and ignored with other S3 compatible object storage services.

Parameters

Param	Type	Description
acceleratedEndpoint	string	Set to new S3 transfer acceleration endpoint.

8. Explore Further

• Build your own Go Music Player App example