README.md - gocloud - Git at Google

 # Google Cloud for Go

 [![Build Status](https://travis-ci.org/GoogleCloudPlatform/google-cloud-go.svg?branch=master)](https://travis-ci.org/GoogleCloudPlatform/google-cloud-go)
 [![GoDoc](https://godoc.org/cloud.google.com/go?status.svg)](https://godoc.org/cloud.google.com/go)

 ``` go
 import "cloud.google.com/go"
 ```

 Go packages for Google Cloud Platform services.

 To install the packages on your system,

 ```
 $ go get -u cloud.google.com/go/...
 ```

 **NOTE:** These packages are under development, and may occasionally make
 backwards-incompatible changes.

 **NOTE:** Github repo is a mirror of [https://code.googlesource.com/gocloud](https://code.googlesource.com/gocloud).

   * [News](#news)
   * [Supported APIs](#supported-apis)
   * [Go Versions Supported](#go-versions-supported)
   * [Authorization](#authorization)
   * [Cloud Datastore](#cloud-datastore-)
   * [Cloud Storage](#cloud-storage-)
   * [Cloud Pub/Sub](#cloud-pub-sub-)
   * [Cloud BigQuery](#cloud-bigquery-)
   * [Stackdriver Logging](#stackdriver-logging-)


 ## News

 _December 12, 2016_

 Beta release of BigQuery, DataStore, Logging and Storage. See the
 [blog post](https://cloudplatform.googleblog.com/2016/12/announcing-new-google-cloud-client.html).

 Also, BigQuery now supports structs. Read a row directly into a struct with
 `RowIterator.Next`, and upload a row directly from a struct with `Uploader.Put`.
 You can also use field tags. See the [package documentation][cloud-bigquery-ref]
 for details.

 _December 5, 2016_

 More changes to BigQuery:

 * The `ValueList` type was removed. It is no longer necessary. Instead of
    ```go
    var v ValueList
    ... it.Next(&v) ..
    ```
    use

    ```go
    var v []Value
    ... it.Next(&v) ...
    ```

 * Previously, repeatedly calling `RowIterator.Next` on the same `[]Value` or
   `ValueList` would append to the slice. Now each call resets the size to zero first.

 * Schema inference will infer the SQL type BYTES for a struct field of
   type []byte. Previously it inferred STRING.

 * The types `uint`, `uint64` and `uintptr` are no longer supported in schema
   inference. BigQuery's integer type is INT64, and those types may hold values
   that are not correctly represented in a 64-bit signed integer.

 * The SQL types DATE, TIME and DATETIME are now supported. They correspond to
   the `Date`, `Time` and `DateTime` types in the new `cloud.google.com/go/civil`
   package.

 _November 17, 2016_

 Change to BigQuery: values from INTEGER columns will now be returned as int64,
 not int. This will avoid errors arising from large values on 32-bit systems.

 _November 8, 2016_

 New datastore feature: datastore now encodes your nested Go structs as Entity values,
 instead of a flattened list of the embedded struct's fields.
 This means that you may now have twice-nested slices, eg.
 ```go
 type State struct {
   Cities  []struct{
     Populations []int
   }
 }
 ```

 See [the announcement](https://groups.google.com/forum/#!topic/google-api-go-announce/79jtrdeuJAg) for
 more details.

 _November 8, 2016_

 Breaking changes to datastore: contexts no longer hold namespaces; instead you
 must set a key's namespace explicitly. Also, key functions have been changed
 and renamed.

 * The WithNamespace function has been removed. To specify a namespace in a Query, use the Query.Namespace method:
   ```go
   q := datastore.NewQuery("Kind").Namespace("ns")
   ```

 * All the fields of Key are exported. That means you can construct any Key with a struct literal:
   ```go
   k := &Key{Kind: "Kind",  ID: 37, Namespace: "ns"}
   ```

 * As a result of the above, the Key methods Kind, ID, d.Name, Parent, SetParent and Namespace have been removed.

 * `NewIncompleteKey` has been removed, replaced by `IncompleteKey`. Replace
   ```go
   NewIncompleteKey(ctx, kind, parent)
   ```
   with
   ```go
   IncompleteKey(kind, parent)
   ```
   and if you do use namespaces, make sure you set the namespace on the returned key.

 * `NewKey` has been removed, replaced by `NameKey` and `IDKey`. Replace
   ```go
   NewKey(ctx, kind, name, 0, parent)
   NewKey(ctx, kind, "", id, parent)
   ```
   with
   ```go
   NameKey(kind, name, parent)
   IDKey(kind, id, parent)
   ```
   and if you do use namespaces, make sure you set the namespace on the returned key.

 * The `Done` variable has been removed. Replace `datastore.Done` with `iterator.Done`, from the package `google.golang.org/api/iterator`.

 * The `Client.Close` method will have a return type of error. It will return the result of closing the underlying gRPC connection.

 See [the announcement](https://groups.google.com/forum/#!topic/google-api-go-announce/hqXtM_4Ix-0) for
 more details.

 _October 27, 2016_

 Breaking change to bigquery: `NewGCSReference` is now a function,
 not a method on `Client`.

 New bigquery feature: `Table.LoaderFrom` now accepts a `ReaderSource`, enabling
 loading data into a table from a file or any `io.Reader`.

 _October 21, 2016_

 Breaking change to pubsub: removed `pubsub.Done`.

 Use `iterator.Done` instead, where `iterator` is the package
 `google.golang.org/api/iterator`.


 [Older news](https://github.com/GoogleCloudPlatform/google-cloud-go/blob/master/old-news.md)

 ## Supported APIs

 Google API                     | Status       | Package
 -------------------------------|--------------|-----------------------------------------------------------
 [Datastore][cloud-datastore]   | beta         | [`cloud.google.com/go/datastore`][cloud-datastore-ref]
 [Storage][cloud-storage]       | beta         | [`cloud.google.com/go/storage`][cloud-storage-ref]
 [Bigtable][cloud-bigtable]     | beta         | [`cloud.google.com/go/bigtable`][cloud-bigtable-ref]
 [BigQuery][cloud-bigquery]     | beta         | [`cloud.google.com/go/bigquery`][cloud-bigquery-ref]
 [Logging][cloud-logging]       | beta         | [`cloud.google.com/go/logging`][cloud-logging-ref]
 [Pub/Sub][cloud-pubsub]        | alpha | [`cloud.google.com/go/pubsub`][cloud-pubsub-ref]
 [Vision][cloud-vision]         | alpha | [`cloud.google.com/go/vision`][cloud-vision-ref]
 [Language][cloud-language]     | alpha | [`cloud.google.com/go/language/apiv1`][cloud-language-ref]
 [Speech][cloud-speech]         | alpha | [`cloud.google.com/go/speech/apiv1beta`][cloud-speech-ref]


 > **Alpha status**: the API is still being actively developed. As a
 > result, it might change in backward-incompatible ways and is not recommended
 > for production use.
 >
 > **Beta status**: the API is largely complete, but still has outstanding
 > features and bugs to be addressed. There may be minor backwards-incompatible
 > changes where necessary.
 >
 > **Stable status**: the API is mature and ready for production use. We will
 > continue addressing bugs and feature requests.

 Documentation and examples are available at
 https://godoc.org/cloud.google.com/go

 Visit or join the
 [google-api-go-announce group](https://groups.google.com/forum/#!forum/google-api-go-announce)
 for updates on these packages.

 ## Go Versions Supported

 We support the two most recent major versions of Go. If Google App Engine uses
 an older version, we support that as well. You can see which versions are
 currently supported by looking at the lines following `go:` in
 [`.travis.yml`](.travis.yml).

 ## Authorization

 By default, each API will use [Google Application Default Credentials][default-creds]
 for authorization credentials used in calling the API endpoints. This will allow your
 application to run in many environments without requiring explicit configuration.

 ```go
 client, err := storage.NewClient(ctx)
 ```

 To authorize using a
 [JSON key file](https://cloud.google.com/iam/docs/managing-service-account-keys),
 pass
 [`option.WithServiceAccountFile`](https://godoc.org/google.golang.org/api/option#WithServiceAccountFile)
 to the `NewClient` function of the desired package. For example:

 ```go
 client, err := storage.NewClient(ctx, option.WithServiceAccountFile("path/to/keyfile.json"))
 ```

 You can exert more control over authorization by using the
 [`golang.org/x/oauth2`](https://godoc.org/golang.org/x/oauth2) package to
 create an `oauth2.TokenSource`. Then pass
 [`option.WithTokenSource`](https://godoc.org/google.golang.org/api/option#WithTokenSource)
 to the `NewClient` function:
 ```go
 tokenSource := ...
 client, err := storage.NewClient(ctx, option.WithTokenSource(tokenSource))
 ```

 ## Cloud Datastore [![GoDoc](https://godoc.org/cloud.google.com/go/datastore?status.svg)](https://godoc.org/cloud.google.com/go/datastore)

 - [About Cloud Datastore][cloud-datastore]
 - [Activating the API for your project][cloud-datastore-activation]
 - [API documentation][cloud-datastore-docs]
 - [Go client documentation](https://godoc.org/cloud.google.com/go/datastore)
 - [Complete sample program](https://github.com/GoogleCloudPlatform/golang-samples/tree/master/datastore/tasks)

 ### Example Usage

 First create a `datastore.Client` to use throughout your application:

 ```go
 client, err := datastore.NewClient(ctx, "my-project-id")
 if err != nil {
 	log.Fatal(err)
 }
 ```

 Then use that client to interact with the API:

 ```go
 type Post struct {
 	Title       string
 	Body        string `datastore:",noindex"`
 	PublishedAt time.Time
 }
 keys := []*datastore.Key{
 	datastore.NewKey(ctx, "Post", "post1", 0, nil),
 	datastore.NewKey(ctx, "Post", "post2", 0, nil),
 }
 posts := []*Post{
 	{Title: "Post 1", Body: "...", PublishedAt: time.Now()},
 	{Title: "Post 2", Body: "...", PublishedAt: time.Now()},
 }
 if _, err := client.PutMulti(ctx, keys, posts); err != nil {
 	log.Fatal(err)
 }
 ```

 ## Cloud Storage [![GoDoc](https://godoc.org/cloud.google.com/go/storage?status.svg)](https://godoc.org/cloud.google.com/go/storage)

 - [About Cloud Storage][cloud-storage]
 - [API documentation][cloud-storage-docs]
 - [Go client documentation](https://godoc.org/cloud.google.com/go/storage)
 - [Complete sample programs](https://github.com/GoogleCloudPlatform/golang-samples/tree/master/storage)

 ### Example Usage

 First create a `storage.Client` to use throughout your application:

 ```go
 client, err := storage.NewClient(ctx)
 if err != nil {
 	log.Fatal(err)
 }
 ```

 ```go
 // Read the object1 from bucket.
 rc, err := client.Bucket("bucket").Object("object1").NewReader(ctx)
 if err != nil {
 	log.Fatal(err)
 }
 defer rc.Close()
 body, err := ioutil.ReadAll(rc)
 if err != nil {
 	log.Fatal(err)
 }
 ```

 ## Cloud Pub/Sub [![GoDoc](https://godoc.org/cloud.google.com/go/pubsub?status.svg)](https://godoc.org/cloud.google.com/go/pubsub)

 - [About Cloud Pubsub][cloud-pubsub]
 - [API documentation][cloud-pubsub-docs]
 - [Go client documentation](https://godoc.org/cloud.google.com/go/pubsub)
 - [Complete sample programs](https://github.com/GoogleCloudPlatform/golang-samples/tree/master/pubsub)

 ### Example Usage

 First create a `pubsub.Client` to use throughout your application:

 ```go
 client, err := pubsub.NewClient(ctx, "project-id")
 if err != nil {
 	log.Fatal(err)
 }
 ```

 ```go
 // Publish "hello world" on topic1.
 topic := client.Topic("topic1")
 msgIDs, err := topic.Publish(ctx, &pubsub.Message{
 	Data: []byte("hello world"),
 })
 if err != nil {
 	log.Fatal(err)
 }

 // Create an iterator to pull messages via subscription1.
 it, err := client.Subscription("subscription1").Pull(ctx)
 if err != nil {
 	log.Println(err)
 }
 defer it.Stop()

 // Consume N messages from the iterator.
 for i := 0; i < N; i++ {
 	msg, err := it.Next()
 	if err == iterator.Done {
 		break
 	}
 	if err != nil {
 		log.Fatalf("Failed to retrieve message: %v", err)
 	}

 	fmt.Printf("Message %d: %s\n", i, msg.Data)
 	msg.Done(true) // Acknowledge that we've consumed the message.
 }
 ```

 ## Cloud BigQuery [![GoDoc](https://godoc.org/cloud.google.com/go/bigquery?status.svg)](https://godoc.org/cloud.google.com/go/bigquery)

 - [About Cloud BigQuery][cloud-bigquery]
 - [API documentation][cloud-bigquery-docs]
 - [Go client documentation][cloud-bigquery-ref]
 - [Complete sample programs](https://github.com/GoogleCloudPlatform/golang-samples/tree/master/bigquery)

 ### Example Usage

 First create a `bigquery.Client` to use throughout your application:
 ```go
 c, err := bigquery.NewClient(ctx, "my-project-ID")
 if err != nil {
     // TODO: Handle error.
 }
 ```
 Then use that client to interact with the API:
 ```go
 // Construct a query.
 q := c.Query(`
     SELECT year, SUM(number)
     FROM [bigquery-public-data:usa_names.usa_1910_2013]
     WHERE name = "William"
     GROUP BY year
     ORDER BY year
 `)
 // Execute the query.
 it, err := q.Read(ctx)
 if err != nil {
     // TODO: Handle error.
 }
 // Iterate through the results.
 for {
     var values []bigquery.Value
     err := it.Next(&values)
     if err == iterator.Done {
         break
     }
     if err != nil {
         // TODO: Handle error.
     }
     fmt.Println(values)
 }
 ```


 ## Stackdriver Logging [![GoDoc](https://godoc.org/cloud.google.com/go/logging?status.svg)](https://godoc.org/cloud.google.com/go/logging)

 - [About Stackdriver Logging][cloud-logging]
 - [API documentation][cloud-logging-docs]
 - [Go client documentation][cloud-logging-ref]
 - [Complete sample programs](https://github.com/GoogleCloudPlatform/golang-samples/tree/master/logging)

 ### Example Usage

 First create a `logging.Client` to use throughout your application:

 ```go
 ctx := context.Background()
 client, err := logging.NewClient(ctx, "my-project")
 if err != nil {
     // TODO: Handle error.
 }
 ```
 Usually, you'll want to add log entries to a buffer to be periodically flushed
 (automatically and asynchronously) to the Stackdriver Logging service.
 ```go
 logger := client.Logger("my-log")
 logger.Log(logging.Entry{Payload: "something happened!"})
 ```
 Close your client before your program exits, to flush any buffered log entries.
 ```go
 err = client.Close()
 if err != nil {
     // TODO: Handle error.
 }
 ```

 ## Contributing

 Contributions are welcome. Please, see the
 [CONTRIBUTING](https://github.com/GoogleCloudPlatform/google-cloud-go/blob/master/CONTRIBUTING.md)
 document for details. We're using Gerrit for our code reviews. Please don't open pull
 requests against this repo, new pull requests will be automatically closed.

 Please note that this project is released with a Contributor Code of Conduct.
 By participating in this project you agree to abide by its terms.
 See [Contributor Code of Conduct](https://github.com/GoogleCloudPlatform/google-cloud-go/blob/master/CONTRIBUTING.md#contributor-code-of-conduct)
 for more information.

 [cloud-datastore]: https://cloud.google.com/datastore/
 [cloud-datastore-ref]: https://godoc.org/cloud.google.com/go/datastore
 [cloud-datastore-docs]: https://cloud.google.com/datastore/docs
 [cloud-datastore-activation]: https://cloud.google.com/datastore/docs/activate

 [cloud-pubsub]: https://cloud.google.com/pubsub/
 [cloud-pubsub-ref]: https://godoc.org/cloud.google.com/go/pubsub
 [cloud-pubsub-docs]: https://cloud.google.com/pubsub/docs

 [cloud-storage]: https://cloud.google.com/storage/
 [cloud-storage-ref]: https://godoc.org/cloud.google.com/go/storage
 [cloud-storage-docs]: https://cloud.google.com/storage/docs
 [cloud-storage-create-bucket]: https://cloud.google.com/storage/docs/cloud-console#_creatingbuckets

 [cloud-bigtable]: https://cloud.google.com/bigtable/
 [cloud-bigtable-ref]: https://godoc.org/cloud.google.com/go/bigtable

 [cloud-bigquery]: https://cloud.google.com/bigquery/
 [cloud-bigquery-docs]: https://cloud.google.com/bigquery/docs
 [cloud-bigquery-ref]: https://godoc.org/cloud.google.com/go/bigquery

 [cloud-logging]: https://cloud.google.com/logging/
 [cloud-logging-docs]: https://cloud.google.com/logging/docs
 [cloud-logging-ref]: https://godoc.org/cloud.google.com/go/logging

 [cloud-vision]: https://cloud.google.com/vision/
 [cloud-vision-ref]: https://godoc.org/cloud.google.com/go/vision

 [cloud-language]: https://cloud.google.com/natural-language
 [cloud-language-ref]: https://godoc.org/cloud.google.com/go/language/apiv1

 [cloud-speech]: https://cloud.google.com/speech
 [cloud-speech-ref]: https://godoc.org/cloud.google.com/go/speech/apiv1beta1

 [default-creds]: https://developers.google.com/identity/protocols/application-default-credentials
	# Google Cloud for Go

	[![Build Status](https://travis-ci.org/GoogleCloudPlatform/google-cloud-go.svg?branch=master)](https://travis-ci.org/GoogleCloudPlatform/google-cloud-go)
	[![GoDoc](https://godoc.org/cloud.google.com/go?status.svg)](https://godoc.org/cloud.google.com/go)

	``` go
	import "cloud.google.com/go"
	```

	Go packages for Google Cloud Platform services.

	To install the packages on your system,

	```
	$ go get -u cloud.google.com/go/...
	```

	NOTE: These packages are under development, and may occasionally make
	backwards-incompatible changes.

	NOTE: Github repo is a mirror of [https://code.googlesource.com/gocloud](https://code.googlesource.com/gocloud).

	* [News](#news)
	* [Supported APIs](#supported-apis)
	* [Go Versions Supported](#go-versions-supported)
	* [Authorization](#authorization)
	* [Cloud Datastore](#cloud-datastore-)
	* [Cloud Storage](#cloud-storage-)
	* [Cloud Pub/Sub](#cloud-pub-sub-)
	* [Cloud BigQuery](#cloud-bigquery-)
	* [Stackdriver Logging](#stackdriver-logging-)


	## News

	_December 12, 2016_

	Beta release of BigQuery, DataStore, Logging and Storage. See the
	[blog post](https://cloudplatform.googleblog.com/2016/12/announcing-new-google-cloud-client.html).

	Also, BigQuery now supports structs. Read a row directly into a struct with
	`RowIterator.Next`, and upload a row directly from a struct with `Uploader.Put`.
	You can also use field tags. See the [package documentation][cloud-bigquery-ref]
	for details.

	_December 5, 2016_

	More changes to BigQuery:

	* The `ValueList` type was removed. It is no longer necessary. Instead of
	```go
	var v ValueList
	... it.Next(&v) ..
	```
	use

	```go
	var v []Value
	... it.Next(&v) ...
	```

	* Previously, repeatedly calling `RowIterator.Next` on the same `[]Value` or
	`ValueList` would append to the slice. Now each call resets the size to zero first.

	* Schema inference will infer the SQL type BYTES for a struct field of
	type []byte. Previously it inferred STRING.

	* The types `uint`, `uint64` and `uintptr` are no longer supported in schema
	inference. BigQuery's integer type is INT64, and those types may hold values
	that are not correctly represented in a 64-bit signed integer.

	* The SQL types DATE, TIME and DATETIME are now supported. They correspond to
	the `Date`, `Time` and `DateTime` types in the new `cloud.google.com/go/civil`
	package.

	_November 17, 2016_

	Change to BigQuery: values from INTEGER columns will now be returned as int64,
	not int. This will avoid errors arising from large values on 32-bit systems.

	_November 8, 2016_

	New datastore feature: datastore now encodes your nested Go structs as Entity values,
	instead of a flattened list of the embedded struct's fields.
	This means that you may now have twice-nested slices, eg.
	```go
	type State struct {
	Cities []struct{
	Populations []int
	}
	}
	```

	See [the announcement](https://groups.google.com/forum/#!topic/google-api-go-announce/79jtrdeuJAg) for
	more details.

	_November 8, 2016_

	Breaking changes to datastore: contexts no longer hold namespaces; instead you
	must set a key's namespace explicitly. Also, key functions have been changed
	and renamed.

	* The WithNamespace function has been removed. To specify a namespace in a Query, use the Query.Namespace method:
	```go
	q := datastore.NewQuery("Kind").Namespace("ns")
	```

	* All the fields of Key are exported. That means you can construct any Key with a struct literal:
	```go
	k := &Key{Kind: "Kind", ID: 37, Namespace: "ns"}
	```

	* As a result of the above, the Key methods Kind, ID, d.Name, Parent, SetParent and Namespace have been removed.

	* `NewIncompleteKey` has been removed, replaced by `IncompleteKey`. Replace
	```go
	NewIncompleteKey(ctx, kind, parent)
	```
	with
	```go
	IncompleteKey(kind, parent)
	```
	and if you do use namespaces, make sure you set the namespace on the returned key.

	* `NewKey` has been removed, replaced by `NameKey` and `IDKey`. Replace
	```go
	NewKey(ctx, kind, name, 0, parent)
	NewKey(ctx, kind, "", id, parent)
	```
	with
	```go
	NameKey(kind, name, parent)
	IDKey(kind, id, parent)
	```
	and if you do use namespaces, make sure you set the namespace on the returned key.

	* The `Done` variable has been removed. Replace `datastore.Done` with `iterator.Done`, from the package `google.golang.org/api/iterator`.

	* The `Client.Close` method will have a return type of error. It will return the result of closing the underlying gRPC connection.

	See [the announcement](https://groups.google.com/forum/#!topic/google-api-go-announce/hqXtM_4Ix-0) for
	more details.

	_October 27, 2016_

	Breaking change to bigquery: `NewGCSReference` is now a function,
	not a method on `Client`.

	New bigquery feature: `Table.LoaderFrom` now accepts a `ReaderSource`, enabling
	loading data into a table from a file or any `io.Reader`.

	_October 21, 2016_

	Breaking change to pubsub: removed `pubsub.Done`.

	Use `iterator.Done` instead, where `iterator` is the package
	`google.golang.org/api/iterator`.


	[Older news](https://github.com/GoogleCloudPlatform/google-cloud-go/blob/master/old-news.md)

	## Supported APIs

	Google API \| Status \| Package
	-------------------------------\|--------------\|-----------------------------------------------------------
	[Datastore][cloud-datastore] \| beta \| [`cloud.google.com/go/datastore`][cloud-datastore-ref]
	[Storage][cloud-storage] \| beta \| [`cloud.google.com/go/storage`][cloud-storage-ref]
	[Bigtable][cloud-bigtable] \| beta \| [`cloud.google.com/go/bigtable`][cloud-bigtable-ref]
	[BigQuery][cloud-bigquery] \| beta \| [`cloud.google.com/go/bigquery`][cloud-bigquery-ref]
	[Logging][cloud-logging] \| beta \| [`cloud.google.com/go/logging`][cloud-logging-ref]
	[Pub/Sub][cloud-pubsub] \| alpha \| [`cloud.google.com/go/pubsub`][cloud-pubsub-ref]
	[Vision][cloud-vision] \| alpha \| [`cloud.google.com/go/vision`][cloud-vision-ref]
	[Language][cloud-language] \| alpha \| [`cloud.google.com/go/language/apiv1`][cloud-language-ref]
	[Speech][cloud-speech] \| alpha \| [`cloud.google.com/go/speech/apiv1beta`][cloud-speech-ref]


	> Alpha status: the API is still being actively developed. As a
	> result, it might change in backward-incompatible ways and is not recommended
	> for production use.
	>
	> Beta status: the API is largely complete, but still has outstanding
	> features and bugs to be addressed. There may be minor backwards-incompatible
	> changes where necessary.
	>
	> Stable status: the API is mature and ready for production use. We will
	> continue addressing bugs and feature requests.

	Documentation and examples are available at
	https://godoc.org/cloud.google.com/go

	Visit or join the
	[google-api-go-announce group](https://groups.google.com/forum/#!forum/google-api-go-announce)
	for updates on these packages.

	## Go Versions Supported

	We support the two most recent major versions of Go. If Google App Engine uses
	an older version, we support that as well. You can see which versions are
	currently supported by looking at the lines following `go:` in
	[`.travis.yml`](.travis.yml).

	## Authorization

	By default, each API will use [Google Application Default Credentials][default-creds]
	for authorization credentials used in calling the API endpoints. This will allow your
	application to run in many environments without requiring explicit configuration.

	```go
	client, err := storage.NewClient(ctx)
	```

	To authorize using a
	[JSON key file](https://cloud.google.com/iam/docs/managing-service-account-keys),
	pass
	[`option.WithServiceAccountFile`](https://godoc.org/google.golang.org/api/option#WithServiceAccountFile)
	to the `NewClient` function of the desired package. For example:

	```go
	client, err := storage.NewClient(ctx, option.WithServiceAccountFile("path/to/keyfile.json"))
	```

	You can exert more control over authorization by using the
	[`golang.org/x/oauth2`](https://godoc.org/golang.org/x/oauth2) package to
	create an `oauth2.TokenSource`. Then pass
	[`option.WithTokenSource`](https://godoc.org/google.golang.org/api/option#WithTokenSource)
	to the `NewClient` function:
	```go
	tokenSource := ...
	client, err := storage.NewClient(ctx, option.WithTokenSource(tokenSource))
	```

	## Cloud Datastore [![GoDoc](https://godoc.org/cloud.google.com/go/datastore?status.svg)](https://godoc.org/cloud.google.com/go/datastore)

	- [About Cloud Datastore][cloud-datastore]
	- [Activating the API for your project][cloud-datastore-activation]
	- [API documentation][cloud-datastore-docs]
	- [Go client documentation](https://godoc.org/cloud.google.com/go/datastore)
	- [Complete sample program](https://github.com/GoogleCloudPlatform/golang-samples/tree/master/datastore/tasks)

	### Example Usage

	First create a `datastore.Client` to use throughout your application:

	```go
	client, err := datastore.NewClient(ctx, "my-project-id")
	if err != nil {
	log.Fatal(err)
	}
	```

	Then use that client to interact with the API:

	```go
	type Post struct {
	Title string
	Body string `datastore:",noindex"`
	PublishedAt time.Time
	}
	keys := []*datastore.Key{
	datastore.NewKey(ctx, "Post", "post1", 0, nil),
	datastore.NewKey(ctx, "Post", "post2", 0, nil),
	}
	posts := []*Post{
	{Title: "Post 1", Body: "...", PublishedAt: time.Now()},
	{Title: "Post 2", Body: "...", PublishedAt: time.Now()},
	}
	if _, err := client.PutMulti(ctx, keys, posts); err != nil {
	log.Fatal(err)
	}
	```

	## Cloud Storage [![GoDoc](https://godoc.org/cloud.google.com/go/storage?status.svg)](https://godoc.org/cloud.google.com/go/storage)

	- [About Cloud Storage][cloud-storage]
	- [API documentation][cloud-storage-docs]
	- [Go client documentation](https://godoc.org/cloud.google.com/go/storage)
	- [Complete sample programs](https://github.com/GoogleCloudPlatform/golang-samples/tree/master/storage)

	### Example Usage

	First create a `storage.Client` to use throughout your application:

	```go
	client, err := storage.NewClient(ctx)
	if err != nil {
	log.Fatal(err)
	}
	```

	```go
	// Read the object1 from bucket.
	rc, err := client.Bucket("bucket").Object("object1").NewReader(ctx)
	if err != nil {
	log.Fatal(err)
	}
	defer rc.Close()
	body, err := ioutil.ReadAll(rc)
	if err != nil {
	log.Fatal(err)
	}
	```

	## Cloud Pub/Sub [![GoDoc](https://godoc.org/cloud.google.com/go/pubsub?status.svg)](https://godoc.org/cloud.google.com/go/pubsub)

	- [About Cloud Pubsub][cloud-pubsub]
	- [API documentation][cloud-pubsub-docs]
	- [Go client documentation](https://godoc.org/cloud.google.com/go/pubsub)
	- [Complete sample programs](https://github.com/GoogleCloudPlatform/golang-samples/tree/master/pubsub)

	### Example Usage

	First create a `pubsub.Client` to use throughout your application:

	```go
	client, err := pubsub.NewClient(ctx, "project-id")
	if err != nil {
	log.Fatal(err)
	}
	```

	```go
	// Publish "hello world" on topic1.
	topic := client.Topic("topic1")
	msgIDs, err := topic.Publish(ctx, &pubsub.Message{
	Data: []byte("hello world"),
	})
	if err != nil {
	log.Fatal(err)
	}

	// Create an iterator to pull messages via subscription1.
	it, err := client.Subscription("subscription1").Pull(ctx)
	if err != nil {
	log.Println(err)
	}
	defer it.Stop()

	// Consume N messages from the iterator.
	for i := 0; i < N; i++ {
	msg, err := it.Next()
	if err == iterator.Done {
	break
	}
	if err != nil {
	log.Fatalf("Failed to retrieve message: %v", err)
	}

	fmt.Printf("Message %d: %s\n", i, msg.Data)
	msg.Done(true) // Acknowledge that we've consumed the message.
	}
	```

	## Cloud BigQuery [![GoDoc](https://godoc.org/cloud.google.com/go/bigquery?status.svg)](https://godoc.org/cloud.google.com/go/bigquery)

	- [About Cloud BigQuery][cloud-bigquery]
	- [API documentation][cloud-bigquery-docs]
	- [Go client documentation][cloud-bigquery-ref]
	- [Complete sample programs](https://github.com/GoogleCloudPlatform/golang-samples/tree/master/bigquery)

	### Example Usage

	First create a `bigquery.Client` to use throughout your application:
	```go
	c, err := bigquery.NewClient(ctx, "my-project-ID")
	if err != nil {
	// TODO: Handle error.
	}
	```
	Then use that client to interact with the API:
	```go
	// Construct a query.
	q := c.Query(`
	SELECT year, SUM(number)
	FROM [bigquery-public-data:usa_names.usa_1910_2013]
	WHERE name = "William"
	GROUP BY year
	ORDER BY year
	`)
	// Execute the query.
	it, err := q.Read(ctx)
	if err != nil {
	// TODO: Handle error.
	}
	// Iterate through the results.
	for {
	var values []bigquery.Value
	err := it.Next(&values)
	if err == iterator.Done {
	break
	}
	if err != nil {
	// TODO: Handle error.
	}
	fmt.Println(values)
	}
	```


	## Stackdriver Logging [![GoDoc](https://godoc.org/cloud.google.com/go/logging?status.svg)](https://godoc.org/cloud.google.com/go/logging)

	- [About Stackdriver Logging][cloud-logging]
	- [API documentation][cloud-logging-docs]
	- [Go client documentation][cloud-logging-ref]
	- [Complete sample programs](https://github.com/GoogleCloudPlatform/golang-samples/tree/master/logging)

	### Example Usage

	First create a `logging.Client` to use throughout your application:

	```go
	ctx := context.Background()
	client, err := logging.NewClient(ctx, "my-project")
	if err != nil {
	// TODO: Handle error.
	}
	```
	Usually, you'll want to add log entries to a buffer to be periodically flushed
	(automatically and asynchronously) to the Stackdriver Logging service.
	```go
	logger := client.Logger("my-log")
	logger.Log(logging.Entry{Payload: "something happened!"})
	```
	Close your client before your program exits, to flush any buffered log entries.
	```go
	err = client.Close()
	if err != nil {
	// TODO: Handle error.
	}
	```

	## Contributing

	Contributions are welcome. Please, see the
	[CONTRIBUTING](https://github.com/GoogleCloudPlatform/google-cloud-go/blob/master/CONTRIBUTING.md)
	document for details. We're using Gerrit for our code reviews. Please don't open pull
	requests against this repo, new pull requests will be automatically closed.

	Please note that this project is released with a Contributor Code of Conduct.
	By participating in this project you agree to abide by its terms.
	See [Contributor Code of Conduct](https://github.com/GoogleCloudPlatform/google-cloud-go/blob/master/CONTRIBUTING.md#contributor-code-of-conduct)
	for more information.

	[cloud-datastore]: https://cloud.google.com/datastore/
	[cloud-datastore-ref]: https://godoc.org/cloud.google.com/go/datastore
	[cloud-datastore-docs]: https://cloud.google.com/datastore/docs
	[cloud-datastore-activation]: https://cloud.google.com/datastore/docs/activate

	[cloud-pubsub]: https://cloud.google.com/pubsub/
	[cloud-pubsub-ref]: https://godoc.org/cloud.google.com/go/pubsub
	[cloud-pubsub-docs]: https://cloud.google.com/pubsub/docs

	[cloud-storage]: https://cloud.google.com/storage/
	[cloud-storage-ref]: https://godoc.org/cloud.google.com/go/storage
	[cloud-storage-docs]: https://cloud.google.com/storage/docs
	[cloud-storage-create-bucket]: https://cloud.google.com/storage/docs/cloud-console#_creatingbuckets

	[cloud-bigtable]: https://cloud.google.com/bigtable/
	[cloud-bigtable-ref]: https://godoc.org/cloud.google.com/go/bigtable

	[cloud-bigquery]: https://cloud.google.com/bigquery/
	[cloud-bigquery-docs]: https://cloud.google.com/bigquery/docs
	[cloud-bigquery-ref]: https://godoc.org/cloud.google.com/go/bigquery

	[cloud-logging]: https://cloud.google.com/logging/
	[cloud-logging-docs]: https://cloud.google.com/logging/docs
	[cloud-logging-ref]: https://godoc.org/cloud.google.com/go/logging

	[cloud-vision]: https://cloud.google.com/vision/
	[cloud-vision-ref]: https://godoc.org/cloud.google.com/go/vision

	[cloud-language]: https://cloud.google.com/natural-language
	[cloud-language-ref]: https://godoc.org/cloud.google.com/go/language/apiv1

	[cloud-speech]: https://cloud.google.com/speech
	[cloud-speech-ref]: https://godoc.org/cloud.google.com/go/speech/apiv1beta1

	[default-creds]: https://developers.google.com/identity/protocols/application-default-credentials