cloud

README

Google Cloud Client Libraries for Go

Go packages for Google Cloud Platform services.

import "cloud.google.com/go"

To install the packages on your system,

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

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

NOTE: Github repo is a mirror of https://code.googlesource.com/gocloud.

• News
• Supported APIs
• Go Versions Supported
• Authorization
• Cloud Datastore
• Cloud Storage
• Cloud Pub/Sub
• Cloud BigQuery
• Stackdriver Logging
• Cloud Spanner

News

March 17, 2017

Breaking Pubsub changes.

• Publish is now asynchronous (announcement).
• Subscription.Pull replaced by Subscription.Receive, which takes a callback (announcement).
• Message.Done replaced with Message.Ack and Message.Nack.

February 14, 2017

Release of a client library for Spanner. See the blog post.

Note that although the Spanner service is beta, the Go client library is alpha.

Older news

Supported APIs

Google API	Status	Package
Datastore	stable	cloud.google.com/go/datastore
Storage	stable	cloud.google.com/go/storage
Bigtable	beta	cloud.google.com/go/bigtable
BigQuery	beta	cloud.google.com/go/bigquery
Logging	stable	cloud.google.com/go/logging
Monitoring	alpha	cloud.google.com/go/monitoring/apiv3
Pub/Sub	alpha	cloud.google.com/go/pubsub
Vision	beta	cloud.google.com/go/vision
Language	beta	cloud.google.com/go/language/apiv1
Speech	beta	cloud.google.com/go/speech/apiv1
Spanner	alpha	cloud.google.com/go/spanner
Translation	beta	cloud.google.com/go/translate
Trace	alpha	cloud.google.com/go/trace
ErrorReporting	alpha	cloud.google.com/go/errors

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 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.

Authorization

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

client, err := storage.NewClient(ctx)

To authorize using a JSON key file, pass option.WithServiceAccountFile to the NewClient function of the desired package. For example:

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 package to create an oauth2.TokenSource. Then pass option.WithTokenSource to the NewClient function: snip:# (auth-ts)

tokenSource := ...
client, err := storage.NewClient(ctx, option.WithTokenSource(tokenSource))

Cloud Datastore

• About Cloud Datastore
• Activating the API for your project
• API documentation
• Go client documentation
• Complete sample program

Example Usage

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

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

Then use that client to interact with the API:

type Post struct {
	Title       string
	Body        string `datastore:",noindex"`
	PublishedAt time.Time
}
keys := []*datastore.Key{
	datastore.NameKey("Post", "post1", nil),
	datastore.NameKey("Post", "post2", 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

• About Cloud Storage
• API documentation
• Go client documentation
• Complete sample programs

Example Usage

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

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

// 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

• About Cloud Pubsub
• API documentation
• Go client documentation
• Complete sample programs

Example Usage

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

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

Then use the client to publish and subscribe:

// Publish "hello world" on topic1.
topic := client.Topic("topic1")
res := topic.Publish(ctx, &pubsub.Message{
	Data: []byte("hello world"),
})
// The publish happens asynchronously.
// Later, you can get the result from res:
...
msgID, err := res.Get(ctx)
if err != nil {
	log.Fatal(err)
}

// Use a callback to receive messages via subscription1.
sub := client.Subscription("subscription1")
err = sub.Receive(ctx, func(ctx context.Context, m *pubsub.Message) {
	fmt.Println(m.Data)
	m.Ack() // Acknowledge that we've consumed the message.
})
if err != nil {
	log.Println(err)
}

Cloud BigQuery

• About Cloud BigQuery
• API documentation
• Go client documentation
• Complete sample programs

Example Usage

First create a bigquery.Client to use throughout your application: snip:# (bq-1)

c, err := bigquery.NewClient(ctx, "my-project-ID")
if err != nil {
	// TODO: Handle error.
}

Then use that client to interact with the API: snip:# (bq-2)

// 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

• About Stackdriver Logging
• API documentation
• Go client documentation
• Complete sample programs

Example Usage

First create a logging.Client to use throughout your application: snip:# (logging-1)

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. snip:# (logging-2)

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. snip:# (logging-3)

err = client.Close()
if err != nil {
	// TODO: Handle error.
}

Cloud Spanner

• About Cloud Spanner
• API documentation
• Go client documentation

Example Usage

First create a spanner.Client to use throughout your application:

client, err := spanner.NewClient(ctx, "projects/P/instances/I/databases/D")
if err != nil {
	log.Fatal(err)
}

// Simple Reads And Writes
_, err = client.Apply(ctx, []*spanner.Mutation{
	spanner.Insert("Users",
		[]string{"name", "email"},
		[]interface{}{"alice", "a@example.com"})})
if err != nil {
	log.Fatal(err)
}
row, err := client.Single().ReadRow(ctx, "Users",
	spanner.Key{"alice"}, []string{"email"})
if err != nil {
	log.Fatal(err)
}

Contributing

Contributions are welcome. Please, see the CONTRIBUTING 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 for more information.

Documentation

Overview

Package cloud is the root of the packages used to access Google Cloud Services. See https://godoc.org/cloud.google.com/go for a full list of sub-packages.

This package documents how to authorize and authenticate the sub packages.

Example (ApplicationDefaultCredentials)

package main

import (
	"cloud.google.com/go/datastore"
	"golang.org/x/net/context"
)

func main() {
	// Google Application Default Credentials is the recommended way to authorize
	// and authenticate clients.
	//
	// See the following link on how to create and obtain Application Default Credentials:
	// https://developers.google.com/identity/protocols/application-default-credentials.
	client, err := datastore.NewClient(context.Background(), "project-id")
	if err != nil {
		// TODO: handle error.
	}
	_ = client // Use the client.
}

Example (ServiceAccountFile)

package main

import (
	"cloud.google.com/go/datastore"
	"golang.org/x/net/context"
	"google.golang.org/api/option"
)

func main() {
	// Use a JSON key file associated with a Google service account to
	// authenticate and authorize. Service Account keys can be created and
	// downloaded from https://console.developers.google.com/permissions/serviceaccounts.
	//
	// Note: This example uses the datastore client, but the same steps apply to
	// the other client libraries underneath this package.
	client, err := datastore.NewClient(context.Background(),
		"project-id", option.WithServiceAccountFile("/path/to/service-account-key.json"))
	if err != nil {
		// TODO: handle error.
	}
	_ = client // Use the client.
}