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Using Go, Python or NodeJS with SNS

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Using Go, Python or NodeJS with SNS

Published on 04 January 2023

AWS provides a number of Software Development Kits (SDKs) which provide language-specific APIs for AWS services, including SNS.

This page provides code samples to show you how to get started using these SDKs with your Scaleway Messaging SNS/SQS namespace, more specifically with SNS.

Identity and Access Management (IAM):

If you have activated IAM, you may need certain IAM permissions to carry out some actions described on this page. This means:

  • you are the Owner of the Scaleway Organization in which the actions will be carried out, or
  • you are an IAM user of the Organization, with a policy granting you the necessary permission sets
Requirements:

Go

Connect to SNS

The following code shows you how to connect to SNS:

import (
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/credentials"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/sns"
)

type AWSCredsProvider struct {
AccessKey string
SecretKey string
}

func (p *AWSCredsProvider) Retrieve() (credentials.Value, error) {
return credentials.Value{
AccessKeyID: p.AccessKey,
SecretAccessKey: p.SecretKey,
SessionToken: "",
ProviderName: "anonymous",
}, nil
}

func (p *AWSCredsProvider) IsExpired() bool {
return false
}

func main() {
awsSession := session.Must(session.NewSession(&aws.Config{
Region: aws.String("fr-par"),
Endpoint: aws.String("http://sns-sns.mnq.fr-par.scw.cloud"),
Credentials: credentials.NewCredentials(&AWSCredsProvider{
AccessKey: AwsAccessKey,
SecretKey: AwsSecretKey,
}),
}))

awsSns := sns.New(awsSession)

[...]
}
Note:

The Endpoint for Scaleway Messaging and Queuing is https://sqs-sns.mnq.fr-par.scw.cloud. The values for the access and secret keys should be the credentials you generated for your SNS/SQS namespace.

Once connected to the SNS service, you can use any of the SDK’s available functions. Be aware though that some functions are not supported by Scaleway Messaging and Queuing, so make sure to check the link for more details on these. See the official SDK documentation for more information on getting started with the SDK, or keep reading for some code examples.

Create topic

createTopicResponse, _ := awsSNS.CreateTopic(&sns.CreateTopicInput{
Name: aws.String("my-test-topic"),
})
fmt.Println(*createTopicResponse.TopicArn)

Publish messages to this topic

Be careful: messages sent to topics with no subscriptions are automatically deleted

for i := 0; i < 10; i++ {
_, _ = awsSNS.Publish(&sns.PublishInput{
Message: aws.String(fmt.Sprintf("Hello World: %d", i)),
TopicArn: createTopicResponse.TopicArn,
})
}

Create subscriptions to this topic

Subscribe to an SQS queue from the same namespace

_, _ = awsSns.Subscribe(&sns.SubscribeInput{
Endpoint: aws.String(QueueArn),
Protocol: aws.String("sqs"),
TopicArn: createTopicResponse.TopicArn,
})

Subscribe to a public Scaleway function

This code triggers the function each time a message is published to the topic.

You can find the value for [Function URL] in the Scaleway console in the Endpoints tab of your function’s Overview page.

_, _ = awsSns.Subscribe(&sns.SubscribeInput{
Endpoint: aws.String(FunctionUrl),
Protocol: aws.String("lambda"),
TopicArn: createTopicResponse.TopicArn,
})

You can also set up an SQS queue from the same namespace, as a [Dead Letter Queue](/serverless/messaging/concepts/#dead-letter-queue):

```go
_, _ = awsSns.Subscribe(&sns.SubscribeInput{
Attributes: map[string]*string{
"RedrivePolicy": aws.String("{\"deadLetterTargetArn\": \"" + QueueARN + "\"}"),
},
Endpoint: aws.String(FunctionUrl),
Protocol: aws.String("lambda"),
TopicArn: createTopicResponse.TopicArn,
})

Subscribe to an HTTP/S endpoint

_, _ = awsSns.Subscribe(&sns.SubscribeInput{
Endpoint: aws.String(Url),
Protocol: aws.String("http"), // or https
TopicArn: createTopicResponse.TopicArn,
})

The HTTP server should receive an HTTP request with a body in json matching the following format:

{
"Type": "SubscriptionConfirmation",
"Token": "<REDACTED-CONFIRMATION-TOKEN>",
"MessageId": "<REDACTED-MESSAGE-ID>",
"TopicArn": "arn:scw:sns:fr-par:<REDACTED-ID>:MyTopic",
"Message": "You have chosen to subscribe to the topic arn:scw:sns:fr-par:<REDACTED-ID>:MyTopic.\nTo confirm the subscription, visit the SubscribeURL included in this message.",
"Timestamp": "2022-06-29T10:03:34Z",
"SignatureVersion": "1",
"Signature": "<REDACTED-SIGNATURE>",
"SigningCertURL": "https://messaging.s3.fr-par.scw.cloud/fr-par/sns/sns_certificate_[certSerialNumber].crt",
"SubscribeURL": "<THE-CONFIRMATION-LINK>" // Get the confirmation link located here
}

The signing certificate of the message is in the JSON of the SigningCertURL. This certificate is also signed by the trust chain certificate (common name sns.mnq.srr.scw.cloud). For more information about verifying the authenticity of the message, refer to the official AWS documentation.

To confirm the subscription, make a request to the SubscribeURL using your browser or curl.

Delete all subscriptions

listSubscriptions, _ := awsSns.ListSubscriptionsByTopic(&sns.ListSubscriptionsByTopicInput{
TopicArn: createTopicResponse.TopicArn,
})
for _, sub := range listSubscriptions.Subscriptions {
awsSns.Unsubscribe(&sns.UnsubscribeInput{
SubscriptionArn: sub.SubscriptionArn,
})
}

Python

Connect to SNS

The following code shows you how to connect to SNS using Boto3’s resource(). You could also use client(), but we favorresource() as it is more pythonesque:

sns = boto3.resource('sns',
endpoint_url=[],
aws_access_key_id=[],
aws_secret_access_key=[],
region_name='fr-par')
Note:

The endpoint_url for Scaleway Messaging and Queuing is https://sqs-sns.mnq.fr-par.scw.cloud. The values for the access and secret keys should be the credentials you generated for your SNS/SQS namespace.

Once connected to the SNS service, you can use any of the SDK’s available functions. However, some functions are not supported by Scaleway Messaging and Queuing, so do check the link to make sure. See the official SDK documentation for more information, or keep reading for some code examples.

Create topic

# Create a topic. This returns an SNS.Topic instance
topic = sns.create_topic(Name='test') # You can now access identifiers and attributes
print(topic.arn)
print(arn.attributes)

Publish messages to this topic

Be careful: messages sent to topics with no subscriptions are automatically deleted

for i in range (0,10):
topic.Publish(Message="Hello World: "+str(i))

Create subscriptions to this topic

Subscribe to an SQS queue from the same namespace

subscription = topic.subscribe(
Protocol='sqs',
Endpoint=[Queue ARN],
ReturnSubscriptionArn=True
)

Subscribe to a public Scaleway function

This code triggers the function each time a message is published to the topic.

You can find the value for [Function URL] in the Scaleway console in the Endpoints tab of your function’s Overview page.

subscription_functions = topic.subscribe(
Protocol='lambda',
Endpoint=[Function URL],
ReturnSubscriptionArn=True
)

You can also set up an SQS queue from the same namespace, as a Dead Letter Queue:

subscription_functions = topic.subscribe(
Protocol='lambda',
Endpoint=[Function URL],
ReturnSubscriptionArn=True,
Attributes={
'RedrivePolicy': '{"deadLetterTargetArn": "[Queue ARN]"}'
}
)

Subscribe to an HTTP/S endpoint

subscription = topic.subscribe(
Protocol='http', //or https
Endpoint=url,
ReturnSubscriptionArn=True
)

The HTTP server should receive an HTTP request with a body in json matching the following format:

{
"Type": "SubscriptionConfirmation",
"Token": "<REDACTED-CONFIRMATION-TOKEN>",
"MessageId": "<REDACTED-MESSAGE-ID>",
"TopicArn": "arn:scw:sns:fr-par:<REDACTED-ID>:MyTopic",
"Message": "You have chosen to subscribe to the topic arn:scw:sns:fr-par:<REDACTED-ID>:MyTopic.\nTo confirm the subscription, visit the SubscribeURL included in this message.",
"Timestamp": "2022-06-29T10:03:34Z",
"SignatureVersion": "1",
"Signature": "<REDACTED-SIGNATURE>",
"SigningCertURL": "http://<REDACTED-URL>/SNStest.crt",
"SubscribeURL": "<THE-CONFIRMATION-LINK>" // Get the confirmation link located here
}

To confirm the subscription, make a request to the SubscribeURL using your browser or curl.

Delete all subscriptions

for subs in topic.subscriptions.all():
subs.delete()

NodeJS

Connect to SNS

The following code sample shows how to connect to SQS:

var sns = new AWS.SNS({
apiVersion: '2010-03-31',
endpoint: '',
accessKeyId:'',
secretAccessKey:'',
region: 'fr-par'
});
Note:

The endpoint_url for Scaleway Messaging and Queuing is https://sqs-sns.mnq.fr-par.scw.cloud. For the access and secret key values, use the credentials you generated for your SNS/SQS namespace.

Once connected to the SNS service, you can use any of the SDK’s available functions. However, some functions are not supported by Scaleway Messaging and Queuing, so do check the link to make sure. See the official SDK documentation for more information, or keep reading for some code examples.

Create topic

You can find all available parameters for createTopic in the AWS documentation.

var params = {
Protocol: 'sqs', /* required */
TopicArn: {SNS Topic Arn}, /* required */
// Attributes: {
// '<attributeName>': 'STRING_VALUE',
// /* '<attributeName>': ... */
// },
Endpoint: {SQS ARN},
ReturnSubscriptionArn: true
};

Publish messages to this topic

Be careful: messages sent to topics with no subscriptions are automatically deleted.

This code sample demonstrates how to send a message with MessageAttributes. For more information on MessageAttributes, refer to the official documentation.

var params = {
Message: 'Test Message', /* required */
MessageAttributes: {
'Name': {
DataType: 'String', /* required */
StringValue: 'John'
}
},
Subject: 'Test',
TopicArn: ''
};
sns.publish(params, function (err, data) {
if (err) console.log(err, err.stack); // an error occurred
else console.log(data); // successful response
});

Subscribe to a topic

You can find all available parameters for the subscribe operation in the AWS documentation (https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/SNS.html#subscribe-property)

Subscribe to an SQS queue from the same namespace

var params = {
Protocol: 'sqs', /* required */
TopicArn: [SNS Topic Arn], /* required */
// Attributes: {
// '<attributeName>': 'STRING_VALUE',
// /* '<attributeName>': ... */
// },
Endpoint: [SQS Queue Arn],
ReturnSubscriptionArn: true
};

sns.subscribe(params, function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else console.log(data); // successful response
});

Subscribe to a public Scaleway function

This code triggers the function each time a message is published to the topic.

You can find the value for [Function URL] in the Scaleway console in the Endpoints tab of your function’s Overview page.

var params = {
Protocol: 'lambda', /* required */
TopicArn: [SNS Topic Arn], /* required */
Endpoint: [Scaleway Serverless Function or Container URL],
ReturnSubscriptionArn: true
};

sns.subscribe(params, function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else console.log(data); // successful response
});

You can also set up an SQS queue from the same namespace, as a Dead Letter Queue:

var params = {
Protocol: 'lambda', /* required */
TopicArn: [SNS Topic Arn], /* required */
Attributes: {
'RedrivePolicy': '{\'deadLetterTargetArn\':\'[SQS Queue Arn]'}',
},
Endpoint: 'https://demodayndhiixus-logall.functions.fnc.fr-par.scw.cloud',
ReturnSubscriptionArn: true
};

sns.subscribe(params, function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else console.log(data); // successful response
});

Subscribe to an HTTP/S endpoint

subscription = topic.subscribe(
Protocol='http', //or https
Endpoint=url,
ReturnSubscriptionArn=True
)

The HTTP server receives an HTTP request with a json body matching the following format:

{
"Type": "SubscriptionConfirmation",
"Token": "<REDACTED-CONFIRMATION-TOKEN>",
"MessageId": "<REDACTED-MESSAGE-ID>",
"TopicArn": "arn:scw:sns:fr-par:<REDACTED-ID>:MyTopic",
"Message": "You have chosen to subscribe to the topic arn:scw:sns:fr-par:<REDACTED-ID>:MyTopic.\nTo confirm the subscription, visit the SubscribeURL included in this message.",
"Timestamp": "2022-06-29T10:03:34Z",
"SignatureVersion": "1",
"Signature": "<REDACTED-SIGNATURE>",
"SigningCertURL": "http://<REDACTED-URL>/SNStest.crt",
"SubscribeURL": "<THE-CONFIRMATION-LINK>" // Get the confirmation link located here
}

To confirm the subscription, make a request to the SubscribeURL using your browser or curl.

Delete all subscriptions

The following code sample deletes all subscriptions to a topic.

var params = {
TopicArn: '', /* required */
};

sns.listSubscriptionsByTopic(params, function (err, data) {
if (err) console.log(err, err.stack); // an error occurred
else
data.Subscriptions.forEach(function (element) {
var params = {
SubscriptionArn: element.SubscriptionArn
}
sns.unsubscribe(params, function (err, data) {
if (err) console.log(err, err.stack); // an error occurred
else console.log(params.SubscriptionArn, "Deleted"); // successful response
});
})
})