AWS SNS - How to get topic arn by topic name

Question

In my application i need to send messages to the given topic name. The topic is already created by other person and in a config file they give only the topic Name. My work is to push the messages in the given topic Name. Is there any way to get topic ARN by topic NAME in java?

score 14 · Answer 1 · edited May 23 '17 at 12:10

14

As stated in this answer using createTopic(topicName) is more direct approach. In case topic have been created before, it will just return you topic ARN.

edited May 23 '17 at 12:10

Community

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answered Mar 30 '17 at 09:01

Bryn

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I think this is a best answer for this question! – harley Feb 17 '19 at 16:14
Although the answer is technically correct, it does not follow the principle of least privilege. If you want to follow this, you should better go through the list of topics or create the ARN according to the pattern. – Tobias Stangl May 16 '23 at 06:25

score 11 · Answer 2 · edited Feb 24 '21 at 23:42

I've done this one of two ways. The ARN is always the same pattern. So, you could just subscribe to "arn:aws:sns:<region>:<account>:<name>" where:

region is from Regions.getCurrentRegion(). Be careful with this as it is a bit expensive of a call and you'll need to handle not being on an EC2/Elastic Beanstalk instance.

account is from AmazonIdentityManagementClient.getUser().getUser().getArn(). You'll have to parse the account number from that. Same warning about not being in an EC2 environment.

name is what you have.

A simpler way is loop through the the topics and look for the name you want in the ARN. You will use the AmazonSNSClient listTopics method to do this. Remember that that method only returns the first 100 topics - you'll want to properly loop over the entire topic list.

score 1 · Answer 3 · edited Sep 24 '20 at 09:18

This might be what you need. Supply the topic and get it from available topics.

import json
import boto3

def lambda_handler(event, context):
    try:

        topic =  event['topic'] 
        subject = event['subject']
        body = event['body']
        subscriber = event['subscriber']
        
        sns_client = boto3.client('sns')
        
        sns_topic_arn = [tp['TopicArn'] for tp in sns_client.list_topics()['Topics'] if topic in tp['TopicArn']]
        
        sns_client.publish(TopicArn = sns_topic_arn[0], Message=body,
            Subject=subject)
        
    except Exception as e:
        print(e)

What is the `event` parameter that you pass in function? – alltej May 18 '22 at 12:28 — alltej, May 18 '22 at 12:28

score 0 · Answer 4 · answered Jun 09 '23 at 05:40

If you have create topic permission, you can try this: link

If you don't have permission, you can try this:

private static Optional<Topic> getTopicByName(SnsClient snsClient, 
                                              String topicName) {
    for (val topicsResponse : snsClient.listTopicsPaginator()) {
        if (topicsResponse.hasTopics()) {
            for (val topic : topicsResponse.topics()) {
                // Arn format => arn:aws:sns:region:account-id:topic-name
                val arn = topic.topicArn();
                val sp = arn.split(":");
                if (topicName.equals(sp[sp.length - 1])) {
                    return Optional.of(topic);
                }
            }
        }
    }
    return Optional.empty();
}

score -5 · Answer 5 · answered Aug 29 '16 at 02:49

-5

What you can do, is to create a table that contains topic and its topicArn.

The topic arn can be retrieve by the console or using the api when you create a topic.

This way no need to loop or try to match a pattern.

answered Aug 29 '16 at 02:49

tainos

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AWS SNS - How to get topic arn by topic name

5 Answers5