AWS SNS - 如何通过主题名称获取主题 arn

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?

Answer 1

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.

Answer 2

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.

Answer 3

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)

Answer 4

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();
}

Answer 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.