SNS

This guide will show you steps to create SNS topics and access them from your service running within App environments.

To proceed with this guide, you would need access to:

1. AWS console with permissions to access SNS console and add policies to an existing IAM role.
2. LocalOps console

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Steps:

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1. Create SNS topic

Login to AWS console and create new SNS topic in the region you want, and with appopriate unique name.

You can follow this official AWS guide to create SNS topic(s).

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2. Add permission to access SNS topic

LocalOps creates a new IAM role in your AWS account, for each app environment, so that your services/containers can access them. So that your code/containers can access any AWS resource without passing AWS_ACCESS_KEY or AWS_SECRET_KEY.

Navigate to LocalOps console and the corresponding environment. In overview section, you can find the APP ROLE whose name ends with app-role and that which you can copy and search in AWS IAM console > Roles section. Once you find the IAM role in IAM console, next step is to add a policy to the IAM role to give permissions for the role to access the SNS topic(s) your created.

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Create a new IAM policy for the SNS topic:

1. Navigate to Policies in AWS IAM console
2. Create a new IAM policy and give it a specific name
3. Add the JSON below, as policy statement:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "sns:Publish",
        "sns:Subscribe",
        "sns:Unsubscribe",
        "sns:Receive",
        "sns:GetTopicAttributes",
        "sns:SetTopicAttributes",
        "sns:ListSubscriptionsByTopic"
      ],
      "Resource": "<sns-topic-arn>"
    }
  ]
}

Replace <sns-topic-arn> with your SNS topic’s ARN.

If you create more than one topic, expand the Resource attribute above to an array of ARN strings.

4. Press save.

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Add the new IAM policy to the IAM role

Navigate back to the IAM role you saw earlier. In its Permissions tab, pick the option to “Add Policy”. In the policy picker, pick the one you created above and add it.

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3. Add topic details as secret

Last step is to give service access to the new SNS topic. In LocalOps console, navigate to the Service settings within the corresponding environment.

In secrets section, add a new key value pair like

- Key: `topic-var-name`
- Value: `topic-name`

Repeat this for each topic you created. Learn more about secrets here.

You can name the key in any way you want. In your code, you can access topic-var-name environment variable to get the name of the topic you created. This can be passed to the AWS SDK used in your code to read/write data. There is no need to provide credentials like access key since we are having role based access control here.

That’s it! 🎉