SNS notification target rule is “unreachable” when tryin to send a notification from code pipeline

Whenever you create an SNS topic by itself, the default access policy will look something like this: The default access policy shown as below is wrong and will not work. 

{
  "Version": "2008-10-17",
  "Id": "__default_policy_ID",
  "Statement": [
    {
      "Sid": "__default_statement_ID",
      "Effect": "Allow",
      "Principal": {
        "AWS": "*"
      },
      "Action": [
        "SNS:Publish",
        "SNS:RemovePermission",
        "SNS:SetTopicAttributes",
        "SNS:DeleteTopic",
        "SNS:ListSubscriptionsByTopic",
        "SNS:GetTopicAttributes",
        "SNS:AddPermission",
        "SNS:Subscribe"
      ],
      "Resource": "arn:aws:sns:us-east-2:123456789012:my-sns-topic",
      "Condition": {
        "StringEquals": {
          "AWS:SourceOwner": "123456789012"
        }
      }
    }
  ]
}

The above is wrong and will not let your CodePipeline access the SNS topic (make it reachable/”Active”)! Change the Access policy for your SNS topic to the following instead:

{
  "Version": "2008-10-17",
  "Statement": [
    {
      "Sid": "CodeNotification_publish",
      "Effect": "Allow",
      "Principal": {
        "Service": "codestar-notifications.amazonaws.com"
      },
      "Action": "SNS:Publish",
      "Resource": "arn:aws:sns:us-east-2:123456789012:my-sns-topic"
    }
  ]
}

NOTE 1: Change 123456789012 to your AWS account ID, and my-sns-topic to the name of your SNS topic.
NOTE 2: If your region is different than us-east-2, then change that too in the above snippet.
NOTE 3: Both the SNS topic and the CodePipeline Notification rule should be in the same region, otherwise this won’t work.

Notification Rule and Notification Rule Target Issue

Whenever you create a Notification Rule and then a Notification Rule Target, the only way possible for AWS to refresh the Notification target status is for you to delete the Notification rule target from CodePipeline -> Settings (on the left side bar) -> Notification rules -> Notification rule targets (this is extremely important!).

NOTE: Deleting the Notification rule target from the notification rule itself won’t do anything; because of that, when you re-add it in that page, the Notification rule target will still be the old one and thus the Notification target status will remain “Unreachable”.

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