serverless-sns-filter-tmp v2.0.0

serverless-sns-filter

A serverless plugin to add SNS Subscription filters to lambda events

• Installation
• Configuration
• Usage
• Limitations
• Contributing

For an example of a working application, see the integration-test

This plugin adds the following resources to your Serverless Cloudformation stack:

• A lambda function (invoked using CloudFormation Custom Resources) that adds an SNS Subscription Filter to a SNS Subscription
• An IAM Role, with a policy, to allow the above Lambda to create the SNS subscription filters including the following:

• Effect: Allow Action: - SNS:ListSubscriptions Resource: - Fn::Sub: arn:aws:sns:${AWS::Region}:${AWS::AccountId}: - Effect: Allow Action: - SNS:setSubscriptionAttributes Resource: Fn::Sub: arn:aws:sns:${AWS::Region}:${AWS::AccountId}:

# Installation

Install the plugin: 

`npm install serverless-sns-filter`

Add the plugin to your `serverless.yml`

plugins:

• serverless-sns-filter

# Configuration

Add a filter policy to your function under the events section:

functions: hello: handler: handler.hello events: - sns: ${self:custom.greeterTopic}

    # filter policy to accept messages with attrib_one values including "foo" OR "bar"
    filter:
      attrib_one:
        - foo
        - bar

# Usage

SNS Subscription filters require SNS notifications to include `MessageAttributes` that the filters are matched against.

Example, NodeJS lambda that shall post a message that shall be received by the hello function above:

serverless.yml:

sendMessage: handler: send.with_attribute environment: TOPIC_ARN: "${{self:custom.greeterTopicArn}}"

`send.js`:

const AWS = require('aws-sdk') let sns = new AWS.SNS()

const publish_sns = (params, callback) => { sns.publish(params).promise().then(done => { console.log(JSON.stringify(done)) callback(null,done) }).catch(error => { console.log(JSON.stringify(error)) callback(error,"send failed") }) }

const with_attribute = (event, context, callback) => { const topicArn = process.env'TOPIC_ARN' console.log(publishing to topic: ${topicArn}) const params = { Message: 'should be received', MessageAttributes: { 'attrib_one': { DataType: 'String', StringValue: 'foo' } }, Subject: "Successful message", TopicArn: topicArn }

publish_sns(params,callback)

}

module.exports = { with_attribute: with_attribute }

# Limitations

* SNS Subscription Filters cannot be removed at the present time.  If you need to remove a filter, then remove the SNS subscription and re-create it without the filter definition.

* The plugin currently only supports a single SNS filter per function.

# Contributing


* The person who found a bug should fix the bug by themself.
* If you find a bug and cannot fix it by yourself, send a pull request and attach test code to reproduce the bug, please.
* The person who want a new feature should implement it by themself.
* For above reasons, we accept pull requests only and disable issues.
* If you're not sure how to fix an issue, please create a pull request demonstrating a [minimal viable complete example](https://stackoverflow.com/help/mcve) as a failing test.
* If you'd like to discuss about a new feature before implement it, make an empty commit and send a WIP pull request. But It is better that the WIP PR has some code than an empty commit.

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request

## Publishing

cd plugin yarn version yarn run test yarn run compile npm login npm publish