In this post I will present a solution for the following business Use Case:

Obtain data from a local Data Base running on isolated network without access to the public internet.

Additional requirements:

• do not store the password to the local Data Base as a clear text at any point in time
• do not share the password to the local Data Base with developers
• encrypt data during transfer to the cloud

In order to realize the above Business Use Case and meet additional requirements we will build a solution presented below:

To setup the local development environment we will use docker-compose template containing following definitions:

• Greengrass Core container attached to both public and private network emulate service deployed at the Edge Server,
• MySQL container running on an internal docker network will emulate a Data Base server without access to the internet.

Greengrass Core will receive encrypted credentials from AWS Secrets Manager and store them securely on the Edge Server. Please check my twitter post for additional details.

Obtained credentials will allow the Lambda function running at the Greengrass Core to log into the local Data Base and execute SQL query.

Received data will be returned in a secure way to AWS IoT Core.

Lambda function running at the Greengrass Core device is created using AWS SAM template.

Setting runtime to python3.7 is important because that version of python3 is supported by Greengrass Core at this time (this might change in the future).

AutoPublishAlias: prod is used to automatically create an alias and publish an updated version of a Lambda function. In order to avoid Greengrass Group configuration updates, you can specify a Lambda alias instead of a specific Lambda version (this way updated versions of this function are going to be pointed by the same alias).

The password for the local Data Base is going to be stored in AWS Secrets Manager (a service that is designed to manage passwords in a secure way).

Secret Resource in Greengrass Group points to the password for the local Data Base stored in Secrets Manager service. This encrypted secret is going to be part of the Greengrass Group Deployment (will be transferred to Greengrass Core device).

Lambda function running at the Greengrass Core is configured as affiliated with Secret - this allows it to access password stored in this Secret and use it to log into the local Data Base.

# read secret
resp = sm_client.get_secret_value(SecretId='greengrass-local-db')
secret = resp.get('SecretString')

...

sec = json.loads(secret)

# connect to local DB using obtained secret
cnx = mysql.connector.connect(user='root',password=sec["db_pass"], host='db',port=3306, database='sys')

Full source code of this Lambda.

Following Subscriptions are configured:

Lambda function is going to be invoked by sending a message to sql/req topic and it will return obtained data in a message send to sql/res topic.

Disclaimer: in actual solution this might or might not be the desired implementation - I used MQTT topics to clearly present the end to end flow of data.

I hope that you will find the above solution useful.

Create an issue in case of any questions and consider following me on twitter if you are interested in AWS and IoT topics.

AWS Greengrass documentation

AWS Secrets Manager documentation

AWS Serverless Application Model (SAM)

AWS IoT Greengrass Core Python SDK

Docker Compose