README.md

greengrass-standalone-demo

Demonstrate the connection of IoT devices to a Greengrass Core when the IoT devices do not have Internet access (i.e., only the Greengrass Core has Internet access).

Caveat

Obviously you don't want to follow this procedure exactly for a production deployment. The Greengrass Core and IoT device private keys should be generated locally, preferably in hardware, on those respective devices.

Demo Setup

Instructions

Feel free to chose your own group and thing names and topics and just replace the references to them. I've used Amazon Linux 2 as the OS for all the devices here (Greengrass Core, IoT device 1, and IoT device 2), but you could easily use any platform that supports Greengrass Core and the AWS IoT Device SDK, by modifying the install instructions.

1. Create a new Greengrass Group called standalone-demo in AWS with the default settings (GUI).
2. Setup the Greengrass Core with the provided config files.
   1. sudo adduser --system ggc_user
sudo groupadd --system ggc_group
curl https://raw.githubusercontent.com/tianon/cgroupfs-mount/951c38ee8d802330454bdede20d85ec1c0f8d312/cgroupfs-mount > cgroupfs-mount.sh
chmod +x cgroupfs-mount.sh
sudo bash ./cgroupfs-mount.sh
sudo yum install java-1.8.0-openjdk
sudo ln -s /usr/bin/java /usr/bin/java8
wget https://github.com/aws-samples/aws-greengrass-samples/raw/master/greengrass-dependency-checker-GGCv1.10.x.zip
unzip greengrass-dependency-checker-GGCv1.10.x.zip
cd greengrass-dependency-checker-GGCv1.10.x
sudo ./check_ggc_dependencies | more
cd
wget https://d1onfpft10uf5o.cloudfront.net/greengrass-core/downloads/1.10.1/greengrass-linux-x86-64-1.10.1.tar.gz
sudo tar xzvf greengrass-linux-x86-64-1.10.1.tar.gz -C /
   2. Upload the config files from step 1.
   3. Finish Greengrass Core setup:
      cd /greengrass
sudo tar xzvf ~/6893d449c9-setup.tar.gz (your config filename will be different)
      cd certs
sudo wget -O root.ca.pem https://www.amazontrust.com/repository/AmazonRootCA1.pem
sudo /greengrass/ggc/core/greengrassd start
3. Add two new IoT devices to the group using default settings. Call one standalone-demo-iot-device-1 and the other standalone-demo-iot-device-2. Save the generated certificates.
4. Create two subscriptions in the group.
   1. Source: standalone-demo-iot-device-1
      Destination: standalone-demo-iot-device-1
      Topic: my/topic
   2. Source: standalone-demo-iot-device-1
      Destination: standalone-demo-iot-device-2
      Topic: my/topic
5. Deploy the Greengrass Group.
6. Record the local IP of the Greengrass Core device. You can find this under the Connectivity screen of the Core in the Console GUI.
7. Save the Greengrass Group CA certificate.
   1. Lookup the Greengrass Group ID in the settings page of the group.
   2. aws greengrass list-group-certificate-authorities --group-id ab358983-29e8-4873-ba57-6eac7a9e16ba
      Use the GroupCertificateAuthorityId that is output here.
   3. aws greengrass get-group-certificate-authority --group-id ab358983-29e8-4873-ba57-6eac7a9e16ba --certificate-authority-id 00b6ae9101d596540e107b554333c4b85133f20a90111a555f7d072e9c02211d | jq -r '.PemEncodedCertificate'
   4. Save this output as ggc-root.ca.pem
8. Prepare two IoT devices with local network connectivity to your Greengrass Core, but not to the Internet. Let's call these device-1 and device-2.
9. Install the Python AWS IoT Device SDK on device-1 and clone this repo there:
   1. sudo yum install python3 git
   2. pip3 install awsiotsdk --user
   3. git clone https://github.com/njlaw/greengrass-standalone-demo
10. Install mosquitto on device-2:
11. sudo amazon-linux-extras install epel
12. sudo yum install mosquitto
13. Upload the saved certificates (from step 3) to device-1 and device-2 respectively.
14. Run mosquitto_sub on device-2:

[ec2-user@device-2 ~]$ mosquitto_sub -h 172.23.4.13 -i standalone-demo-iot-device-2 -p 8883 -t my/topic --cert f47ecc169f.cert.pem --key f47ecc169f.private.key -d --cafile ggc-root.ca.pem
Client standalone-demo-iot-device-2 sending CONNECT
Client standalone-demo-iot-device-2 received CONNACK (0)
Client standalone-demo-iot-device-2 sending SUBSCRIBE (Mid: 1, Topic: my/topic, QoS: 0, Options: 0x00)
Client standalone-demo-iot-device-2 received SUBACK
Subscribed (mid: 1): 0

13. Run standalone_pubsub.py on device-1:

[ec2-user@device-1 ~]$ cd greengrass-standalone-demo
[ec2-user@device-1 greengrass-standalone-demo]$ python3 standalone_pubsub.py --endpoint 172.23.4.13 --cert ~/4d80d07ab1.cert.pem --key ~/4d80d07ab1.private.key --root-ca ~/ggc-root.ca.pem --client-id standalone-demo-iot-device-1
Connecting to 172.23.4.13 with client ID 'standalone-demo-iot-device-1'...
Connected!
Subscribing to topic 'my/topic'...
Subscribed with QoS.AT_MOST_ONCE
Sending 10 message(s)
Publishing message to topic 'my/topic': Hello World! [1]
Received message from topic 'my/topic': b'Hello World! [1]'
Publishing message to topic 'my/topic': Hello World! [2]
Received message from topic 'my/topic': b'Hello World! [2]'
Publishing message to topic 'my/topic': Hello World! [3]
Received message from topic 'my/topic': b'Hello World! [3]'
...

14. Check the output on device-2 as well:

Client standalone-demo-iot-device-2 received PUBLISH (d0, q0, r1, m0, 'my/topic', ... (16 bytes))
Hello World! [1]
Client standalone-demo-iot-device-2 received PUBLISH (d0, q0, r1, m0, 'my/topic', ... (16 bytes))
Hello World! [2]
Client standalone-demo-iot-device-2 received PUBLISH (d0, q0, r1, m0, 'my/topic', ... (16 bytes))
Hello World! [3]

Changes from pubsub.py

standalone_pubsub.py is mostly the same as the pubsub.py example from AWS's SDK. The following changes were made:

1. Removed command line options that don't make sense in this scenario (e.g., related to WebSocket and HTTP proxies);
2. Made required parameters required by ArgumentParser;
3. Added a --port option;
4. Removed the if args.use_websocket == True section; and,
5. Changed the QoS to AT_MOST_ONCE since AT_LEAST_ONCE isn't supported by Greengrass.