#20 Install aws amazon sdk on Raspberry Pi 3 and Test connection (Publish - Subscribe IoT Architecture) | APDaga Tech

IoT Tutorial #20 [ Raspberry Pi Tutorials #8 ]

In this post,

We will send messages over the internet from one python script (aws_iot_pub.py) to another python script (aws_iot_sub.py) running on Raspberry Pi 3 using aws amazon cloud (publish-subscribe IoT Architecture)

In order to use Amazon cloud services on Raspberry Pi, we need to install aws amazon sdk on Raspberry Pi (Raspbian stretch OS).

Recommended Internet of Things (IOT) Courses:

1. Udemy: Complete Guide to Build IOT Things from Scratch to Market
2. LinkedIn: IoT Foundations: Fundamentals
3. edX: Introduction to the Internet of Things (IoT)
4. edureka: IoT Certification Training on Azure
5. Coursera: An Introduction to Programming the Internet of Things (IOT) Specialization
6. Eduonix: Internet Of Things (IOT) Bundle

Steps to install aws amazon sdk om Raspberry Pi 3 and Test connection:

1.       Sign up on AWS Amazon website and (login from Raspberry Pi)
 and Go to: Services > AWS IoT (IoT Core) > Onboard > Get Started

a.       Choose Platform: Linux/OSX

b.      Choose an AWS IoT Device SDK: Python

c.       Set any name of a thing (we will refer it as <Thing_Name>)

d.      Download connect kit on Raspberry Pi.
 Click on Next > Next > Finish/Done to complete the configuration of the device/thing.

2.       Install:
  Unzip the downloaded file. You should have following files:

a.       <Thing_Name>.cert.pem

b.      <Thing_Name>.private.key

c.       <Thing_Name>.public.key

d.      start.sh

                    Put all the unzipped files in one folder.

3.       Run following commands to Check Versions and install paho-mqtt:

$ openssl version
OpenSSL 1.1.0f  25 May 2017

$ python –V
Python 2.7.13

$ openssl version
OpenSSL 1.1.0f  25 May 2017

$ sudo pip install paho-mqtt

$ sudo  apt-get update

4.       Download "root-CA.crt" and sample sdk using start.sh script:
  Give executable permissions to "start.sh"

 Open terminal go to above unzipped directory
 Run following commands:

$ pip install AWSIoTPythonSDK

$ ./start.sh

And wait for the installation to complete...
Try it 2-3 times, It might show an error similar to:

error: could not create '/usr/local/lib/python2.7/dist-packages/AWSIoTPythonSDK': Permission denied

But try again and again 2-3 times till you see msg similar to below on terminal and press "ctrl + c"

{"message": "Hello World!", "sequence": 5}

  "root-CA.crt" & sample SDK is now downloaded in the same folder as that of "start.sh"

NOTE: If "root-CA.crt" is not downloaded, then click here to download. 

Steps to test the connection with aws cloud:

5.       Download "aws_iot_pub.py" and "aws_iot_sub.py" and
 paste it to the folder having all aws unzipped files

 Make the changes in both python script (as mentioned in those python script)
 Provide Executable permission to both python script.
 Run both python scripts on RPi3.

You will see all the messages published by "aws_iot_pub.py" received by "aws_iot_sub.py"

NOTE:

·         aws_iot_pub.py will generate random temperature data in the range of 20 to 25 degree celcius and send it to the amazon aws broker to the topic “temperature”

·         aws_iot_sub.py will receive all the messages published to all the topics on registered thing on amazon aws cloud.

  THESE MEANS YOUR ARE CONNECTED TO "AWS AMAZON IOT BROKER" SUCCESSFULLY!!!

For Better understanding you can watch the demonstration video given below:

Downloads:

Download link is given in the Description of the YouTube video shown below.

Demonstration:

aws_iot_pub.py:

#!/usr/bin/python

############################################ 
# PROBLEM STATEMENT:
# This program will publish test mqtt messages using the AWS IOT hub
# 
# To test this program you have to run first its companinon aws_iot_sub.py
# that will subscribe and show all the messages sent by this program
#
############################################

############################################
# STEPS:
#
# 1. Sign in to AWS Amazon > Services > AWS IoT > Settings > copy Endpoint
#    This is your awshost
# 
# 2. Change following things in the below program:
#    a. awshost   (from step 1)
#    b. clientId  (Thing_Name)
#    c. thingName (Thing_Name)
#    d. caPath    (root-CA_certificate_Name)
#    e. certPath  (<Thing_Name>.cert.pem)
#    f. keyPath   (<Thing_Name>.private.key)
# 
# 3. Paste aws_iot_pub.py & aws_iot_sub.py python scripts in folder where all unzipped aws files are kept. 
# 4. Provide Executable permition for both the python scripts.
# 5. Run aws_iot_sub.py script
# 6. Run this aws_iot_pub.py python script
#
############################################

# importing libraries
import paho.mqtt.client as paho
import os
import socket
import ssl
from time import sleep
from random import uniform
 
connflag = False
 
def on_connect(client, userdata, flags, rc):                # func for making connection
    global connflag
    print "Connected to AWS"
    connflag = True
    print("Connection returned result: " + str(rc) )
 
def on_message(client, userdata, msg):                      # Func for Sending msg
    print(msg.topic+" "+str(msg.payload))
 
#def on_log(client, userdata, level, buf):
#    print(msg.topic+" "+str(msg.payload))
 
mqttc = paho.Client()                                       # mqttc object
mqttc.on_connect = on_connect                               # assign on_connect func
mqttc.on_message = on_message                               # assign on_message func
#mqttc.on_log = on_log

#### Change following parameters #### 
awshost = "a1r7yoit83fln7.iot.us-east-2.amazonaws.com"      # Endpoint
awsport = 8883                                              # Port no.   
clientId = "aws_thing1"                                     # Thing_Name
thingName = "aws_thing1"                                    # Thing_Name
caPath = "root-CA.crt"                                      # Root_CA_Certificate_Name
certPath = "aws_thing1.cert.pem"                            # <Thing_Name>.cert.pem
keyPath = "aws_thing1.private.key"                          # <Thing_Name>.private.key
 
mqttc.tls_set(caPath, certfile=certPath, keyfile=keyPath, cert_reqs=ssl.CERT_REQUIRED, tls_version=ssl.PROTOCOL_TLSv1_2, ciphers=None)  # pass parameters
 
mqttc.connect(awshost, awsport, keepalive=60)               # connect to aws server
 
mqttc.loop_start()                                          # Start the loop
 
while 1==1:
    sleep(5)
    if connflag == True:
        tempreading = uniform(20.0,25.0)                        # Generating Temperature Readings 
        mqttc.publish("temperature", tempreading, qos=1)        # topic: temperature # Publishing Temperature values
        print("msg sent: temperature " + "%.2f" % tempreading ) # Print sent temperature msg on console
    else:
        print("waiting for connection...")                  

aws_iot_sub.py:

#!/usr/bin/python

############################################ 
# PROBLEM STATEMENT:
#
# This program will subscribe and show all the messages sent by its companion 
# aws_iot_pub.py using AWS IoT hub
#
############################################

############################################
# STEPS:
#
# 1. Sign in to AWS Amazon > Services > AWS IoT > Settings > copy Endpoint
#    This is your awshost
# 
# 2. Change following things in the below program:
#    a. awshost   (from step 1)
#    b. clientId  (Thing_Name)
#    c. thingName (Thing_Name)
#    d. caPath    (root-CA_certificate_Name)
#    e. certPath  (<Thing_Name>.cert.pem)
#    f. keyPath   (<Thing_Name>.private.key)
# 
# 3. Paste aws_iot_pub.py & aws_iot_sub.py python scripts in folder where all unzipped aws files are kept. 
# 4. Provide Executable permition for both the python scripts.
# 5. Run aws_iot_sub.py script
# 6. Run this aws_iot_pub.py python script
#
############################################

# importing libraries
import paho.mqtt.client as paho
import os
import socket
import ssl
 
def on_connect(client, userdata, flags, rc):                # func for making connection
    print("Connection returned result: " + str(rc) )
    # Subscribing in on_connect() means that if we lose the connection and
    # reconnect then subscriptions will be renewed.
    client.subscribe("#" , 1 )                              # Subscribe to all topics
 
def on_message(client, userdata, msg):                      # Func for receiving msgs
    print("topic: "+msg.topic)
    print("payload: "+str(msg.payload))
 
#def on_log(client, userdata, level, msg):
#    print(msg.topic+" "+str(msg.payload))
 
mqttc = paho.Client()                                       # mqttc object
mqttc.on_connect = on_connect                               # assign on_connect func
mqttc.on_message = on_message                               # assign on_message func
#mqttc.on_log = on_log

#### Change following parameters ####  
awshost = "a1r7yoit83fln7.iot.us-east-2.amazonaws.com"      # Endpoint
awsport = 8883                                              # Port no.   
clientId = "aws_thing1"                                     # Thing_Name
thingName = "aws_thing1"                                    # Thing_Name
caPath = "root-CA.crt"                                      # Root_CA_Certificate_Name
certPath = "aws_thing1.cert.pem"                            # <Thing_Name>.cert.pem
keyPath = "aws_thing1.private.key"                          # <Thing_Name>.private.key
 
mqttc.tls_set(caPath, certfile=certPath, keyfile=keyPath, cert_reqs=ssl.CERT_REQUIRED, tls_version=ssl.PROTOCOL_TLSv1_2, ciphers=None)      # pass parameters
 
mqttc.connect(awshost, awsport, keepalive=60)               # connect to aws server
 
mqttc.loop_forever()                                        # Start receiving in loop

---

UPDATES:

Many of you were facing the issue like : "Waiting for connection..." 

The reason behind it is, In a year, few things are changed on AWS, one of them is policy associated with the thing we create.
As per the new policies, After successful download and installation of the "root-CA.crt" & Sample SDK (As shown in step 4), A sample Pub-sub program run on our Raspberry Pi.

Now if you go to policies associated with our newly created thing on aws, you will see the parameter "Resource" and its value is set to some python or java program (These scripts are nothing but the default scripts from SDK to run a sample pub-sub). So that, only those scripts can access our aws thing.

Now, In order to run our pub-sub scripts you have to do either of the change:

• Either Add your python script name in the Resource list in the policy
• or Remove all the name from Resource parameter and replace it by "*"

NOTE: "*" means Set Resource as all.

The good news is, Solution is available for it. Detailed steps are as given below:

Follow the below steps:

1. Login to your AWS account, Go to AWS IOT (IOT Core)
2. Go to Secure > Policies > Click on the Policy Associated with your thing.
   Eg.If your thing name is aws_thing1 then the policy related to this may be aws_thing1-Policy
3. Click on Edit policy document
4. Delete everything and paste the following in that space:
   

   {
     "Version": "2012-10-17",
     "Statement": [
       {
         "Effect": "Allow",
         "Action": [
           "iot:Publish",
           "iot:Subscribe",
           "iot:Connect",
           "iot:Receive"
         ],
         "Resource": [
           "*"
         ]
       }
     ]
   }

5. Click on save as a new version
6. The problem is solved. Now run your aws_iot_pub.py and aws_iot_sub.py on your Raspberry Pi.

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Click here to see more codes for Raspberry Pi 3 and similar Family.

&
Click here to see more codes for NodeMCU ESP8266 and similar Family.
&
Click here to see more codes for Arduino Mega (ATMega 2560) and similar Family.

Feel free to ask doubts in the comment section. I will try my best to solve it.

If you find this helpful by any mean like, comment and share the post.

This is the simplest way to encourage me to keep doing such work.

Thanks and Regards,

-Akshay P. Daga