I have a rails application, and when there is an update to one of the rows in my database, I want to run a python script which is on a raspberry pi (example: lights up a LED when a user is created). I'm using PostgreSQL and have looked into NOTIFY/LISTEN channels, but can't quite figure that out. Is there an easy way to do this? The raspberry pi will not be on the same network as the rails application.
There are many "easy" ways, depending on your skills.
Maybe: "Write triggers, which are sending the notify on insert/update" is the hint you need?
Related
I am currently working on a project in which I am using a webcam attached to a raspberry pi to then show what the camera is seeing through a website using a client and web server based method through python, However, I need to know how to link the raspberry pi to a website to then output what it sees through the camera while then also outputting it through the python script, but then i don't know where to start
If anyone could help me I would really appreciate it.
Many thanks.
So one way to do this with python would be to capture the camera image using opencv in a loop and display it to a website hosted on the Pi using a python frontend like flask (or some other frontend). However as others have pointed out, the latency on this would be so bad any processing you wish to do would be nearly impossible.
If you wish to do this without python, take a look at mjpg-streamer, that can pull a video feed from an attached camera and display it on a localhost website. The quality is fairly good on localhost. You can then forward this to the web (if needed) using port forwarding or an application like nginx.
If you want to split the recorded stream into 2 (to forward one to python and to broadcast another to a website), ffmpeg is your best bet, but the FPS and quality would likely be terrible.
I'm currently making a small hobby project where I use a Raspberry Pi Zero to control a set of RGB LED's.
I've got a basic python app so far that is built on Flask that allows me to set up a web server so that the LED colours can be set remotely.
My main concern is that I'm self-taught as far as programming goes and I don't know squat about security.
The plan is essentially to be sending any port 80 traffic to the raspberry pi on my home network and give friends my IP. I may eventually get a domain name to simplify things.
Should I have any security concerns when I set this up live full-time? I don't know if it's possible to access my private network via the raspberry pi or if I'm just being paranoid.
You can try putting your Raspberry PI on separate vlan and put your home devices on another vlan. Please note you need a router which supports vlan and configure it in a way that the both vlans cant talk to each other
Also, try using HTTPS for your webserver and don't run the webserver process as root user. If you want to go more crazy you can put a firewall.
These are generic suggestions for hardening the security for any web app.
If your experimenting and learning... might be a great opportunity to try out something called wire-guard, if you don't have the network equipment to support vlans.
https://engineerworkshop.com/blog/how-to-set-up-wireguard-on-a-raspberry-pi/
You and your friends can directly connect to the pi, add some appropriate iptables firewall, and you can restrict them just to that machine.
If you want learn more about secure coding, there are tons of resources. Maybe even get you and your friends 'to capture the pi' .... and learn from each other!
What ever you do , keeping hacking away, and keep having fun....
I am working on a student project involving a drone which runs on the Pixhawk platform but has a 'companion computer' in the form of a Raspberry Pi. The Pi runs its own Python software and uses DroneKit (and therefore MAVLink?) to communicate with the Pixhawk via USB - giving it commands, transferring data and so on. Additionally, we have a 'ground station' laptop running ArduPilot Mission Planner which can view and interact with the aircraft remotely and also view it's telemetry. I noticed a 'Messages' tab which essentially acts like a remote console, showing 'logged' messages from the Pixhawk - this is what the question is referring to.
For debugging and information purposes, I would like to be able to add to this from Python on the Pi. I assumed this would be easily achievable through DroneKit but it does not seem trivial - send_mavlink and message_factory looked hopeful but I have found nobody else trying to do this specifically.
How can I easily redirect my 'console messages' from Python to the ground station? I realise there are alternative methods but going through the Pixhawk's existing telemetry system seems a much better option.
Thanks
One thing you can do is to create a bridge (proxy) between Pixhawk and GCS with your RPi, similar to this question.
Then in the middle of that you can send your own text messages with:
gcs_conn.mav.statustext_send(mavutil.mavlink.MAV_SEVERITY_INFO, "your message here")
Be careful not blocking too much the telemetry transmission, otherwise you could have intermittent connection to the drone from your GCS.
I am trying to program a raspberry pi 3 to run a traffic light on a breadboard.I also have a sensor that detects color of the traffic light, which is connected to the same raspberry pi. Can anyone help me with this? How would I do that, and also HOW can I send that detected information to another raspberry pi?
Thank you!
You can use messaging protocol like RabbitMQ, MQTT tech to make an easy communication between the raspberries.
But another Simplest way is to develop HTTP REST endpoints if you don't have stron background in messaging protocols (MQTT).
Easy way is develop HTTP REST endpoints using python flask.
Suppose you have a method in python flask as turnOnLED() bind with a URL as /on on Raspberry PI X. Now you can call this REST Endpoint using the IP of this raspberry X from another Raspberry Y.
You can similarly write a method in python to interact with **GPIO** and make that method available through your URL (ip/endpoints) to another Raspberry. From other Raspberry you can call that method by calling the URL for the first one.
Make research on RESTful APIs using Python, GPIO, PGPIOD, WiringPI, Pythong flask or any other framework to write REST Endpoints rapidly.
You need knowledge in all these buddy.
Hi everyone I am trying to make a relatively simple home automation system with ifttt and my raspberry pi model b+. My goal is to create a python script which hosts a web server which can be posted to by ifttt maker channel. The pi needs to be able to detect the post by ifttt and then run an action in my case change the color/brightness/state of an RGB LED. I have already tried use email to control actions but that was very slow and whenever wifi dropped out on my pi the script crashed so I also will need a detection system that can detect when wifi is out to prevent crashes. I am currently 11 years old (Shocker) but I need some help because currently, i am struggling to get anywhere close to my goal. Any help will be greatly appreciated.
The RPi side
There are two separate scripts you need:
1) Python script which will host a web-server.
2) Python script which can manipulate RGB data.(Guess you already have this)
On IFTTT side First of all, check out this IFTTT service called Maker Web-hooks.
Basically, IFTTT is able to hit URLs(in your case, your python web-services). So you expose an API, tell IFTTT to listen to a trigger of you choice. And upon trigger, invoke your web API. This should be very fast.
A Few Notes
1) The RPi's server needs to be accessible from the internet, not just the local wi-fi. This is because IFTTT is going to try to reach out to your RPi web-server.
2) For quick message delivery, you can evaluate MQTT. This has been explained in another answer here. The only shortfall is, you need to register(for free) for an MQTT broker service. So there's essentially an additional entity between IFTTT and your RPi.
3) Like #anjsimmo has said, exception handling is a must. You'll need to do it with any sort of code.
I'm running my personal home-automation system with the same RPi model, using MQTT. Publisher is an Android app and subscriber is the RPi. All the best with your project!