Read twitter stream for keywords and reply to users with pictures captured from a Raspberry Pi.

1. Internet Of
Things
Bologna 2015, June 17

2. Taking pictures!!
For Internet Of Things!

3. Raspbery Pi
About 30$
Big as a credit card
A powerful ARM!
GNU/Linux on board
More...

4. The Camera module
About 30$
around 25 x 20 x 9 mm
5 Megapixels
Supports 1080p30, 720p60, VGA90 video
More...

5. Grab pictures
Enable the camera module via raspi-config
Just use it: raspistill -o me.jpg

6. Hey @CorleyCloud here is your picture:
pic.2015.cloudconf.it/CorleyCloud/61…
pic.twitter.com/LW8jUSPIa7
3:33 PM ­ 16 Jun 2015
16 JunCorley
​@CorleyCloud
#cloudconf2015 #pic
CloudConf
​@_CloudConf_
Follow
Read for tweets and reply back with pictures!

7.
The tweet process
Raspberry read a twitter stream for #cloudconf2015 #pic
Raspberry upload the original picture to AWS S3
AWS Lambda resize the image and optimize it for the web
AWS Lambda tweet the picture to the final user

8. On Raspberry Pi
Golang
Powerful
available for multiple platforms (x86, ARM, ...)
self-contained binaries
Much more!

9. Read the Twitter Stream
import (
tw "github.com/wdalmut/twitterstream/async"
)
client := tw.NewClient(
config.ConsumerKey,
config.ConsumerSecret,
config.AccessToken,
config.AccessSecret,
)
client.TrackAndServe("cloudconf2015", func(tweet *twitterstream.Tweet) {
// Here the logic!
})
github.com/wdalmut/twitterstream/async
github.com/darkhelmet/twitterstream

10. Grab pictures using commands! (easy)
cmd := exec.Command(
"raspistill", // Command name
"­a", "www.cloudconf.it ­ #cloudconf2015", //Watermarks
"­t", "500",
"­vf", "­hf", //Rotate
"­w", "1024", "­h", "768", //1024x768
"­­quality", "60", //60%
"­o", "/tmp/pic.jpg") // Put in /tmp folder
err := cmd.Run()
You can also take pictures using OS Signals

11. Upload on AWS S3
// Upload it!
err = bucket.Put(path, bytes, "image/jpg", s3.ACL("public­read"), s3.Options{})
Prepare the AWS client
AWSAuth := aws.Auth{
AccessKey: config.Key,
SecretKey: config.Secret,
}
region := aws.EUWest
connection := s3.New(AWSAuth, region)
bucket := connection.Bucket(BUCKET)
https://github.com/wdalmut/raspi-twitter-cloudconf

12. Cross-Compiling (install GO for ARM)
Prepare your environment
$ cd $GOROOT/src
$ GOOS=linux GOARCH=arm ./make.bash ­­no­clean
Compile your source code
$ GOARM=6 GOARCH=arm GOOS=linux go build

13. Use a Makefile
default: all
all: test
GOARM=6 GOARCH=arm GOOS=linux go build ­a
ssh pi@$(TARGET) 'killall picme | true'
scp start.sh pi@$(TARGET):~
scp picme pi@$(TARGET):~
scp config.json pi@$(TARGET):~
ssh pi@$(TARGET) './picme < /dev/null >/tmp/picme.log 2>&1 &'
test:
go test ­v ./...
Compile it locally, copy it into the Raspi and run it on board!
TARGET=192.168.1.53make

14. Lambda receive the S3 upload event
... now we have to tweet the picture

15. AWS Lambda works with Javascript
But
I prefer Coffeescript

16. Coffeescript and Lambda
/* Prepare the "twitter" client ... */
exports.handler = (event, context) ­> /** <­­ EVENT and the CONTEXT **/
twitter.tweetAbout(event).then(
() ­>
context.done null, ""
(err) ­>
context.done err, "Unable to tweet!"
)
Just code with your event!

17. S3 upload event!
{
"Records": [
{
"s3": {
"bucket": {
"name": "sourcebucket",
"ownerIdentity": {
"principalId": "XXXXXXXXXXXXXXXXX"
},
"arn": "arn:aws:s3:::example.walterdalmut.com"
},
"object": {
"key": "walterdalmut/1924762.jpg",
"size": 1024,
"eTag": "11111111111111111111111111111111"
}
}
}
]
}
Please consider that this is not a real S3 event (just a part of it...)

18. Test your Lambdas
handler = require '../src/lambda'
describe "Lambda callback", ­>
beforeEach ­>
@context = {}
@context.done = () ­>
@event = {
"Records": [
{ /* ... */ }
]
}
it "should expose the lambda handler", ­>
spyOn(handler, "handler").and.returnValue null
handler.handler(@event, @context)
expect(handler.handler).toHaveBeenCalled()

19. A look into the Lambda function
https://github.com/wdalmut/lambda-twitter-cloudconf

20. Deploy on AWS Lambda
Simple prepare a ZIP artifact gruntdist

21. tweetit!#cloudconf2015#pic

22. Thanks for listening