Plaλ (pronounced 'plambda') is an approach to make unmodified Play apps work using AWS lambda. Judged from the outset as a comedic attempt destined to fail, the results are surprisingly good - though far from perfect and some way from usable. No matter - it's a great lesson in AWS lambda's limitations and how this technique could be applied to web frameworks in order to accelerate the move to serverless.

1. Plaλ!
Running the Play! framework in AWS Lambda
@sihil

2. Simon Hildrew
Lead Software Developer
The Guardian
@sihil
simon.hildrew@theguardian.com

3. @sihil
+

4. @sihil

5. @sihil
HTTP JSON

6. @sihil
Plaλ wrapper
appHTTP JSON

7. Will this work?
@sihil
Plaλ wrapper
app

8. Let's try!
@sihil

9. @sihil
topLevelDirectory in Universal := None

10. Baby steps
@sihil
class LambdaEntrypoint {
def run(event: JMap[String, Object], lambdaContext: Context): Unit = {
// Start a play application
val application: Application = {
val environment = Environment(new File("/"),
getClass.getClassLoader, Mode.Prod)
val context = ApplicationLoader.createContext(environment)
val loader = ApplicationLoader(context)
loader.load(context)
}
Play.start(application)
context.logger.log("AWS Lambda has started your Play application")
}
}

11. @sihil
https://www.flickr.com/photos/
jarld/14374126748

12. @sihil
val request = FakeRequest("GET", "/management/healthcheck")
// actually call the router
val maybeResult = Helpers.route(app, request)
maybeResult.map(Helpers.contentAsString).foreach{result =>
context.getLogger.log(result)
}

13. @sihil
def transform(request: LambdaRequest): FakeRequest[AnyContentAsEmpty.type] = {
val queryString = for {
queryMap <- request.queryStringParameters.toList
(name, value) <- queryMap
} yield s"$name=$value"
val pathWithQueryString =
if (queryString.isEmpty) request.path
else queryString.mkString(s"${request.path}?", "&", "")
FakeRequest(
method = request.httpMethod,
uri = pathWithQueryString,
headers = FakeHeaders(request.headers.map(_.toList).getOrElse(Nil)),
body = AnyContentAsEmpty
)
}

14. Limitations
• Strictly defined request and response mappings
• Multiple Set-Cookie headers
• Binary data
• Performance
@sihil

15. @sihil

16. Limitations
• Strictly defined request and response mappings
• Multiple Set-Cookie headers
• Binary data
• Performance
@sihil

17. @sihil

18. @sihil
Plaλ wrapper
appJSON
Set-Cookie & Redirect for nextcookie
/auth
/plambda/moreCookies?c=xxx&r=XXX
Set-Cookie & Redirect to final dest

19. Limitations
• Strictly defined request and response mappings
• Multiple Set-Cookie headers
• Binary data
• Performance
@sihil

20. UTF8 💩
@sihil
$ curl -s https://<plambda-url>/assets/images/fav-versions-32.png | md5
d17aec342d33ae61c775c118d605fa10
$ md5 public/images/fav-versions-32.png
38f8b0476d6beef91350c79f76b88210

21. @sihil
Plaλ wrapper
appJSON
Redirect to S3
/asset/binary-data.png
s3://plambda-data/asset/binary-data.png?signature=???
Binary data response
PutObject

22. Limitations
• Strictly defined request and response mappings
• Multiple Set-Cookie headers
• Binary data
• Performance
@sihil

23. ¯_( )_/¯
@sihil

24. @sihil
CMS
snapshot restore

25. @sihil
Server Plaλ (Cold-ish)

26. @sihil

27. @sihil
Server Plaλ (Warm)

28. @sihil

29. $0.02 - $0.50 / mo
@sihil

30. @sihil
Plaλ (Play!)
https://github.com/sihil/plambda
AWS Serverless Express (Node Express)
https://github.com/awslabs/aws-serverless-express
Zappa (Python WSGI)
https://www.zappa.io/
Quaich (Scala)
https://github.com/bwmcadams/quaich
Serverless (Node)
https://serverless.com/
Chalice (Python)
https://github.com/awslabs/chalice

31. Thanks!
@sihil