Presentation for the Zurich Python Use Group hosted on October 2017

1. Writing and deploying serverless
Python applications
César Cárdenas Desales
Zurich Python User Group, October 2017

2. About me
Software Architect at Webrepublic AG
Python User since v.2.0
Co-organizer of the Swiss Python Summit (next on Feb. 2018)
@ccdesales

3. Intro What is it?

4. Architecture Archeology - Client server
A fat do-it-all Server
Mostly on-premises server
Upfront investment
Capacity planning
Scaling was a nightmare

5. Cloud based architectures
+ Servers can be disposable, unless
they’re snowflakes
+ Application architecture can make
scaling easier or more difficult
- Capacity planning still required
- Still pay ($$) if your server is idle

6. Capacity planning
How many servers?
How powerful?
How much memory?
What do we do with excess resources?
What if we have too little resources?
How do we (dynamically) grow or shrink resources?
Resources become obsolete
What if we suffer the Slashdot effect?

7. Serverless: a very simple yet powerful idea
● You submit units of work for execution
● Pay only for computing time you consume
● A.k.a. Function as a Service: FAAS

8. Serverless: Well, there’s actually a server...

9. What does Serverless mean for you?
● Less Work
○ No need to run servers in premises
○ No need to manage servers in the cloud (admin, patches)
○ No need to plan capacity or scaling
● Potential money savings
○ Only pay for computing time you use

10. Why does it make me excited
● I’m an aging developer

11. Why does serverless make me excited?
● I’m an aging developer
● Potentially unlimited scaling
● Computing resources are
disposable
● Low level maintenance is
abstracted out…
● (it’s somebody else’s problem)
● IT assets are programmable

12. Serverless with AWS Lambda

13. AWS Lambda
● Amazon Web Services’ serverless platform

14. Supported technologies

15. Choose
template
Choose
trigger
Add config
& code
Test
Write
client
The process

16. Choose
template
Choose
trigger
Add config
& code
Test
Write
client

17. Choose template

18. Choose template

19. Choose
template
Choose
trigger
Add config
& code
Test
Write
client

20. Choose trigger

21. Choose
template
Choose
trigger
Add config
& code
Test
Write
client

22. Add config & code
● Upload .ZIP file
● Upload file from
Amazon S3

23. Add config & code
● VPC
● Env variables
● Security roles
Max. 300 secs

24. Choose
template
Choose
trigger
Add config
& code
Test
Write
client

25. Test

26. Test

28. Choose
template
Choose
trigger
Add config
& code
Test
Write
client

29. Client

30. Output - synchronous call

31. Output - Asynchronous call

32. Precondition to run the exercises
tree ~/.aws cat ~/.aws/config
[default]
region = eu-west-1
cat ~/.aws/credentials
[default]
aws_access_key_id = SOME_ID
aws_secret_access_key = AKEY

33. Serverless the
easy way:
Zappa

34. What is zappa?
● A python framework for serverless applications
● Used as command line tool
● Manages application lifecycle
○ Creation
○ Deploy
○ Update
○ Undeploy Configure Deploy Test

35. pip install zappa
● Installs latest zappa
Configure Deploy Test

36. zappa init
● Optional
● Initializes project
● Creates zappa_settings.json file
● YAML format also available
Configure Deploy Test

37. Zappa code looks like Flask
● example.py
● zappa_settings.json
Configure Deploy Test

38. zappa deploy dev
Calling deploy for stage dev..
Downloading and installing dependencies..
Packaging project as zip.
Uploading servless-dev-1506419080.zip (5.9MiB)..
100%|███████████████| 6.16M/6.16M [00:01<00:00, 2.16MB/s]
Scheduling..
Scheduled servless-dev-zappa-keep-warm-handler.keep_warm_callback
with expression rate(4 minutes)!
TestConfigure Deploy Test

39. zappa deploy dev
Uploading servless-dev-template-1506419092.json (1.6KiB)..
100%|███████████████| 1.61K/1.61K [00:00<00:00, 3.71KB/s]
Waiting for stack servless-dev to create (this can take a bit)..
75%|███████████▎ | 3/4 [00:09<00:04, 4.94s/res]
Deploying API Gateway..
Deployment complete!:
https://x0doi1ioid.execute-api.eu-west-1.amazonaws.com/dev
TestConfigure Deploy Test

40. zappa deploy dev
Uploading servless-dev-template-1506419092.json (1.6KiB)..
100%|███████████████| 1.61K/1.61K [00:00<00:00, 3.71KB/s]
Waiting for stack servless-dev to create (this can take a bit)..
75%|███████████▎ | 3/4 [00:09<00:04, 4.94s/res]
Deploying API Gateway..
Deployment complete!:
https://x0doi1ioid.execute-api.eu-west-1.amazonaws.com/dev
TestConfigure Deploy Test

41. TestConfigure Deploy Test
Restful API
Boto3

42. curl https://x0doi1ioid.execute-api.eu-west-1.amazonaws.com/dev
hello from Flask
TestConfigure Deploy Test

43. Other commands
zappa tail
● Show latest logs
zappa update dev
● Update code and
settings
zappa undeploy dev
● Remove lambda
function
● Remove AWS API
Gateway

44. Zappa creates and deploys the Lambda

45. Zappa goodies
● Creates deployment package (modules from current virtualenv)
● Performs deployments (no manual *.zip uploads)
● Support for stages (dev, stage, prod)
● Manages settings:
○ Environment variables
○ Logging (AWS CloudWatch)
○ Domain names
○ VPC
○ Security roles
○ Certificates and keys
● API creation

46. Zappa creates a (AWS API Gateway) RESTful API

47. Why API Gateway?
● Interoperability
○ It’s only JSON over HTTP
○ Other platforms
○ Other AWS technologies
○ Other languages
○ Clients not tied to boto
● RESTful API
● Request Throttling/Limits
● Authorization tokens

48. Pitfalls & tips

49. Pitfalls
● 300 seconds execution time limit
● Calls must be stateless
● Cold start for 1st request -> Keep warm calls
○ An computing instance must be started
○ Can also happen during low traffic periods
● Logging only to CloudWatch

50. Pitfalls
● Fragmentation in a myriad of microservices
● Data leaves Switzerland
● Flame wars
○ 1 (Git) repository per service
○ All services in 1 (Git) repository
● Potential vendor lock-in
● Flow control and error handling gets tricky

51. The upsell - AWS Steps Functions
● Orchestration of Lambdas

52. AWS Steps Functions - Parallel
Diagram Amazon States Language

53. AWS Steps Functions
Job status poller Wait state

54. AWS Steps Functions
Retry failure Catch failure

55. AWS Steps Functions
Choice state Task timer

56. Geography matters
● Regions
● Availability
zones
● Edge locations

57. Edge Locations
● AWS CloudFront: Amazon’s CDN
● Content served by edge location
closest to client
○ Images
○ Pages
○ Streams

58. Edge Locations
● AWS CloudFront: Amazon’s CDN
● Content served by edge location
closest to client
○ Images
○ Pages
○ Streams

59. Lambda Functions deployed into Regions
● Or, into a EC2 instance < AZ < Region
● High latency on requests from distant
areas

60. AWS Lambda@Edge
● Lambdas deployed to edge
locations
● Requests to Lambdas served by
closest (edge) location
● Lambda is automatically run
@edge, no provisioning needed

61. AWS Lambda pricing
Requests
First 1 million requests
per month are free
$0.20 per 1 million
requests thereafter
($0.0000002 per request)
Duration
Billing rounded up to the
nearest 100ms
Depending on the
amount of allocated
memory
Other
Data transfer (external)
Data storage
AWS API Gateway, $3.50
per million API calls
received

62. AWS Lambda pricing
Free tier
First dosis is free

63. Alternatives
Vendor
Google Cloud Functions
(Beta, only JS, no env
vars)
Microsoft Azure
Functions
Python libs
Chalice
Apex
Vendor agnostic
The Serverless
framework
https://goo.gl/yYh2M4

64. Shameless plug
● Swiss Python Summit 2018
● February 16th, 2018
● HSR University of Applied Sciences in
Rapperswil
● CFP
● Call for helpers
● www.python-summit.ch

65. Thank
@ccdesales
https://github.com/ccdesales/serverless_examples
you!