There’s a new class of applications that are becoming more prevalent these days: serverless applications. Serverless computing allows you to build and run applications without having to think about servers. Serverless apps don’t require you to provision or scale any servers. How can we take advantage of serverless computing as python developers? What tools and frameworks are available that make writing serverless apps a breeze? And most importantly, how do we design and structure our applications in this serverless world to ensure we’re best utilizing the underlying services? This is a practical talk on serverless architecture. In this talk, we’ll look at several serverless architecture patterns covering real world use cases. We’ll also look at actual open source serverless applications so we have concrete code examples we can review. These open source serverless applications leverage various AWS services including AWS Lambda and Amazon API Gateway. Come learn how to design serverless applications in python so you can focus on writing your core applications rather than worrying about managing servers.

1. A Crash Course on
Serverless Applications in Python
James Saryerwinnie
@jsaryer

2. Serverless Computing Overview
Serverless Architecture
Serverless Application in Python

3. Serverless Computing Overview
Serverless Architecture
Serverless Application in Python

4. Serverless Computing Overview
Build and run applications without thinking about servers

5. No servers to provision,
scale, or manage
Flexible scaling Built-in availability and fault tolerance
Serverless Computing

6. AWS Lambda
Run code without thinking about servers.
Pay for only the compute time you consume.
Lambda takes care of everything required to run and
scale your code with high availability.

7. AWS Lambda Function
def handler(event, context):
return 'hello world!'

8. def handler(event, context):
return 'hello world!'
AWS Lambda Function

9. def handler(event, context):
return 'hello world!'
AWS Lambda Function
1 Define python function

10. def handler(event, context):
return 'hello world!'
AWS Lambda Function
1 Define python function
2 event - data about what triggered invocation
context - runtime information about your function

11. def handler(event, context):
return 'hello world!'
AWS Lambda Function
1 Define python function
3 Return value sent back as response
2 event - data about what triggered invocation
context - runtime information about your function

12. def handler(event, context):
return 'hello world!'
AWS Lambda Function
1 Define python function
3 Return value sent back as response
2 event - data about what triggered invocation
context - runtime information about your function
app.py

13. def handler(event, context):
return 'hello world!'
AWS Lambda Function
1 Define python function
3 Return value sent back as response
2 event - data about what triggered invocation
context - runtime information about your function
app.py

14. def handler(event, context):
return 'hello world!'
AWS Lambda Function
1 Define python function
3 Return value sent back as response
2 event - data about what triggered invocation
context - runtime information about your function
app.py
$ python
>>> import app
>>> app.handler(event={}, context=None)
'hello world!'

15. def handler(event, context):
return 'hello world!'
AWS Lambda Function
1 Define python function
3 Return value sent back as response
2 event - data about what triggered invocation
context - runtime information about your function
app.py

16. def handler(event, context):
return 'hello world!'
AWS Lambda Function
1 Define python function
3 Return value sent back as response
2 event - data about what triggered invocation
context - runtime information about your function
app.py
$ pip install awscli

17. def handler(event, context):
return 'hello world!'
AWS Lambda Function
1 Define python function
3 Return value sent back as response
2 event - data about what triggered invocation
context - runtime information about your function
app.py
$ pip install awscli
$ aws configure

18. def handler(event, context):
return 'hello world!'
AWS Lambda Function
1 Define python function
3 Return value sent back as response
2 event - data about what triggered invocation
context - runtime information about your function
app.py

19. def handler(event, context):
return 'hello world!'
AWS Lambda Function
1 Define python function
3 Return value sent back as response
2 event - data about what triggered invocation
context - runtime information about your function
app.py
$ aws lambda create-function --function-name hello --handler app.handler --zip-file ...

20. def handler(event, context):
return 'hello world!'
AWS Lambda Function
1 Define python function
3 Return value sent back as response
2 event - data about what triggered invocation
context - runtime information about your function
app.py
$ aws lambda create-function --function-name hello --handler app.handler --zip-file ...
$ aws lambda invoke --function-name hello

21. def handler(event, context):
return 'hello world!'
AWS Lambda Function
1 Define python function
3 Return value sent back as response
2 event - data about what triggered invocation
context - runtime information about your function
app.py
$ aws lambda create-function --function-name hello --handler app.handler --zip-file ...
$ aws lambda invoke --function-name hello
hello world!

22. def handler(event, context):
return event['foo'].upper()
AWS Lambda Function Input
app.py

23. def handler(event, context):
return event['foo'].upper()
AWS Lambda Function Input
app.py
$ aws lambda invoke --function-name hello --payload '{"foo": "bar"}'

24. def handler(event, context):
return event['foo'].upper()
AWS Lambda Function Input
app.py
$ aws lambda invoke --function-name hello --payload '{"foo": "bar"}'

25. def handler(event, context):
return event['foo'].upper()
AWS Lambda Function Input
app.py
$ aws lambda invoke --function-name hello --payload '{"foo": "bar"}'
BAR

26. def handler(event, context):
return event['foo'].upper()
AWS Lambda Function Input
app.py
$ aws lambda invoke --function-name hello --payload '{"foo": "bar"}'
BAR
$ aws lambda invoke --function-name hello --payload '{"foo": "baz"}'

27. def handler(event, context):
return event['foo'].upper()
AWS Lambda Function Input
app.py
$ aws lambda invoke --function-name hello --payload '{"foo": "bar"}'
BAR
$ aws lambda invoke --function-name hello --payload '{"foo": "baz"}'
BAZ

28. AWS Lambda Function Invocation
https://docs.aws.amazon.com/lambda/latest/dg/running-lambda-code.html
https://youtu.be/oQFORsso2go?t=422

29. AWS Lambda Function Invocation
$ aws lambda invoke --function-name hello --payload '{"foo": "bar"}'
https://docs.aws.amazon.com/lambda/latest/dg/running-lambda-code.html
https://youtu.be/oQFORsso2go?t=422

30. AWS Lambda Function Invocation
$ aws lambda invoke --function-name hello --payload '{"foo": "bar"}'
Download your code
https://docs.aws.amazon.com/lambda/latest/dg/running-lambda-code.html
https://youtu.be/oQFORsso2go?t=422

31. AWS Lambda Function Invocation
$ aws lambda invoke --function-name hello --payload '{"foo": "bar"}'
Download your code Start new container
https://docs.aws.amazon.com/lambda/latest/dg/running-lambda-code.html
https://youtu.be/oQFORsso2go?t=422

32. AWS Lambda Function Invocation
$ aws lambda invoke --function-name hello --payload '{"foo": "bar"}'
Download your code Start new container Bootstrap the runtime
https://docs.aws.amazon.com/lambda/latest/dg/running-lambda-code.html
https://youtu.be/oQFORsso2go?t=422

33. AWS Lambda Function Invocation
$ aws lambda invoke --function-name hello --payload '{"foo": "bar"}'
Start your codeDownload your code Start new container Bootstrap the runtime
https://docs.aws.amazon.com/lambda/latest/dg/running-lambda-code.html
https://youtu.be/oQFORsso2go?t=422

34. AWS Lambda Function Invocation
$ aws lambda invoke --function-name hello --payload '{"foo": "bar"}'
Start your codeDownload your code Start new container Bootstrap the runtime
Cold Start
https://docs.aws.amazon.com/lambda/latest/dg/running-lambda-code.html
https://youtu.be/oQFORsso2go?t=422

35. AWS Lambda Function Invocation
$ aws lambda invoke --function-name hello --payload '{"foo": "bar"}'
Start your codeDownload your code Start new container Bootstrap the runtime
Cold Start Warm Start
https://docs.aws.amazon.com/lambda/latest/dg/running-lambda-code.html
https://youtu.be/oQFORsso2go?t=422

36. AWS Lambda Function Invocation
$ aws lambda invoke --function-name hello --payload '{"foo": "bar"}'
Start your codeDownload your code Start new container Bootstrap the runtime
Cold Start Warm Start
$ aws lambda invoke --function-name hello --payload '{"foo": "baz"}'
https://docs.aws.amazon.com/lambda/latest/dg/running-lambda-code.html
https://youtu.be/oQFORsso2go?t=422

37. Focus on your core product instead of
worrying about managing and
operating servers or runtimes.

38. Serverless Computing Overview
Serverless Architecture
Serverless Application in Python

39. Serverless Architecture Patterns

40. Serverless Architecture
Event Trigger Lambda Services
Amazon API Gateway
request
Timer
SQS message
Amazon DynamoDB
Amazon S3

41. Serverless Architecture
Event Trigger Lambda Services
Amazon API Gateway
request
Timer
SQS message
Amazon DynamoDB
Amazon S3Think in terms of events

42. Serverless Architecture
Event Trigger Lambda Services
API Gateway request
Timer
SQS message
Amazon S3
Amazon DynamoDB

43. Serverless Architecture
Event Trigger Lambda Services
API Gateway request
Timer
SQS message
Amazon S3
Amazon DynamoDB
Decompose code into separate functions

44. Synchronous Invocation
Event Trigger Lambda
Manual invocation
$ aws lambda invoke

45. Synchronous Invocation
Event Trigger Lambda
GET /users
Rest API Request
{"http": "response"}

46. Async Invocation
Event Trigger Lambda Services

47. Async Invocation
Event Trigger Lambda Services
Amazon S3
object uploaded
1

48. Return immediately
2
Async Invocation
Event Trigger Lambda Services
Amazon S3
object uploaded
1

49. Return immediately
2
Async Invocation
Event Trigger Lambda Services
Amazon S3
object uploaded
1
Event trigger notification3

50. Return immediately
2
Async Invocation
Event Trigger Lambda Services
Amazon S3
object uploaded
1
Generates thumbnail4
Event trigger notification3

51. Return immediately
2
Async Invocation
Event Trigger Lambda Services
Amazon S3
object uploaded
1
Generates thumbnail4
Uploads to output bucket
Upload complete
5
Event trigger notification3

52. Stream/Poll Invocation
Stream Lambda Poller Lambda

53. Stream/Poll Invocation
Stream Lambda Poller Lambda
Return immediately2
Amazon SQS
message added
1

54. Stream/Poll Invocation
Stream Lambda Poller Lambda
Return immediately2
Amazon SQS
message added
1
3 Poll for messages

55. Stream/Poll Invocation
Stream Lambda Poller Lambda
Return immediately2
Amazon SQS
message added
1
3 Poll for messages
Message batch4

56. Lambda function invoked5
Stream/Poll Invocation
Stream Lambda Poller Lambda
Return immediately2
Amazon SQS
message added
1
3 Poll for messages
Message batch4

57. Lambda function invoked5
Stream/Poll Invocation
Stream Lambda Poller Lambda
Function execution finished
Return immediately2
Amazon SQS
message added
1
3 Poll for messages
Message batch4

58. Synchronous Asynchronous Stream
Blocks until response is returned
from Lambda function
Lambda function triggered in
response to an event, decoupled
from event trigger
Lambda service polls for
changes on a stream, invokes
Lambda function with batch of
messages

59. Synchronous Asynchronous Stream
Blocks until response is returned
from Lambda function
Lambda function triggered in
response to an event, decoupled
from event trigger
Lambda service polls for
changes on a stream, invokes
Lambda function with batch of
messages
$ aws lambda invoke
Amazon API Gateway
request
/users

60. Synchronous Asynchronous Stream
Blocks until response is returned
from Lambda function
Lambda function triggered in
response to an event, decoupled
from event trigger
Lambda service polls for
changes on a stream, invokes
Lambda function with batch of
messages
Timer
Amazon S3 Object
Amazon SNS Topic
$ aws lambda invoke
Amazon API Gateway
request
/users

61. Synchronous Asynchronous Stream
Blocks until response is returned
from Lambda function
Lambda function triggered in
response to an event, decoupled
from event trigger
Lambda service polls for
changes on a stream, invokes
Lambda function with batch of
messages
Timer
Amazon S3 Object
Amazon SNS Topic
Amazon SQS Message
Amazon DynamoDB Stream
Amazon Kinesis Stream
$ aws lambda invoke
Amazon API Gateway
request
/users

62. Serverless Computing Overview
Serverless Architecture
Serverless Application in Python

63. Serverless Applications in Python

64. AWS Lambda
def handler(event, context):
return 'hello world!'

65. Setting up from scratch
AWS Lambda
AWS IAM role
IAM.create_role()IAM.put_role_policy()
Lambda.create_function()
Zip of code and
dependencies
IAM policy

66. Setting up from scratch
AWS Lambda
AWS IAM role
IAM.create_role()IAM.put_role_policy()
Lambda.create_function()
Zip of code and
dependencies
IAM policy
1

67. Setting up from scratch
AWS Lambda
AWS IAM role
IAM.create_role()IAM.put_role_policy()
Lambda.create_function()
Zip of code and
dependencies
IAM policy
1
2

68. Setting up from scratch
AWS Lambda
AWS IAM role
IAM.create_role()IAM.put_role_policy()
Lambda.create_function()
Zip of code and
dependencies
IAM policy
1
2
3

69. Creating our first Lambda function

70. Creating our first Lambda function
$ zip -r app.zip app.py1

71. Creating our first Lambda function
$ zip -r app.zip app.py1
2 $ aws iam create-role
--role-name MyApp
--assume-role-policy-document '{
"Version": "2012-10-17",
"Statement": [{
"Sid": "",
"Effect": "Allow",
"Principal": {
"Service": "lambda.amazonaws.com"
},
"Action": "sts:AssumeRole"
}]
}'

72. Creating our first Lambda function
$ zip -r app.zip app.py $ aws lambda create-function
--function-name Hello
--role-name MyApp
--runtime python3.6
--handler app.handler
--zip-file fileb://app.zip
1
2
3
$ aws iam create-role
--role-name MyApp
--assume-role-policy-document '{
"Version": "2012-10-17",
"Statement": [{
"Sid": "",
"Effect": "Allow",
"Principal": {
"Service": "lambda.amazonaws.com"
},
"Action": "sts:AssumeRole"
}]
}'

73. Creating our first Lambda function
$ zip -r app.zip app.py $ aws lambda create-function
--function-name Hello
--role-name MyApp
--runtime python3.6
--handler app.handler
--zip-file fileb://app.zip
1
2
3
$ aws iam create-role
--role-name MyApp
--assume-role-policy-document '{
"Version": "2012-10-17",
"Statement": [{
"Sid": "",
"Effect": "Allow",
"Principal": {
"Service": "lambda.amazonaws.com"
},
"Action": "sts:AssumeRole"
}]
}'

74. Creating our first Lambda function
$ zip -r app.zip app.py $ aws lambda create-function
--function-name Hello
--role-name MyApp
--runtime python3.6
--handler app.handler
--zip-file fileb://app.zip
1
2
3
$ aws iam create-role
--role-name MyApp
--assume-role-policy-document '{
"Version": "2012-10-17",
"Statement": [{
"Sid": "",
"Effect": "Allow",
"Principal": {
"Service": "lambda.amazonaws.com"
},
"Action": "sts:AssumeRole"
}]
}'

75. Return immediately
2
Image Resizer
Event Trigger Lambda Services
Amazon S3
object uploaded
1
λEvent trigger notification3
Generates thumbnail4
Uploads to output bucket
Upload complete
5

76. Amazon S3 AWS Lambda
AWS IAM role
IAM.create_role()IAM.put_role_policy()
Lambda.create_function()S3.put_bucket_notification_configuration()
Zip of code and
dependenciesNotification Config
IAM policy
Lambda.add_permsission(S3)
Image Resizer

77. Amazon S3 AWS Lambda
AWS IAM role
IAM.create_role()IAM.put_role_policy()
Lambda.create_function()S3.put_bucket_notification_configuration()
Zip of code and
dependenciesNotification Config
IAM policy
Lambda.add_permsission(S3)
Image Resizer
1. Third party packages
2. S3 notification configuration
3. IAM Permissions

78. Amazon S3 AWS Lambda
AWS IAM role
IAM.create_role()IAM.put_role_policy()
Lambda.create_function()S3.put_bucket_notification_configuration()
Zip of code and
dependenciesNotification Config
IAM policy
Lambda.add_permsission(S3)
Image Resizer
1. Third party packages
2. S3 notification configuration
3. IAM Permissions

79. Amazon S3 AWS Lambda
AWS IAM role
IAM.create_role()IAM.put_role_policy()
Lambda.create_function()S3.put_bucket_notification_configuration()
Zip of code and
dependenciesNotification Config
IAM policy
Lambda.add_permsission(S3)
Image Resizer
1. Third party packages
2. S3 notification configuration
3. IAM Permissions

80. Amazon S3 AWS Lambda
AWS IAM role
IAM.create_role()IAM.put_role_policy()
Lambda.create_function()S3.put_bucket_notification_configuration()
Zip of code and
dependenciesNotification Config
IAM policy
Lambda.add_permsission(S3)
Image Resizer
1. Third party packages
2. S3 notification configuration
3. IAM Permissions

81. AWS Chalice
Python serverless framework for AWS
Quickly create and deploy serverless applications
Integration with many AWS services

82. Lambda
handler.py
AWS Lambda
Chalice Integration
def hello_world(event, context):
return 'hello world!'

83. Lambda
chalice
app.py
AWS Lambda
from chalice import Chalice
app = Chalice('helloworld')
@app.lambda_function()
def hello_world(event, context):
return 'hello world!'
Chalice Integration

84. Lambda
chalice
app.py
AWS Lambda
from chalice import Chalice
app = Chalice('helloworld')
@app.lambda_function()
def hello_world(event, context):
return 'hello world!'
Chalice Integration
1 app defined at module level

85. Lambda
chalice
app.py
AWS Lambda
from chalice import Chalice
app = Chalice('helloworld')
@app.lambda_function()
def hello_world(event, context):
return 'hello world!'
Chalice Integration
1 app defined at module level
2 One or more decorators to defined resources

86. Deployment
$ chalice deploy
Creating deployment package.
Updating policy for IAM role: helloworld-dev
Creating lambda function: helloworld-dev-hello_world
Resources deployed:
- Lambda ARN: arn:aws:lambda:us-west-2:1:function:helloworld...
$ chalice invoke -n hello_world
"hello world!"

87. S3 Image Resizer app.py
import tempfile
import boto3
from PIL import Image
from chalice import Chalice
app = Chalice(app_name='s3resize', debug=True)
s3_client = boto3.client('s3')
@app.on_s3_event(bucket='mybucket',
prefix='images/', suffix='.jpg')
def resize_image(event):
app.log.debug("Resizing image for s3://%s/%s",
event.bucket, event.key)
with tempfile.NamedTemporaryFile('w') as f:
s3_client.download_file(event.bucket, event.key, f.name)
resized_file = f.name + '.thumbnail.jpg'
with open(Image.open(f.name)) as image:
image.thumbnail((256, 256))
image.save(resized_file)
s3_client.upload_file(
filename=resized_file,
bucket='mybucket',
key=f'thumbnails/{event.key.split("/", 1)[1]}'
)

88. S3 Image Resizer app.py
import tempfile
import boto3
from PIL import Image
from chalice import Chalice
app = Chalice(app_name='s3resize', debug=True)
s3_client = boto3.client('s3')
@app.on_s3_event(bucket='mybucket',
prefix='images/', suffix='.jpg')
def resize_image(event):
app.log.debug("Resizing image for s3://%s/%s",
event.bucket, event.key)
with tempfile.NamedTemporaryFile('w') as f:
s3_client.download_file(event.bucket, event.key, f.name)
resized_file = f.name + '.thumbnail.jpg'
with open(Image.open(f.name)) as image:
image.thumbnail((256, 256))
image.save(resized_file)
s3_client.upload_file(
filename=resized_file,
bucket='mybucket',
key=f'thumbnails/{event.key.split("/", 1)[1]}'
)
3rd party package
with C extension
automatically handled
from requirements.txt

89. S3 Image Resizer app.py
import tempfile
import boto3
from PIL import Image
from chalice import Chalice
app = Chalice(app_name='s3resize', debug=True)
s3_client = boto3.client('s3')
@app.on_s3_event(bucket='mybucket',
prefix='images/', suffix='.jpg')
def resize_image(event):
app.log.debug("Resizing image for s3://%s/%s",
event.bucket, event.key)
with tempfile.NamedTemporaryFile('w') as f:
s3_client.download_file(event.bucket, event.key, f.name)
resized_file = f.name + '.thumbnail.jpg'
with open(Image.open(f.name)) as image:
image.thumbnail((256, 256))
image.save(resized_file)
s3_client.upload_file(
filename=resized_file,
bucket='mybucket',
key=f'thumbnails/{event.key.split("/", 1)[1]}'
)
Client created in module scope
Only part of cold-start time

90. S3 Image Resizer app.py
import tempfile
import boto3
from PIL import Image
from chalice import Chalice
app = Chalice(app_name='s3resize', debug=True)
s3_client = boto3.client('s3')
@app.on_s3_event(bucket='mybucket',
prefix='images/', suffix='.jpg')
def resize_image(event):
app.log.debug("Resizing image for s3://%s/%s",
event.bucket, event.key)
with tempfile.NamedTemporaryFile('w') as f:
s3_client.download_file(event.bucket, event.key, f.name)
resized_file = f.name + '.thumbnail.jpg'
with open(Image.open(f.name)) as image:
image.thumbnail((256, 256))
image.save(resized_file)
s3_client.upload_file(
filename=resized_file,
bucket='mybucket',
key=f'thumbnails/{event.key.split("/", 1)[1]}'
)
Client created in module scope
Only part of cold-start time
Start your codeDownload your code Start new container Bootstrap the runtime
Cold Start Warm Start
Module Import

91. S3 Image Resizer app.py
import tempfile
import boto3
from PIL import Image
from chalice import Chalice
app = Chalice(app_name='s3resize', debug=True)
s3_client = boto3.client('s3')
@app.on_s3_event(bucket='mybucket',
prefix='images/', suffix='.jpg')
def resize_image(event):
app.log.debug("Resizing image for s3://%s/%s",
event.bucket, event.key)
with tempfile.NamedTemporaryFile('w') as f:
s3_client.download_file(event.bucket, event.key, f.name)
resized_file = f.name + '.thumbnail.jpg'
with open(Image.open(f.name)) as image:
image.thumbnail((256, 256))
image.save(resized_file)
s3_client.upload_file(
filename=resized_file,
bucket='mybucket',
key=f'thumbnails/{event.key.split("/", 1)[1]}'
)
Trigger function when
objects uploaded to
s3://mybucket/images/**/*.jpg

92. S3 Image Resizer app.py
import tempfile
import boto3
from PIL import Image
from chalice import Chalice
app = Chalice(app_name='s3resize', debug=True)
s3_client = boto3.client('s3')
@app.on_s3_event(bucket='mybucket',
prefix='images/', suffix='.jpg')
def resize_image(event):
app.log.debug("Resizing image for s3://%s/%s",
event.bucket, event.key)
with tempfile.NamedTemporaryFile('w') as f:
s3_client.download_file(event.bucket, event.key, f.name)
resized_file = f.name + '.thumbnail.jpg'
with open(Image.open(f.name)) as image:
image.thumbnail((256, 256))
image.save(resized_file)
s3_client.upload_file(
filename=resized_file,
bucket='mybucket',
key=f'thumbnails/{event.key.split("/", 1)[1]}'
)

93. S3 Image Resizer app.py
import tempfile
import boto3
from PIL import Image
from chalice import Chalice
app = Chalice(app_name='s3resize', debug=True)
s3_client = boto3.client('s3')
@app.on_s3_event(bucket='mybucket',
prefix='images/', suffix='.jpg')
def resize_image(event):
app.log.debug("Resizing image for s3://%s/%s",
event.bucket, event.key)
with tempfile.NamedTemporaryFile('w') as f:
s3_client.download_file(event.bucket, event.key, f.name)
resized_file = f.name + '.thumbnail.jpg'
with open(Image.open(f.name)) as image:
image.thumbnail((256, 256))
image.save(resized_file)
s3_client.upload_file(
filename=resized_file,
bucket='mybucket',
key=f'thumbnails/{event.key.split("/", 1)[1]}'
)
Event dictionary mapped to
python object
download_file method from boto3
will download file parts in parallel

94. S3 Image Resizer app.py
import tempfile
import boto3
from PIL import Image
from chalice import Chalice
app = Chalice(app_name='s3resize', debug=True)
s3_client = boto3.client('s3')
@app.on_s3_event(bucket='mybucket',
prefix='images/', suffix='.jpg')
def resize_image(event):
app.log.debug("Resizing image for s3://%s/%s",
event.bucket, event.key)
with tempfile.NamedTemporaryFile('w') as f:
s3_client.download_file(event.bucket, event.key, f.name)
resized_file = f.name + '.thumbnail.jpg'
with open(Image.open(f.name)) as image:
image.thumbnail((256, 256))
image.save(resized_file)
s3_client.upload_file(
filename=resized_file,
bucket='mybucket',
key=f'thumbnails/{event.key.split("/", 1)[1]}'
)
Generate 256x256 image and save
image to a temporary file.

95. S3 Image Resizer app.py
import tempfile
import boto3
from PIL import Image
from chalice import Chalice
app = Chalice(app_name='s3resize', debug=True)
s3_client = boto3.client('s3')
@app.on_s3_event(bucket='mybucket',
prefix='images/', suffix='.jpg')
def resize_image(event):
app.log.debug("Resizing image for s3://%s/%s",
event.bucket, event.key)
with tempfile.NamedTemporaryFile('w') as f:
s3_client.download_file(event.bucket, event.key, f.name)
resized_file = f.name + '.thumbnail.jpg'
with open(Image.open(f.name)) as image:
image.thumbnail((256, 256))
image.save(resized_file)
s3_client.upload_file(
filename=resized_file,
bucket='mybucket',
key=f'thumbnails/{event.key.split("/", 1)[1]}'
)
Upload thumbnail back to S3.
upload_file from boto3
will use parallelized multi part
uploaded if needed.

96. Chalice architecture
.
!"" app.py
#"" requirements.txt

97. Chalice architecture
$ chalice deploy

98. Chalice architecture
AWS IAM role
IAM.create_role()
$ chalice deploy

99. Chalice architecture
AWS IAM role
$ chalice deploy
IAM policy

100. Chalice architecture
AWS IAM role
IAM.put_role_policy()
$ chalice deploy
IAM policy

101. Chalice architecture
AWS IAM role
IAM.put_role_policy()
$ chalice deploy

102. Chalice architecture
AWS IAM role
$ chalice deploy
.
!"" app.py
#"" requirements.txt

103. Chalice architecture
AWS IAM role
$ chalice deploy

104. Chalice architecture
AWS IAM role
$ chalice deploy
deploy.zip
Chalice runtime

105. Chalice architecture
AWS IAM role
$ chalice deploy
deploy.zip
Chalice runtime
Lambda.create_function()
AWS Lambda

106. Chalice architecture
AWS IAM role
$ chalice deploy
deploy.zip
Chalice runtime
Lambda.create_function()
AWS Lambda

107. Chalice architecture
AWS IAM role
$ chalice deploy
AWS Lambda

108. Chalice architecture
$ chalice deploy
S3.put_bucket_notification_configuration()
AWS Lambda
Amazon S3
Lambda.add_permission(S3)

109. @app.on_s3_event('mybucket')
def resize_image(event):
pass
@app.schedule('rate(5 minutes)')
def rate_handler(event):
pass
@app.on_sns_message(topic='mytopic')
def handler(event):
pass
@app.on_sqs_message(queue='myqueue')
def handler(event):
pass
@app.lambda_function()
def handler(event, context):
pass
@app.route('/resource/{value}',
methods=['PUT'])
def resource(value):
pass
@app.authorizer(ttl_seconds=30)
def jwt_auth(auth_request):
pass
Additional Chalice Decorators

110. Serverless Computing Overview
Serverless Architecture
Serverless Application in Python

111. Continuous Delivery
Code changes are automatically built, tested, and
prepared for a release to production.
Every code change is built, tested, and then pushed to a
non-production testing or staging environment.
Deliver Updates Faster

112. Source Control Build Beta Production
Commit changes Run build and unit tests Deploy to test environment
Run integration tests
Deploy to production environment

113. Source Control Build Beta Production
Commit changes Run build and unit tests Deploy to test environment
Run integration tests
Deploy to production environment

114. Source Control Build Beta Production
Commit changes Run build and unit tests Deploy to test environment
Run integration tests
Deploy to production environment

115. Source Control Build Beta Production
Commit changes Run build and unit tests Deploy to test environment
Run integration tests
Deploy to production environment

116. Source Control Build Beta Production
Commit changes Run build and unit tests Deploy to test environment
Run integration tests
Deploy to production environment

117. Application Lifecycle

118. Application Lifecycle
Local Dev Laptop
chalice local

119. Application Lifecycle
Local Dev Laptop
chalice local
Dev Stack
AWS Lambda
chalice deploy
Amazon S3

120. Application Lifecycle
Local Dev Laptop
chalice local
Full CD Pipeline
Source
Build
Beta
Test
Prod
AWS CodePipeline
chalice generate-pipeline
Dev Stack
AWS Lambda
chalice deploy
Amazon S3

121. Next Steps
Todo App tutorial: https://chalice-workshop.readthedocs.io/en/latest/todo-app/index.html
Media query tutorial: https://chalice-workshop.readthedocs.io/en/latest/media-query/index.html
Chalice GitHub repository: https://github.com/aws/chalice
Chalice documentation: http://chalice.readthedocs.io/en/latest/
Serverless Black Belt (re:Invent 2017): https://www.youtube.com/watch?v=oQFORsso2go

122. Thanks!
James Saryerwinnie
@jsaryer