AWS Lambda from the Trenches

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AWS LAMBDA FROM THE TRENCHES
what you should know before you go to production

- Dan North
“lead time to someone saying
thank you is the only reputation
metric that matters.”

security
complexity
OUTSIDE the code
deployment
load balancing
caching
monitoring
config management
https://www.infoq.com/presentations/complexity-simplicity-esb
centralised logging
elastic scaling
setup server

minimise
undifferentiated
heavy-lifting

fuelling
the Yubl
platform
evolution

Legacy Monolith Amazon Kinesis Amazon Lambda

Amazon CloudSearchAmazon API Gateway Amazon Lambda

Google BigQuery

Google BigQuery
1 developer, 2 days
design production
(his 1st serverless project)

Google BigQuery
“nothing ever got done
this fast at Skype!”
- Chris Twamley

Amazon Lambda GrapheneDBAmazon API Gateway
Amazon API Gateway Amazon Lambda Facebook Graph API

https://github.com/claudiajs/claudia

Amazon Lambda
Amazon Kinesis
Amazon IOT
Amazon IOT

“I thought of objects being like
biological cells and/or individual
computers on a network, only
able to communicate with
messages.”
- Alan Kay

“OOP to me means only
messaging, local retention and
protection and hiding of state-
process, and extreme late-
binding of all things.”
- Alan Kay

Level of Testing
1.Unit
do our objects do the right thing?
are they easy to work with?

Level of Testing
1.Unit
2.Integration
does our code work against code we
can’t change?

handler
test by invoking
the handler

Level of Testing
1.Unit
2.Integration
3.Acceptance
does the whole system work?

Level of Testing
unit
integration
acceptance

Level of Testing
unit
integration
acceptance
can do all 3 with Lambda

“…We find that tests that mock external
libraries often need to be complex to
get the code into the right state for the
functionality we need to exercise.
The mess in such tests is telling us that
the design isn’t right but, instead of
fixing the problem by improving the
code, we have to carry the extra
complexity in both code and test…”
Don’t Mock Types You Can’t Change

“…The second risk is that we have to be
sure that the behaviour we stub or mock
matches what the external library will
actually do…
Even if we get it right once, we have to
make sure that the tests remain valid
when we upgrade the libraries…”

Services

“…Wherever possible, an acceptance
test should exercise the system end-to-
end without directly calling its internal
code.
An end-to-end test interacts with the
system only from the outside: through
its interface…”
Testing End-to-End

Test Input

Test Input
Validate

“…We prefer to have the end-to-end
tests exercise both the system and the
process by which it’s built and
deployed…
This sounds like a lot of effort (it is), but
has to be done anyway repeatedly
during the software’s lifetime…”
Testing End-to-End

Jenkins build config deploys and tests
unit + integration tests
deploy
acceptance tests

build.sh allows repeatable builds on both local & CI

easily propagate
environmental changes
GOALS

GOALS
sensitive data are
encrypted at rest
(credentials, connection string, etc.)

hand-rolled with KMS
(encrypted at rest)

plug-ins
serverless-plugin-kmsvariables
serverless-secrets
serverless-meta-sync

set goals
choose a way
document

create project templates/scaffolds

set goals
choose a way
evaluate document

set goals
choose a way
evaluate document
share

2016-07-12T12:24:37.571Z 994f18f9-482b-11e6-8668-53e4eab441ae
GOT is off air, what do I do now?

2016-07-12T12:24:37.571Z 994f18f9-482b-11e6-8668-53e4eab441ae
GOT is off air, what do I do now?
UTC Timestamp API Gateway Request Id
your log message

organised by Function + Version

CloudWatch Logs AWS Lambda
LogStash ElasticSearch

AWS Elasticsearch

AWS Elasticsearch
Elastic Cloud

AWS Elasticsearch
Elastic Cloud
?

PRO TIP
don’t forget to set
up alarms

PRO TIP
add application-level
metrics

“how do I return
HTTP error codes?”

{ “status” : 404, “errorMessage” : ”oops” }

s-templates.json
{ “status” : 404, “errorMessage” : ”oops” }

every Lambda function has
a timeout setting

use error regex to map it to
a HTTP 504

PRO TIP
avoid using 128mb
setting for production

PRO TIP
proactively time out
your function

“what’s the retry strategy with
Kinesis and SNS?”

“…If the invocation for one record
times out, is throttled, or
encounters any other error,
Lambda will retry until it
succeeds (or the record reaches
its 24-hour expiration) before
moving on to the next record…”
http://aws.amazon.com/lambda/faqs

• do nothing
• swallow errors
• track retry count
effort

• retry forever
• no retry
• retry N times

PRO TIP
use local state to track
no. of retries; move on
after N retries

PRO TIP
record CloudWatch
metrics for error count;
alarm if necessary

functions are unloaded if
idle for a while

noticeable cold start time
(package size matters)

CloudWatch Event AWS Lambda
ping
ping
ping
ping

CloudWatch Event AWS Lambda
ping
ping
ping
ping
HEALTH CHECKS?

functions are recycled
every few hours

PRO TIP
don’t make hard
assumptions about
function lifetime

max 50 MB deployment package size

max 50 MB deployment package size
max 75 GB total deployment package size*
* limit is per AWS region

max 6 MB request payload size*
max 6 MB response payload size
* for a request-response event type

default max 100 concurrent executions*
* soft-limit, can be raised via support ticket

IBM OpenWhisk
Amazon Lambda Azure Web Functions
Google Cloud Functions
competition
faster innovation
lower prices

@theburningmonk
@theburningmonk
theburningmonk.com
github.com/theburningmonk

AWS Lambda from the Trenches

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