Build reactive systems on lambda

+ =
BUILDING REACTIVE SYSTEMS WITH
LAMBDA

hi, my name is Yan Cui
@theburningmonk

“as a Software Engineer,
what is my job?”

“to write code, of course!”
- Me, circa 2006

“to provide value to users &
stakeholders”
- Me, 2016

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

performance
security
scalability
simplicity
cost
team
time to market

“Programmers know
the benefits of
everything and the
tradeoffs of nothing.”
- Rich Hickey
https://www.infoq.com/presentations/Simple-Made-Easy

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

AWS re:invent 2014https://www.youtube.com/watch?v=9eHoyUVo-yg

AWS re:invent 2014https://www.youtube.com/watch?v=9eHoyUVo-yg
FAAS
(Function-As-A-Service)

hi guys,
come back at 10 to find
out who won!

everyone
came back at
exactly 10pm!

everyone
came back at
exactly 10pm!
Lambda scaled
instantly

these spikes happen to us
ALL THE TIME

minimise
undifferentiated
heavy-lifting

important, but
invisible subsystems

first Lambda function went live
(team size : 4)

(team size : 7)
155 prod deployments!

now, we stand at 130 Lambda
functions in prod, with 170 in dev

fuelling
the Yubl
platform
evolution

“What would a good
architecture for us look like?”

small, incremental deployments
fast deployments
no downtime
no lock-step deployments
features deployed independently
features loosely-coupled through messages
minimise cost for unused resources
minimise ops effort

oh, and do all these whilst continue
to deliver value, thanks :-)
love, your users

Legacy Monolith Amazon Kinesis Amazon Lambda
Amazon CloudSearch

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

“JavaScript doesn’t scale
well with complexity”
- People on the Internet

“limit complexity, and
JavaScript isn’t so bad”
- Me

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

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
?

nowhere to install
monitoring agents

• Invocation Count
• Error Count
• Latency (avg, min, max, sum)
• Throttling
• Granular to the minute
• Support custom metrics

• Same basic metrics
• Better dashboard
• Support custom metrics
https://www.datadoghq.com/blog/monitoring-lambda-functions-datadog/

PRO TIP
don’t forget to set
up alarms

PRO TIP
add application-level
metrics

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?

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

@theburningmonk
@theburningmonk
theburningmonk.com
github.com/theburningmonk
slides at http://bit.ly/2ecqEql

Build reactive systems on lambda

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