CNCF SERVERLESS WHITEPAPER V1.0 • Serverless computing refers to the concept of building and running applications that do not require server management • A platform may provide one or both of the following: • Functions-as-a-Service (FaaS) • Backend-as-a-Service (BaaS) • Products or platforms deliver the following benefits to developers: • Zero Server Ops • No Compute Cost When Idle
SERVERLESS USE CASES (FROM CNCF WP) • Asynchronous, concurrent, easy to parallelize into independent units of work • Infrequent or has sporadic demand, with large, unpredictable variance in scaling requirements • Stateless, ephemeral, without a major need for instantaneous cold start time • Highly dynamic in terms of changing business requirements that drive a need for accelerated developer velocity • Non-HTTP-centric and non-elastic scale workloads that weren’t good fits for an IaaS, PaaS, or CaaS solution (Event Driven workloads)
“There are many workloads that are stateful and/or not easy to parallelize” ͱࢥͬͯ·ͤΜ͔ʁ “Asynchronous and Event Driven processing is too difficult for humans”
IS SERVERLESS DIFFICULT TO GUARANTEE THE RELIABILITY? • Strongly depends on FaaS platform and BaaS products • Lose the business continuity (Reliability, Availability) • Distributed Instances • Lose the traceability (Serviceability) • Hard to develop • All become functions (Serviceability) • NoSQL matches better than RDB (Integrity)
FaaSͷΑ͋͘Δ՝ • How to test the functions? • Granularity of the functions • Messaging between the functions and backends • Handling request and response (Error Handling) • Log Aggregation, Traceability • Monitoring
THE INTERNAL FLOW OF PROCESSING https://github.com/apache/incubator-openwhisk/blob/master/docs/about.md#the-internal-flow-of-processing Πϕϯτ(HTTP)͕ॲཧ͞ΕΔྲྀΕΛ௫Ή ετϦʔϜΩϡʔΛڬΜͰࢄॲཧ͢Δͷ͕جຊ ֎͔ΒݟͯಉظͰதඇಉظ͔ͭࢄ
RELIABILITYͷߟ͑ํ • Make the reliability by myself • Serverless will help you, but will not protect your business • Think simple • Apply generally development/operation practices • If you can't apply the practices, take care of the serverless mechanism • Keep simple • Don't be afraid that increase the number of the functions • We should be afraid complicated architecture • Change your mind as a software • Everything is part of your application
ALL EVENTS FLOWS IN THE SAME DIRECTION • They will be naturally Asynchronous and Functional • Asynchronous processing is Retriable • Functional processing is Reproducible • The clients get the results by myself • However, polling is not good choise... • Pushing is better choice • Can we be happy with AppSync? (Pushing via Websocket)
UNIFY THE ENDPOINTS BETWEEN THE SERVICES • Microservices • Separate the services by the domains (One BaaS is one of your service) • The endpoint of the service is not unique, it has the endpoints for each operations • Wrap the endpoints to abstract them • Like a “MySQL Server” and “libmysql” • Do you call “libmysql” directly? • You can make Failover/Failsafe mechanism • Like a Reverse Proxy • Do you connect to multiple “Read replicas” from “each app servers”? • Trafic controlling, Caching
ALL SERIES OF EVENTS HAVE THE SAME ID • Log Aggregation • A series of events can be traced by the ID • Monitor the progress • Log all event messages • Execution control • At least once -> Exactly once • e.g. DynamoDB Conditional Writes • Make it easy to implement with something like a decorator
DATA MODELING • Become the friend with DynamoDB • Distributed by Partition Key and Indexed(B-tree) by Sort Key, LSI • GSI is a projection of sorted(indexed) data • The consistency can be guaranteed without ACID transaction • Denormalization • Strong consistency reading, Conditional Writing • There are some difficult situation • Write asynchronous to RDB
GRANULARITY OF THE FUNCTIONS •Testable!! • Unit testing is justice in the serverless world • Make the dependencies of other services are replaceable • Would be replaceable to the mocks • Easy to Failover/Failsafe
HOW TO TEST THE FUNCTIONS • Unit testing is justice in the serverless world (2ճ) • Deploy a new environment if the mocks are not enough at integration testing • It is easy with some frameworks (e.g. Serverless, SAM) • The services outside of AWS are needed to be easily to deploy (via API) • Continuous E2E testing with traceable ID • It become a monitoring
RELIABILITY MONITORING • The greatest monitoring is the notifications from the application • Be sure to catch the errors and notify them • Collect the metrics of the services • CloudWatch • This is a condition to choice the services outside of AWS • Continuous E2E testing with traceable ID
“SERVERLESS IS NOT SPECIAL” THANKS!! “MAKE THE RELIABILITY BY MYSELF” “THINK SIMPLE, KEEP SIMPLE” “EVERYTHING IS PART OF YOUR APPLICATION” “LET'S EXPAND SERVERLESS WORLD”
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