Yuya Okuyama gRPC at OA Dev LINE Developer Meetup @ 2020/7/29 

About me • Yuya Okuyama • 2019೥4݄ೖࣾ • Official Account ։ൃࣨ • LINEެࣜΞΧ΢ϯτؔ࿈ͷ৽نαʔϏε ( ) • line-bot-sdk-python ϝϯς 2 

Outline • What’s gRPC? • gRPC at OA Dev • Our system overview • gRPC server built with Armeria • Error handling • Documentation • Summary 3 

What’s gRPC? 

What’s gRPC • Google ͕։ൃͨ͠ RPC ϑϨʔϜϫʔΫ. ݱࡏ͸, ͷϓϩδΣΫτ. • Protocol Buffers (ΠϯλʔϑΣΠεఆٛݴޠ) • εΩʔϚϑΝʔετͳ։ൃ • ಛఆͷݴޠʹґଘ͠ͳ͍ϝοηʔδ΍αʔϏεͷఆٛ • JSON ͱͷ૬ޓม׵ • લํ/ޙํޓ׵ੑΛอͭมߋ • ίϯύΫτ͔ͭޮ཰తͳΤϯίʔσΟϯά • HTTP/2 ͰσʔλΛૹड৴͢Δ • ૒ํ޲௨৴ 5 

gRPC at LINE 6 • Our service • LINE Official Account • LINE LIVE Commerce • LINE MUSIC • LINE Financial • etc. • Java, Kotlin, Scala • Go • Python • JavaScript (gRPC-Web) Services Languages Thrift http://thrift.apache.org/ Facebook ੡ͷ RPC ϑϨʔϜϫʔΫ. ࣾ಺ͷଟ͘ͷՕॴͰར༻͞Ε͍ͯΔ. 

What should we do to deploy gRPC app? • Logging • Metrics • Distributed tracing • Circuit breaker • Retry • Load balancing • Debug tool • Error handling • Documentation 7 

gRPC at OA Dev 

Our system overview 9 #SPXTFS 1BSUOFS
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gRPC server built with 12 • gRPC ϑϨʔϜϫʔΫͱͯ͠, LINE ੡ϚΠΫϩαʔϏεϑϨʔϜϫʔΫ Armeria Λ࠾༻. • Reasons: • LogNet/grpc-spring-boot-starter, yidongnan/grpc-spring-boot-starter ΑΓ׆ൃ • ࣾ಺੡ͳͷͰ feature request ͠΍͍͢ • ࣾ֎ͷํͰ΋ line-armeria.slack.com Ͱؾܰʹ • grpc/grpc-java ͷ interface Λ࢖͍ͬͯΔͷͰ, gRPC ΤίγεςϜ͔Βҳ୤͠ͳ͍ • ศརͰଟ࠼ͳػೳ: • ϚΠΫϩαʔϏεͰఆ൪ͳػೳ͕؆୯ʹ࢖͑Δ • Client-side load balancing and service discovery • Circuit breaker • Retry • Distributed tracing (Zipkin) • DocService (Swagger UI తͳը໘) 

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Armeria: DocService • Protocol Buffers Ͱఆٛͨ͠ service, message ͷҰཡ΍ gRPC ͷݺͼग़͕͠Ͱ͖Δ 15 

Armeria: DocService 16 

What should we do to deploy gRPC app? (reappeared) • Logging • Metrics • Distributed tracing • Circuit breaker • Retry • Load balancing • Debug tool • Error handling • Documentation 17 } 

Error handling • REST ͱҧͬͯ, ΤϥʔϖΠϩʔυΛ HTTP Body Ͱฦͤͳ͍ • ํ๏ • grpc-status, grpc-message ͷΈΛฦ͢ • શͯͷϨεϙϯεఆٛʹΤϥʔ༻ͷϑΟʔϧυΛ௥Ճ͢Δ • google/rpc/error_details.proto Λ Metadata (http header) ʹؚΊͯฦ͢ • ࣗ෼Ͱఆٛͨ͠ϝοηʔδΛ Metadata (http header) ʹؚΊͯฦ͢ 18 

Error handling • REST ͱҧͬͯ, ΤϥʔϖΠϩʔυΛ HTTP Body Ͱฦͤͳ͍ • ํ๏ • grpc-status, grpc-message ͷΈΛฦ͢ • શͯͷϨεϙϯεఆٛʹΤϥʔ༻ͷϑΟʔϧυΛ௥Ճ͢Δ • google/rpc/error_details.proto Λ Metadata (http header) ʹؚΊͯฦ͢ • ࣗ෼Ͱఆٛͨ͠ϝοηʔδΛ Metadata (http header) ʹؚΊͯฦ͢ 19 

Error handling: Returning custom error message 20 proto Server Client 

Error handling: Returning custom error message 21 proto Server Client ϖΠϩʔυΛ ProtoBuf ͰόΠφϦΤϯίʔυͯ͠, Metadata (http header) ܦ༝ͰૹΔ 

Error handling: Returning custom error message 22 proto Server Client ϖΠϩʔυΛ ProtoBuf ͰόΠφϦΤϯίʔυͯ͠, Metadata (http header) ܦ༝ͰૹΔ ड͚औΓख͕ࣗ෼ͰσγϦΞϥΠζ͢Δ 

Documentation • protoc-gen-docs ͱ͍͏υΩϡϝϯτੜ੒ثΛ࢖ͬͯ, proto ϑΝΠϧͷίϝϯτ΍
 Φϓγϣϯ͔ΒଞνʔϜʹڞ༗͢ΔυΩϡϝϯτΛੜ੒. 23 

What should we do to deploy gRPC app? (reappeared) • Logging • Metrics • Distributed tracing • Circuit breaker • Retry • Load balancing • Debug tool • Error handling • Documentation 24 } Metadata ʹΤϥʔϖΠϩʔυΛؚΊΔ protoc-gen-docs 

How was gRPC? • εΩʔϚϑΝʔετ • ࣮૷Ͱ͸ͳ͘εΩʔϚ(࢓༷)͕͋ΔͷͰ, ίʔυϨϏϡʔ͕͠΍͍͢ • proto ϑΝΠϧͰؔ਺໊΍ϑΟʔϧυ໊ͷมߋΛιʔείʔυ΁มߋ͢Δͷ͕πϥ͍ • HTTP/2 • ࣾ಺LB, Nginx Ͱ͸ଟগ໘౗͕ͩͬͨ, େͨ͠໰୊͸ͳ͔ͬͨ • ΤίγεςϜ • CLI ͔ΒϦΫΤετ͢ΔͨΊͷ gRPCurl,υΩϡϝϯτΛੜ੒͢Δ protoc-gen-docs
 ͳͲ, ศརͳπʔϧ͸ͦͦ͋͜͜Δ • GUI Client ΋͍͔ͭ͋͘Δ͕, Ϧονͳػೳ͸ͳ͍ 25 

Summary 

Takeaways • LINE ࣾͰ΋গͣͭ͠ gRPC ͕ϓϩμΫγϣϯͰ࢖ΘΕ͍ͩͯ͠Δ • (For Java,) Armeria Λ࢖͑͹, production ready ͳ gRPC αʔόʔΛ؆୯ʹߏஙͰ͖Δ • gRPC Ͱͷ error handling ͸ REST ΑΓͪΐͬͱ໘౗ • εΩʔϚϑΝʔετͩͱ, ϨϏϡʔ΋υΩϡϝϯτੜ੒΋͠΍͍͢ 27 

Thank you! Any questions?