A Date with gRPC - Speaker Deck

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A Date with gRPC YWC Programmer Meetup 2019

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Me ● Manatsawin Hanmongkolchai ● Architect at Wongnai - We build the platform for Wongnai of tomorrow ● Owner at TipMe - Donate platform for streamers

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Today's Agenda ● RPC vs REST ● Brief introduction to gRPC ● gRPC on Kubernetes ● … ??

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RPC?

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REST

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import requests requests.post("http://sealerd/documents/1/seal", json={ "key": 1, })

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What now?

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XML? JSON?

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{ "success": true }

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{ "response": { "success": true }, "status": 200 }

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Error handling

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try: req = requests.post("http://sealerd/documents/1/seal") except requests.HTTPError: print("Server error") return body = req.json() if "error" in body: print(body["error"]) return print("Seal success!!") Why this is not exception?

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It's not hard to solve It just more boilerplate to write (Or you could make it a library)

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Then why don't you just use gRPC?

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gRPC 101

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Step 1: Write a service declaration

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syntax = "proto3"; package tipme.sealerd; service Sealerd { rpc Seal (SealRequest) returns (SealResponse); } message SealRequest { string path = 1; } message SealResponse { } Free API Docs, with types!

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Step 2: Generate

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python -m grpc_tools.protoc -I=. \ --python_out=. \ --grpc_python_out=. sealerd.proto

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# -*- coding: utf-8 -*- # Generated by the protocol buffer compiler. DO NOT EDIT! # source: sealerd/sealerd.proto import sys _b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1')) from google.protobuf import descriptor as _descriptor from google.protobuf import message as _message from google.protobuf import reflection as _reflection from google.protobuf import symbol_database as _symbol_database # @@protoc_insertion_point(imports) _sym_db = _symbol_database.Default() DESCRIPTOR = _descriptor.FileDescriptor( name='sealerd/sealerd.proto', package='tipme.sealerd', syntax='proto3', serialized_options=None, serialized_pb=_b('\n\x15sealerd/sealerd.proto\x12\rtipme.sealerd\"\x1b\n\x0bSealRequest\x12\x0c\n\x04path\x18\x01 \x01(\t\"\x0e\n\x0cSealResponse2J\n\x07Sealerd\x12?\n\x04Seal\x12\x1a.tipme.sealerd.SealRequest\x1a\x1b.tipme.sealerd.SealResponseb\x06proto3') ) _SEALREQUEST = _descriptor.Descriptor( name='SealRequest', full_name='tipme.sealerd.SealRequest', filename=None, file=DESCRIPTOR, containing_type=None, fields=[ _descriptor.FieldDescriptor( name='path', full_name='tipme.sealerd.SealRequest.path', index=0, number=1, type=9, cpp_type=9, label=1, has_default_value=False, default_value=_b("").decode('utf-8'), message_type=None, enum_type=None, containing_type=None, is_extension=False, extension_scope=None, serialized_options=None, file=DESCRIPTOR), ], extensions=[ ], nested_types=[], enum_types=[ ], serialized_options=None, is_extendable=False, syntax='proto3', extension_ranges=[], oneofs=[ ], serialized_start=40, serialized_end=67,

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Step 3: Run

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import grpc from proto_gen.sealerd.sealerd_pb2 import SealRequest from proto_gen.sealerd.sealerd_pb2_grpc import SealerdStub channel = grpc.insecure_channel("sealerd:4000") client = SealerdStub(channel) result = client.Seal(SealRequest(path=path)) print(result)

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What you get ● Exception on errors ● Typed request & response ● More efficient serialization ● (Optional) Server to server verification & encryption ● Connection reuse ● Load balancing

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Sounds great?

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gRPC, in real world, in Kubernetes

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How Kubernetes do load balancing

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Kubernetes service balance connections, not calls

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What we think

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What we actually get with gRPC

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What we actually get with gRPC

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It's even worse: server shutdown

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Client Server Client Client Server Client Server Connection Reset Service IP

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Solution

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1. gRPC client side load balance

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It's Go only

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2. Read Kubernetes Blog

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(Yes, I used their image earlier)

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2. Use service mesh (Maybe it'll be ready in 2020….)

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3. Disable connection pool? It'll be slower, but it won't break my infra

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No disable! Only set connection lifetime

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4. Use REST

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5. Join guild of gRPC haters

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import requests requests.post("http://sealerd/twirp/tipme.Sealerd/Seal", json={ "document": 1, "key": 1, })

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import requests requests.post("http://sealerd/twirp/tipme.Sealerd/Seal", json={ "key": 1, }) but… ● Client library ● Still standardized request/response/error ● Send either Protobuf or JSON = easy to debug ● HTTP 1.1 + Bring your own server = can integrate into existing stack ● No streaming/bidirectional support (yet)