A Date with gRPC

Pain of gRPC on Kubernetes
YWC Programmer Meetup #6

Transcript

1. A Date with gRPC YWC Programmer Meetup 2019
2. Me • Manatsawin Hanmongkolchai • Architect at Wongnai - We build the platform for Wongnai of tomorrow • Owner at TipMe - Donate platform for streamers
3. Today's Agenda • RPC vs REST • Brief introduction to gRPC • gRPC on Kubernetes • … ??
4. RPC?
5. REST
6. import requests requests.post("http://sealerd/documents/1/seal", json={ "key": 1, })
7. What now?
8. XML? JSON?
9. { "success": true }
10. { "response": { "success": true }, "status": 200 }
11. Error handling
12. 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?
13. 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!!") How could I know there is error field? What if load balancer errors?
14. It's not hard to solve It just more boilerplate to write (Or you could make it a library)
15. Then why don't you just use gRPC?
16. gRPC 101
17. Step 1: Write a service declaration
18. syntax = "proto3"; package tipme.sealerd; service Sealerd { rpc Seal (SealRequest) returns (SealResponse); } message SealRequest { string path = 1; } message SealResponse { } Free API Docs, with types!
19. Step 2: Generate
20. python -m grpc_tools.protoc -I=. \ --python_out=. \ --grpc_python_out=. sealerd.proto
21. # -*- 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,
22. Step 3: Run
23. 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)
24. What you get • Exception on errors • Typed request & response • More efficient serialization • (Optional) Server to server verification & encryption • Connection reuse • Load balancing
25. Sounds great?
26. gRPC, in real world, in Kubernetes
27. How Kubernetes do load balancing
28. Kubernetes service balance connections, not calls
29. What we think
30. What we actually get with gRPC
31. What we actually get with gRPC
32. It's even worse: server shutdown
33. Client Server Client Client Server Client Server Connection Reset Service IP
36. Solution
37. 1. gRPC client side load balance
39. It's Go only
40. 2. Read Kubernetes Blog
42. (Yes, I used their image earlier)
43. 2. Use service mesh (Maybe it'll be ready in 2020….)
44. 3. Disable connection pool? It'll be slower, but it won't break my infra
48. No disable! Only set connection lifetime
49. 4. Use REST
50. 5. Join guild of gRPC haters
53. import requests requests.post("http://sealerd/twirp/tipme.Sealerd/Seal", json={ "document": 1, "key": 1, })
54. 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)
55. Porting
56. Have fun! And pray for service mesh