inlinekeepalive

inlinekeepalive is a package that sends "keepalive" messages over existing grpc streams. See doc.go for full package description

Diagrams

These diagrams demonstrate the intended usage of inline keepalives within Waypoint.

ClientStream

sequenceDiagram
autonumber

actor Waypoint Runner
participant Client
participant ClientInterceptor
participant ALB
participant ServerInterceptor
participant RunnerConfig Server Handler
participant Server


Waypoint Runner ->> +Client: RunnerConfig

%% Unnecessary detail
%% Client ->> ServerInterceptor: Open connection for RunnerConfig
%% ServerInterceptor -x ClientInterceptor: Not a ServerStream - DOES NOT send keepalives

Client ->> ClientInterceptor: Create the GRPC client handler

ClientInterceptor ->> +Server: GetVersionInfo

Server -->> -ClientInterceptor: Has feature inlinekeepalives

loop Async send inline keepalives for duration of RPC
    activate ClientInterceptor
    ClientInterceptor -) +ServerInterceptor: SendMsg(InlineKeepalive)

    %% Critical
    ServerInterceptor -x RunnerConfig Server Handler: Recognizes InlineKeepalive. DOES NOT forward.
   
    deactivate ServerInterceptor
    deactivate ClientInterceptor
end

Waypoint Runner ->> Client: Send(event)
Client ->> ClientInterceptor: Send(event) to interceptor
ClientInterceptor ->> ServerInterceptor: Passthrough event to server

%% Critical
ServerInterceptor ->> RunnerConfig Server Handler: Not a keepalive, passthrough

deactivate Client

ServerStream

sequenceDiagram
autonumber

actor User
participant Client
participant ClientInterceptor
participant ALB
participant ServerInterceptor
participant GetLogStream Server Handler
actor CEB


User ->> +Client: GetLogStream

Client ->> +ServerInterceptor: Open connection for RunnerConfig, including inline-keepalive GRPC metadata

loop Async send inline keepalives for duration of RPC
    ServerInterceptor -) +ClientInterceptor: SendMsg(InlineKeepalive)
    
    %% Critical
    ClientInterceptor -x Client: Recognizes InlineKeepalive. DOES NOT forward.
    
    deactivate ClientInterceptor
end

Client ->> ClientInterceptor: Create the GRPC client handler

CEB ->> GetLogStream Server Handler: Send(Log)
GetLogStream Server Handler ->> ServerInterceptor: Send(Log)
ServerInterceptor ->> ClientInterceptor: Send(event) to interceptor

%% Critical
ClientInterceptor ->> Client: Not a keepalive, passthrough

Client ->> User: 

deactivate Client