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© Black Inc.
Cloud Gaming Platform
with Go
castaneai
Backend engineer
Black Inc.
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© Black Inc.
Agenda
● Introduction of Cloud Gaming
● Backend Architecture and Go
○ Stateful game server
○ Video streaming
● Cloud Native Infrastructure
○ Cloud providers support
○ Build and deploy
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Introduction of
Cloud Gaming
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What is cloud gaming?
Player Gaming Server
Player Action
Video Streaming
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OOParts
Our cloud gaming platform for visual novels
https://oo.parts
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Backend Architecture
and Go
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OOParts Architecture
Frontend Backend
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92.6%
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Why Go?
How Go?
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Stateful game server
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Player Gaming Server
Player Action
Video Streaming
Game Session
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Handling a stateful game server
● Game session is “Stateful”
○ Web-based frontend, but game server is NOT a HTTP Server
○ Long-time (1h~)
○ Resumable
---> Stateful is complex
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Handling a stateful game server
● How do we handle stateful?
● Real-world examples
○ TCP Socket
○ WebRTC Agent
○ ...
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Handling a stateful game server
● State machine
Waiting For
Session
Starting Game
Playing Game
Waiting For
Reconnect
Shutdown
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Handling a stateful game server
type State string
const (
StateWaitingForSession State = "WaitingForSession"
StateStartingGame State = "StartingGame"
StatePlayingGame State = "PlayingGame"
...
)
type StateLogic interface {
Run(ctx context.Context, ts Transition) (State, Transition)
}
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Handling a stateful game server
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State machine loop & logging
func (a *Agent) MainLoop(ctx context.Context) error {
for {
prevState := nextState
nextState, transition = logic.Run(ctx, transition)
log.Infof(" +++ State [%s] -> [%s]", prevState, nextState)
...
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Handling asynchronous events
● Many asynchronous events on cloud gaming 😱
Key-frame
request
Player
disconnected
SIGTERM
game window
resized
game exited
Player input
Game Server
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Handling asynchronous events in Go
● Goroutine
● Channel
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Handling asynchronous events in Go
select {
}
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Handling asynchronous events in Go
select {
}
Player
disconnected
SIGTERM
game exited
Player input
case <-
case <-
case <-
case <-
...
...
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🎉
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Stateful and asynchronous events
select {
}
case <-
return StateB
case <-
case <-
State A
select {
}
case <-
case <-
case <-
return StateA
State B
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Stateful and asynchronous events
select {
}
case <-
case <-
case <-
case <-
State A
select {
}
case <-
case <-
case <-
case <-
State D
select {
}
case <-
case <-
case <-
case <-
State B
select {
}
case <-
case <-
case <-
case <-
State C
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Why Go, How Go?
● Go provides good asynchronous event handling
○ Goroutine and Channel
○ Handling async events with `select` statement
● Good debugging for asynchronous
○ built-in race detector
○ built-in goroutine profiler (pprof)
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Video streaming
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Player Gaming Server
Player Action
Video Streaming
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How to deliver low-latency video?
● low-latency streaming
● peer-to-peer (P2P) connection
● standardization by W3C and IETF
● media processing (video/audio)
● free and open-source
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How to deliver low-latency video?
Player
X11
Game
PulseAudio
Capturing frame
and encoding
Peering and
streaming media
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What language?
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https://en.wikipedia.org/wiki/GStreamer
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What language?
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https://en.wikipedia.org/wiki/GStreamer https://en.wikipedia.org/wiki/WebRTC
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go-gst
● https://github.com/tinyzimmer/go-gst
● Gstreamer bindings and utilities for golang
● Using CGO
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Pion WebRTC
● https://github.com/pion/webrtc
● A Pure Go implementation of WebRTC API
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Why Go, How Go?
● We use gstreamer and WebRTC for video streaming
○ Both of them have Go libraries!
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Cloud Native
Infrastructure
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Cloud Native Infrastructure
● Multi services, multi containers
● Immutable infrastructure
● Using managed service in public cloud
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Cloud providers
support
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gocloud
● https://github.com/google/go-cloud
● Abstraction layer for cloud providers
○ Amazon, Azure, Google, …
○ Local environment support
● Storage, KVS, DB, PubSub, Secrets, ...
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gocloud
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import (
"gocloud.dev/blob"
_ "gocloud.dev/blob/fileblob"
)
import (
"gocloud.dev/blob"
_ "gocloud.dev/blob/gcsblob"
)
Local Google Cloud
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Build and Deploy
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Build and Deploy
How do we build and deploy game servers?
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Build and Deploy
How do we build and deploy game servers?
Build Deploy
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ko
● https://github.com/google/ko
● container image builder for Go applications
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Without ko
FROM golang as builder
RUN CGO_ENABLED=0 go build ...
FROM scratch
COPY --from=builder ...
$ docker build -t gcr.io/...
$ docker push gcr.io/...
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Writing Dockerfile per container
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Without ko
FROM golang as builder
RUN CGO_ENABLED=0 go build ...
FROM scratch
COPY --from=builder ...
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service A
FROM golang as builder
RUN CGO_ENABLED=0 go build ...
FROM scratch
COPY --from=builder ...
service B
FROM golang as builder
RUN CGO_ENABLED=0 go build ...
FROM scratch
COPY --from=builder ...
service C
FROM golang as builder
RUN CGO_ENABLED=0 go build ...
FROM scratch
COPY --from=builder ...
service D, ...
FROM golang as builder
RUN CGO_ENABLED=0 go build ...
FROM scratch
COPY --from=builder ...
FROM golang as builder
RUN CGO_ENABLED=0 go build ...
FROM scratch
COPY --from=builder ...
😅
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With ko
FROM golang as builder
RUN CGO_ENABLED=0 go build ...
FROM scratch
COPY --from=builder ...
$ ko publish ./src/app
=> gcr.io/...
$ docker build -t gcr.io/...
$ docker push gcr.io/...
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Go package path
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Deploying game servers
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apiVersion: "agones.dev/v1"
kind: Fleet
spec:
template:
spec:
template:
spec:
containers:
- name: agent
image: ko://path/to/... kustomize
apply YAML
replace the image
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go-task
● https://github.com/go-task/task
● simpler GNU Make alternative written in Go
● We use go-task as a task runner
○ build
○ deploy
○ code generation
○ ...
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go-task
$ task deploy:serviceA-local
$ task deploy:serviceA-dev
$ task deploy:serviceA-prd
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common deploy
task
local
variables
dev
variables
...
● YAML-based
● flexible variables
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Conclusion
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Conclusion
● Go is well suited for cloud gaming platform development
○ features for writing stateful servers
○ bindings of media frameworks (gstreamer, WebRTC)
● Many of the tools for Cloud Native are powered by Go
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… and more!
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© Black Inc.
Cloud Gaming Platform
with Go
castaneai
Backend engineer
Black Inc.