Gateway APIs, Envoy Gateway, and API Gateways

Gateway APIs and API Gateways @mt165
Modern Ingress Demystiﬁed
Gateway APIs and API
Gateways
Matt Turner
KubeHuddle, Edinburgh UK | October 2022 @mt165 | mt165.co.uk

THE ENTERPRISE SERVICE MESH COMPANY

Outline
● Recap: Ingress
● Gateway API
● Envoy Gateway
● [Envoy] [API] Gateway
● Where Next?

Ingress Networking

Service
A
Backend
*.example.com
Service
A
Service
A

Service
A
Backend
Load
Balancer
*.example.com
Service
A
Service
A

Service
A
Backend
Load
Balancer
Node
port
*.example.com
Service
A
Service
A

Backend
Load
Balancer
Node
port
Cluster
IP
*.example.com
Service
A
Service
A
Service
A

Backend
Proxy
Proxy
Proxy
Proxy
Ingress
Load
Balancer
Node
port
Cluster
IP
*.example.com
Service
A
Service
A
Service
A

Service
A
Backend
Proxy
Proxy
Proxy
Proxy
Ingress
Load
Balancer
Node
port
Cluster
IP
*.example.com
Cluster
IP
Service
A
Service
A

Service
A
Backend
Proxy
Proxy
Proxy
Proxy
Ingress
Load
Balancer
Node
port
*.example.com
Service
A
Service
A
Ingress
Controller
Service
A

Service
A
Backend
Proxy
Proxy
Proxy
Proxy
Ingress
Load
Balancer
Node
port
*.example.com
Service
A
Service
A
Ingress
Controller
Service
A
K8s API
Server
etcd

Service
A
Backend
Proxy
Proxy
Proxy
Proxy
Ingress
Load
Balancer
Node
port
*.example.com
Service
A
Service
A
Ingress
Controller
Service
A
K8s API
Server
etcd
Ingress

😅

The Ingress API

Ingress API
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: minimal-ingress
spec:
rules:
- host: example.com
http:
paths:
- path: /test
backend:
service:
name: test
port:
number: 80

Ingress API
kind: Ingress
metadata:
annotations:
nginx.ingress.kubernetes.io/rewrite-target: /
spec:
rules:
- host: example.com
http:
paths:
- path: /test
backend:
service:
name: test
port:
number: 80

Ingress API
kind: Ingress
metadata:
annotations:
kubernetes.io/ingress.class: "nginx"
spec:
rules:
- host: example.com
http:
paths:
- path: /test
backend:
service:
name: test
port:
number: 80

Ingress API
kind: Ingress
metadata:
annotations:
spec:
ingressClassName: nginx
rules:
- host: example.com
http:
paths:
- path: /test
pathType: Prefix
backend:
service:
name: test
port:
number: 80

Ingress API
kind: IngressClass
metadata:
name: nginx
spec:
controller: example.com/nginx-ingress-controller

Ingress API
kind: IngressClass
metadata:
name: nginx
spec:
controller: example.com/nginx-ingress-controller
---
kind: Deployment
spec:
template:
spec:
containers:
- name: nginx
args:
- /nginx-ingress-controller
- '--ingress-class=k8s.io/nginx'
- '--controller-class=example.com/nginx-ingress-controller'

Ingress API
kind: Ingress
metadata:
annotations:
nginx.ingress.kubernetes.io/configuration-snippet: |
more_set_headers "Request-Id: $req_id";
spec:
ingressClassName: nginx
rules:
- host: example.com
http:
…

Ingress API: Implementations
● Nginx
● Haproxy
● Apache
● Traefik
● Contour
● Ambassador
● Kong
● Tyk
● Avi
● Istio
● etc

😅😅

Gateway API

xkcd, Creative Commons Attribution 2.5

Recap: The Storage API
StorageClass
PersistentVolume
Pod
PersistentVolume
Claim
Pod
Pod
(AWS, gp2)
(10Gi, ReadOnce)
PersistentVolume
Claim
Infra provider / cluster builder:
Infra admin:
App dev:
PersistentVolume

The Gateway API

The Gateway API
● Not built-in yet; packaged as CRDs
● >1 resource
● gateway.networking.k8s.io
○ GatewayClass/v1beta1
○ Gateway/v1beta1
○ HTTPRoute/v1beta1
○ TLSRoute/v1alpha1 - SNI routing
○ GRPCRoute/v1alpha1
○ TCPRoute/v1alpha1
○ UDPRoute/v1alpha1

GatewayClass
apiVersion: gateway.networking.k8s.io/v1beta1
kind: GatewayClass
metadata:
name: my-class
spec:
controllerName: gateway.envoyproxy.io/gatewayclass-controller

kind: Gateway
metadata:
name: my-gateway
spec:
gatewayClassName: my-class
listeners:
- name: http
protocol: HTTP
port: 80
- name: https
protocol: HTTPS
port: 443
Gateway

HTTPRoute
kind: HTTPRoute
metadata:
name: http-log
spec:
parentRefs: [{name: my-gateway}]
hostnames: ["www.example.com"]
rules:
- matches:
- path: {value: /http-log, type: PathPrefix}
backendRefs:
- {group: "", kind: Service, name: http-log, port: 80, weight: 1}

What else does it look like?
● Heavily based on the Istio API
● In turn, Istio implements the Gateway API
○ Currently beta
○ Will be default when gw-api hits v1
● Also implemented by the SMI Meshes (Linkerd2, Consul, Open Service Mesh,
etc)

A Mesh API?
● Gain resources to describe East-West (service mesh)
● GAMMA group trying to get meshes to adopt the GW API, and conversely to
get GW API to model mesh concerns
(https://gateway-api.sigs.k8s.io/contributing/gamma/)

Reference Implementation: Envoy Gateway

What’s a standard?
Nginx-ingress currently the de facto standard
● Surely the most common, certainly when you discount cloud providers’
ingress
● Only one mentioned in the main upstream docs

An Envoy-Based Gateway
● But nginx isn’t very modern
○ Reads its config from a file, not an API
○ The operator hides this, and that’s fine; that’s its job
○ But those reload events cause the drop of in-flight requests, which isn’t ok
○ Plus other operational issues
○ Hard to extend
● Envoy is more modern, and designed for this kinda stuff
○ xDS API
○ It’s proven itself as Ingress, Sidecar, even GFE
● A new gateway in town!

Another One?
● Contour, Emissary (formerly Ambassador) agreed to rebase onto the EG
code, but will keep their brands, add value

Demo!

🍺
An offering to the demo gods...

👀

An Adventure in Metrics
● Pod: <EG Operator>
○ Container <main>: no metrics port
○ Container kube-rbac-proxy: https metrics port, just controller_runtime’s default stats
● Pod: <Envoy Instance>
○ Container Envoy: prom-format metrics on admin at localhost:19000 (unreachable)

Other Features
● cert-manager has experimental support (hard to demo locally)

A Work-in-Progress
● v0.2 targeting KubeCon
○ Full compliance to the Gateway API
○ Doesn’t seem to mean other basics, like metrics
● To follow the project
○ https://github.com/envoyproxy/gateway
○ Envoy Slack #gateway-dev

Gateway API API Gateway

What Even is an API Gateway?
You might think
● TLS termination
● Load Balancing
● L7 Routing
● WAF
● Rate-limiting and quotas
● Bot-blocking
● OIDC auth
● Caching
● Body validation and transformation
● Version and staging support
● etc

What Even is an API Gateway?
“Basic” features
● TLS termination
● Load Balancing
● L7 Routing
“API Gateway” features
● WAF
● Rate-limiting and quotas
● Bot-blocking
● OIDC auth
● Caching
● Body validation and transformation
● Version and staging support
● etc

Envoy (API) Gateway
● Extensible code
● Extensible API
● New, clean codebase

Gateway API models API Gateways
● Gain resources to describe API Gateway features
○ Auth one in progress
● On-going discussion about making the API extensible to model the different
features in all the implementations, but in a consistent, first-class way
● “GEP” - Gateway Enhancement Proposal
(https://gateway-api.sigs.k8s.io/contributing/gep/)
● Graduation path
○ Vendor extension
○ GW-API extension
○ GW-API core

A Work-in-the-Future
● Needs the API
● Needs the Extensions
● None being worked on yet (that I know of)
● Except Coraza: a Golang implementation of mod_security

Recap

Where Next?
● Release of Envoy Gateway 0.2 for KubeCon Detroit
● Emissary, Contour rebasing eventually
● Get Gateway API into upstream k8s
● Extend the GW-API to model API-GW concerns
○ Solve problems like modelling deploy of redis for global ratelimits
● Build API-GW feature plugins
● Gateway API v1?
● Envoy Gateway 1.0?

Recap
● Ingress API sucks
● Gateway API doesn’t
○ Ingress
○ East-West
○ API Gateway
● Envoy Gateway exists. It hasn’t got far but you can try it at home.
● Envoy Gateway will become an API Gateway
○ That needs lots of work

Thanks!
Slides
Videos
Demo code
mt165.co.uk
Questions @mt165

Gateway APIs, Envoy Gateway, and API Gateways

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