playing around with GKE Gateway MCGs and traffic splitting
i'm setting this up across 2 existing GKE Autopilot clusters (autopilot-cluster-us-central1 and autopilot-cluster-us-east4, and the context names match the cluster names). these clusters already have MCS / Gateway enabled on them, so if you want to learn about the basics of setup, go here.
in this example, we're just going to demo traffic splitting across two versions (one named flip, the other flop) of whereami.
# create namespace
kubectl --context autopilot-cluster-us-central1 create ns whereami
kubectl --context autopilot-cluster-us-east4 create ns whereami
# create whereami base
mkdir whereami
mkdir whereami/base
cat <<EOF > whereami/base/kustomization.yaml
resources:
- github.com/GoogleCloudPlatform/kubernetes-engine-samples/whereami/k8s
EOF
# deploy `flip` on both clusters
mkdir whereami/flip-variant
cat <<EOF > whereami/flip-variant/cm-flag.yaml
apiVersion: v1
kind: ConfigMap
metadata:
name: whereami
data:
BACKEND_ENABLED: "False" # assuming you don't want a chain of backend calls
METADATA: "flip"
EOF
cat <<EOF > whereami/flip-variant/service-type.yaml
apiVersion: "v1"
kind: "Service"
metadata:
name: "whereami"
spec:
type: ClusterIP
EOF
cat <<EOF > whereami/flip-variant/kustomization.yaml
nameSuffix: "-flip"
namespace: whereami
commonLabels:
app: whereami-flip
resources:
- ../base
patches:
- path: cm-flag.yaml
target:
kind: ConfigMap
- path: service-type.yaml
target:
kind: Service
EOF
kubectl --context=autopilot-cluster-us-central1 apply -k whereami/flip-variant
kubectl --context=autopilot-cluster-us-east4 apply -k whereami/flip-variant
# deploy `flop` on both clusters
mkdir whereami/flop-variant
cat <<EOF > whereami/flop-variant/cm-flag.yaml
apiVersion: v1
kind: ConfigMap
metadata:
name: whereami
data:
BACKEND_ENABLED: "False" # assuming you don't want a chain of backend calls
METADATA: "flop"
EOF
cat <<EOF > whereami/flop-variant/service-type.yaml
apiVersion: "v1"
kind: "Service"
metadata:
name: "whereami"
spec:
type: ClusterIP
EOF
cat <<EOF > whereami/flop-variant/kustomization.yaml
nameSuffix: "-flop"
namespace: whereami
commonLabels:
app: whereami-flop
resources:
- ../base
patches:
- path: cm-flag.yaml
target:
kind: ConfigMap
- path: service-type.yaml
target:
kind: Service
EOF
kubectl --context=autopilot-cluster-us-central1 apply -k whereami/flop-variant
kubectl --context=autopilot-cluster-us-east4 apply -k whereami/flop-variant
# create serviceExports
cat <<EOF > flip_svc_export.yaml
kind: ServiceExport
apiVersion: net.gke.io/v1
metadata:
name: whereami-flip
namespace: whereami
EOF
kubectl --context=autopilot-cluster-us-central1 apply -f flip_svc_export.yaml
kubectl --context=autopilot-cluster-us-east4 apply -f flip_svc_export.yaml
cat <<EOF > flop_svc_export.yaml
kind: ServiceExport
apiVersion: net.gke.io/v1
metadata:
name: whereami-flop
namespace: whereami
EOF
kubectl --context=autopilot-cluster-us-central1 apply -f flop_svc_export.yaml
kubectl --context=autopilot-cluster-us-east4 apply -f flop_svc_export.yaml
# create multi-cluster gateway
cat <<EOF > gateway.yaml
kind: Gateway
apiVersion: gateway.networking.k8s.io/v1beta1
metadata:
name: external-http
namespace: whereami
spec:
gatewayClassName: gke-l7-global-external-managed-mc
listeners:
- name: http
protocol: HTTP
port: 80
allowedRoutes:
kinds:
- kind: HTTPRoute
EOF
kubectl --context=autopilot-cluster-us-central1 apply -f gateway.yaml
# create httpRoute to flip, to test
cat << EOF > default-httproute.yaml
apiVersion: gateway.networking.k8s.io/v1beta1
kind: HTTPRoute
metadata:
name: default-httproute
namespace: whereami
spec:
parentRefs:
- name: external-http
namespace: whereami
rules:
- backendRefs:
- group: net.gke.io
kind: ServiceImport
name: whereami-flip
port: 80
weight: 50
- group: net.gke.io
kind: ServiceImport
name: whereami-flop
port: 80
weight: 50
EOF
kubectl --context=autopilot-cluster-us-central1 apply -f default-httproute.yaml
# test
export GATEWAY_IP=$(kubectl --context=autopilot-cluster-us-central1 -n whereami get gateway/external-http -o jsonpath='{.status.addresses[0].value}')
echo $GATEWAY_IP
watch -n 0.2 'curl http://${GATEWAY_IP} -s | jq'