Simple CQRS example in Kubernetes with Nodejs / TypeScript
What is this project ?
In this project, I try to build a simple app following CQRS architecture. I created a simple ordering platform. You can make orders to buy some apples and pears. The merchant will be able to see the total number and price of product ordered. For simplicity, here the two databases are just NodeJS app.
Using this project locally :
With kubernetes, on OVH :
./build-docker-k8s 1.0.0 all docker-pseudo
kubectl get deploy,pod,svc
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/cqrs-command-order 1/1 1 1 3h56m
deployment.apps/cqrs-dispatcher 1/1 1 1 4h41m
deployment.apps/cqrs-order-db 1/1 1 1 108m
deployment.apps/cqrs-process-data 1/1 1 1 97m
deployment.apps/cqrs-query-order 1/1 1 1 19m
deployment.apps/cqrs-stats-order-db 1/1 1 1 79m
NAME READY STATUS RESTARTS AGE
pod/cqrs-command-order-8586cc964b-qwwxr 1/1 Running 0 3h54m
pod/cqrs-dispatcher-544cd494fd-t4xfh 1/1 Running 0 3h54m
pod/cqrs-order-db-b4fb7c758-7x2k2 1/1 Running 0 108m
pod/cqrs-process-data-b988f897d-hf6j7 1/1 Running 0 5m15s
pod/cqrs-query-order-657b9f87d-jqh7j 1/1 Running 0 17m
pod/cqrs-stats-order-db-74768cbd54-8t9l9 1/1 Running 0 64m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/cqrs-command-order-svc ClusterIP 10.3.188.8 <none> 80/TCP 3h56m
service/cqrs-dispatcher-svc LoadBalancer 10.3.20.108 XXXXXXXXXXXXXXXX.gra7.k8s.ovh.net 80:30874/TCP 4h38m
service/cqrs-order-db-svc ClusterIP 10.3.77.252 <none> 80/TCP 108m
service/cqrs-process-data-svc ClusterIP 10.3.112.183 <none> 80/TCP 100m
service/cqrs-query-order-svc ClusterIP 10.3.29.20 <none> 80/TCP 19m
service/cqrs-stats-order-db-svc ClusterIP 10.3.29.173 <none> 80/TCP 79m
service/kubernetes ClusterIP 10.3.0.1 <none> 443/TCP 23dWhat is CQRS ?
CQRS is about separating reads and writes, thought having two separate databases.
- The action of reading the database is called a query, equivalent in HTTP of a GET Request
- The action of writing the database is called a command, equivalent in HTTP of a POST, PUT and DELETE
CQRS is suitable for systems in which the number of writing and reading accesses differs greatly. With CQRS, read and write will scale independently. However, it adds a lot of complexity, and your data will be "eventual consistent" : the synchronisation between your read and write databases may extend the time to see the result of a write.
More info on CQRS :
- Greg Young on CQRS and Event Sourcing https://www.youtube.com/watch?v=JHGkaShoyNs
- Clear explaination of CQRS : https://community.risingstack.com/when-to-use-cqrs/
- Nice schemas : https://martinfowler.com/bliki/CQRS.html
Event Sourcing is not implemented in this project. Event Sourcing is commonly found with CQRS architectures.
How to setup NodeJS / TypeScript on VSCode
https://github.com/dleurs/learn_nodejs_ts
Other
build-docker-k8s.sh script is a bit tricky. I will try to look for cleaner solutions, maybe Tekton
kubectl top pod
NAME CPU(cores) MEMORY(bytes)
cqrs-command-order-8586cc964b-qwwxr 0m 23Mi
cqrs-dispatcher-544cd494fd-t4xfh 0m 24Mi
cqrs-order-db-b4fb7c758-7x2k2 0m 22Mi
cqrs-process-data-b988f897d-hf6j7 0m 23Mi
cqrs-query-order-657b9f87d-jqh7j 0m 23Mi
cqrs-stats-order-db-74768cbd54-8t9l9 0m 22MiInstall guide
Get a K8s cluster
With OVH : https://www.ovh.com/manager/public-cloud/
In OVH, two B2-7-FLEX (2 CPU, 7Go RAM) will do.
It will take around 15 minuts to setup.
Then, get the kubeconfig and put it on ~/.kube/config
Install Knative and Istio
https://knative.dev/docs/install/any-kubernetes-cluster/
Install the Custom Resource Definitions :
kubectl apply --filename https://github.com/knative/serving/releases/download/v0.16.0/serving-crds.yamlInstall the core components of Serving :
kubectl apply --filename https://github.com/knative/serving/releases/download/v0.16.0/serving-core.yamlInstall istioctl on your laptop terminal
curl -L https://istio.io/downloadIstio | sh -
cd istio-1.6.5
export PATH=$PWD/bin:$PATHInstall Istio 1.6.5 for Knative with sidecar injection
cat << EOF > ./istio-minimal-operator.yaml
apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
spec:
values:
global:
proxy:
autoInject: enabled
useMCP: false
# The third-party-jwt is not enabled on all k8s.
# See: https://istio.io/docs/ops/best-practices/security/#configure-third-party-service-account-tokens
jwtPolicy: first-party-jwt
addonComponents:
pilot:
enabled: true
prometheus:
enabled: false
components:
ingressGateways:
- name: istio-ingressgateway
enabled: true
- name: cluster-local-gateway
enabled: true
label:
istio: cluster-local-gateway
app: cluster-local-gateway
k8s:
service:
type: ClusterIP
ports:
- port: 15020
name: status-port
- port: 80
name: http2
- port: 443
name: https
EOFistioctl manifest apply -f istio-minimal-operator.yaml
rm -rf istio-minimal-operator.yamlkubectl label namespace knative-serving istio-injection=enabledcat <<EOF | kubectl apply -f -
apiVersion: "security.istio.io/v1beta1"
kind: "PeerAuthentication"
metadata:
name: "default"
namespace: "knative-serving"
spec:
mtls:
mode: PERMISSIVE
EOFKnative Istio controller
kubectl apply --filename https://github.com/knative/net-istio/releases/download/v0.16.0/release.yamlChecking the install
kubectl get pods --namespace istio-system
kubectl get pods --namespace knative-servingTest with a hello world
cat <<EOF | kubectl apply -f -
apiVersion: serving.knative.dev/v1 # Current version of Knative
kind: Service
metadata:
name: helloworld-go # The name of the app
namespace: default # The namespace the app will use
spec:
template:
spec:
containers:
- image: gcr.io/knative-samples/helloworld-go # Reference to the image of the app
env:
- name: TARGET # The environment variable printed out by the sample app
value: "Go Sample v1"
EOFkubectl get ksvc
kubectl --namespace istio-system get service istio-ingressgateway
curl -H "Host: helloworld-go.default.example.com" http://51.178.XXX.XXX # Hello WorldDNS configuation
Without DNS setup, after creating helloworld
kubectl get ksvc
kubectl --namespace istio-system get service istio-ingressgateway
curl -H "Host: helloworld-go.default.example.com" http://51.178.XXX.XXXMagic DNS (xip.io)
kubectl apply --filename https://github.com/knative/serving/releases/download/v0.16.0/serving-default-domain.yamlIf you want to set up a custom domain :
https://knative.dev/docs/serving/using-a-custom-domain/
kubectl edit cm config-domain --namespace knative-servingapiVersion: v1
data:
mydomain.com: ""
kind: ConfigMap
[...]To publish your domain, you need to update your DNS provider to point to the IP address for your service ingress.
In OVH, Web > Domains > mydomain.com > DNS Zone > Add an entry >
*.default IN A 51.178.XXX.XXXTo remove namespace from URL, for example http://helloworld-go.dleurs.fr instead of http://helloworld-go.default.dleurs.fr :
In OVH, Web > Domains > mydomain.com > Redirect > Add a redirection
helloworld-go.dleurs.fr, with tick wwww. > Tick to other web address > Tick invisible redirect > http://helloworld-go.default.dleurs.fr
Step 1 : No CICD > bash script
Step 2 : Install Tekton Pipeline
Tested only for small exampleow
Install Tekton
kubectl apply --filename https://storage.googleapis.com/tekton-releases/pipeline/latest/release.yamlkubectl get pods --namespace tekton-pipelinesStep 3 : Testing Tekton
https://github.com/tektoncd/pipeline/blob/master/docs/README.md
https://github.com/tektoncd/pipeline/blob/master/docs/auth.md#basic-authentication-git
kubectl create secret docker-registry docker-creds \
--docker-server=index.docker.io \
--docker-username=<your-name> \
--docker-password=<your-pword> kubectl apply -f cicd-tekton/tekton-sa.yaml
kubectl apply -f cicd-tekton/docker-targets-resc.yaml
kubectl apply -f cicd-tekton/build-task.yamlChoose what service you want to build
kubectl apply -f cicd-tekton/git-source-resc.yaml # Modify image git
kubectl apply -f cicd-tekton/build-XXXXXX-task-run.yamltkn taskrun describe build-dispatcher-task-run
tkn taskrun logs build-dispatcher-task-runtkn taskrun delete build-dispatcher-task-run --force
kubectl delete -f cicd-tekton
kubectl delete secret docker-creds
tkn taskrun delete build-dispatcher-task-run --force; kubectl apply -f cicd-tekton/builds-task-run.yamlStep 4 : Install Tekton Triggers
Configure HTTPS
Not yet tested
https://knative.dev/docs/serving/using-a-tls-cert/
https://knative.dev/docs/serving/using-auto-tls/
https://cert-manager.io/docs/configuration/acme/dns01/Installation using Rancher
helm install rancher rancher-latest/rancher \
--namespace cattle-system \
--set hostname=rancher.default.dleurs.fr \
--set ingress.tls.source=letsEncrypt \
--set letsEncrypt.email=contact@dleurs.fr