Simple microservice boilerplate.
Pinger is an app which continuously calls any URL, to check if it's up or not. It also records the latency, response code, size etc.
This app has 3 services:
frontend- which provides the UI, and calls different APIspinger- runs a loop and calls the list of URLs provided by the UI and records all statsdetails- service which providers more details about a URL
Start by installing a local kubernetes cluster using kind: https://kind.sigs.k8s.io/
A sample cluster configuration can be found in: k8s/cluster/kind-cluster-config.yaml
This creates a 3 node cluster along with a control plane.
Example:
kind create cluster --config k8s/cluster/kind-cluster-config.yaml
Creating cluster "kind" ...
✓ Ensuring node image (kindest/node:v1.20.2) 🖼
✓ Preparing nodes 📦 📦 📦 📦
✓ Writing configuration 📜
✓ Starting control-plane 🕹️
✓ Installing CNI 🔌
✓ Installing StorageClass 💾
✓ Joining worker nodes 🚜
Set kubectl context to "kind-kind"
You can now use your cluster with:
kubectl cluster-info --context kind-kind
Have a question, bug, or feature request? Let us know! https://kind.sigs.k8s.io/#community 🙂
Check using:
$ kubectl get no --context kind-kind
NAME STATUS ROLES AGE VERSION
kind-control-plane Ready control-plane,master 2m50s v1.20.2
kind-worker Ready <none> 2m16s v1.20.2
kind-worker2 Ready <none> 2m16s v1.20.2
kind-worker3 Ready <none> 2m16s v1.20.2
Now, that you have a cluster running... Let's build the application and load the images into the cluster.
./scripts/build-docker.sh - This script build and uploads the images to the kind cluster.
Now, if you want to do it yourself, follow this guide
Check the sample deployment configuration. This has basic k8s deployment and service spec.
k8s/configs/pinger-all-in-one.yaml
Example:
$ kubectl apply -f k8s/configs/pinger-all-in-one.yaml
deployment.apps/frontend created
service/frontend-service created
deployment.apps/details created
service/details-service created
deployment.apps/pinger-v1 created
service/pinger-v1-service created
deployment.apps/pinger-v2 created
service/pinger-v2-service created
Verify if everything was successfully created.
Check pods:
$ kubectl get po
NAME READY STATUS RESTARTS AGE
details-77498f8c7d-gvqcm 1/1 Running 0 10m
frontend-7486854785-4rpm4 1/1 Running 0 10m
pinger-v1-7bcc658775-ftbfs 1/1 Running 0 10m
pinger-v2-fff76cdc-85j5j 1/1 Running 0 10m
Check services:
$ kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
details-service ClusterIP 10.96.242.219 <none> 4000/TCP 10m
frontend-service ClusterIP 10.96.111.87 <none> 9000/TCP 10m
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 72m
pinger-v1-service ClusterIP 10.96.10.155 <none> 3000/TCP 10m
pinger-v2-service ClusterIP 10.96.152.94 <none> 3000/TCP 10m
Check deployments:
$ kubectl get deploy
NAME READY UP-TO-DATE AVAILABLE AGE
details 1/1 1 1 11m
frontend 1/1 1 1 11m
pinger-v1 1/1 1 1 11m
pinger-v2 1/1 1 1 11m
Let's expose the application locally and check if things are working together correctly.
Get the pod name for frontend:
$ kubectl get po | grep frontend
frontend-7486854785-4rpm4 1/1 Running 0 13m
Let's forward this to the local machine:
$ kubectl port-forward frontend-7486854785-4rpm4 9000:9000
Forwarding from 127.0.0.1:9000 -> 9000
Forwarding from [::1]:9000 -> 9000
Now open you browser: http://localhost:9000 You should be able to see the page.
Here, we used kubectl port-forward <pod-name> <local-port>:<remote-port> to forward local connections
to the container running in the cluster.
Here, the frontend pod calls the pinger and details service.
frontend service's deployment configuration has the following environment variable:
containers:
- name: frontend
image: localhost/frontend:v1
env:
- name: PINGER_BASE_URL
value: "http://pinger-v1-service:3000"
- name: DETAILS_BASE_URL
value: "http://details-service:4000"
ports:
In the sample configuration, they are calling the service names configured for the other deployments.
Thus, the frontend, inside k8s, will use these internal DNS names to access pinger and details service.
These variables can be changed to point to the correct services. If one of the services isn't working as expected, the UI would show error messages. You can try this by deleting some service or deployment.
For checking logs of a pod, use:
kubectl logs -f <pod-name>
Example:
$ kubectl logs -f frontend-7486854785-4rpm4
2021-05-06T22:05:29.573Z | Frontend listening at: 9000
::ffff:172.18.0.3 - - [06/May/2021:22:14:25 +0000] "GET / HTTP/1.1" 200 6351 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.93 Safari/537.36"
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