DEV Community

AWS Community Builders profile image Shakir
Shakir for AWS Community Builders

Posted on • Edited on

HarperDB on EKS

#aws #eks #harperdb #kubernetes

Hi there 👋, let's see how to deploy HarperDB on EKS, and then test it with an API call from CURL. You can get the Kubernetes manifests that we make in this post from this link.

Hope you are already familiar with topics such as Deployment, Load Balancer service, Secret and Persistent volume claim

Ensure you have the required IAM permissions, have installed the aws, eksctl & kubectl cli tools, and have setup the config and credentials.

For me the config is as follows.

$ cat ~/.aws/config
[default]
region=us-east-1
Enter fullscreen mode Exit fullscreen mode

Cluster

We can now create an EKS cluster with eksctl. You may see this video for cluster creation from the CLI.

$ eksctl create cluster --name eks-cluster --zones=us-east-1a,us-east-1b
Enter fullscreen mode Exit fullscreen mode

This has taken around 20 mins for me. Once it's done we can update the kubeconfig.

$ aws eks update-kubeconfig --name eks-cluster
Enter fullscreen mode Exit fullscreen mode

Docker hub

We can visit the docker hub page of harperdb to get an idea on the ports, environment variables, volume path etc.

They have given an example docker command as below.

docker run -d \
  -v /host/directory:/opt/harperdb/hdb \
  -e HDB_ADMIN_USERNAME=HDB_ADMIN \
  -e HDB_ADMIN_PASSWORD=password \
  -p 9925:9925 \
  harperdb/harperdb
Enter fullscreen mode Exit fullscreen mode

This tells us the volume mount path in the container is /opt/harperdb/hdb, there are 2 environment variables for username and password, and the container port is 9925. Finally the image is harperdb/harperdb.

We now have enough info to start writing our Kubernetes manifests.

Kubernetes manifests

I am going to create a directory by name harperdb where I would keep all the manifests.

$ mkdir harperdb    
$ cd harperdb
Enter fullscreen mode Exit fullscreen mode

Let's begin with the environment variables, we can write both username and password in a secret object.

$ cat <<EOF > secret.yaml 
---
apiVersion: v1
kind: Secret
metadata:
  name: harperdb
  namespace: harperdb
stringData:
  HDB_ADMIN_USERNAME: admin
  HDB_ADMIN_PASSWORD: password12345
...
EOF
Enter fullscreen mode Exit fullscreen mode

We can now go with a persistent volume claim, that can dynamically create an EBS volume of size 5Gi in AWS.

$ cat <<EOF > pvc.yaml 
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: harperdb
  namespace: harperdb
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi
...
EOF
Enter fullscreen mode Exit fullscreen mode

Then comes the deployment manifest, where we can define the container image, refer to the secret for the env vars, and pvc for the volume. Note that the volume mount path matches with that in the docker command.

$ cat <<EOF > deploy.yaml 
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: harperdb
  namespace: harperdb
spec:
  selector:
    matchLabels:
      app: harperdb
  template:
    metadata:
      labels:
        app: harperdb
    spec:
      containers:
      - name: harperdb
        image: harperdb/harperdb
        envFrom:
        - secretRef:
            name: harperdb
        volumeMounts:
        - name: data
          mountPath: /opt/harperdb/hdb
      volumes:
      - name: data
        persistentVolumeClaim:
          claimName: harperdb
...
EOF
Enter fullscreen mode Exit fullscreen mode

Finally, we have to expose the deployment with a service, we know from the docker command that the container port is 9925.

$ cat <<EOF > svc.yaml
---
apiVersion: v1
kind: Service
metadata:
  name: harperdb
  namespace: harperdb
spec:
  selector:
    app: harperdb
  type: LoadBalancer
  ports:
  - name: http
    port: 8080
    targetPort: 9925
...
EOF
Enter fullscreen mode Exit fullscreen mode

Note that we have used 8080 as the service port.

Workloads

Create a namespace by name harperdb, where we can create our objects.

$ kubectl create ns harperdb
namespace/harperdb created
Enter fullscreen mode Exit fullscreen mode

We are good to create objects with the 4 manifests.

$ ls
deploy.yaml pvc.yaml    secret.yaml svc.yaml

$ kubectl create -f .
deployment.apps/harperdb created
persistentvolumeclaim/harperdb created
secret/harperdb created
service/harperdb created
Enter fullscreen mode Exit fullscreen mode

Fix PVC

The pvc should be in pending status.

$ kubectl get pvc
NAME       STATUS    VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
harperdb   Pending                                      gp2            7m3s
Enter fullscreen mode Exit fullscreen mode

Please follow this link to add IAM role in AWS cloud, and ebs csi objects on the cluster. This should fix the PVC issue.

Once done, the pvc should be bound to a persistent volume(pv).

$ kubectl get pvc -n harperdb    
NAME       STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
harperdb   Bound    pvc-7c83e38c-b00a-4194-8c67-ba5c9c1118e7   5Gi        RWO            gp2            9s
Enter fullscreen mode Exit fullscreen mode

And the pv should be mapped to an EBS volume.

$ kubectl get pv 
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                  STORAGECLASS   REASON   AGE
pvc-7c83e38c-b00a-4194-8c67-ba5c9c1118e7   5Gi        RWO            Delete           Bound    harperdb/harperdb      gp2                     64s

$ kubectl describe pv pvc-7c83e38c-b00a-4194-8c67-ba5c9c1118e7 | grep VolumeID
    VolumeID:   vol-0bbca736346f02aa1
Enter fullscreen mode Exit fullscreen mode

Note that a persistent volume is a cluster level object and not bound to a namespace. We can check the volume details from the aws cli.

$ aws ec2 describe-volumes --volume-ids vol-0bbca736346f02aa1 --query "Volumes[0].Size"      
5

$ aws ec2 describe-volumes --volume-ids vol-0bbca736346f02aa1 --query "Volumes[0].Tags"
[
    {
        "Key": "ebs.csi.aws.com/cluster",
        "Value": "true"
    },
    {
        "Key": "CSIVolumeName",
        "Value": "pvc-7c83e38c-b00a-4194-8c67-ba5c9c1118e7"
    },
    {
        "Key": "kubernetes.io/created-for/pv/name",
        "Value": "pvc-7c83e38c-b00a-4194-8c67-ba5c9c1118e7"
    },
    {
        "Key": "kubernetes.io/created-for/pvc/namespace",
        "Value": "harperdb"
    },
    {
        "Key": "kubernetes.io/created-for/pvc/name",
        "Value": "harperdb"
    }
]
Enter fullscreen mode Exit fullscreen mode

Volume permission fix

So the pvc seems good. Let's check our application status.

$ kubectl get po -n harperdb
NAME                        READY   STATUS             RESTARTS      AGE
harperdb-79694c8b75-6ckn7   0/1     CrashLoopBackOff   4 (80s ago)   3m25s
Enter fullscreen mode Exit fullscreen mode

The application was crashing, but the volume was getting mounted, and the env vars were fine too. I tried commenting out volumeMounts and volume and updated the deployment.

$ cat deploy.yaml | grep #
        #volumeMounts:
        #- name: data
          #mountPath: /opt/harperdb/hdb
      #volumes:
      #- name: data
        #persistentVolumeClaim:
          #claimName: harperdb

$ kubectl apply -f deploy.yaml
Enter fullscreen mode Exit fullscreen mode

The pod was running, and I checked the permissions of the directory where we need to mount the volume. And subsequently the id of the group.

$ kubectl exec -it deploy/harperdb -n harperdb -- bash

ubuntu@harperdb-858cc7967d-5jcqm:~$ ls -l /opt/harperdb
total 0
drwxr-xr-x 11 ubuntu ubuntu 155 Jan  9 06:59 hdb

ubuntu@harperdb-858cc7967d-5jcqm:~$ id
uid=1000(ubuntu) gid=1000(ubuntu) groups=1000(ubuntu)

ubuntu@harperdb-858cc7967d-5jcqm:~$ exit
Enter fullscreen mode Exit fullscreen mode

So the group id of the running user is 1000, hence we can set this as the group owner for the volume directory with the fsGroup option. If we don't specify this then the mountPath would by default be set with root(user) and root(group) as the owner for the directory and the running user ubuntu wouldn't have permissions on the mountPath to create any new files. This video has information about fsGroup.

We have to change the deployment as follows. We have added the security context with the fsGroup.

$ cat deploy.yaml 
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: harperdb
  namespace: harperdb
spec:
  selector:
    matchLabels:
      app: harperdb
  template:
    metadata:
      labels:
        app: harperdb
    spec:
      securityContext:
        fsGroup: 1000
      containers:
      - name: harperdb
        image: harperdb/harperdb
        envFrom:
        - secretRef:
            name: harperdb
        volumeMounts:
        - name: data
          mountPath: /opt/harperdb/hdb
      volumes:
      - name: data
        persistentVolumeClaim:
          claimName: harperdb
...
Enter fullscreen mode Exit fullscreen mode

Alternately, we could also set mountPath to just /opt/harperdb, where we wouldn't have to set the securityContext. But I thought this is a good use case to know about the fsGroup.

Update the deployment.

$ kubectl apply -f deploy.yaml
Enter fullscreen mode Exit fullscreen mode

Check the workloads.

$ kubectl get all -n harperdb
NAME                           READY   STATUS    RESTARTS   AGE
pod/harperdb-cc4f49dfc-m7d5p   1/1     Running   0          55s

NAME               TYPE           CLUSTER-IP     EXTERNAL-IP                                                              PORT(S)          AGE
service/harperdb   LoadBalancer   10.100.54.78   a0ba701c9c5a4463bb636551c79b4158-169592876.us-east-1.elb.amazonaws.com   8080:31819/TCP   55s

NAME                       READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/harperdb   1/1     1            1           57s

NAME                                 DESIRED   CURRENT   READY   AGE
replicaset.apps/harperdb-cc4f49dfc   1         1         1       57s
Enter fullscreen mode Exit fullscreen mode

API call

Send a CURL command to test schema creation. The endpoint is from the external IP column in the service. You may check this video to know how to obtain the curl command for harperdb.

$ HDB_API_ENDPOINT=http://a0ba701c9c5a4463bb636551c79b4158-169592876.us-east-1.elb.amazonaws.com:8080

$ curl --location --request POST ${HDB_API_ENDPOINT} \
--header 'Content-Type: application/json' \
--header 'Authorization: Basic YWRtaW46cGFzc3dvcmQxMjM0NQ==' \
--data-raw '{
    "operation": "create_schema",
    "schema": "qa" 
}'

{"message":"schema 'qa' successfully created"}
Enter fullscreen mode Exit fullscreen mode

All good, it's working...

Persistence

Test persistence by deleting the pod.

$ kubectl delete po -n harperdb -l app=harperdb
pod "harperdb-cc4f49dfc-m7d5p" deleted
Enter fullscreen mode Exit fullscreen mode

This should launch a new pod.

$ kubectl get po -n harperdb
NAME                       READY   STATUS    RESTARTS   AGE
harperdb-cc4f49dfc-c6vnc   1/1     Running   0          57s
Enter fullscreen mode Exit fullscreen mode

We can try sending the same API call again.

$ curl --location --request POST ${HDB_API_ENDPOINT} \
--header 'Content-Type: application/json' \
--header 'Authorization: Basic YWRtaW46cGFzc3dvcmQxMjM0NQ==' \
--data-raw '{
    "operation": "create_schema",
    "schema": "qa"
}'

{"error":"Schema 'qa' already exists"}
Enter fullscreen mode Exit fullscreen mode

It's not creating a new schema, because the existing schema is restored from the attached volume. Hence, it's persistent.

Clean up

Let's do the clean up...

Delete all the objects that were created via manifests.

$ kubectl delete -f .
deployment.apps "harperdb" deleted
persistentvolumeclaim "harperdb" deleted
secret "harperdb" deleted
service "harperdb" deleted
Enter fullscreen mode Exit fullscreen mode

Then delete the namespace.

$ kubectl delete ns harperdb
namespace "harperdb" deleted
Enter fullscreen mode Exit fullscreen mode

Delete the folder.

$ cd ..
$ rm -rf harperdb
Enter fullscreen mode Exit fullscreen mode

Finally delete the cluster.

$ eksctl delete cluster --name eks-cluster
Enter fullscreen mode Exit fullscreen mode

That's it for the post, Thank you for reading !!!

Top comments (0)

Read next

jutionck profile image

Kubernetes: Install Tools

Jution Candra Kirana -

smkhub profile image

AWS CDK

Sharad Khambe -

hulk-pham profile image

AWS Storage - Part 4: Amazon S3

Hulk Pham -

fady_nabil10 profile image

New features in Amazon Bedrock Prompt Management

Fady Nabil -