Cloud adoption continues to increase rapidly worldwide, and not only in the software industry. Every year more and more companies move their applications to the cloud. In the last JHipster community survey, from December 2021, participants valued JHipster’s ability to get them to production faster, and requested more tutorials on deployment to cloud platforms. DigitalOcean is among the most popular “other” cloud vendors, according to some surveys. This post is a quick walk-through of the deployment of a JHipster microservices architecture to a Kubernetes cluster in DigitalOcean’s cloud.
This tutorial was created with the following frameworks and tools:
- JHipster 7.8.1
- Java OpenJDK 11
- Okta CLI 0.10.0
- doctl 1.72.0-release
- kubectl 1.23
- minikube v1.25.2
- k9s v0.25.18
- Docker 20.10.12
Table of Contents
- About DigitalOcean
- Set up a microservices architecture for Kubernetes
- Configure authentication with OpenID Connect
- Run locally with minikube
- Deploy to DigitalOcean Kubernetes
- Secure web traffic with HTTPS
- Inspect and manage cluster resources
- Learn more about JHipster and Kubernetes
DigitalOcean is a cloud services company founded in 2011 by brothers Ben and Moisey Uretsky. Their headquarters are in New York City in the United States, and they also have offices in Massachusetts and Bangalore. Last March 2022, DigitalOcean reached its IPO (Initial Public Offering), and some press articles describe it as the cloud services provider for small businesses: “Cloud services for the Little Guy”.
DigitalOcean Kubernetes (DOKS) is a managed Kubernetes service that lets you deploy Kubernetes clusters without the complexities of handling the control pane and containerized infrastructure. Clusters are compatible with standard Kubernetes toolchains and integrate natively with DigitalOcean load balancers and block storage volumes. DOKS offers fast provisioning and deployment, and provides a free high-availability control pane, for reliability management. It can also provide a Cluster Autoscaler that automatically adjusts the size of the cluster by adding or removing nodes based on the cluster’s capacity to schedule pods. Pricing for Kubernetes workloads is based on resources required by the cluster, droplets, block storage, and load balancers.
The company publishes its data center certification reports on its website, and all the data centers have approved two or more of the following certifications: SOC (System and Organization Controls) 1 Type II, SOC 2 Type II, SOC 3 Type II, and ISO/IEC 27001:2013 (Security techniques - Information security management systems). PCI-DSS (Payment Card Industry - Data Security Standard) has been certified in all data centers.
Set up a microservices architecture for Kubernetes
Before working on the application, you need to install JHipster. The classical way of working with JHipster is to do a local installation with NPM.
npm install -g generator-jhipster@7
If you’d rather use Yarn or Docker, follow the instructions at jhipster.tech.
For this test, start from the
reactive-jhipster example in the
java-microservices-examples repository on GitHub. The example is a JHipster reactive microservices architecture with Spring Cloud Gateway and Spring WebFlux, Vue as the client framework, and Gradle as the build tool. You can read about how it was built in Reactive Java Microservices with Spring Boot and JHipster.
git clone https://github.com/oktadev/java-microservices-examples.git
If you inspect the project folder, you will find sub-folders for the
gateway service, which will act as the front-end application, and a gateway to the
blog microservices, which also have their subfolders. A
docker-compose sub-folder contains the service definitions for running the application containers.
The next step is to generate the Kubernetes deployment descriptors. In the project root folder, create a
kubernetes directory and run the
k8s JHipster sub-generator:
Choose the following options when prompted:
- Type of application: Microservice application
- Root directory: ../
- Which applications? (select all)
- Set up monitoring? No
- Which applications with clustered databases? select store
- Admin password for JHipster Registry: (generate one)
- Kubernetes namespace: demo
- Docker repository name: (your docker hub username)
- Command to push Docker image:
- Enable Istio? No
- Kubernetes service type? LoadBalancer
- Use dynamic storage provisioning? Yes
- Use a specific storage class? (leave empty)
NOTE: You can leave the Docker repository name blank for running Kubernetes locally, but a repository will be required for the cloud deployment, so go ahead and create a DockerHub personal account, and the image pull configuration will be ready for both local and cloud deployments.
blog services container images with Jib. As Jib will push the images to DockerHub, you first need to do a
If you have two-factor authentication enabled, you must generate a token and use it as the password for the login. In the Docker web, go to the user menu and choose Account Settings. Then in the left menu choose Security and New Access Token.
For example, for building the
gateway service image:
./gradlew bootJar -Pprod jib -Djib.to.image=<docker-repo-name>/gateway
IMPORTANT NOTE: Unfortunately the application example does not build with Java 17 at the moment of writing this post. As specified in the introduction, this example was built with Java 11.
Check that the images were uploaded to DockerHub, and navigate to the project root folder in the terminal for the next step.
Configure authentication with OpenID Connect
One more configuration step before running the architecture locally, let’s configure Okta for authentication.
Before you begin, you’ll need a free Okta developer account. Install the Okta CLI and run
okta register to sign up for a new account. If you already have an account, run
okta apps create jhipster. Select the default app name, or change it as you see fit.
Accept the default Redirect URI values provided for you.
What does the Okta CLI do?
The Okta CLI streamlines configuring a JHipster app and does several things for you:
- Creates an OIDC app with the correct redirect URIs:
ROLE_USERgroups that JHipster expects
- Adds your current user to the
- Creates a
groupsclaim in your default authorization server and adds the user’s groups to it
http://localhost:8761* redirect URIs are for the JHipster Registry, which is often used when creating microservices with JHipster. The Okta CLI adds these by default.
You will see output like the following when it’s finished:
Okta application configuration has been written to: /path/to/app/.okta.env
cat .okta.env (or
type .okta.env on Windows) to see the issuer and credentials for your app. It will look like this (except the placeholder values will be populated):
NOTE: You can also use the Okta Admin Console to create your app. See Create a JHipster App on Okta for more information.
Add the settings from the generated
Enable the OIDC authentication in the
jhipster-registry service by adding the
oauth2 profile in the
- name: SPRING_PROFILES_ACTIVE
Run locally with minikube
For minikube, you will need at least 2 CPUs. Start minikube with your number of CPUs:
minikube --cpus <ncpu> start
minikube will log the Kubernetes and Docker versions on start:
Preparing Kubernetes v1.23.3 on Docker 20.10.12 ...
store-mongodb deployment to work, the property
Service.spec.publishNotReadyAddresses was required, instead of the annotation
service.alpha.kubernetes.io/tolerate-unready-endpoints, as the latter was deprecated in Kubernetes release 1.11.
kubernetes/store-k8s/store-mongodb.yml and add the
publishNotReadyAddresses: true property to the
spec key near the bottom of the file:
# Headless service for DNS record
- name: peer
Then deploy the application to minikube. In the
kubernetes directory, run:
Now is a good time to install k9s, a terminal-based UI to interact with Kubernetes clusters. Then run k9s with:
k9s -n demo
Check out the commands list, some useful ones are:
:namespace: show all available namespaces
:pods: show all available pods
You can navigate the pods with
ENTER and go back with
Set up port-forwarding for the JHipster Registry.
kubectl port-forward svc/jhipster-registry -n demo 8761
http://localhost:8761 and sign in with your Okta credentials. When the registry shows all services in green, Set up port-forwarding for the gateway as well.
kubectl port-forward svc/gateway -n demo 8080
http://localhost:8080, sign in, and create some entities to verify everything is working fine.
After looking around, stop minikube before the cloud deployment:
Also delete the minikube cluster to have a clean slate for future tests:
Deploy to DigitalOcean Kubernetes
Now that the architecture works locally, let’s proceed to the cloud deployment. First, create a DigitalOcean account. The registration requires a $5 PayPal payment, or providing a credit card.
Most of the cluster tasks, if not all, can be accomplished using doctl, the command-line interface (CLI) for the DigitalOcean API. Install the tool, and perform the authentication with DigitalOcean:
doctl auth init
You will be prompted to enter the DigitalOcean access token that you can generate in the DigitalOcean control panel. Sign in, and then in the left menu go to API, click Generate New Token. Enter a token name, and click Generate Token. Copy the new token from the Tokens/Keys table.
You can find a detailed list of pricing for cluster resources at DigitalOcean, and with
doctl you can quickly retrieve a list of node size options available for your account:
doctl k options sizes
Create the cluster with the following command line:
doctl k cluster create do1 -v --size s-4vcpu-8gb-intel
After creating a cluster,
doctl adds a configuration context to
kubectl and makes it active, so you can start monitoring your cluster right away with k9s. First, apply the resources configuration to the DigitalOcean cluster:
Monitor the deployment with k9s:
k9s -n demo
Once you see the
jhipster-registry pods are up, set up port forwarding again so you can also monitor the status of the services in the registry UI.
Notes on DigitalOcean’s node sizes and volumes
Deploying to a Kubernetes cluster on DigitalOcean’s cloud can be tricky if you don’t specify enough capacity from the start.
At first, I tested the cluster with the highest size Intel nodes available for my account,
s-2vcpu-4gb-intel. I attempted to run the application in the default cluster configuration, a three-node cluster with a single node pool in the nyc1 region, using the latest Kubernetes version. As I started to see pods not running due to
insufficient CPU, I increased the number of nodes and got everything working. DigitalOcean’s latest and default Kubernetes version at the moment of writing this post was 1.22.8.
If you need to find out the reason why a pod is not running, you can get the pod events with
kubectl describe, for example, for the
kubectl describe pod jhipster-registry-0 -n demo
The output of the command, in the events section, for a pod that has failed due to insufficient cpu, looks like the following:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal NotTriggerScaleUp 4m30s cluster-autoscaler pod didn't trigger scale-up:
Warning FailedScheduling 69s (x3 over 95s) default-scheduler 0/3 nodes are available: 3 Insufficient cpu.
If you see a pod failing in
k9s, check the events for that pod with
kubectl describe pod as in the example above.
To add CPU, increase the number of nodes with
doctl k cluster node-pool update do1 do1-default-pool --count 4
You don’t need to restart pods when adding nodes.
After I increased CPU (adding one more node to the cluster), some of the pods, in the
store-mongodb stateful set with 3 replicas, did not run due to unbound immediate PersistentVolumeClaims. This was reported in the pod events, in the output of
kubectl describe pod, for the failing pods. I then inspected persistent volume claims with the following commands:
kubectl get pvc -n demo
kubectl describe pvc datadir-store-mongodb-2 -n demo
kubectl describe pvc command output was showing provisioning errors, and instructed to contact support:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Provisioning 3m6s (x10 over 11m) dobs.csi.digitalocean.com_master-do3_cebb3451-5eba-4805-956c-753ec148e2ea External provisioner is provisioning volume for claim "demo/datadir-store-mongodb-2"
Warning ProvisioningFailed 3m5s (x10 over 11m) dobs.csi.digitalocean.com_master-do3_cebb3451-5eba-4805-956c-753ec148e2ea failed to provision volume with StorageClass "do-block-storage": rpc error: code = ResourceExhausted desc = volume limit (10) has been reached. Current number of volumes: 10. Please contact support.
Normal ExternalProvisioning 103s (x43 over 11m) persistentvolume-controller waiting for a volume to be created, either by external provisioner "dobs.csi.digitalocean.com" or manually created by system administrator
As instructed by the event message, I contacted DigitalOcean support and they fixed it.
Finally, as I first registered for the free trial account, I had to open a second support ticket requesting higher node sizes, so I could use the size
s-4vcpu-8gb-intel. Not all the size options were available after signing up for the trial, but that is not the case for a standard account. Billing should be under $10 USD for a short Kubernetes service test.
Find your gateway’s external IP and update redirect URIs
Once all the pods are running, find the gateway external IP with the
kubectl describe command:
kubectl describe service gateway -n demo
The output will look like this:
Annotations: kubernetes.digitalocean.com/load-balancer-id: e81d2b8c-6c28-430d-8ba8-6dab29a1ba76
IP Family Policy: SingleStack
IP Families: IPv4
LoadBalancer Ingress: 22.214.171.124
Port: http 8080/TCP
NodePort: http 31048/TCP
Session Affinity: None
External Traffic Policy: Cluster
Update the redirect URIs in Okta to allow the gateway address as a valid redirect. Run
okta login, open the returned URL in your browser, and sign in to the Okta Admin Console. Go to the Applications section, find your application, edit, and add:
- Sign-in redirect URIs:
- Sign-out redirect URIs:
http://<load-balancer-ingress-ip>:8080 and rejoice when everything works!
Secure web traffic with HTTPS
Since the gateway service acts as the application front-end, in the k8s descriptors it is defined as a
LoadBalancer service type. This exposes the service externally using the cloud provider’s load balancer. DigitalOcean load balancers are a fully-managed, highly available network load-balancing service. Load balancers distribute traffic to groups of droplets, which decouples the overall health of a backend service from the health of a single server to ensure that your services stay online.
The standard practice is to secure web traffic to your application with HTTPS. For traffic encryption, you need a TLS (SSL) certificate. DigitalOcean also provides automatic certificate creation and renewal if you manage your domain with DigitalOcean’s DNS, which is free. But domain registration is not provided. To use DigitalOcean’s DNS, you need to register a domain name with a registrar and update your domain’s NS records to point to DigitalOcean’s name servers.
Then, for using DigitalOcean’s managed domain and certificate, you must delegate the domain, updating NS records in the registrar. Because of this requirement, you cannot use free DNS services where you cannot set up NS records, like nip.io.
IMPORTANT NOTE: Before changing the registrar NS records (the nameservers), add your domain to DigitalOcean, to minimize service disruptions.
You can create the certificate and the domain at the same time in the DigitalOcean control panel, when you set up the load balancer HTTPS forwarding.
DigitalOcean load balancers support two main configurations for encrypted web traffic:
- SSL termination: decrypts SSL requests at the load balancer and sends them unencrypted to the backend at the Droplets’ private IP address. The slower and CPU-intensive work of decryption is performed at the load balancer, and certificate management is simplified. The traffic between the load balancer and the backend is secured by routing over the VPC network, but data is readable inside the private network.
- SSL passthrough: sends the encrypted SSL requests directly to the backend at the Droplets’ private IP address, traffic between the load balancer and the backend is secured. Every backend server must have the certificate, and client information contained in
X-forwarded-*headers might be lost.
Taking advantage of the simplified certificate management, SSL termination will be configured in the following steps through the DigitalOcean control panel.
Log in to your DigitalOcean account, and in the left menu choose Kubernetes. Then choose your cluster, and on the cluster page, choose Resources. In the LOAD BALANCERS list, choose the single load balancer that must have been created. On the load balancer page, choose the Settings tab. Click Edit in the Forwarding Rules. Add a forwarding rule for HTTPS in port 443, and in the certificate drop-down, choose New certificate.
In the New Certificate form, choose the Use Let’s Encrypt tab, and then in the domain box, choose Add new domain. Then enter your domain name, and list other subdomains to include. Add a name for the certificate and click Generate Certificate.
Back in the Forwarding rules page, check that the generated certificate is selected, and forward the traffic to the droplet HTTP port where the gateway is running. Tick the checkbox Create DNS records for all the new Let’s Encrypt certificates and then Save the forwarding settings.
Finally, in the SSL section of the settings, tick the checkbox Redirect HTTP to HTTPS.
Once again, update the redirect URIs in Okta to allow the newly configured domain. Add the following redirect URIs:
- Sign-in redirect URIs:
- Sign-out redirect URIs:
Test the configuration by navigating to
http://<your-domain>. First, the load balancer should redirect to HTTPs, and then the gateway should redirect to the Okta sign-in page.
Inspect and manage cluster resources
You can retrieve the cluster associated resources with the following
doctl k cluster list-associated-resources do1
The output will list the volumes and load balancers created for the cluster, which generate billing charges besides the cost of the nodes:
Volumes Volume Snapshots Load Balancers
[a33dbaba-cb22-11ec-9383-0a58ac145375 a6e18809-cb22-11ec-8723-0a58ac14468c 65fb3778-cb23-11ec-9383-0a58ac145375 ac106c49-cb22-11ec-9383-0a58ac145375 c7122288-cb22-11ec-bd08-0a58ac14467d]  [8ebbcbf2-1e67-46f5-b38a-eddae17f00f3]
Unfortunately, there is no way to pause the cluster. According to DigitalOcean, you can power a droplet off, but this does not halt the billing. Billing costs can be reduced by taking a snapshot of the droplet and then destroying it. The snapshot cost is less expensive.
While testing the platform, you can delete the cluster in between sessions, to avoid spending the trial credit while not actively working on it.
doctl k cluster delete do1
Volumes provisioned to the cluster are not deleted with the cluster, and charges are generated hourly. You can delete volumes using the control panel or with the following commands:
doctl compute volume list
doctl compute volume delete <volume-id>
The load balancers are not deleted with the cluster either:
doctl compute load-balancer list
doctl compute load-balancer delete <load-balancer-id>
During registration, a project must have been created, allowing you to organize resources. You can list all the resources associated with a project with the following command:
doctl projects list
doctl projects resources list <project-id>
Learn more about JHipster and Kubernetes
This has been a brief walkthrough for deploying JHipster to a DigitalOcean’s managed Kubernetes cluster. Some important topics for production deployment were not covered in this post, to focus in particular on DigitalOcean resource requirements. Some key topics we did not cover in this post include external configuration storage with Spring Cloud Config and Git as well as secrets encryption both for the cloud configuration and Kubernetes configuration. You can learn about these good practices in the first post of this cloud deployment series: Kubernetes to the Cloud with Spring Boot and JHipster.
Keep learning, and for more content on JHipster, check out the following links:
- Kubernetes Microservices on Azure with Cosmos DB
- Introducing Spring Native for JHipster: Serverless Full-Stack Made Easy
- Full Stack Java with React, Spring Boot, and JHipster
- Fast Java Made Easy with Quarkus and JHipster