java-prototype

Owner: Kris Nova

Author: Kris Nova Github

Overview

java-prototype simulates a troublesome monolithic Java application that is designed to be hard to orchestrate in containers.

Install

Installing with maven

mvn clean package

Also for a quick development run the following command to build and run the application.

make dev

Configuring

MySQL

There are three environmental variables that need to be defined in order to authenticate with a MySQL server.

export JAVAPROTOTYPE_MYSQL_CONNECTION_STRING="jdbc:mysql://my.server.url/database"
export JAVAPROTOTYPE_MYSQL_CONNECTION_USER="user"
export JAVAPROTOTYPE_MYSQL_CONNECTION_PASS="password"

Cloud Deployment

GCP: Create a build trigger using cloudbuild.yaml linking your clone or fork of this repo.
AWS: Include buildspec.yaml in a CodeBuild object linking your clone or fork of this repo.

There are two containers to build, a frontend (the java app) and a backend (the mysql database). NOTE This is not a secure database image, and therefore should not be used in production.

This deployment strategy requires helm, with a tiller installation that has appropriate RBAC roles and rolebindings. Optionally, it is recommended to install ahmetb's kubectx and kubens and the Farmotive cloud-native dev tools:kex, kpoof, klog, and kud. If on a Mac, install these with Homebrew:

brew tap farmotive/k8s
brew install kpoof klog kex kud

Deployment One: the mysql database container

Set environment variables in order to install the mysql chart using helm:

export NAMESPACE=java-prototype
export DEPLOY_NAME=java-prototype-mysql
export JAVAPROTOTYPE_MYSQL_CONNECTION_PASS="password" #alter this if exposing this deployment externally
export JAVAPROTOTYPE_MYSQL_CONNECTION_USER="java-prototype"
export SIZE=1Gi #If cost is not a concern, increase this to a desired capacity, or omit ",persistence.size=$SIZE" below to use the default 10Gi allocation.

Install the backend deployment:

kubectl create namespace java-prototype
kubens java-prototype
helm install --namespace $NAMESPACE \
--name=$DEPLOY_NAME \
--set mysqlUser=$JAVAPROTOTYPE_MYSQL_CONNECTION_USER,mysqlPassword=$JAVAPROTOTYPE_MYSQL_CONNECTION_PASS,mysqlDatabase=java-prototype,persistence.size=$SIZE \
stable/mysql

Once the deployment is successful, obtain the randomly generated root password from the secret for MYSQL_ROOT_PASSWORD:

kubectl get secret --namespace $NAMESPACE java-prototype-mysql-mysql -o jsonpath="{.data.mysql-root-password}" | base64 --decode; echo

Then connect to the mysql instance (kpoof, Sequel Pro, mysql client, etc) and import java-prototype.sql

mysql -u root -p java-prototype < java-prototype.sql

When prompted, use the password echoed above.

Deployment Two: the java application

Modify the image name in java-prototype/values.yaml image.name to match the image generated by cloudbuild.yaml. It will resemble gcr.io/$PROJECT_ID/java-prototype. Modify the password in java-prototype/values.yaml env.pass to match the JAVAPROTOTYPE_MYSQL_CONNECTION_PASS export (if JAVAPROTOTYPE_MYSQL_CONNECTION_PASS was altered).

helm install java-prototype/ --namespace java-prototype --name java

Once the output of the NOTES.txt displays, run kubectl get pods -w to see the java deployment succeed. Use ctrl-C to regain a prompt.

Manipulating the application

NOTE The following activities require multiple terminal sessions.

Create a local connection for the database

kpoof

Select the mysql pod. Port 3306 will be forwarded. Connect using the database manager of your choosing with 127.0.0.1 as the host, java-prototype as the user, and the value for $JAVAPROTOTYPE_MYSQL_CONNECTION_PASS as the password. Choose java-prototype as the schema and getrequests as the table. You should see column headers of id, timestamp, and hash with an empty row set.

In a new terminal session, create a local connection for the application

kpoof

Select the java app pod. Port 8080 will be forwarded. Connect using the browser of your choosing to localhost:8080. Once resolved, Success! will appear.

In a new terminal session run the following infinite loop to create entries in the database:

while true; do curl localhost:8080; done

Optional:

In a new terminal session:

klog -f

Select the java pod. It is likely that the application will log outOfMemory errors. Additionally, logs will contain the writes to the database as well as free memory (if any).

Review each terminal window. The terminal for logs will update with a crash or a new write statement with a random hash. For each successful curl, the terminal for port-forwarding the app will show a valid connection to 8080. The database manager, when refreshed, will show database rows for each successful connection.

Challenge Round

Uncomment the liveness and readiness probes in java-prototype/templates/deployment.yaml and modify the values, iterating through upgrades of the java app deployment until the pod shows ready.

Cleanup

helm delete --purge java java-prototype-mysql
kubectl delete namespace java-prototype

Troubleshooting

If you encounter any problems that the documentation does not address, file an issue or talk to us on the Kubernetes Slack team channel #monolith.

Contributing

Thanks for taking the time to join our community and start contributing!

Feedback and discussion is available on the mailing list.

Please familiarize yourself with the Code of Conduct before contributing.
See CONTRIBUTING.md for instructions on the developer certificate of origin that we require.

billkoch/java-prototype