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Step 9: Databases

Postgres via Deployments

  1. PersistentVolume

  2. PersistentVolumeClaim

  3. Deployment

  4. Service

$ minikube --profile 9steps docker-env
# or
$ minishift docker-env

$ eval $(minikube --profile 9steps docker-env)

Pre-pull the docker image

$ docker pull postgres:10.5

Check to see if you have any preconfigured PVs

$ kubectl get pv --all-namespaces

Create the PV, PVC, Deployment and Service

$ kubectl create -f kubefiles/postgres-pv.yml
$ kubectl get pv/postgres-pv
NAME          CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM     STORAGECLASS   REASON    AGE
postgres-pv   2Gi        RWO            Retain           Available             mystorage                14s

$ kubectl create -f kubefiles/postgres-pvc.yml
$ kubectl get pv/postgres-pv
NAME          CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS    CLAIM               STORAGECLASS   REASON    AGE
postgres-pv   2Gi        RWO            Retain           Bound     myspace/postgres-pvc   mystorage                49s

$ kubectl get pvc/postgres-pvc
NAME           STATUS    VOLUME        CAPACITY   ACCESS MODES   STORAGECLASS   AGE
postgres-pvc   Bound     postgres-pv   2Gi        RWO            mystorage      27s

$ kubectl create -f kubefiles/postgres-deployment.yml
$ kubectl get pods
NAME                       READY     STATUS    RESTARTS   AGE
postgres-bf856c974-9hdrp   1/1       Running   0          5s

$ kubectl create -f kubefiles/postgres-service.yml

Now, make the Postgres port 5432 available at localhost

$ kubectl port-forward <posgtres-pod> 5433:5432
pgAdmin Add Server
Figure 1. pgAdmin Add Server
pgAdmin Add Server 2
Figure 2. pgAdmin Add Server 2

Select Tools → Query Tool and write and execute the following

CREATE ROLE myuser WITH LOGIN PASSWORD 'mypassword';
ALTER ROLE myuser CREATEDB;
CREATE DATABASE mydb;
ALTER DATABASE mydb owner to "myuser";

Note: You can also run psql CLI from within the Postgres Pod

$ kubectl exec -it postgres-bf856c974-xqtf8 /bin/bash
# replacing postgres-bf856c974-xqtf8 with your pod id
$ psql --username "$POSTGRES_USER" --dbname "$POSTGRES_DB"

postgresdb-# \l

psql tips:

\l (list databases)
\c newDatabase (switch database)
\dt (list tables)
\q quit

Run the Spring Boot + Postgres app on localhost. This is using Hibernate’s ability to generate database schema from the object model

$ cd hellodata/boot_postgres

$ mvn spring-boot:run -Dspring-boot.run.arguments=--spring.config.location=src/main/resources/application-local.properties

There are 2 application.properties files, one for localhost testing and one for "production" when it runs inside of Kubernetes/OpenShift

Check pgAdmin

pgAdmin Tables
Figure 3. pgAdmin Tables

Add a test question by POST’ing the testquestion.json file

$ curl -X POST http://localhost:8080/questions -d @testquestion.json --header "Content-Type: application/json"

Query for the questions in the database via the REST API

$ curl http://localhost:8080/questions
pgAdmin Questions
Figure 4. pgAdmin Questions

Now, let’s run the Spring Boot app as a Pod

$ mvn clean package -DskipTests
$ docker build -t 9stepsawesome/mybootdata:v1 .
$ cd ../../
$ kubectl create -f kubefiles/mybootdata-deployment.yml
$ kubectl create -f kubefiles/mybootdata-service.yml
$ kubectl get service/mybootdata -o jsonpath="{.spec.ports[*].nodePort}"
$ QAHOSTPORT=$(minikube --profile 9steps ip):$(kubectl get service/mybootdata -o jsonpath="{.spec.ports[*].nodePort}")
$ curl $QAHOSTPORT/questions
$ cd hellodata/boot_postgres
$ curl -X POST $QAHOSTPORT/questions -d @anotherquestion.json --header "Content-Type: application/json"
$ curl $QAHOSTPORT/questions
pgAdmin Questions
Figure 5. pgAdmin Questions
Browser Questions
Figure 6. Browser Questions

Let’s see if the data sticks around

$ kubectl delete pod -l app=postgres

and after the pod gets recreated, check your /questions endpoint

$ curl $QAHOSTPORT/questions
{"content":[{"createdAt":"2019-10-08T17:41:50.869+0000","updatedAt":"2019-10-08T17:41:50.869+0000","id":1000,"title":"How to walk my dog?","description":"I need to walk my dog on a regular basis, the dog is about 20 pounds and has rather short legs.  She is always eager to go but often I am too busy or distracted.  What are some strategies for insuring the dog gets walked more often?"},{"createdAt":"2019-10-08T21:46:49.825+0000","updatedAt":"2019-10-08T21:46:49.825+0000","id":1051,"title":"How to shave my yak?","description":"My boss has asked for daily TPS reports, how can I convince him this is simply yak shaving?"}],"pageable":{"sort":{"sorted":false,"unsorted":true},"pageSize":20,"pageNumber":0,"offset":0,"paged":true,"unpaged":false},"last":true,"totalPages":1,"totalElements":2,"first":true,"sort":{"sorted":false,"unsorted":true},"numberOfElements":2,"size":20,"number":0}

make sure to restart the port forwarding

$ kubectl port-forward postgres-645fbb48f-hml79 5433:5432

Sharing the in-container data with the host MacOS or Windows

To share the in-VM directory with the host OS

minikube automatically shares /Users with the VM

minikube --profile 11steps ssh
cd /Users

minishift does not automatically share a folder with the VM, so for equivalent functionality

minishift hostfolder add -t sshfs --source /Users --target /Users Users

Note: The Postgres image will not start by default on /Users/ due to permissions problems

1. Admin login details can be found in the kubefiles/postgres-depoloyment.yml