In this minimalistic Java sample we show you how to use a wallet downloaded by the [Oracle Database Operator for Kubernetes](https://github.com/oracle/oracle-database-operator).

An example is also provided to use a wallet downloaded from the Cloud Console.

This microservice can also be used to validate connectivity with the database by looking at its log or issuing http requests.

To configure the database wallet you only need to update [src/main/k8s/app.yaml](src/main/k8s/app.yaml) to use the same secret name that you used to download the wallet with the Operator.

The key part to understand its simplicity is that the deployment file uses the same mount path that the container configures in the oracle.net.wallet_location VM parameter [src/main/docker/Dockerfile](src/main/docker/Dockerfile). You don't need to change this file if you are going to use the example's mount path.

If you want to configure a previously downloaded wallet you can just create the secret (and use the same secret name for the Pod's spec) pointing to the directory where you unzipped the wallet:

kubectl create secret generic instance-wallet --from-file=<path-to-wallets-unzipped-folder>

The Java microservice retrieves username, password and url also from a secret. To create it you can use the following script as an example:

kubectl create secret generic user-jdbc \

--from-literal=user='<username>' \

--from-literal=password='<password>' \

--from-literal=url='jdbc:oracle:thin:@<alias-in-tnsnames.ora>'

It is as simple as to build the maven project, create the docker image and deploy the Pod:

mvn clean install

docker build -t adb-health-check target

kubectl apply -f target/app.yaml

After successsful installation you can validate first connectivity through the Pod's log:

kubectl logs pods/adb-health-check

And you can use the Pod's http listener to validate connectivity (for local tests you can just port forward a local port):

kubectl port-forward adb-health-check 8080:8080 &

curl -X GET http://localhost:8080

<project xmlns="http://maven.apache.org/POM/4.0.0"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">

<modelVersion>4.0.0</modelVersion>

<groupId>adb-health-check</groupId>

<artifactId>adb-health-check</artifactId>

<version>0.0.1-SNAPSHOT</version>

<name>demok8s</name>

<properties>

<package>adb-health-check</package>

<mainClass>com.oracle.healthcheck.Client</mainClass>

<maven.compiler.source>11</maven.compiler.source>

<maven.compiler.target>${maven.compiler.source}</maven.compiler.target>

<libs.classpath.prefix>libs</libs.classpath.prefix>

<copied.libs.dir>${project.build.directory}/${libs.classpath.prefix}</copied.libs.dir>

<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>

<argLine>-Dfile.encoding=UTF-8</argLine>

<checkstyle.config.location>etc/checkstyle.xml</checkstyle.config.location>

</properties>

<build>

<finalName>${project.artifactId}</finalName>

<pluginManagement>

<plugins>

<plugin>

<groupId>org.apache.maven.plugins</groupId>

<artifactId>maven-compiler-plugin</artifactId>

<version>3.8.1</version>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>

<artifactId>maven-surefire-plugin</artifactId>

<version>2.19.1</version>

<dependencies>

<dependency>

<groupId>org.junit.platform</groupId>

<artifactId>junit-platform-surefire-provider</artifactId>

<version>1.1.0</version>

</dependency>

</dependencies>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>

<artifactId>maven-dependency-plugin</artifactId>

<version>3.1.1</version>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>

<artifactId>maven-resources-plugin</artifactId>

<version>3.1.0</version>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>

<artifactId>maven-jar-plugin</artifactId>

<version>3.1.2</version>

<configuration>

<archive>

<manifest>

<addClasspath>true</addClasspath>

<classpathPrefix>${libs.classpath.prefix}</classpathPrefix>

<mainClass>${mainClass}</mainClass>

</manifest>

</archive>

</configuration>

</plugin>

</plugins>

</pluginManagement>

<plugins>

<plugin>

<groupId>org.apache.maven.plugins</groupId>

<artifactId>maven-dependency-plugin</artifactId>

<executions>

<execution>

<id>copy-dependencies</id>

<phase>prepare-package</phase>

<goals>

<goal>copy-dependencies</goal>

</goals>

<configuration>

<outputDirectory>${copied.libs.dir}</outputDirectory>

<overWriteReleases>false</overWriteReleases>

<overWriteSnapshots>false</overWriteSnapshots>

<overWriteIfNewer>true</overWriteIfNewer>

<overWriteIfNewer>true</overWriteIfNewer>

<includeScope>runtime</includeScope>

<excludeScope>test</excludeScope>

</configuration>

</execution>

</executions>

</plugin>

<plugin>

<groupId>org.apache.maven.plugins</groupId>

<artifactId>maven-resources-plugin</artifactId>

<executions>

<execution>

<id>copy-dockerfile</id>

<phase>process-resources</phase>

<goals>

<goal>copy-resources</goal>

</goals>

<configuration>

<outputDirectory>${project.build.directory}</outputDirectory>

<resources>

<resource>

<directory>src/main/docker</directory>

<filtering>true</filtering>

<includes>

<include>Dockerfile</include>

</includes>

</resource>

<resource>

<filtering>true</filtering>

<directory>src/main/k8s</directory>

<includes>

<include>app.yaml</include>

</includes>

</resource>

</resources>

</configuration>

</execution>

</executions>

</plugin>

</plugins>

</build>

<dependencies>

<dependency>

<groupId>com.oracle.database.jdbc</groupId>

<artifactId>ojdbc11</artifactId>

<version>21.3.0.0</version>

</dependency>

<dependency>

<groupId>com.oracle.database.jdbc</groupId>

<artifactId>ucp</artifactId>

<version>21.3.0.0</version>

</dependency>

<dependency>

<groupId>com.oracle.database.ha</groupId>

<artifactId>ons</artifactId>

<version>21.3.0.0</version>

</dependency>

<dependency>

<groupId>com.oracle.database.security</groupId>

<artifactId>oraclepki</artifactId>

<version>21.3.0.0</version>

</dependency>

<dependency>

<groupId>com.oracle.database.security</groupId>

<artifactId>osdt_core</artifactId>

<version>21.3.0.0</version>

</dependency>

<dependency>

<groupId>com.oracle.database.security</groupId>

<artifactId>osdt_cert</artifactId>

<version>21.3.0.0</version>

</dependency>

</dependencies>

</project>

FROM openjdk:11

RUN mkdir /app

COPY libs /app/libs

COPY ${project.artifactId}.jar /app

CMD ["java", \

"-Doracle.net.tns_admin=/app/wallet", \

"-Doracle.net.wallet_location=/app/wallet", \

"-Doracle.jdbc.fanEnabled=false", \

"-jar", \

"/app/${project.artifactId}.jar"]

package com.oracle.healthcheck;

import java.io.IOException;

import java.io.OutputStream;

import java.net.InetSocketAddress;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import javax.net.ssl.HttpsURLConnection;

import com.sun.net.httpserver.HttpServer;

import oracle.jdbc.internal.OracleConnection;

import oracle.jdbc.pool.OracleDataSource;

public class Client {

public static void main(String[] args)

throws SQLException, IOException {

// Retrieve user credentials from environment variables.

// They are set in the Pod from a Secret in src/main/k8s/app.yaml

OracleDataSource ds = new OracleDataSource();

ds.setURL(System.getenv("url"));

ds.setUser(System.getenv("user"));

ds.setPassword(System.getenv("password"));

// Validate and log connection

OracleConnection connection = (OracleConnection) ds.getConnection();

System.out.println("Retrieving connections: " + connection.isValid(0));

System.out

.println("Database version: "

+ connection.getMetaData().getDatabaseMajorVersion() + "."

+ connection.getMetaData().getDatabaseMinorVersion());

// Start an HttpServer listening on port 8080 to send database status.

HttpServer server = HttpServer.create(new InetSocketAddress(8080), 0);

server.createContext("/", (httpExchange) -> {

try (OracleConnection conn = (OracleConnection) ds.getConnection();

Statement stmt = conn.createStatement()) {

// Database message: version and sysdate

ResultSet rs = stmt.executeQuery("select SYSDATE from dual");

rs.next();

String message = "{\"database-version\": \""

+ conn.getMetaData().getDatabaseMajorVersion() + "."

+ conn.getMetaData().getDatabaseMinorVersion()

+ "\", \"database-sysdate\": \"" + rs.getString(1) + "\"}";

System.out.println(message);

// Send message, status and flush

httpExchange

.sendResponseHeaders(HttpsURLConnection.HTTP_OK, message.length());

OutputStream os = httpExchange.getResponseBody();

os.write(message.getBytes());

os.close();

} catch (SQLException e) {

e.printStackTrace();

}

});

server.setExecutor(null);

server.start();

}

}

kind: Pod

apiVersion: v1

metadata:

name: adb-health-check

spec:

volumes:

- name: wallet

secret:

secretName: instance-wallet

containers:

- name: adb-health-check

image: adb-health-check

imagePullPolicy: IfNotPresent

volumeMounts:

- name: wallet

mountPath: "/app/wallet"

readOnly: true

env:

- name: user

valueFrom:

secretKeyRef:

name: user-jdbc

key: user

- name: password

valueFrom:

secretKeyRef:

name: user-jdbc

key: password

- name: url

valueFrom:

secretKeyRef:

name: user-jdbc

key: url