Unable to read file keystore and truststore from classpath resources

Question

I am facing an issue while packaging the spring boot application as jar with secrets externalized with application properties.

It is unable to find the keystore/mykeystore.jks and truststore/mytruststore.jks files from the classpath resources in pod deployment.

here is my application properties file which holds the trust store and key store paths.

spring:
  db2:
    datasource:
      driver-class-name: com.ibm.db2.jcc.DB2Driver
      jdbcUrl: ${jdbc_url}
      testWhileIdle: true
      validationQuery: SELECT 1
      keyStore: classpath:keystore/mykeystore.jks
      keyStorePassword: keystorepass
      keyStoreType: JKS
      trustStore: classpath:truststore/mytruststore.jks
      trustStorePassword: truststorepass

Here is my config property bean--

@Component
@ConfigurationProperties(prefix = "spring.db2.datasource")
@Data
@Slf4j
public class SSLConfigProperties {
  
    private  String keyStore;
    private  String keyStorePassword;
    private  String keyStoreType;
    private  String trustStore;
    private  String trustStorePassword;

}

Here is SSLConfig bean: this bean will be loaded during the application startup.

@Slf4j
@RequiredArgsConstructor
public class SSLConfig {
   private final ResourceLoader resourceLoader;
   private final SSLConfigProperties sslConfigProperties;

   @PostConstruct
   private void loadKeyStoreAndTrustStore() throws Exception {
    
       try {
            Resource trustStoreResource = resourceLoader.getResource(sslConfigProperties.getTrustStore());
            //Java 9 approach - not working in local and pod deployment
            //String trustStoreData = new String(trustStoreResource.getInputStream().readAllBytes(), StandardCharsets.UTF_8);

            //Byte array approach -  not working in local and pod deployment
            //byte[] tdataArr = FileCopyUtils.copyToByteArray(trustStoreResource.getInputStream());
            //String trustStoreData = new String(tdataArr, StandardCharsets.UTF_8);
            //Path approach -  working in local and pod deployment
            String trustStoreData = trustStoreResource.getFile().getAbsolutePath();
            log.info("trustStoreResource:: {}", trustStoreResource.getFile().getAbsolutePath());

            System.setProperty("javax.net.ssl.trustStore", trustStoreData);
            //System.setProperty("javax.net.ssl.trustStore", trustStoreResource.getFile().getAbsolutePath());
            System.setProperty("javax.net.ssl.trustStorePassword", sslConfigProperties.getTrustStorePassword());

            Resource keyStoreResource = resourceLoader.getResource(sslConfigProperties.getKeyStore());

            //Java 9 approach-- not working in local and pod deployment
            //String keyStoreData = new String(trustStoreResource.getInputStream().readAllBytes(), StandardCharsets.UTF_8);

            //Byte array approach - not working in local and pod deployment
            //byte[] kDataArr = FileCopyUtils.copyToByteArray(trustStoreResource.getInputStream());
            //String keyStoreData = new String(kDataArr, StandardCharsets.UTF_8);

            //Path approach - working in local but not working deployed environment
            String keyStoreData = keyStoreResource.getFile().getAbsolutePath();
            log.info("keyStoreResource:: {}", keyStoreResource.getFile().getAbsolutePath());

            System.setProperty("javax.net.ssl.keyStoreType", sslConfigProperties.getKeyStoreType());
            //System.setProperty("javax.net.ssl.keyStore", keyStoreResource.getFile().getAbsolutePath());
            System.setProperty("javax.net.ssl.keyStore", keyStoreData);
            System.setProperty("javax.net.ssl.keyStorePassword", sslConfigProperties.getKeyStorePassword());

        }catch (Exception ex) {
            log.info("Error while loading trust and keystore files into System properties.. ",ex);
        }
      
   }
}

Could you please help how to set the keystore and truststore values in System properties. ?