Spring Boot: SSL/HTTPS for embedded Tomcat

If your Spring Boot app is running on embedded Tomcat, you need to use the TomcatConnectionCustomizer class to set up the HTTPS in Tomcat.

Get the source code

Source Code for this tutorial is available on my github under the SpringBootHttps tag: https://github.com/yacekmm/looksok/tree/SpringBootHttps

1. Prepare keystore and certificate

First you need to have your certificate. If you already have it, go to point 2., else, follow the step 1 and 2 from this tutorial: https://looksok.wordpress.com/2014/11/16/configure-sslhttps-on-tomcat-with-self-signed-certificate/

2. Put your keystore in defined location

You need to locate your keystore file in path on your machine. On my machine this is:

D:\keystore\server.p12

This path I will use in my app configuration.

3. Customize Tomcat Connection

Create class implementing the TomcatConnectorCustomizer, and override its customize(Connection) method. As you can see, in customize() I set exactly the same properties as in stantalone Tomcat xml configuration (see this post). Note that in class constructor I convert the alias string to lowercase – in keystore only these are allowed.

public class MyTomcatConnectionCustomizer implements TomcatConnectorCustomizer {

  private String absoluteKeystoreFile;
  private String keystorePassword;
  private String keystoreType;
  private String keystoreAlias;

  public MyTomcatConnectionCustomizer(String absoluteKeystoreFile,
      String keystorePassword, String keystoreType, String keystoreAlias) {
    this.absoluteKeystoreFile = absoluteKeystoreFile;
    this.keystorePassword = keystorePassword;
    this.keystoreType = keystoreType;
    this.keystoreAlias = keystoreAlias.toLowerCase();

  }

  @Override
  public void customize(Connector connector) {
    connector.setPort(443);
    connector.setSecure(true);
    connector.setScheme("https");
    
    connector.setAttribute("SSLEnabled", true);
        connector.setAttribute("sslProtocol", "TLS");
        connector.setAttribute("protocol", "org.apache.coyote.http11.Http11Protocol");
        connector.setAttribute("clientAuth", false);
        connector.setAttribute("keystoreFile", absoluteKeystoreFile);
        connector.setAttribute("keystoreType", keystoreType);
        connector.setAttribute("keystorePass", keystorePassword);
        connector.setAttribute("keystoreAlias", keystoreAlias);
        connector.setAttribute("keyPass", keystorePassword);
  }
}

4. Create containerCustomizer Bean

Now to use the TomcatConnectionCustomizer, create the bean as follows:

@Bean
public EmbeddedServletContainerCustomizer containerCustomizer() throws FileNotFoundException {

  final String absoluteKeystoreFile = ResourceUtils.getFile("D:\\keystore\\server.p12").getAbsolutePath();

  final TomcatConnectorCustomizer customizer = new MyTomcatConnectionCustomizer(
      absoluteKeystoreFile, "keyPwd", "PKCS12", "keyalias"); 

  return new EmbeddedServletContainerCustomizer() {

    @Override
    public void customize(ConfigurableEmbeddedServletContainer container) {
      if(container instanceof TomcatEmbeddedServletContainerFactory) {
        TomcatEmbeddedServletContainerFactory containerFactory = (TomcatEmbeddedServletContainerFactory) container;
        containerFactory.addConnectorCustomizers(customizer);
      }
    };
  };
}

5. Test it

Start Spring Boot App and go to the:

https:\\127.0.0.1

Your browser will propably warn you about the untrusted certificate:

Note: Don’t use Self_signed certificates in production! Use it only in test / dev environment

Get the source code

Source Code for this tutorial is available on my github under the SpringBootHttps tag: https://github.com/yacekmm/looksok/tree/SpringBootHttps

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