What is this

If you have ever tried getting Let’s Encrypt certificate for Spring Boot application, you know that it is painful as it involves using either CertBot or Docker-sidecar/Cron-job to manage certificate lifecycle. This library solves these problems by managing certificate lifecycle directly in Java code with the help of awesome Acme4j library.

Key features:

  1. Obtain Let’s Encrypt certificate on fresh start
  2. Store generated keys and certificate into single KeyStore (server.ssl.keystore)
  3. Renew Let’s Encrypt certificate (it watches for certificate expiration date and updates it to new before old is expired)
  4. No JVM restart needed when certificate gets updated

Application requirements

To perform HTTP-01 ACME (Automatic Certificate Management Environment) challenge, the application must listen on port 80, this library will automatically create Tomcat connector to this port, so the only thing needed on your side is to open 80 port for the application.

Servlet containers supported (embedded)

Usage

From JitPack maven repository

1. Import this library:

For Tomcat:

Gradle:
 allprojects {
     repositories {
         ...
         maven { url 'https://jitpack.io' }
     }
 }

dependencies {
   implementation 'com.github.valb3r.letsencrypt-helper:letsencrypt-helper-tomcat:0.2.4'
}
Maven:
<repositories>
     <repository>
         <id>jitpack.io</id>
         <url>https://jitpack.io</url>
     </repository>
 </repositories>

<dependencies>
   <dependency>
      <groupId>com.github.valb3r.letsencrypt-helper</groupId>
      <artifactId>letsencrypt-helper-tomcat</artifactId>
      <version>0.2.4</version>
   </dependency>
</dependencies>

For Jetty:

Gradle:
 allprojects {
     repositories {
         ...
         maven { url 'https://jitpack.io' }
     }
 }

dependencies {
   implementation 'com.github.valb3r.letsencrypt-helper:letsencrypt-helper-jetty:0.2.4'
}
Maven:
<repositories>
     <repository>
         <id>jitpack.io</id>
         <url>https://jitpack.io</url>
     </repository>
 </repositories>

<dependencies>
   <dependency>
      <groupId>com.github.valb3r.letsencrypt-helper</groupId>
      <artifactId>letsencrypt-helper-jetty</artifactId>
      <version>0.2.4</version>
   </dependency>
</dependencies>

2. Declare on your configuration

Tomcat:

@Import(TomcatWellKnownLetsEncryptChallengeEndpointConfig.class)

Jetty:

@Import(JettyWellKnownLetsEncryptChallengeEndpointConfig.class)

3. Define following properties in your application configuration or environment:

  1. lets-encrypt-helper.domain the domain to issue certificate for
  2. lets-encrypt-helper.contact your contact for Let’s Encrypt (i.e. your email in format mailto:john.doe@example.com)

4. Configure SSL as usual for Tomcat+TLS using server.ssl.keystore for certificate and keys storage

Configuration

Property Description Default value, if any
server.ssl.key-store Path to the KeyStore, where Let’s Encrypt certificates and account key are to be stored (or are already there)  
server.ssl.key-store KeyStore type (i.e. PKCS12)  
server.ssl.key-store-pasword Password for KeyStore with Let’s Encrypt certificate and account key  
server.ssl.key-alias Let’s Encrypt certificate key alias in the keystore  
server.port Port (secure SSL/TLS) on which your application is deployed  
lets-encrypt-helper.domain Your applications’ domain (i.e. example.com)  
lets-encrypt-helper.contact The contact of person responsible for the domain (i.e. mailto:john@example.com)  
lets-encrypt-helper.account-key-alias Account key alias letsencrypt-user
lets-encrypt-helper.letsencrypt-server Let’s Encrypt server to use acme://letsencrypt.org
lets-encrypt-helper.key-size Certificate and Account key RSA key size 2048
lets-encrypt-helper.update-before-expiry Start trying to update certficate this time before expiration P7D (7 days)
lets-encrypt-helper.busy-wait-interval Busy wait interval for thread that checks if the certificate is valid PT1M (1 minute)
lets-encrypt-helper.account-cert-validity Validity duration for Account key P3650D (3650 days)
lets-encrypt-helper.enabled Is the helper enabled true
lets-encrypt-helper.development-only.http01-challenge-port For development only, port for HTTP-01 ACME challenge 80

Example configuration

Launch your application with -Dspring.profiles.active=ssl

application-ssl.yaml:

server:
  port: 443
  ssl:
    key-store: file:/home/user/letsencrypt/application-keystore # Path to KeyStore with certificates and keys
    key-store-password: change-me # Password for KeyStore protection
    key-store-type: PKCS12
    key-alias: tomcat # Certificate name in KeyStore
    enabled: true # Important to place this explicitly
lets-encrypt-helper:
  domain: my-domain.example.com # Domain to issue certificate for
  contact: mailto:john.doe@mymail.example.com # Your contact for Let's Encrypt

Note: On your server ensure you have opened port 80 for Java (i.e. in Firewall) and Java can bind to it (i.e. follow Linux allow listening to low port without sudo to open ports 80,443 for java)

Example project with SSL and Let’s Encrypt management using this library for Tomcat is located here

Alternative

The library is itself just 1 Java class. You can add library dependencies and:

Testing locally

The library has integration tests in:

directories. One can adapt these tests according to own needs, as they use Pebble - LetsEncrypt testing server.