How to install a certificate in Tomcat and other Java servers

Before you start

• Your server certificate (the leaf certificate), the CA’s intermediate certificate or certificates, and the private key, as PEM files, or a PKCS #12 file that holds all three.
• Tomcat 9, 10.1 or 11 on a supported Java; the attributes below are the same in all three.
• Write access to Tomcat’s conf/server.xml and the right to restart it.

Why it matters: Java servers send the chain you configure, and Java clients do not fetch a missing intermediate, so a short chain breaks every Java, Python and Node.js client that calls your service.

Steps

1. Prepare the files, readable by Tomcat only

Keep the leaf, the chain and the key in separate files; step 2 explains why. On Ubuntu, Tomcat runs as the user tomcat:

sudo mkdir -p /etc/tomcat10/tls
sudo cp www.example.com.crt /etc/tomcat10/tls/cert.pem
sudo cp intermediate.crt    /etc/tomcat10/tls/chain.pem
sudo cp www.example.com.key /etc/tomcat10/tls/privkey.pem
sudo chown root:tomcat /etc/tomcat10/tls/*
sudo chmod 640 /etc/tomcat10/tls/privkey.pem

Unlike nginx and Apache, Tomcat reads the key as its own unprivileged user, so the key must be readable by that user and nobody else.

2. Configure the HTTPS connector with PEM files

Add a connector inside <Service> in server.xml (Tomcat HTTP connector):

<Connector port="8443" protocol="org.apache.coyote.http11.Http11NioProtocol"
           maxThreads="150" SSLEnabled="true">
    <SSLHostConfig hostName="_default_" protocols="TLSv1.2+TLSv1.3">
        <Certificate certificateFile="/etc/tomcat10/tls/cert.pem"
                     certificateChainFile="/etc/tomcat10/tls/chain.pem"
                     certificateKeyFile="/etc/tomcat10/tls/privkey.pem" />
    </SSLHostConfig>
</Connector>

protocols defaults to all, which includes TLS 1.0 and 1.1, so state it. Port 8443 is Tomcat’s convention; for 443, put a load balancer or reverse proxy in front, or give Java permission to bind low ports.

3. Or use a PKCS #12 keystore

A keystore works with Tomcat’s JSSE implementation and with most other Java servers, such as Jetty and WildFly. Build it with the chain included (PFX and PEM; from an old JKS file, see JKS to PKCS #12):

openssl pkcs12 -export -out www.p12 -inkey www.example.com.key -in www.example.com.crt -certfile intermediate.crt -name tomcat

<SSLHostConfig hostName="_default_" protocols="TLSv1.2+TLSv1.3">
    <Certificate certificateKeystoreFile="/etc/tomcat10/tls/www.p12"
                 certificateKeystorePassword="use-a-real-secret"
                 certificateKeystoreType="PKCS12" />
</SSLHostConfig>

The password sits in server.xml, so keep that file readable only by root and Tomcat as well.

4. Restart and read the log

sudo systemctl restart tomcat10
sudo journalctl -u tomcat10 | grep 'Connector \[https'

Our test logged which files each connector loaded (timestamp removed):

Connector [https-openssl-nio-29445], TLS virtual host [_default_], certificate type [UNDEFINED] configured from key [/etc/tomcat10/tls/privkey.pem], certificate [/etc/tomcat10/tls/cert.pem] and certificate chain [/etc/tomcat10/tls/chain.pem] with trust store [null]

The name shows the implementation: https-openssl-nio or https-jsse-nio. Read the log after every change: in our tests Tomcat kept running even when the HTTPS connector failed to start.

5. Spring Boot

Embedded Tomcat in Spring Boot takes PEM files directly (Spring Boot: configure SSL). An SSL bundle can also reload renewed files without a restart (SSL bundles):

server:
  port: 8443
  ssl:
    bundle: "web"
spring:
  ssl:
    bundle:
      pem:
        web:
          reload-on-update: true
          keystore:
            certificate: "file:/etc/myapp/tls/fullchain.pem"
            private-key: "file:/etc/myapp/tls/privkey.pem"

Run the same outside check (below) on Spring Boot: we did not test how its PEM loader handles a full chain in one file.

6. Plan for renewal

Tomcat reads the files at start-up. After a renewal, restart it, or reload only the TLS files with the Manager application’s /manager/text/sslReload?tlsHostName=_default_ command (Manager how-to). With short certificate lifetimes, automate this step.

Check it worked

From another machine if you can:

openssl s_client -connect www.example.com:8443 -servername www.example.com </dev/null 2>/dev/null | grep -E '^ [0-9] s:|Verify return code'

Our test server (private test CA, so we added -CAfile corp-root.crt):

 0 s:CN = intranet.example.com
 1 s:C = BE, O = Example Corp, CN = Example Corp Issuing CA 1
Verify return code: 0 (ok)

Two certificates and code 0. Paste the -showcerts output into the chain checker:

Try it: Chain checkerOpen the full tool

Runs in your browser. Nothing you paste is sent anywhere.

Paste the chain

Try a sampleChoose a sample…A complete chain: leaf, intermediate and rootA server that forgets its intermediateA chain in the wrong orderA self-signed root CA

-----BEGIN CERTIFICATE----- MIIC1zCCAnygAwIBAgIQWTTOzqWiPshGdQhNb6kmNjAKBggqhkjOPQQDAjB+MQsw CQYDVQQGEwJCRTEZMBcGA1UEChMQUEtJIFplcm8gdG8gSGVybzEnMCUGA1UECxMe U2FtcGxlcyAtIG5vdCBwdWJsaWNseSB0cnVzdGVkMSswKQYDVQQDEyJQS0kgWmVy byB0byBIZXJvIFNhbXBsZSBJc3N1aW5nIENBMB4XDTI2MTAwMTAwMDAwMFoXDTM2 MTAwMTAwMDAwMFowGjEYMBYGA1UEAxMPd3d3LmV4YW1wbGUuY29tMFkwEwYHKoZI zj0CAQYIKoZIzj0DAQcDQgAEw4og6Y/SOr+WrqSv+ng7tOBEsc5N3A3yZRk+9hsR XzPQvB9672aHZHTYFNlSY93RWVcTRieE+8XnIbWIYfwxIqOCAT4wggE6MAwGA1Ud EwEB/wQCMAAwDgYDVR0PAQH/BAQDAgeAMBMGA1UdJQQMMAoGCCsGAQUFBwMBMCcG A1UdEQQgMB6CD3d3dy5leGFtcGxlLmNvbYILZXhhbXBsZS5jb20wHQYDVR0OBBYE FALMipe4vcXJTpwO926S15Y/bobzMB8GA1UdIwQYMBaAFN+ph37v40SN23r6Fg/z OvSNjJqeMEgGCCsGAQUFBwEBBDwwOjA4BggrBgEFBQcwAoYsaHR0cDovL3BraS5l eGFtcGxlLmNvbS9zYW1wbGUtaXNzdWluZy1jYS5jcnQwPQYDVR0fBDYwNDAyoDCg LoYsaHR0cDovL3BraS5leGFtcGxlLmNvbS9zYW1wbGUtaXNzdWluZy1jYS5jcmww EwYDVR0gBAwwCjAIBgZngQwBAgEwCgYIKoZIzj0EAwIDSQAwRgIhAM5dJUPhL+qV artvWtQinfnykhVflJTjMXe8M6PnqQfaAiEAhOLGj1hSEkNxQoMrYNXRaIe69nq6 2unibVFSVw1AC80= -----END CERTIFICATE----- -----BEGIN CERTIFICATE----- MIIE2TCCAsGgAwIBAgIQPh9PeiGf4STnEQriHxExjDANBgkqhkiG9w0BAQsFADB7 MQswCQYDVQQGEwJCRTEZMBcGA1UEChMQUEtJIFplcm8gdG8gSGVybzEnMCUGA1UE CxMeU2FtcGxlcyAtIG5vdCBwdWJsaWNseSB0cnVzdGVkMSgwJgYDVQQDEx9QS0kg WmVybyB0byBIZXJvIFNhbXBsZSBSb290IENBMB4XDTI1MDEwMTAwMDAwMFoXDTQw MDEwMTAwMDAwMFowfjELMAkGA1UEBhMCQkUxGTAXBgNVBAoTEFBLSSBaZXJvIHRv IEhlcm8xJzAlBgNVBAsTHlNhbXBsZXMgLSBub3QgcHVibGljbHkgdHJ1c3RlZDEr MCkGA1UEAxMiUEtJIFplcm8gdG8gSGVybyBTYW1wbGUgSXNzdWluZyBDQTBZMBMG ByqGSM49AgEGCCqGSM49AwEHA0IABBFqObJ/j93aHrAuebO5+KWnj0xRFzUS8/Jh Idj6jR/p4zqaNT8+gOqxZ+zhpNO/weIpz/nzXjQ7RJS+EebYRNijggEfMIIBGzAS BgNVHRMBAf8ECDAGAQH/AgEAMA4GA1UdDwEB/wQEAwIBhjAdBgNVHSUEFjAUBggr BgEFBQcDAQYIKwYBBQUHAwIwHQYDVR0OBBYEFN+ph37v40SN23r6Fg/zOvSNjJqe MB8GA1UdIwQYMBaAFIVx1Hy1TuED0pMkxEcdM+DWWPGiMEUGCCsGAQUFBwEBBDkw NzA1BggrBgEFBQcwAoYpaHR0cDovL3BraS5leGFtcGxlLmNvbS9zYW1wbGUtcm9v dC1jYS5jcnQwOgYDVR0fBDMwMTAvoC2gK4YpaHR0cDovL3BraS5leGFtcGxlLmNv bS9zYW1wbGUtcm9vdC1jYS5jcmwwEwYDVR0gBAwwCjAIBgZngQwBAgEwDQYJKoZI hvcNAQELBQADggIBAFa8c1kEzTTPW2aPDRPb3+OQc8GTgwpZV0pWNR3e6X8mJi7A D/RGrz4t354IwGzTts+tX23sY3fORKST3/BkqeHZwAZHvGNWi0+Co342eo2BySxo bcyy31AJBSSHOC2b7KJ11coMX++bvaHgtwOloy6DnHRDYIFwWRHg91wo1MKJGNVb OQH0vmqn6YPDLZ4BYL8VHOVtlRddBwd6bKyyp3Lw0MEMgfmg87Yd/U0yRZFaLKNb b5vgDg7n+J1ozFwvumQlN6WVEyPsQdvI73K5bgMHkUeeUQ6j9KOeDMZMjbqQSC8x 1khcyT/qhqZLDJIHvmWS11FcYaLQUuvQiAzQieTNIuOM8WJw95LlxYSNIkZeOuLf f+JboiuT1cmqmvdbngAXtBIWRJ+Byeqdq2Z0d8Xfln6gWhHmm93+DO5uTaTxBwTr DayFTdTFxBZydXs48S+I/rVQvQtwkRh3rOcZpwTMsGzfoiCsOhEaiBOFk0C5FEKi um55SDXCMR6yXDhWqFPBIdle4izj5g2YmuZ3YD4G3PlcX5okW7aKTNU3RGWEOMk3 Ob9bkPnCsY7Ei4OqDqTBt/8HH/2kA4om4RzKGLw5Zc/Y+KhpbFhT52gtL7WDEEVZ NqFHgi6fdHgsczFNpCKhC8vM+mAM/gBiVR8hYIpt5lPFyXpFJO5Wn5BcEkv3 -----END CERTIFICATE----- -----BEGIN CERTIFICATE----- MIIFxDCCA6ygAwIBAgIQV3/H8mpwNp5raCafwOtSezANBgkqhkiG9w0BAQsFADB7 MQswCQYDVQQGEwJCRTEZMBcGA1UEChMQUEtJIFplcm8gdG8gSGVybzEnMCUGA1UE CxMeU2FtcGxlcyAtIG5vdCBwdWJsaWNseSB0cnVzdGVkMSgwJgYDVQQDEx9QS0kg WmVybyB0byBIZXJvIFNhbXBsZSBSb290IENBMCAXDTI1MDEwMTAwMDAwMFoYDzIw NTAwMTAxMDAwMDAwWjB7MQswCQYDVQQGEwJCRTEZMBcGA1UEChMQUEtJIFplcm8g dG8gSGVybzEnMCUGA1UECxMeU2FtcGxlcyAtIG5vdCBwdWJsaWNseSB0cnVzdGVk MSgwJgYDVQQDEx9QS0kgWmVybyB0byBIZXJvIFNhbXBsZSBSb290IENBMIICIjAN BgkqhkiG9w0BAQEFAAOCAg8AMIICCgKCAgEAnYTGHkYMca54QPkZcZENin3BHB3t uKdHkDZeKZvJHWqpfXpcZfusLvtJFeTrwWlEDBJuV20vmhaLeV29QeYKaIkm1Ul2 qCkrLUpWn/W9CPosfVqMd1nOrd+Ka9iPSeKlW3YX1P5WqQEjieJhBzT9comdj8qN /PynceTDcLa2mgYw7QhU8trBoLzhYqIJFfoUBk+7lahae8b9G5wKCbDicRM8/ATt 0dO9jCxi6RxJpkKl24ULgNOuFP9gG4nubWA8+BaMeM0LU64wNciFofgM2g/3iHHn zmcoe1z80C7WN+GuzNkWkN8D/tcqrbua0O5fREKKw6PyyxwQsjeMghpxLb0h1KeA ihpQMVgpWbhRkkpvF5odkF9vTJP89Z2y+8cgnUMyTpXATrt8KgC5LdWo5mlTNXC/ MvbCUb1Vz9bvcEx2y29tUeLIAUmyBzhF7zgMUPAOtDbLLCuxgR78T2TWaXB/8WBT XL44Wk5rOe7U+KuBr/t12AcZjaq0AGiNsvfd1P+IFbRivElegpdrM+S3arjOjptP M9sUl9Hc+cszaTpEVcQFFxcIyvq5HVjTlZr4vLKdqlhSkQB9hZUFuWNpnUZEYEnA 1vn/GkHNTJ6pv8XxdNXkFeRaUv3ajCn7CQ3UP/EXJqzBw5fl6aa9lqKTS5kF9rgw EIhwNaSd2O557KUCAwEAAaNCMEAwDwYDVR0TAQH/BAUwAwEB/zAOBgNVHQ8BAf8E BAMCAQYwHQYDVR0OBBYEFIVx1Hy1TuED0pMkxEcdM+DWWPGiMA0GCSqGSIb3DQEB CwUAA4ICAQBMdaOOM84aoItvumQ/sNzOhXvmLwboTb3oe67wda9TvPMSf2aP3JtP UWsR/9UbZgNE9M41p2+XZlVpsGP1BLEvi5ZwfMWmR876Mw1Zkt8ouY3DWN08egnm IdV2vKwDHhDE93IQ12fjNc8iuMCasoYiXTsmXx3R/+PkNbeBAupZEk6EwTr75PCY IJ2cheL7jQ06xeCCZv815rG+63jGk3tys7A+nUXKqOp9oN/dkEhi+YWiHG9UJ2w/ BDZCFUUoJBia7C3+hcXZAVxtWwTy0A5T/plEsqGcdfCMFA4cOFstthyS/Wnnuw8y cpSiXdUAQbLkJ+CGavr6MXVmDicmnV9p3Pv9EbpGPV8UlxwvoQMf+ajEE4EAaJkN Gc85wOC7Y7wwWkBnzjiyLztqRqOFdHEdM13V+2Gw2545Jk8o2gRizBQ6Ey6rlt2u YdYFqFFQhe2H+VqvJiLKefkN1mVQhvhfAvuoxZWIsDtyJWGs12L06xMj3wG98kne mUJjPzze3swZU39eiaC1MBs6U0oLZE6ZqubmjJd/ppmGyK+7o2SMi0juouvw6rcA J9eUJQLNpiVKmiwzKvPejASpunK5B5JO3Y7NAb4SVU22ItR73bBiRAugPwVajlBN RGcjMkDSiW07/dhN6GgjsNAzXHcTR7/nbILOAWbhBstNFK1mgejlbQ== -----END CERTIFICATE-----

Every certificate the server sends, leaf first. The output of openssl s_client -showcerts -connect example.com:443 works as it is: we ignore the text around the certificates.

Check the chainClearChoose a file

If something goes wrong

• One certificate is sent; clients report unable to verify the first certificate, unable to get local issuer certificate or, in Java, PKIX path building failed. Move the intermediates to certificateChainFile (step 2), or rebuild the keystore with -certfile (step 3). See build the full chain.
• java.io.IOException: keystore password was incorrect in the log. The certificateKeystorePassword does not match the file.
• java.io.FileNotFoundException: /etc/tomcat10/tls/www.p12 (Permission denied). The Tomcat user cannot read the file (step 1).
• java.net.BindException: Address already in use. Another process holds that port.
• Java clients report Received fatal alert: handshake_failure. No common protocol or cipher, or the connector started without a certificate; read the Tomcat log first.
• The key does not match the certificate. Check them before you restart.

Why this works

Tomcat builds a TLS context per SSLHostConfig from the certificate, chain and key you name, then presents that chain in the TLS handshake and proves it holds the key. The client builds a certificate chain from your leaf through the intermediates to a root in its own trust store. See Certificate chains and path validation, The TLS 1.3 handshake and Certificate file formats.

Go deeper

• Tomcat 10.1: SSL support in the HTTP connector: every SSLHostConfig and Certificate attribute.
• Tomcat SSL/TLS how-to: keystores, PEM files and the two implementations.
• Spring Boot: SSL bundles: PEM bundles and reloading.