I'm using Spring Boot 2.7.3 and would like to use the following, recently introduced, properties for specifying TLS keys in PEM format:

server.ssl.enabled=true
server.ssl.certificate=classpath:tls.crt
server.ssl.certificate-private-key=classpath:tls.key

This works for RSA keys but not for ECDSA keys. The issue can be reproduced with the following tls.crt and tls.key files:

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

-----BEGIN EC PRIVATE KEY-----
MHcCAQEEIFlNVej0A5XWAR3PjOvwyQrYYwYgwrYy6wRk5Myk0DFtoAoGCCqGSM49
AwEHoUQDQgAEscyFplNscAIeHo78ldXLOAa7NE/Iv+rwcaidetXi52UocD3nPmaj
eYWUjqI2dJcCgRsJNkqFSv8vdPfKiOpxrw==
-----END EC PRIVATE KEY-----

I'm getting the following exception:

Caused by: java.lang.IllegalStateException: Unrecognized private key format in classpath:tls.key
        at org.springframework.boot.web.server.PrivateKeyParser.parse(PrivateKeyParser.java:79) ~[spring-boot-2.7.4.jar:2.7.4]
        at org.springframework.boot.web.server.CertificateFileSslStoreProvider.createKeyStore(CertificateFileSslStoreProvider.java:83) ~[spring-boot-2.7.4.jar:2.7.4]
        at org.springframework.boot.web.server.CertificateFileSslStoreProvider.getKeyStore(CertificateFileSslStoreProvider.java:51) ~[spring-boot-2.7.4.jar:2.7.4]
        at org.springframework.boot.web.embedded.tomcat.SslConnectorCustomizer.configureSslStoreProvider(SslConnectorCustomizer.java:129) ~[spring-boot-2.7.4.jar:2.7.4]
        ... 15 common frames omitted

The problem seems to lie in the patterns used by the PrivateKeyParser which supports "RSA" in the header/footer but not "EC".

Comment From: scottfrederick

Certificate and private key files can also be used to configure the connection to the Docker daemon when using the Maven spring-boot:build-image goal and Gradle bootBuildImage task. We've added support for ECDSA keys to the Docker configuration in Spring Boot 2.6, in addition to supporting ECDSA keys with server.ssl.certificate-private-key and server.ssl.trust-certificate-private-key in Spring Boot 2.7.