Hi all, Currently I have a Flink 1.4 cluster running on kubernetes and with SSL configuration based on https://ci.apache.org/projects/flink/flink-docs- master/ops/security-ssl.html.
However, as the IP of the nodes are dynamic (from the nature of kubernetes), we are using only the DNS which we can control using kubernetes services. So we add to the Subject Alternative Name(SAN) the flink-jobmanager DNS and also the DNS for the task managers *.flink-taskmanager-svc (each task manager has a DNS in the form flink-taskmanager-0.flink-taskmanager-svc). Additionally we set the jobmanager.rpc.address property on all the nodes and each task manager sets the taskmanager.host property, all matching the ones on the certificate. This is working well when using Job with Parallelism set to 1. The SSL validations are good and the Jobmanager can communicate with Task manager and vice versa. But when we set the parallelism to more than 1 we have exceptions on the SSL validation like this: Caused by: java.security.cert.CertificateException: No subject alternative names matching IP address 172.30.247.163 found at sun.security.util.HostnameChecker.matchIP(HostnameChecker.java:168) at sun.security.util.HostnameChecker.match(HostnameChecker.java:94) at sun.security.ssl.X509TrustManagerImpl.checkIdentity( X509TrustManagerImpl.java:455) at sun.security.ssl.X509TrustManagerImpl.checkIdentity( X509TrustManagerImpl.java:436) at sun.security.ssl.X509TrustManagerImpl.checkTrusted( X509TrustManagerImpl.java:252) at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted( X509TrustManagerImpl.java:136) at sun.security.ssl.ClientHandshaker.serverCertificate( ClientHandshaker.java:1601) ... 21 more >From the logs I see the Jobmanager is correctly registering the taskmanagers: org.apache.flink.runtime.instance.InstanceManager - Registered TaskManager at flink-taskmanager-1 (akka.ssl.tcp://flink@taiga- flink-taskmanager-1.flink-taskmanager-svc.default.svc. cluster.local:6122/user/taskmanager) as 1a3f59693cec8b3929ed8898edcc2700. Current number of registered hosts is 3. Current number of alive task slots is 6. And also each taskmanager is correctly registered to use the hostname for communication: org.apache.flink.runtime.taskmanager.TaskManager - TaskManager will use hostname/address 'flink-taskmanager-1.flink-taskmanager-svc.default.svc.cluster.local' (172.30.247.163) for communication. ... akka.remote.Remoting - Remoting started; listening on addresses :[akka.ssl.tcp://flink@flink-taskmanager-1.flink- taskmanager-svc.default.svc.cluster.local:6122] ... org.apache.flink.runtime.io.network.netty.NettyConfig - NettyConfig [server address: flink-taskmanager-1.flink-taskmanager-svc.default.svc. cluster.local/172.30.247.163, server port: 6121, ssl enabled: true, memory segment size (bytes): 32768, transport type: NIO, number of server threads: 2 (manual), number of client threads: 2 (manual), server connect backlog: 0 (use Netty's default), client connect timeout (sec): 120, send/receive buffer size (bytes): 0 (use Netty's default)] ... org.apache.flink.runtime.taskmanager.TaskManager - TaskManager data connection information: bf4a9b50e57c99c17049adb66d65f685 @ flink-taskmanager-1.flink-taskmanager-svc.default.svc.cluster.local (dataPort=6121) But even with that, it seems like the taskmanagers are using the IP communicate between them and the SSL validation fails. Do you know if it's possible to make the taskmanagers to use the hostname to communicate instead of the IP ? or Do you have any advice to get the SSL configuration to work on this environment ? Thanks in advance. Regards, Edward
