Add support for truststore and keystore password parameters in Kafdrop

[wkd-woo]

Description

This PR introduces support for specifying passwords for the truststore and keystore used in SSL communication with Kafka brokers in Kafdrop.

Previously, while the truststore file location could be specified using the KAFKA_TRUSTSTORE_FILE parameter, there was no way to provide the password required to access it.

This enhancement addresses that limitation.

refer: https://docs.oracle.com/javadb/10.8.3.0/adminguide/cadminsslclient.html

Key changes include

1. New Configuration Parameters

• Added KAFKA_TRUSTSTORE_PASSWORD to specify the truststore password.
• Added KAFKA_KEYSTORE_PASSWORD to specify the keystore password.

2. Code Changes

• Modified KafkaConfiguration.java to handle these new parameters and set ssl.truststore.password and ssl.keystore.password in the Kafka properties if provided.
• Ensured that these parameters are optional, maintaining backward compatibility for users who do not require truststore or keystore passwords.

3. Configuration File Updates

• Updated application.yml to include placeholders for the new parameters, making them configurable via environment variables:
  • KAFKA_TRUSTSTORE_PASSWORD
  • KAFKA_KEYSTORE_PASSWORD

[Bert-R]

I do not understand the objective of this PR. As mentioned in the README, you can use kafka.properties for configuration information "including key/truststore passwords".

What do you want to add to that?

[wkd-woo]

@Bert-R
As mentioned in the README, I have already tried specifying truststore.password in kafka.properties, but Kafdrop still couldn't connect to our TLS-enabled Kafka brokers. This issue persisted even though the kafka.properties file was correctly mounted as a volume.

Additionally, in the company I work for, security policies prohibit storing passwords in configuration files like properties. (Honestly, I find this requirement quite perplexing myself.) However, storing passwords in objects such as Kubernetes Secrets is allowed.

This is why I created this PR. I believe that passwords required for certificate access should also be managed as separate parameters.

[Bert-R]

In that case, I suggest a much simpler implementation. We already support SSL_KEY_STORE_PASSWORD. If you search for that string, you'll find two occurrences:

• kafdrop/README.md

  Line 338 in 87c6f77

  | `SSL_KEY_STORE_PASSWORD` | Keystore password

• kafdrop/src/main/resources/application.yml

  Line 12 in 87c6f77

  key-store-password: ${SSL_KEY_STORE_PASSWORD:}

If you copy these lines and adapt them for the trust store, you're all set.