Enable Support to get DB Username/Password from enivonment variable for jberet.properties

[lokeshnaik808]

Currently if JDBC memory type is used, we need to store the DB username passwort etc. as plain text in jberet.properties file. There is no way to parse environment variables in BatchSEEnvironment file so that plaintext password need to be given in jberet.properties file to avoid security vulnerability.

[liweinan]

@chengfang Do you have any suggestion on this?

[chengfang]

@lokeshnaik808 thanks for raising the issue.

That will be a nice enhancement. I think we can support both the clear text credentials in properties file, and an expression in properties file that can resolve to env variables. And the expression will also support a default value. This gives us something similar to expressions used in WildFly config.

jberet.properties:

db-user = ${DB_USER:admin}
db-password = ${DB_PASSWORD:xxxxx}

If the values are not expression, then we take them as clear text values.

[lokeshnaik808]

I will create a PR soon for this enhacement

[liweinan]

@chengfang I propose a stricter pattern checking to avoid security issues: #394 could you pls review it? Thanks! @lokeshnaik808 wdyt about this solution?

[liweinan]

Add a blog post: jberet/jberet.github.io#8