I am using kubernetes for a web application deployement.

  containers:
  - name: myapp
    image: tomcat8-jre8:latest
    imagePullPolicy: Always
    env:     
    - name: DATABASE_HOST
      valueFrom:
        secretKeyRef:
          name: my-secret
          key: external.database.host
    - name: DATABASE_USER
      valueFrom:
        secretKeyRef:
          name: my-secret
          key: external.database.user
    - name: DATABASE_PASSWORD
      valueFrom:
        secretKeyRef:
          name: my-secret
          key: external.database.password

I also use tomcat JNDI with a custom server.xml and catalina.properties

 <Resource factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
            name="jdbc/mysource" 
            auth="Container" 
            type="javax.sql.DataSource" 
            driverClassName="org.postgresql.Driver" 
            url="jdbc:postgresql://******" # secret url
            username="${database.user}"      
            password="${database.password}" />

I tried puting a new property into catalina.properties

### catalina specific configuration
database.user = ${DATABASE_USER}              
database.password = ${DATABASE_PASSWORD}   

server.xml can well read the property but could not resolve the environment variable ${DATABASE_USER} and ${DATABASE_PASSWORD}

Both server.xml and catalina.properties are mounted as config maps, the sensitive information are being held in environment variables. we don't know their values

the environment variable are set when I log into the pod and are recognizable from my webapp (java based) but could not read it from catalina.properties (and/or server.xml)

Can anyone give me a tip on this ? Is it possible to inject environment variables within tomcat configuration ?

Thanks