Config files unable to acess env variable value in Ubuntu

Elastic Stack Logstash
3

Logstash version is 5.1.1

I am setting the environment variables in Ubuntu in /etc/environment like this:

...
DRIVER_CLASS=com.mysql.jdbc.Driver
DB_URL=jdbc:mysql://localhost:3306/mydb
...

I have installed logstash via the.deb file. So I start it using sudo service logstash start command