How do I run a command from one Docker container in another?

Question

I've got an application and a database container. I bring them up with Docker Compose. The app container needs to wait until the db container is up and then execute a schema initialization SQL. I need to do it after my wait-for-db script is executed thus it should be executed in the CMD of the app container. The problem is that the db container doesn't contain ssh. How do I run a specific command like

sqlplus system/oracle @schema.sql

from the app container against the db container?

Thank you very much!

UPDATE: maybe, there is a way to execute SQL via HTTP in Oracle 12c?

Answer 1

Your DB container shouldn't need ssh. Your wait-for-it script on the app container can test for availability of the oracle listener port 1521 on the db container before proceeding.

Eg in your docker-compose entry for the app container, assuming that "db" is the name of the db container:

command: "./wait-for-it.sh db:1521 runsql.sh"

where runsql.sh is a script that obtains the necessary oracle environment vars and runs sqlplus.