How do I check if Oracle is up in Docker?

i'm using wnameless/oracle-xe-11g-r2 and this works for me

version: '3'services:   db:      image: wnameless/oracle-xe-11g-r2      environment:      - ORACLE_ALLOW_REMOTE=true      ports:      - 49261:1521      volumes:      - ./0_init.sql:/docker-entrypoint-initdb.d/0_init.sql      healthcheck:         test: [ "CMD", "bash", "-c", "echo 'select 1 from dual;' | ORACLE_HOME=/u01/app/oracle/product/11.2.0/xe /u01/app/oracle/product/11.2.0/xe/bin/sqlplus -s USERNAME/PASSWORD@localhost"]         # docker inspect --format "{{json .State.Health }}"  myproject_db_1         interval: 10s         timeout: 10s         retries: 60   myservice:      image: xxx      depends_on:         db:            condition: service_healthy

You can mimic tnsping in your Java app: How to do oracle TNSPING with java?

If you can't modify the app, tnsping can be called from a bash script - if you have Oracle client installed. If you don't, simply create a simple application from the link above and execute it in a script.

I've finished with a simple check for APEX:

while [[ "$(curl -s -o /dev/null -w ''%{http_code}'' db:8080/apex)" != "302" ]]; do sleep 5; done

302 is used because it redirects /apex to /apex/some_stuff. In my case db is the name of the container with Oracle:

version: '3'services:  ...  * other containers *  ...  db:    image: some/image    ports:      - "8383:8080"      - "1521:1521"

Hope it helps someone!