Camunda didn't see db pool from Tomcat context

Question

I have some troubles with running my code in Camunda

Camunda 7.17.0 - run container based on camunda/camunda-bpm-platform:7.17.0

Dockerfile for my custom image

FROM camunda/camunda-bpm-platform:7.17.0

COPY camunda_test_engine.jar /camunda/lib

COPY context.xml /camunda/conf/

ENV JAVA_OPTS="-Xmx4096m -Xms2024m"

JDK - liberica 11.0.22

delegate code

public class getStore implements JavaDelegate{
    @Override
    public void execute(DelegateExecution execution) throws Exception {
        InitialContext ctx = new InitialContext();
        DataSource ds = (DataSource) ctx.lookup("java:/comp/env/jdbc/tstECOM");
        try (Connection connection = ds.getConnection()) {
            try {
                Store Store = new Store(connection);
                Store.getStoreFromECOM();
                Store.getStocksForStore(); 
                Store.getHubForThisStore(); 
                try{
                    ObjectValue typedStoreValue = Variables.objectValue(Store)
                            .serializationDataFormat(SerializationDataFormats.JAVA)
                            .create();
                    execution.setVariable("store", typedStoreValue);
                } catch (Exception e) {
                    e.getMessage();
                }
            } catch (Exception e) {
                throw new BpmnError("cantCreateInstanceOfStore", "can't create Store");
            }
        } catch (SQLException e) {
            throw new BpmnError("cantGetStoreFromECOM", "can't reach to DB");
        }
    }
}

Also I add connection to context.xml in

<Resource name="jdbc/tstECOM" auth="Container" type="javax.sql.DataSource" driverClassName="com.mysql.jdbc.Driver" url="jdbc:mysql://database.org:3306/ecom" username="user" password="password" maxTotal="20" maxIdle="10" maxWaitMillis="-1"/>

after deploy I try to run my process and got that:

org.camunda.bpm.engine.impl.pvm.PvmException: couldn't execute activity <serviceTask id="getStoreFromECOM" ...>: Name [comp/env/jdbc/tstECOM] is not bound in this Context. Unable to find [comp].

I'm newbie in Java & Camunda - maybe I should add resource from context.xml anywhere else?

I tried to add resource to Camunda's web.xml file, but it broke my container after restart