why ELASTIC_APM_ENVIRONMENT not picked up from .env

[nagkumar]

            - ELASTIC_APM_ENVIRONMENT=production
            - ELASTIC_APM_SECRET_TOKEN=${ELASTIC_APM_SECRET_TOKEN}
            - ELASTIC_APM_SERVER_URL=${ELASTIC_APM_SERVER_URL}
            - ELASTIC_APM_SERVICE_NAME=java-favorite-elastic-manual
            - REDIS_HOST=redis
            - TOGGLE_SERVICE_DELAY=${TOGGLE_SERVICE_DELAY:-0}
            - TOGGLE_CANARY_DELAY=${TOGGLE_CANARY_DELAY:-0}
            - TOGGLE_CANARY_FAILURE=${TOGGLE_CANARY_FAILURE:-0}

what is ELASTIC_APM_ENVIRONMENT?

What is the definition of the value production