/dev/tcp is bash-specific
This seems to be not present on the /dev filesystem but to implemented by the bash interpreter. Executing in docker-compose with /bin/sh
failed (it is symlinked to /bin/dash
in the image).
In fact, this script is executed with /bin/bash
in this configuration:
https://gitlab.coko.foundation/yld/xpub-deployment-config-postgres/blob/master/templates/xpub-collabra-deployment.yaml#L49