Using Podman instead of Docker

Iceberg-rust does not require containerization, except for integration tests, where “docker” and “docker-compose” are used to start containers for minio and various catalogs. Below instructions setup “rootful podman” and docker's official docker-compose plugin to run integration tests as an alternative to docker or Orbstack.

1. Have podman v4 or newer.

   $ podman --version
   podman version 4.9.4-rhel
   

2. Create a docker wrapper script:

• Create a fresh /usr/bin/docker file and add the below contents:

  #!/bin/sh
  [ -e /etc/containers/nodocker ] || \
  echo "Emulate Docker CLI using podman. Create /etc/containers/nodocker to quiet msg." >&2
  exec sudo /usr/bin/podman "$@"
  

• Set new /usr/bin/docker file to executable.

  sudo chmod +x /usr/bin/docker
  

3. Install the docker compose plugin. Check for successful installation.

   $ docker compose version
   Docker Compose version v2.28.1
   

4. Append the below to ~/.bashrc or equivalent shell config:

   export DOCKER_HOST=unix:///run/podman/podman.sock
   

5. Start the “rootful” podman socket.

   sudo systemctl start podman.socket
   sudo systemctl status podman.socket
   

6. Check that the following symlink exists.

   $ ls -al /var/run/docker.sock
   lrwxrwxrwx 1 root root 27 Jul 24 12:18 /var/run/docker.sock -> /var/run/podman/podman.sock
   

   If the symlink does not exist, create it.

   sudo ln -s /var/run/podman/podman.sock /var/run/docker.sock
   

7. Check that the docker socket is working.

   sudo curl -H "Content-Type: application/json" --unix-socket /var/run/docker.sock http://localhost/_ping
   

8. Try some integration tests!

   cargo test -p iceberg --test file_io_s3_test
   

References

• https://docs.docker.com/compose/install/linux
• https://www.redhat.com/sysadmin/podman-docker-compose

Note on rootless containers

As of podman v4, “To be succinct and simple, when running rootless containers, the container itself does not have an IP address” This causes issues with iceberg-rust's integration tests, which rely upon ip-addressable containers via docker-compose. As a result, podman “rootful” containers are required throughout to ensure containers have IP addresses. Perhaps as a future work or with updates to default podman networking, the need for “rootful” podman containers can be eliminated.

• https://www.redhat.com/sysadmin/container-ip-address-podman
• https://github.com/containers/podman/blob/main/docs/tutorials/basic_networking.md

Debugging Note:

• Fix for error: Error: short-name "apache/iceberg-rest-fixture" did not resolve to an alias and no unqualified-search registries are defined in "/etc/containers/registries.conf"
  • Add or modify the /etc/containers/registries.conf file:

  [[registry]]
  prefix = "docker.io"
  location = "docker.io"