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OpenC3 COSMOS Using Rootless Podman and Docker-Compose

These directions are for installing and running COSMOS using Podman instead of Docker. If you have Docker available, that is a simpler method.

Podman is an alternative container technology to Docker that is actively promoted by RedHat. The key benefit is that Podman can run without a root-level daemon service, making it significantly more secure by design, over standard Docker. However, it is a little more complicated to use. These directions will get you up and running with Podman. The following directions have been tested against RHEL 8.8, and RHEL 9.2, but should be similar on other operating systems.

NFS does not work for holding container storage due to issues with user ids and group ids. There are workarounds available but they all involve moving container storage to another location: either a different partition on the host local disk, or into a special mounted disk image. See: [] Note that there is also a newish Podman setting that allows you to more easily change where the storage location is in /etc/containers/storage.conf called rootless_storage_path. See

Redhat 8.8 and 9.2 Instructions

  1. Install Prerequisite Packages

    Note: This downloads and installs docker-compose from the latest 2.x release on Github. If your operating system has a docker-compose package, it will be easier to install using that instead. RHEL8 does not have a docker-compose package.

    sudo yum update
    sudo yum install git podman-docker netavark
    curl -SL -o docker-compose
    sudo mv docker-compose /usr/local/bin/docker-compose
    sudo chmod +x /usr/local/bin/docker-compose
    sudo ln -s /usr/local/bin/docker-compose /usr/bin/docker-compose
  2. Configure Host OS for Redis

    sudo su
    echo never > /sys/kernel/mm/transparent_hugepage/enabled
    echo never > /sys/kernel/mm/transparent_hugepage/defrag
    sysctl -w vm.max_map_count=262144
  3. Configure Podman to use Netavark for DNS

    sudo cp /usr/share/containers/containers.conf /etc/containers/.
    sudo vi /etc/containers/containers.conf

    Then edit the network_backend line to be "netavark" instead of "cni"

  4. Start rootless podman socket service

    systemctl enable --now --user podman.socket
  5. Put the following into your .bashrc file (or .bash_profile or whatever)

    export DOCKER_HOST="unix://$XDG_RUNTIME_DIR/podman/podman.sock"
  6. Source the profile file for your current terminal

    source .bashrc
  7. Get COSMOS - A release or the current main branch (main branch shown)

    git clone
  8. Optional - Set Default Container Registry

    If you don't want podman to keep querying you for which registry to use, you can create a $HOME/.config/containers/registries.conf and modify to just have the main docker registry (or modify the /etc/containers/registries.conf file directly)

    mkdir -p $HOME/.config/containers
    cp /etc/containers/registries.conf $HOME/.config/containers/.
    vi $HOME/.config/containers/registries.conf

    Then edit the unqualified-search-registries = line to just have the registry you care about (probably

  9. Edit cosmos/compose.yaml

    cd cosmos
    vi compose.yaml

    Edit compose.yaml and uncomment the user: 0:0 lines and comment the user: "${OPENC3_USER_ID}:${OPENC3_GROUP_ID}" lines. You may also want to update the traefik configuration to allow access from the internet by removing and probably switching to either an SSL config file, or the allow http one. Also make sure your firewall allows whatever port you choose to use in. Rootless podman will need to use a higher numbered port (not 1-1023).

  10. Run COSMOS

    ./ run
  11. Wait until everything is built and running and then goto http://localhost:2900 in your browser

Podman can also be used on MacOS, though we still generally recommend Docker Desktop

MacOS Instructions

  1. Install podman

    brew install podman
  2. Start the podman virtual machine

    podman machine init
    podman machine start
    # Note: update to your username in the next line or copy paste from what 'podman machine start' says
    export DOCKER_HOST='unix:///Users/ryanmelt/.local/share/containers/podman/machine/qemu/podman.sock'
  3. Install docker-compose

    brew install docker-compose # Optional if you already have Docker Desktop
  4. Edit cosmos/compose.yaml

    Edit compose.yaml and uncomment the user: 0:0 lines and comment the user: "${OPENC3_USER_ID}:${OPENC3_GROUP_ID}" lines.

    Important: on MacOS you must also remove all :z from the volume mount lines

    You may also want to update the traefik configuration to allow access from the internet.

  5. Run COSMOS

    cd cosmos
    ./ run