cstor-dist

This project exposes containers-storage (as used by podman) via the standard OCI distribution spec (also known as a container registry).

The registry is read-only and provides a way to serve local container images over HTTP.

Use Cases

• Enable local virtual machines to fetch content directly from the host's container storage
• Particularly useful with bootc for local development workflows (see below)

Running the Service

While this project can run outside of a container, it currently requires a patched version of skopeo. Therefore, running it as a container is recommended.

A pre-built container image is available for x86_64; see below.

Requirements

Storage Configuration

You must bind mount your host's container storage into /var/lib/containers/storage in the container:

• For rootless podman: ~/.local/share/containers/storage
• For rootful podman: /var/lib/containers/storage

Privileges

The container requires --privileged mode for two reasons:

• Write access to storage for locking (this requirement will be removed in a future update)
• SELinux labeling support

Network Configuration

The service listens on port 8000 by default. You can map this to any desired host port.

Example Usage

Start the registry proxy:

podman run --name regproxy --privileged --rm -d \
    -p 8000:8000 \
    -v ~/.local/share/containers/storage/:/var/lib/containers/storage \
    ghcr.io/cgwalters/cstor-dist:latest

Using the Registry

Important: By default, the server does not use TLS. You can globally configure container tools (skopeo, podman, bootc) to automatically fall back to plain http via configuring registries.conf:

Here's an example shell command to configure things for a development virtual machine where the gateway is hosting the cstor-dist service:

$
cat >/etc/containers/registries.conf.d/10-local-insecure.conf <<EOF
[[registry]]
location="$(ip -j route | jq -r '.[0].gateway'):8000"
insecure=true
EOF

For example when using qemu with user networking, the host IP address is commonly 10.0.2.2. You can find the host gateway via the route command.

Building from Source

1. Clone the repository:

git clone https://github.com/cgwalters/cstor-dist.git
cd cstor-dist

2. Build using podman or docker:

podman build -t cstor-dist .

Integration with bootc

Overview

While containers are typically run on the same machine where they're built when using podman/docker, bootc is commonly used in a distributed setup where you build on one machine and test on another.

This project works particularly well with Anaconda on Linux host systems. You'll just need to point your ostreecontainer at the cstor-dist endpoint.

Efficient Development Workflow

This enables a quicker iteration workflow:

1. Build containers in your regular unprivileged podman storage
2. Use bootc upgrade to efficiently deploy changes without data transfer overhead