Docker Hoster

A lightweight tool for dynamically injecting DNS entries into the host's /etc/hosts file to resolve names of local Docker containers.

Docker Hoster runs as a Docker container itself, monitoring Docker events to automatically add or remove host entries for running containers. This enables seamless name resolution without manual configuration.

Quick Start

Run Docker Hoster with the following command:

docker run -d \
    --name docker-hoster \
    -v /var/run/docker.sock:/tmp/docker.sock \
    -v /etc/hosts:/tmp/hosts \
    ghcr.io/mrmohebi/docker-hoster:latest

• The /var/run/docker.sock volume allows Hoster to access Docker events and container metadata.
• The /etc/hosts volume (mounted to /tmp/hosts inside the container) enables Hoster to update the host's DNS resolution file.

Hoster will insert one entry per container IP, updating the file in real-time as containers start, stop, or are renamed.

How It Works

• Event Listening: Hoster connects to the Docker daemon via the socket and listens for container events (e.g., start, stop, die, destroy, rename).
• Hosts File Management: Entries are added in a dedicated section of /etc/hosts (marked by #-----------Docker-Hoster-Domains---------- and #-----Do-not-add-hosts-after-this-line-----). This section is safely updated or cleared without affecting other content.
• Supported Docker Versions: Compatible with recent Docker releases (tested up to Docker 29).
• Built With: Python 3.14 and the Docker SDK.

Container Registration

By default, Hoster registers the following domains for each container:

• Container name (e.g., --name mycontainer)
• Hostname (e.g., --hostname myhostname or with domain if specified)
• Container ID (shortened)
• Network aliases (e.g., --network-alias myserver.com)

For example, running:

docker run -d \
    --name mycontainer \
    --hostname myhostname \
    --network somenetwork --network-alias "myserver.com" \
    alpine

Would make the container resolvable as mycontainer, myhostname, its ID (e.g., abc123def456), and myserver.com.

Custom Domains via Labels

Add extra domains using the hoster.domains label with comma-separated values:

docker run -d \
    --name mycontainer \
    -l hoster.domains="example.com,api.example.com" \
    alpine

These will be appended to all default domains for broader resolution.

Contributions

Contributions are welcome! Feel free to submit issues or pull requests on the GitHub repository. The project includes GitHub Actions for automated image builds and publishing to GHCR on releases.