Port Forwarding

CodeForge runs inside a Docker container. When a service inside the container listens on a port (e.g., a dev server on port 3000 or the Claude Dashboard on port 7847), you need a forwarding mechanism to access it from your host machine. Which mechanism to use depends on your DevContainer client.

Mechanisms

Mechanism	Client	Discovery	Setup Required
VS Code auto-detect	VS Code only	Dynamic — all ports	None
devcontainer-bridge (dbr)	Any terminal client	Dynamic — polls /proc/net/tcp	Host daemon required
SSH tunneling	Any SSH client	Manual	Per-port command

VS Code Auto-Detect

VS Code automatically detects ports opened inside the container and forwards them to your host. CodeForge configures this in devcontainer.json:

• All ports are auto-forwarded with a notification prompt
• Port 7847 (Claude Dashboard) gets a friendly label in the Ports panel

No setup required — ports appear in the VS Code Ports panel as services start. Click the local address to open in your browser.

Requires VS Code to be running

Port forwarding only works while VS Code is open and connected to the devcontainer. If you close VS Code or disconnect, all forwarded ports become inaccessible. For persistent port forwarding that doesn’t depend on your editor, use devcontainer-bridge.

Note

This only works inside VS Code and GitHub Codespaces. The devcontainer CLI, JetBrains Gateway, and DevPod ignore portsAttributes in devcontainer.json.

devcontainer-bridge (dbr)

devcontainer-bridge provides dynamic port forwarding for any terminal-based workflow. It works with the DevContainer CLI, SSH connections, or any other way you access the container.

How It Works

1. A lightweight daemon inside the container polls /proc/net/tcp to discover listening ports
2. A host-side daemon maintains SSH tunnels for each discovered port
3. Ports are forwarded automatically as services start and stop — no manual configuration

The container daemon auto-starts when the container boots and is inert (zero overhead) until the host daemon connects.

Setup

Inside the container — already done. CodeForge installs dbr as a DevContainer feature.

On your host machine, install and start the host daemon:

# Install dbr on your host (see https://github.com/bradleybeddoes/devcontainer-bridge/releases)
# Then start the host daemon:
dbr host-daemon

The host daemon discovers running containers and establishes port forwarding automatically. Leave it running in the background while you work.

Verify

Once the host daemon is running, any port opened inside the container becomes accessible on localhost on your host. Test with:

# Inside the container
python -m http.server 8080

# On your host
curl http://localhost:8080

Platform Support

Platform	Host Daemon	Auto-Forward	Status
macOS	Supported	Expected to work	Not fully confirmed
Linux	Supported	Expected to work	Not fully confirmed
Windows	Not yet supported	—	Future fix planned

Note

devcontainer-bridge auto-forwarding on macOS and Linux has not been fully validated across all configurations. If you encounter issues, fall back to SSH tunneling and report the issue. Windows host daemon support is planned for a future release.

SSH Tunneling

For one-off port forwarding or environments where dbr isn’t available, use SSH tunneling directly:

# Forward a single port
ssh -L 3000:localhost:3000 <container-user>@<container-host>

# Forward multiple ports
ssh -L 3000:localhost:3000 -L 7847:localhost:7847 <container-user>@<container-host>

This requires SSH access to the container, which is available when connecting via the devcontainer CLI or any Docker SSH setup.

Which Should I Use?

If you use…	Recommended mechanism
VS Code	Auto-detect (built-in, zero config)
DevContainer CLI	dbr (dynamic, automatic) — see the CLI guide
JetBrains Gateway	Gateway’s built-in forwarding, or dbr as fallback
Codespaces	Auto-detect (built-in to Codespaces)
DevPod	DevPod’s built-in SSH tunneling, or dbr
Direct SSH	SSH tunneling for specific ports, or dbr for all ports

Configuration

Port forwarding behavior is configured in .devcontainer/devcontainer.json:

"forwardPorts": [],
"portsAttributes": {
    "7847": {
        "label": "Claude Dashboard",
        "onAutoForward": "notify"
    },
    "*": {
        "onAutoForward": "notify"
    }
}

• forwardPorts — static port list (empty by default; VS Code auto-detects dynamically instead)
• portsAttributes — labels and behavior for auto-detected ports (VS Code / Codespaces only)

These settings are ignored by non-VS Code clients. Use dbr or SSH tunneling instead.