Port forwarding lets developers securely access processes on their Coder workspace from a local machine. A common use case is testing web applications in a browser.
There are multiple ways to forward ports in Coder:
Method Details Coder Desktop Uses a VPN tunnel to your workspaces and provides access to all running ports. Supports peer-to-peer connections for the best performance.coder port-forward
command Can be used to forward specific TCP or UDP ports from the remote workspace so they can be accessed locally. Supports peer-to-peer connections for the best performance. Dashboard Proxies traffic through the Coder control plane. SSH Forwards ports over an SSH connection. Coder Desktop
Coder Desktop provides seamless access to your remote workspaces, eliminating the need to install a CLI or manually configure port forwarding. Access all your ports at <workspace-name>.coder:PORT
.
coder port-forward
command
This command can be used to forward TCP or UDP ports from the remote workspace so they can be accessed locally. Both the TCP and UDP command line flags (--tcp
and --udp
) can be given once or multiple times.
The supported syntax variations for the --tcp
and --udp
flag are:
local_port[:remote_port]
local_port1,local_port2
start_port-end_port
Forward the remote TCP port 8080
to local port 8000
:
coder port-forward myworkspace --tcp 8000:8080
Forward the remote TCP port 3000
and all ports from 9990
to 9999
to their respective local ports.
coder port-forward myworkspace --tcp 3000,9990-9999
For more examples, see coder port-forward --help
.
To enable port forwarding via the dashboard, Coder must be configured with a wildcard access URL. If an access URL is not specified, Coder will create a publicly accessible URL to reverse proxy the deployment, and port forwarding will work.
There is a DNS limitation where each segment of hostnames must not exceed 63 characters. If your app name, agent name, workspace name and username exceed 63 characters in the hostname, port forwarding via the dashboard will not work.
From a coder_app resourceOne way to port forward is to configure a coder_app
resource in the workspace's template. This approach shows a visual application icon in the dashboard. See the following coder_app
example for a Node React app and note the subdomain
and share
settings:
# node app resource "coder_app" "node-react-app" { agent_id = coder_agent.dev.id slug = "node-react-app" icon = "https://upload.wikimedia.org/wikipedia/commons/a/a7/React-icon.svg" url = "http://localhost:3000" subdomain = true share = "authenticated" healthcheck { url = "http://localhost:3000/healthz" interval = 10 threshold = 30 } }
Valid share
values include owner
- private to the user, authenticated
- accessible by any user authenticated to the Coder deployment, and public
- accessible by users outside of the Coder deployment.
Another way to port forward in the dashboard is to use the "Open Ports" button to specify an arbitrary port. Coder will also detect if apps inside the workspace are listening on ports, and list them below the port input (this is only supported on Windows and Linux workspace agents).
Sharing portsYou can share ports as URLs, either with other authenticated coder users or publicly. Using the open ports interface, you can assign a sharing levels that match our coder_app
’s share option in Coder terraform provider.
owner
(Default): The implicit sharing level for all listening ports, only visible to the workspace ownerorganization
: Accessible by authenticated users in the same organization as the workspace.authenticated
: Accessible by other authenticated Coder users on the same deployment.public
: Accessible by any user with the associated URL.Once a port is shared at either authenticated
or public
levels, it will stay pinned in the open ports UI for better visibility regardless of whether or not it is still accessible.
Note
The sharing level is limited by the maximum level enforced in the template settings in licensed deployments, and not restricted in OSS deployments.
This can also be used to change the sharing level of port-based coder_app
s by entering their port number in the sharable ports UI. The share
attribute on coder_app
resource uses a different method of authentication and is not impacted by the template's maximum sharing level, nor the level of a shared port that points to the app.
Both listening and shared ports can be configured to use either HTTP
or HTTPS
to connect to the port. For listening ports the protocol selector applies to any port you input or select from the menu. Shared ports have protocol configuration for each shared port individually.
You can also access any port on the workspace and can configure the port protocol manually by appending a s
to the port in the URL.
# Uses HTTP https://33295--agent--workspace--user--apps.example.com/ # Uses HTTPS https://33295s--agent--workspace--user--apps.example.com/
First, configure SSH on your local machine. Then, use ssh
to forward like so:
ssh -L 8080:localhost:8000 coder.myworkspace
You can read more on SSH port forwarding here.
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