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Networking

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Coder's network topology has three types of nodes: workspaces, coder servers, and users.

The coder server must have an inbound address reachable by users and workspaces, but otherwise, all topologies just work with Coder.

When possible, we establish direct connections between users and workspaces. Direct connections are as fast as connecting to the workspace outside of Coder. When NAT traversal fails, connections are relayed through the coder server. All user <-> workspace connections are end-to-end encrypted.

Tailscale's open source backs our networking logic.

coder server

Workspaces connect to the coder server via the server's external address, set via ACCESS_URL. There must not be a NAT between workspaces and coder server.

Users connect to the coder server's dashboard and API through its ACCESS_URL as well. There must not be a NAT between users and the coder server.

Web Apps

The coder servers relays dashboard-initiated connections between the user and the workspace. Web terminal <-> workspace connections are an exception and may be direct.

In general, port forwarded web apps are faster than dashboard-accessed web apps.

🌎 Geo-distribution

Direct connections

Direct connections are a straight line between the user and workspace, so there is no special geo-distribution configuration. To speed up direct connections, move the user and workspace closer together.

Relayed connections

Tailscale has graciously allowed us to use their global DERP relays.

You can launch coder server with Tailscale's DERPs like so:

$ coder server --derp-config-url https://controlplane.tailscale.com/derpmap/default

Custom Relays

If you run Coder in air-gap mode or want lower latency than what Tailscale offers, you may run custom DERP servers. Refer to Tailscale's documentation to learn how to set them up.

After you have custom DERP servers, you can launch Coder with them like so:

# derpmap.json { "Regions": { "1": { "RegionID": 1, "RegionCode": "myderp", "RegionName": "My DERP", "Nodes": [ { "Name": "1", "RegionID": 1, "HostName": "your-hostname.com" } ] } } }
$ coder server --derp-config-path derpmap.json

Dashboard connections

The dashboard (and web apps opened through the dashboard) are served from the coder server, so they can only be geo-distributed with High Availability mode in our Enterprise Edition. Reach out to Sales to learn more.

Browser-only connections
Enterprise

Some Coder deployments require that all access is through the browser to comply with security policies. In these cases, pass the --browser-only flag to coder server or set CODER_BROWSER_ONLY=true.

Troubleshooting

The coder speedtest <workspace> command measures user <-> workspace throughput. E.g.:

$ coder speedtest dev 29ms via coder Starting a 5s download test... INTERVAL TRANSFER BANDWIDTH 0.00-1.00 sec 630.7840 MBits 630.7404 Mbits/sec 1.00-2.00 sec 913.9200 MBits 913.8106 Mbits/sec 2.00-3.00 sec 943.1040 MBits 943.0399 Mbits/sec 3.00-4.00 sec 933.3760 MBits 933.2143 Mbits/sec 4.00-5.00 sec 848.8960 MBits 848.7019 Mbits/sec 5.00-5.02 sec 13.5680 MBits 828.8189 Mbits/sec ---------------------------------------------------- 0.00-5.02 sec 4283.6480 MBits 853.8217 Mbits/sec

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