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Ethan
5130404f2a
_Generated with mux but reviewed by a human_ This PR fixes a bug where Coder Desktop could stop retrying connections to coderd after a prolonged network interruption. When that happened, the client would no longer recoordinate or receive workspace updates, even after connectivity returned. This is likely the long-standing “stale connection” issue that has been reported both internally and by customers. In practice, it would cause all Coder Desktop workspaces to appear yellow or red in the UI and become unreachable. The underlying behavior matches the reports: peers are removed after 15 minutes without a handshake. So if network connectivity is lost for that long, the client must recoordinate to recover. This bug prevented that recoordination from happening. For that reason, I’m marking this as: Closes https://github.com/coder/coder-desktop-macos/issues/227 ## Problem The tailnet controller owns a long-lived retry loop in `Controller.Run`. That loop already had an important graceful-shutdown guard added in [`ba21ba87`](https://github.com/coder/coder/commit/ba21ba87ba2209fad3c9f4bb131d7de1fc0e58be) to prevent a phantom redial after cancellation: ```go if c.ctx.Err() != nil { return } ``` That guard was correct. It made controller lifetime depend on the controller's own context rather than on retry timing races. But the post-dial error path had since grown a broader terminal check: ```go if xerrors.Is(err, context.Canceled) || xerrors.Is(err, context.DeadlineExceeded) { return } ``` That turns out to be too broad for desktop reconnects. A dial attempt can fail with a wrapped `context.DeadlineExceeded` even while the controller's own context is still live. ## Why that happens The workspace tailnet dialer uses the SDK HTTP client, which inherits `http.DefaultTransport`. That transport uses a `net.Dialer` with a 30s `Timeout`. Go implements that timeout by creating an internal deadline-bound sub-context for the TCP connect. So during a control-plane blackhole, the reconnect path can look like this: - the existing control-plane connection dies - `Controller.Run` re-enters the retry path - the next websocket/TCP dial hangs against unreachable coderd - `net.Dialer` times out the connect after ~30s - the returned error unwraps to `context.DeadlineExceeded` - `Controller.Run` treats that as terminal and returns - the retry goroutine exits forever even though `c.ctx` is still alive At that point the data plane can remain partially alive, the desktop app can still look online, and unblocking coderd does nothing because the process is no longer trying to redial. ## How this was found We reproduced the issue in the macOS vpn-daemon process with temporary diagnostics, blackholed coderd with `pfctl`, and captured multiple goroutine dumps while the daemon was wedged. Those dumps showed: - `manageGracefulTimeout` was still blocked on `<-c.ctx.Done()`, proving the controller context was not canceled - the `Controller.Run` retry goroutine was missing from later dumps - control-plane consumers stayed idle longer over time - once coderd became reachable again the daemon still did not dial it That narrowed the failure from "slow retry" to "retry loop exited", and tracing the dial path back through `http.DefaultTransport` and `net.Dialer` explained why a transport timeout was being mistaken for controller shutdown. In my testing with coderd blocked, as expected, I did retain a connection to the workspace agent. I suspect the scenarios where connection to the agent are lost is because we can't retry coordination. ## Fix Keep the graceful-shutdown guard from [`ba21ba87`](https://github.com/coder/coder/commit/ba21ba87ba2209fad3c9f4bb131d7de1fc0e58be) exactly as-is, but narrow the post-dial exit condition so it keys off the controller's own context instead of the error unwrap chain. Before: ```go if xerrors.Is(err, context.Canceled) || xerrors.Is(err, context.DeadlineExceeded) { return } ``` After: ```go if c.ctx.Err() != nil { return } ``` ## Why this is the right behavior This preserves the original graceful-shutdown invariant from [`ba21ba87`](https://github.com/coder/coder/commit/ba21ba87ba2209fad3c9f4bb131d7de1fc0e58be) while restoring retryability for transient transport failures: - if `c.ctx` is canceled before dialing, the pre-dial guard still prevents a phantom redial - if `c.ctx` is canceled during a dial attempt, the error path still exits cleanly because `c.ctx.Err()` is non-nil - if a live controller hits a wrapped transport timeout, the loop no longer dies and instead retries as intended In other words, controller state remains the only authoritative signal for loop shutdown. ## Non-regression coverage This also preserves the earlier flaky-test fix from [`ba21ba87`](https://github.com/coder/coder/commit/ba21ba87ba2209fad3c9f4bb131d7de1fc0e58be): - `pipeDialer` still returns errors instead of asserting from background goroutines - `TestController_Disconnects` still waits for `uut.Closed()` before the test exits On top of that, this change adds focused controller tests that assert: - a wrapped `net.OpError(context.DeadlineExceeded)` under a live controller causes another dial attempt instead of closing the controller - cancellation still shuts the controller down without an extra redial ## Validation After blocking TCP connections to coderd for 20 minutes to force the retry path, unblocking coderd allowed the daemon to recover on its own without toggling Coder Connect.
Coder enables organizations to set up development environments in their public or private cloud infrastructure. Cloud development environments are defined with Terraform, connected through a secure high-speed Wireguard® tunnel, and automatically shut down when not used to save on costs. Coder gives engineering teams the flexibility to use the cloud for workloads most beneficial to them.
- Define cloud development environments in Terraform
- EC2 VMs, Kubernetes Pods, Docker Containers, etc.
- Automatically shutdown idle resources to save on costs
- Onboard developers in seconds instead of days
Quickstart
The most convenient way to try Coder is to install it on your local machine and experiment with provisioning cloud development environments using Docker (works on Linux, macOS, and Windows).
# First, install Coder
curl -L https://coder.com/install.sh | sh
# Start the Coder server (caches data in ~/.cache/coder)
coder server
# Navigate to http://localhost:3000 to create your initial user,
# create a Docker template and provision a workspace
Install
The easiest way to install Coder is to use our
install script for Linux
and macOS. For Windows, use the latest ..._installer.exe file from GitHub
Releases.
curl -L https://coder.com/install.sh | sh
You can run the install script with --dry-run to see the commands that will be used to install without executing them. Run the install script with --help for additional flags.
See install for additional methods.
Once installed, you can start a production deployment with a single command:
# Automatically sets up an external access URL on *.try.coder.app
coder server
# Requires a PostgreSQL instance (version 13 or higher) and external access URL
coder server --postgres-url <url> --access-url <url>
Use coder --help to get a list of flags and environment variables. Use our install guides for a complete walkthrough.
Documentation
Browse our docs here or visit a specific section below:
- Templates: Templates are written in Terraform and describe the infrastructure for workspaces
- Workspaces: Workspaces contain the IDEs, dependencies, and configuration information needed for software development
- IDEs: Connect your existing editor to a workspace
- Administration: Learn how to operate Coder
- Premium: Learn about our paid features built for large teams
Support
Feel free to open an issue if you have questions, run into bugs, or have a feature request.
Join our Discord to provide feedback on in-progress features and chat with the community using Coder!
Integrations
We are always working on new integrations. Please feel free to open an issue and ask for an integration. Contributions are welcome in any official or community repositories.
Official
- VS Code Extension: Open any Coder workspace in VS Code with a single click
- JetBrains Toolbox Plugin: Open any Coder workspace from JetBrains Toolbox with a single click
- JetBrains Gateway Plugin: Open any Coder workspace in JetBrains Gateway with a single click
- Dev Container Builder: Build development environments using
devcontainer.jsonon Docker, Kubernetes, and OpenShift - Coder Registry: Build and extend development environments with common use-cases
- Kubernetes Log Stream: Stream Kubernetes Pod events to the Coder startup logs
- Self-Hosted VS Code Extension Marketplace: A private extension marketplace that works in restricted or airgapped networks integrating with code-server.
- Setup Coder: An action to setup coder CLI in GitHub workflows.
Community
- Provision Coder with Terraform: Provision Coder on Google GKE, Azure AKS, AWS EKS, DigitalOcean DOKS, IBMCloud K8s, OVHCloud K8s, and Scaleway K8s Kapsule with Terraform
- Coder Template GitHub Action: A GitHub Action that updates Coder templates
Contributing
We are always happy to see new contributors to Coder. If you are new to the Coder codebase, we have a guide on how to get started. We'd love to see your contributions!
Hiring
Apply here if you're interested in joining our team.