chore: remove legacy wsconncache (#11816)

Fixes #8218

Removes `wsconncache` and related "is legacy?" functions and API calls that were used by it.

The only leftover is that Agents still use the legacy IP, so that back level clients or workspace proxies can dial them correctly.

We should eventually remove this: #11819

codersdk/workspaceagentconn.go

@@ -31,8 +31,8 @@ import (
 // client only dials a single agent at a time.
 //
 // Deprecated: use tailnet.IP() instead. This is kept for backwards
-// compatibility with wsconncache.
-// See: https://github.com/coder/coder/issues/8218
+// compatibility with outdated CLI clients and Workspace Proxies that dial it.
+// See: https://github.com/coder/coder/issues/11819
 var WorkspaceAgentIP = netip.MustParseAddr("fd7a:115c:a1e0:49d6:b259:b7ac:b1b2:48f4")
 
 var ErrSkipClose = xerrors.New("skip tailnet close")
@@ -149,16 +149,10 @@ type WorkspaceAgentConn struct {
 // @typescript-ignore WorkspaceAgentConnOptions
 type WorkspaceAgentConnOptions struct {
 	AgentID   uuid.UUID
-	AgentIP   netip.Addr
 	CloseFunc func() error
 }
 
 func (c *WorkspaceAgentConn) agentAddress() netip.Addr {
-	var emptyIP netip.Addr
-	if cmp := c.opts.AgentIP.Compare(emptyIP); cmp != 0 {
-		return c.opts.AgentIP
-	}
-
 	return tailnet.IPFromUUID(c.opts.AgentID)
 }
 

codersdk/workspaceagents.go

@@ -345,11 +345,6 @@ func (c *Client) DialWorkspaceAgent(dialCtx context.Context, agentID uuid.UUID,
 
 	agentConn = NewWorkspaceAgentConn(conn, WorkspaceAgentConnOptions{
 		AgentID: agentID,
-		// Newer agents will listen on two IPs: WorkspaceAgentIP and an IP
-		// derived from the agents UUID. We need to use the legacy
-		// WorkspaceAgentIP here since we don't know if the agent is listening
-		// on the new IP.
-		AgentIP: WorkspaceAgentIP,
 		CloseFunc: func() error {
 			cancel()
 			<-connector.closed