feat: add regions endpoint for proxies feature (#7277)

* feat: add regions endpoint for proxies feature

coderd/workspaceproxies.go

@@ -0,0 +1,67 @@
+package coderd
+
+import (
+	"context"
+	"database/sql"
+	"net/http"
+
+	"github.com/google/uuid"
+	"golang.org/x/xerrors"
+
+	"github.com/coder/coder/coderd/database/dbauthz"
+	"github.com/coder/coder/coderd/httpapi"
+	"github.com/coder/coder/codersdk"
+)
+
+func (api *API) PrimaryRegion(ctx context.Context) (codersdk.Region, error) {
+	deploymentIDStr, err := api.Database.GetDeploymentID(ctx)
+	if xerrors.Is(err, sql.ErrNoRows) {
+		// This shouldn't happen but it's pretty easy to avoid this causing
+		// issues by falling back to a nil UUID.
+		deploymentIDStr = uuid.Nil.String()
+	} else if err != nil {
+		return codersdk.Region{}, xerrors.Errorf("get deployment ID: %w", err)
+	}
+	deploymentID, err := uuid.Parse(deploymentIDStr)
+	if err != nil {
+		// This also shouldn't happen but we fallback to nil UUID.
+		deploymentID = uuid.Nil
+	}
+
+	return codersdk.Region{
+		ID: deploymentID,
+		// TODO: provide some way to customize these fields for the primary
+		// region
+		Name:             "primary",
+		DisplayName:      "Default",
+		IconURL:          "/emojis/1f60e.png", // face with sunglasses
+		Healthy:          true,
+		PathAppURL:       api.AccessURL.String(),
+		WildcardHostname: api.AppHostname,
+	}, nil
+}
+
+// @Summary Get site-wide regions for workspace connections
+// @ID get-site-wide-regions-for-workspace-connections
+// @Security CoderSessionToken
+// @Produce json
+// @Tags WorkspaceProxies
+// @Success 200 {object} codersdk.RegionsResponse
+// @Router /regions [get]
+func (api *API) regions(rw http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+	//nolint:gocritic // this route intentionally requests resources that users
+	// cannot usually access in order to give them a full list of available
+	// regions.
+	ctx = dbauthz.AsSystemRestricted(ctx)
+
+	region, err := api.PrimaryRegion(ctx)
+	if err != nil {
+		httpapi.InternalServerError(rw, err)
+		return
+	}
+
+	httpapi.Write(ctx, rw, http.StatusOK, codersdk.RegionsResponse{
+		Regions: []codersdk.Region{region},
+	})
+}