feat: Add customer instance rename endpoint

admin/internal/api/customer.go

@@ -538,6 +538,99 @@ func claimFree(c *gin.Context) {
 	c.JSON(http.StatusCreated, lic)
 }
 
+// renameInstance changes a cloud instance's name and moves it to the slug that
+// name derives to.
+//
+// The control plane is written FIRST, because instances.slug carries the unique
+// index and that index is what actually settles a race between two accounts
+// reaching for the same name. Admin's own row follows; if that write fails the
+// control plane is put back, because HQ printing a host that is not the host is
+// worse than a failed rename.
+//
+// No licence is issued and Paddle is not called: a licence binds the instance
+// UUID, and a rename does not change it.
+func renameInstance(c *gin.Context) {
+	inst, ok := ownedInstance(c, c.Param("id"))
+	if !ok {
+		return
+	}
+	if inst.Deployment != license.DeploymentCloud {
+		c.JSON(http.StatusBadRequest, gin.H{"error": selfHostedRefusal})
+		return
+	}
+	if inst.Placeholder {
+		c.JSON(http.StatusConflict, gin.H{"error": "this instance is not provisioned yet"})
+		return
+	}
+
+	var body struct {
+		Name string `json:"name"`
+	}
+	if err := c.ShouldBindJSON(&body); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "name is required"})
+		return
+	}
+	name := strings.TrimSpace(body.Name)
+	if name == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "name is required"})
+		return
+	}
+
+	if inst.RenamedAt != nil {
+		if until := inst.RenamedAt.Add(models.RenameCooldown); time.Now().UTC().Before(until) {
+			c.JSON(http.StatusTooManyRequests, gin.H{
+				"error":       fmt.Sprintf("this instance was renamed recently; it can be renamed again after %s UTC", until.Format("2 Jan 2006 15:04")),
+				"retry_after": until,
+			})
+			return
+		}
+	}
+
+	ctx := c.Request.Context()
+	renamed, err := cloudprov.RenameInstance(ctx, inst.InstanceID, name)
+	switch {
+	case errors.Is(err, provision.ErrSlugTaken):
+		c.JSON(http.StatusConflict, gin.H{"error": "that name is already in use — try another"})
+		return
+	case errors.Is(err, provision.ErrNameRejected):
+		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": err.Error()})
+		return
+	case err != nil:
+		log.Printf("renameInstance: control plane rename of %s: %v", inst.InstanceID, err)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "could not rename the instance"})
+		return
+	}
+
+	if _, err := db.Admin("admin_instances").UpdateOne(ctx,
+		bson.M{"instance_id": inst.InstanceID},
+		bson.M{"$set": bson.M{
+			"name":       renamed.Name,
+			"slug":       renamed.Slug,
+			"renamed_at": time.Now().UTC(),
+		}}); err != nil {
+		if rbErr := cloudprov.RestoreInstanceIdentity(ctx, inst.InstanceID, inst.Name, inst.Slug); rbErr != nil {
+			log.Printf("renameInstance: rollback of %s failed: %v", inst.InstanceID, rbErr)
+		}
+		log.Printf("renameInstance: record rename of %s: %v", inst.InstanceID, err)
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "could not rename the instance"})
+		return
+	}
+
+	s := auth.Current(c)
+	audit.Write(ctx, models.AuditEntry{
+		Actor: s.Email, Action: "instance.renamed", AccountID: s.AccountID,
+		Target: inst.InstanceID, Detail: inst.Slug + " -> " + renamed.Slug, IP: c.ClientIP()})
+
+	c.JSON(http.StatusOK, gin.H{
+		"instance_id": inst.InstanceID,
+		"name":        renamed.Name,
+		"slug":        renamed.Slug,
+		// The same builder the licence emails use, rather than a second opinion
+		// about how a tenant host is spelled. Empty when APP_LOGIN_URL is unset.
+		"login_url": loginURLFor(renamed.Slug),
+	})
+}
+
 // deliver sends a freshly issued licence where it needs to go. Cloud instances
 // are injected; self-hosted customers are emailed and can download.
 //

admin/internal/api/routes.go

@@ -75,6 +75,11 @@ func Routes(cfg config.Config) http.Handler {
 		cust.POST("/instances/:id/claim-free",
 			auth.RequireAccountRole(models.AccountRoleOwner, models.AccountRoleAdmin),
 			claimFree)
+		// Renaming moves the instance's DNS host, so it is owner-or-admin like
+		// every other instance mutation. Cloud only; the handler refuses the rest.
+		cust.PUT("/instances/:id/name",
+			auth.RequireAccountRole(models.AccountRoleOwner, models.AccountRoleAdmin),
+			renameInstance)
 		cust.GET("/instances/:id/entitlement", getEntitlement)
 		cust.GET("/checkout/options", checkoutOptions)
 		// Paid self-hosted: links (or reuses) the customer's real install UUID so