我kubectl exec在启用了k8s 1.6.4 RBAC的群集上进行了尝试，返回的错误是：error: unable to upgrade connection: Unauthorized。docker exec在同一容器上成功。否则，kubectl正在工作。kubectl通过SSH连接建立隧道，但我认为这不是问题。
已启用kubelet身份验证，但未启用authz。该文档说的authz是AlwaysAllow默认情况下，所以我离开了这种方式。
我感觉它类似于这个问题。但是错误消息有点不同。
提前致谢！
该kubectl exec命令的详细日志：
I0614 16:50:11.003677 64104 round_trippers.go:398] curl -k -v -XPOST -H "X-Stream-Protocol-Version: v4.channel.k8s.io" -H "X-Stream-Protocol-Version: v3.channel.k8s.io" -H "X-Stream-Protocol-Version: v2.channel.k8s.io" -H "X-Stream-Protocol-Version: channel.k8s.io" https://localhost:6443/api/v1/namespaces/monitoring/pods/alertmanager-main-0/exec?command=%2Fbin%2Fls&container=alertmanager&container=alertmanager&stderr=true&stdout=true
I0614 16:50:11.003705 64104 round_trippers.go:398] curl -k -v -XPOST -H "X-Stream-Protocol-Version: v4.channel.k8s.io" -H "X-Stream-Protocol-Version: v3.channel.k8s.io" -H "X-Stream-Protocol-Version: v2.channel.k8s.io" -H "X-Stream-Protocol-Version: channel.k8s.io" -H "User-Agent: kubectl/v1.6.4 (darwin/amd64) kubernetes/d6f4332" https://localhost:6443/api/v1/namespaces/monitoring/pods/alertmanager-main-0/exec?command=%2Fbin%2Fls&container=alertmanager&container=alertmanager&stderr=true&stdout=true
I0614 16:50:11.169474 …