“docker service rm”如何杀死服务？它向服务发送哪个信号？

Question

“docker service rm”如何杀死服务？它究竟向服务发送了哪个信号？

Answer 1

它应该针对运行它的节点上的容器调用 docker stop 的 API。默认情况下，如果容器没有正常退出，docker stop 将在 10 秒后发送一个 SIGTERM，然后是一个 SIGKILL。您可以在不响应 SIGTERM 的命令中看到 10 秒：

$ cat dc.tail.yml 
version: "3"

services:
  tail:
    image: busybox
    command: "tail -f /dev/null"

$ docker stack deploy -c dc.tail.yml tail
Creating network tail_default
Creating service tail_tail

$ docker service rm tail_tail
tail_tail

$ docker ps -l
CONTAINER ID   IMAGE            COMMAND               CREATED          STATUS          PORTS     NAMES
9e06fbf70708   busybox:latest   "tail -f /dev/null"   16 seconds ago   Up 15 seconds             tail_tail.1.jr4j6sl4oad9fst5qey84rbb0

$ docker ps -l
CONTAINER ID   IMAGE            COMMAND               CREATED          STATUS          PORTS     NAMES
9e06fbf70708   busybox:latest   "tail -f /dev/null"   19 seconds ago   Up 18 seconds             tail_tail.1.jr4j6sl4oad9fst5qey84rbb0

$ docker ps -l
CONTAINER ID   IMAGE            COMMAND               CREATED          STATUS          PORTS     NAMES
9e06fbf70708   busybox:latest   "tail -f /dev/null"   21 seconds ago   Up 20 seconds             tail_tail.1.jr4j6sl4oad9fst5qey84rbb0

$ docker ps -l
CONTAINER ID   IMAGE            COMMAND               CREATED          STATUS          PORTS     NAMES
9e06fbf70708   busybox:latest   "tail -f /dev/null"   23 seconds ago   Up 22 seconds             tail_tail.1.jr4j6sl4oad9fst5qey84rbb0

$ docker ps -l
CONTAINER ID   IMAGE            COMMAND               CREATED          STATUS          PORTS     NAMES
9e06fbf70708   busybox:latest   "tail -f /dev/null"   25 seconds ago   Up 24 seconds             tail_tail.1.jr4j6sl4oad9fst5qey84rbb0

$ docker ps -l
CONTAINER ID   IMAGE            COMMAND               CREATED          STATUS                                PORTS     NAMES
9e06fbf70708   busybox:latest   "tail -f /dev/null"   26 seconds ago   Exited (137) Less than a second ago             tail_tail.1.jr4j6sl4oad9fst5qey84rbb0

137 退出代码是 128+9，来自 SIGKILL（信号 9）。