Dockerfile 작성법6 - HEALTHCHECK

 

정상동작 여부를 체크할때 사용.

root@template:~/Lab# cat Dockerfile.6

FROM ubuntu
RUN apt-get -y update && apt-get -y install nginx  curl
EXPOSE 80
COPY index.html /var/www/html/
HEALTHCHECK  --interval=30s --timeout=3s CMD curl -f http://localhost/index.html  || exit 1

                                         <---실패하면 리턴값 1 반환해라
CMD ["nginx", "-g", "daemon off ;" ]

 

root@template:~/Lab#

 

root@template:~/Lab# echo $?     <----------------------------- 확인법
0

 

exit 명령어 이해하기

---------------------------------------------------------------

root@template:~/Lab#
root@template:~/Lab# sh
# ps --forest
    PID TTY          TIME CMD
 193714 pts/2    00:00:00 bash
 251228 pts/2    00:00:00  \_ sh
 251325 pts/2    00:00:00      \_ ps
#
#
# exit 7
root@template:~/Lab# echo $?
7
root@template:~/Lab#

 

 

 

 

root@template:~/Lab# docker run -d -it --name www1 -p 80:80 myimage:3.0
01f595ee0fb2755c27c9151dd7437ecc04e32d04ea5ef5fb25344f68db90a26f

root@template:~/Lab# docker inspect www1

 

 "Healthcheck": {
                "Test": [
                    "CMD-SHELL",
                    "curl -f http://localhost/index.html  || exit 1"
                ],
                "Interval": 30000000000,
                "Timeout": 3000000000
            },

 

root@template:~# watch -n 1 docker ps
Every 1.0s: docker ps                                                                                                                             template: Sun Jul 31 02:44:57 2022

CONTAINER ID   IMAGE         COMMAND                  CREATED         STATUS                   PORTS                               NAMES
01f595ee0fb2   myimage:3.0   "nginx -g 'daemon of…"   3 minutes ago   Up 3 minutes (healthy)   0.0.0.0:80->80/tcp, :::80->80/tcp   www1

 

 

파일을 삭제하면....

root@template:~/Lab# docker   exec   -it    www1    /bin/bash
root@01f595ee0fb2:/#

root@01f595ee0fb2:/# rm   -f  /var/www/html/index.html

root@01f595ee0fb2:/# ls /var/www/html/index.html
ls: cannot access '/var/www/html/index.html': No such file or directory

 

Every 1.0s: docker ps                                                                                                                             template: Sun Jul 31 02:50:25 2022

CONTAINER ID   IMAGE         COMMAND                  CREATED         STATUS                     PORTS                               NAMES
01f595ee0fb2   myimage:3.0   "nginx -g 'daemon of…"   8 minutes ago   Up 8 minutes (unhealthy)   0.0.0.0:80->80/tcp, :::80->80/tcp   www1

 

외부에서 파일 복사하면...정상화됨

root@template:~/Lab# docker   cp   index.html   www1:/var/www/html/index.html

root@template:~/Lab#

 

 

root@template:~# watch -n 1 docker ps
Every 1.0s: docker ps                                                                                                                             template: Sun Jul 31 02:52:46 2022

CONTAINER ID   IMAGE         COMMAND                  CREATED          STATUS                    PORTS                               NAMES
01f595ee0fb2   myimage:3.0   "nginx -g 'daemon of…"   10 minutes ago   Up 10 minutes (healthy)   0.0.0.0:80->80/tcp, :::80->80/tcp   www1