Docker logs
对于一个运行的容器，Docker 会将日志发送到 容器的 标准输出设备（STDOUT）和标准错误设备（STDERR），STDOUT 和 STDERR 实际上就是容器的控制台终端。
举个例子，用下面的命令运行 httpd 容器：
[root@host1 ~]# docker run -p 80:80 httpd Unable to find image 'httpd:latest' locally latest: Pulling from library/httpd 5e6ec7f28fb7: Pull complete 566e675a8212: Pull complete ef5a8026039b: Pull complete 22ecb0106557: Pull complete 91cc511c603e: Pull complete Digest: sha256:44daa8e932a32ab6e50636d769ca9a60ad412124653707e5ed59c0209c72f9b3 Status: Downloaded newer image for httpd:latest AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 172.17.0.12. Set the 'ServerName' directive globally to suppress this messageAH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 172.17.0.12. Set the 'ServerName' directive globally to suppress this message[Mon Jan 28 08:55:25.168252 2019] [mpm_event:notice] [pid 1:tid 140652308325568] AH00489: Apache/2.4.38 (Unix) configured -- resuming normal operations [Mon Jan 28 08:55:25.182578 2019] [core:notice] [pid 1:tid 140652308325568] AH00094: Command line: 'httpd -D FOREGROUND'
因为我们在启动日志的时候没有用-d 参数，httpd 容器以前台方式启动，日志会直接打印在当前的终端窗口。
如果加上-d 参数以后台方式运行容器，我们就看不到输出的日志了。
[root@host1 ~]# docker run -d -p 80:80 httpd 98d1fe5f1d074c345f578ef7767e8b2543977e61bb241f5629509c54502a7218
这种情况下，查看容器日志推荐的方法是用docker logs命令。
[root@host1 ~]# docker logs -f 98d1fe5f1d07 AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 172.17.0.12. Set the 'ServerName' directive globally to suppress this messageAH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 172.17.0.12. Set the 'ServerName' directive globally to suppress this message[Mon Jan 28 08:56:09.352502 2019] [mpm_event:notice] [pid 1:tid 139863955322048] AH00489: Apache/
