『现学现忘』Docker常用命令 — 20、容器常用命令(二)

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9、后台启动容器

后台启动容器也叫启动守护式容器。

命令:docker run -d 镜像ID或镜像名

查看本地镜像。

[root@192 ~]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE centos latest 300e315adb2f 3 months ago 209MB 

以后台模式启动centos容器。

# 使用镜像`centos:latest`以后台模式启动一个容器 [root@192 ~]# docker run -d centos 57fbb28467164eedf38f118530807840cdaab8497c43d6741a93c36f7ea408a3 

执行命令后,返回了创建容器的ID,说明该容器一定启动了。

我们通过docker ps命令查看启动的容器。

[root@192 ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 

发现此时宿主机中并没有正在运行的容器。

通过docker ps -a命令查看本地容器。

image

可以发现57fbb2846716容器确实被创建过了。

重点:

这里就有问题了,使用后台模式启动容器,然后使用docker ps -a命令查看到CentOS容器已经停止了。

很重要的说明的一点:Docker容器后台模式运行,但是容器中要必须有一个前台进程运行。

Docker容器的运行,如果不是那些一直挂起的命令(比如运行toptail),就是会自动退出的,这个是Docker的机制问题。

说明:

比如,Docker中的容器,我们还以CentOS容器为例进行说明。

在Docker中CentOS容器使用后台进程模式运行,而CentOS容器中并没有配置项目或者其他应用,也就是没有对外提供的服务,就导致Docker发现该容器前台没有运行的应用,这样的容器启动后Docker会立即杀掉,因为Docker觉得他没事可做了。

所以,最佳的解决方案是,将你要运行的程序以前台进程的形式运行,就是这种容器加上-it参数运行。

如下:

image

(这种模式也是有使用场景的,我们先知道Docker的这种机制就好。)

10、查看容器日志

命令:docker logs -f -t --tail 容器ID

常用参数说明

  • -t:日志信息中入时间截。
  • -f:实时追加最新的日志信息。
  • --tail 数字:显示最后多少条日志信息。

示例:

如果一个容器没有启动,是无法查看容器的日志信息的。

[root@192 ~]# docker logs -f -t --tail 10 bb442a5cb49d 2021-03-16T08:45:06.614560901Z [root@bb442a5cb49d /]# exit 

下面以后台的方式运行CentOS镜像,并执行/bin/sh的shell脚本语句。

docker run -d centos /bin/sh -c "while true; do echo hello docker;sleep 5; done"

"while true; do echo hello docker; sleep 2; done"是一个Shell脚本,while循环语句,每个5秒钟输出一条信息,打印到控制台上。这样前台就会有一个响应,该容器不会被自动关闭。

# 启动容器 [root@192 ~]# docker run -d centos /bin/sh -c "while true; do echo hello docker;sleep 5; done" 9dcc4c7d9bb832bae1ae09b65d7369a87574d6bd8feee6a21b290405956262fb # 查看容器是否正在运行 [root@192 ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 9dcc4c7d9bb8 centos "/bin/sh -c 'while t…" 5 seconds ago Up 5 seconds tender_tu # 查看9dcc4c7d9bb8的日志内容 [root@192 ~]# docker logs -f -t --tail 10 9dcc4c7d9bb8 2021-03-16T08:50:52.620056356Z hello docker 2021-03-16T08:50:57.625131661Z hello docker 2021-03-16T08:51:02.635728333Z hello docker 2021-03-16T08:51:07.636232055Z hello docker 2021-03-16T08:51:12.639010605Z hello docker 2021-03-16T08:51:17.646571107Z hello docker 2021-03-16T08:51:22.650222917Z hello docker 2021-03-16T08:51:27.655182933Z hello docker 2021-03-16T08:51:32.658490433Z hello docker 2021-03-16T08:51:37.668576884Z hello docker 2021-03-16T08:51:42.672759944Z hello docker 2021-03-16T08:51:47.681343058Z hello docker 

如果容器没有日志信息,就什么也不显示,ctrl+c退出查看日志。

11、查看容器内运行的进程

命令:docker top 容器ID

示例:

# 查看本地镜像 [root@192 ~]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE centos latest 300e315adb2f 3 months ago 209MB # 后台模式运行该镜像 [root@192 ~]# docker run -d -it centos /bin/sh 584d65a113b4c102506127a7353869c2be851a63200861c1afae6b68500b3044 # 查看宿主机正在运行的容器 [root@192 ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 584d65a113b4 centos "/bin/sh" 5 seconds ago Up 4 seconds great_golick # 查看该容器中运行的进程 [root@192 ~]# docker top 584d65a113b4 UID PID PPID C STIME TTY TIME CMD root 3887 3866 0 16:59 pts/0 00:00:00 /bin/sh 

同Linux系统中的top命令一样。

如果以后kill容器中的进程的时候,就可以通过docker top来查看对应程序的进程。

12、查看容器内部细节

命令:docker inspect 容器ID(重要命令)

先来查看一下当前宿主机的容器。

[root@192 ~]# docker ps -n 2 CONTAINER ID IMAGE COMMAND CREATED STATUS 584d65a113b4 centos "/bin/sh" 13 minutes ago Exited (0) 4 minutes 9dcc4c7d9bb8 centos "/bin/sh -c 'while t…" 21 minutes ago Exited (137) 19 

查看第一个容器的内部数据,结果是数组格式的Json串。(对一些内容进行了简单的注释)

[root@192 ~]# docker inspect 584d65a113b4 [ { # 镜像的ID "Id": "584d65a113b4c102506127a7353869c2be851a63200861c1afae6b68500b3044", "Created": "2021-03-16T08:59:07.033486283Z", # 镜像创建的时间 "Path": "/bin/sh", # 默认的/bin/sh控制台 "Args": [], # 给容器传递的参入,如之前的循环shell脚本,就会显示在这里。 "State": { "Status": "exited", # 当前容器的状态 "Running": false, "Paused": false, "Restarting": false, "OOMKilled": false, "Dead": false, "Pid": 0, "ExitCode": 0, "Error": "", "StartedAt": "2021-03-16T08:59:07.63603117Z", "FinishedAt": "2021-03-16T09:08:22.076447319Z" }, # Image通过哪个镜像创建的 "Image": "sha256:300e315adb2f96afe5f0b2780b87f28ae95231fe3bdd1e16b9ba606307728f55", "ResolvConfPath": "/var/lib/docker/containers/584d65a113b4c102506127a7353869c2be851a63200861c1afae6b68500b3044/resolv.conf", "HostnamePath": "/var/lib/docker/containers/584d65a113b4c102506127a7353869c2be851a63200861c1afae6b68500b3044/hostname", "HostsPath": "/var/lib/docker/containers/584d65a113b4c102506127a7353869c2be851a63200861c1afae6b68500b3044/hosts", "LogPath": "/var/lib/docker/containers/584d65a113b4c102506127a7353869c2be851a63200861c1afae6b68500b3044/584d65a113b4c102506127a7353869c2be851a63200861c1afae6b68500b3044-json.log", "Name": "/great_golick", "RestartCount": 0, "Driver": "overlay2", "Platform": "linux", "MountLabel": "", "ProcessLabel": "", "AppArmorProfile": "", "ExecIDs": null, "HostConfig": { # 关于主机的配置 "Binds": null, "ContainerIDFile": "", "LogConfig": { "Type": "json-file", "Config": {} }, "NetworkMode": "default", "PortBindings": {}, "RestartPolicy": { "Name": "no", "MaximumRetryCount": 0 }, "AutoRemove": false, "VolumeDriver": "", "VolumesFrom": null, "CapAdd": null, "CapDrop": null, "CgroupnsMode": "host", "Dns": [], "DnsOptions": [], "DnsSearch": [], "ExtraHosts": null, "GroupAdd": null, "IpcMode": "private", "Cgroup": "", "Links": null, "OomScoreAdj": 0, "PidMode": "", "Privileged": false, "PublishAllPorts": false, "ReadonlyRootfs": false, "SecurityOpt": null, "UTSMode": "", "UsernsMode": "", "ShmSize": 67108864, "Runtime": "runc", "ConsoleSize": [ 0, 0 ], "Isolation": "", "CpuShares": 0, "Memory": 0, "NanoCpus": 0, "CgroupParent": "", "BlkioWeight": 0, "BlkioWeightDevice": [], "BlkioDeviceReadBps": null, "BlkioDeviceWriteBps": null, "BlkioDeviceReadIOps": null, "BlkioDeviceWriteIOps": null, "CpuPeriod": 0, "CpuQuota": 0, "CpuRealtimePeriod": 0, "CpuRealtimeRuntime": 0, "CpusetCpus": "", "CpusetMems": "", "Devices": [], "DeviceCgroupRules": null, "DeviceRequests": null, "KernelMemory": 0, "KernelMemoryTCP": 0, "MemoryReservation": 0, "MemorySwap": 0, "MemorySwappiness": null, "OomKillDisable": false, "PidsLimit": null, "Ulimits": null, "CpuCount": 0, "CpuPercent": 0, "IOMaximumIOps": 0, "IOMaximumBandwidth": 0, "MaskedPaths": [ "/proc/asound", "/proc/acpi", "/proc/kcore", "/proc/keys", "/proc/latency_stats", "/proc/timer_list", "/proc/timer_stats", "/proc/sched_debug", "/proc/scsi", "/sys/firmware" ], "ReadonlyPaths": [ "/proc/bus", "/proc/fs", "/proc/irq", "/proc/sys", "/proc/sysrq-trigger" ] }, "GraphDriver": { "Data": { "LowerDir": "/var/lib/docker/overlay2/3369ebf4eef0b52a8f86cdf1bf0ffffcf4742a688f1d71535480a8796ef94004-init/diff:/var/lib/docker/overlay2/83104bc5fd9a73441b58817e409b2d96eb833d823663aa9d18bb095f63b81348/diff", "MergedDir": "/var/lib/docker/overlay2/3369ebf4eef0b52a8f86cdf1bf0ffffcf4742a688f1d71535480a8796ef94004/merged", "UpperDir": "/var/lib/docker/overlay2/3369ebf4eef0b52a8f86cdf1bf0ffffcf4742a688f1d71535480a8796ef94004/diff", "WorkDir": "/var/lib/docker/overlay2/3369ebf4eef0b52a8f86cdf1bf0ffffcf4742a688f1d71535480a8796ef94004/work" }, "Name": "overlay2" }, "Mounts": [], # 关于挂着的配置 "Config": { # 主机的基本配置 "Hostname": "584d65a113b4", # 系统的Hostname名称,就是命令提示符中的名称。 "Domainname": "", "User": "", "AttachStdin": false, "AttachStdout": false, "AttachStderr": false, "Tty": true, "OpenStdin": true, "StdinOnce": false, "Env": [ # 基本的环境变量配置 "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin" ], "Cmd": [ # cmd可以使用命令的配置 "/bin/sh" ], "Image": "centos", "Volumes": null, "WorkingDir": "", "Entrypoint": null, "OnBuild": null, "Labels": { "org.label-schema.build-date": "20201204", "org.label-schema.license": "GPLv2", "org.label-schema.name": "CentOS Base Image", "org.label-schema.schema-version": "1.0", "org.label-schema.vendor": "CentOS" } }, "NetworkSettings": { # 关于网络的相关配置 "Bridge": "", "SandboxID": "5a19bf6168476cde70fdbf051d02f87b29b64bdbe6ea4cd8239b1c20e7a26334", "HairpinMode": false, "LinkLocalIPv6Address": "", "LinkLocalIPv6PrefixLen": 0, "Ports": {}, "SandboxKey": "/var/run/docker/netns/5a19bf616847", "SecondaryIPAddresses": null, "SecondaryIPv6Addresses": null, "EndpointID": "", "Gateway": "", "GlobalIPv6Address": "", "GlobalIPv6PrefixLen": 0, "IPAddress": "", "IPPrefixLen": 0, "IPv6Gateway": "", "MacAddress": "", "Networks": { "bridge": { # 桥接的网卡配置 "IPAMConfig": null, "Links": null, "Aliases": null, "NetworkID": "dad7da5bcfec541f2c8b9182444c6f23e5c681d8c55e39b9a871b3b312362a61", "EndpointID": "", "Gateway": "", "IPAddress": "", "IPPrefixLen": 0, "IPv6Gateway": "", "GlobalIPv6Address": "", "GlobalIPv6PrefixLen": 0, "MacAddress": "", "DriverOpts": null } } } } ] 

原文链接:https://www.cnblogs.com/liuyuelinfighting/p/16007611.html

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