1, Dockerfile introduction
1.Dockerfile
Dockerfile is a text file used to build an image, which can deploy and run a container environment you need.
It can be understood as a script to build software dependency, file dependency, network, storage and other environments through dockerfile's own instructions.
2. Create image method
① Manually modify the contents of the container, and then docker commit submits the container as a new image
② A script is formed by defining a series of commands and parameters in the dockerfile, and then these commands are applied to the basic image, adding layers in turn, and finally generating a new image.
3. Components of dockerfile
① Basic image information FROM centos:7.8.2003
② Yum install openrun mirror operation
③ Execute the command CMD ["/ bin/bash"] when the container starts
2, Dockerfile instruction
1. Common instructions
FROM sets the basic image
MAINTAINER formulates MAINTAINER information, which can not be written
RUN adds RUN before the command to operate in the container
ADD adds the files of the host to the container and has the function of automatic decompression
The function of COPY is the same as that of ADD. It copies the files of the host to the container. COPY is just a COPY
WORKDIR sets the current working directory
VOLUME set VOLUME, Mount Host Directory
Export specifies the external port
CMD specifies what to do after the container starts
2. Other directives
COPY copy file
ENV environment variable
The command executed after the ENTRYPOINT container is started
3, Write Dockerfile
1. Create Dockerfile file
[root@node1 ~]# mkdir -p /docker [root@node1 ~]# cd /docker/ [root@node1 docker]# vim Dockerfile
2. Prepare Dockerfile file
[root@node1 docker]# cat Dockerfile FROM nginx RUN echo '<meta charset=utf8>I want to study docker!' > /usr/share/nginx/html/index.html
3. Build Dockerfile
[root@node1 docker]# docker build . Sending build context to Docker daemon 2.048kB Step 1/2 : FROM nginx ---> 4cdc5dd7eaad Step 2/2 : RUN echo '<meta charset=utf8>I want to study docker!' > /usr/share/nginx/html/index.html ---> Running in 670e11acd981 Removing intermediate container 670e11acd981 ---> ecda82f680dc Successfully built ecda82f680dc [root@node1 docker]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE <none> <none> ecda82f680dc 23 seconds ago 133MB ittest/centos-vim-7.8.2003 latest 91e91af846d6 11 hours ago 386MB ubuntu latest c29284518f49 9 days ago 72.8MB nginx latest 4cdc5dd7eaad 2 weeks ago 133MB redis latest 08502081bff6 4 weeks ago 105MB fedora latest 055b2e5ebc94 2 months ago 178MB centos latest 300e315adb2f 7 months ago 209MB centos 7.8.2003 afb6fca791e0 14 months ago 203MB opensuse latest d9e50bf28896 2 years ago 111MB
4. Modify the image name
[root@node1 docker]# docker tag ecda82f680dc my_nginx [root@node1 docker]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE my_nginx latest ecda82f680dc About a minute ago 133MB ittest/centos-vim-7.8.2003 latest 91e91af846d6 11 hours ago 386MB ubuntu latest c29284518f49 9 days ago 72.8MB nginx latest 4cdc5dd7eaad 2 weeks ago 133MB redis latest 08502081bff6 4 weeks ago 105MB fedora latest 055b2e5ebc94 2 months ago 178MB centos latest 300e315adb2f 7 months ago 209MB centos 7.8.2003 afb6fca791e0 14 months ago 203MB opensuse latest d9e50bf28896 2 years ago 111MB
5. Run image
[root@node1 docker]# docker run -d -p 80:80 my_nginx 5fbf299d43ea252596fba7afbdfb9ba388cc586793016acb2adc9dad92ef7bdb [root@node1 docker]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 5fbf299d43ea my_nginx "/docker-entrypoint...." 5 seconds ago Up 5 seconds 0.0.0.0:80->80/tcp, :::80->80/tcp eager_pike
6. Test port 80 of the host
4, Dickerfile Instruction Learning
1.COPY
The COPY instruction copies files / directories from the host to a new layer of image
copy file*.txt /home # Multiple files and wildcards are supported to copy. The syntax needs to meet the filepath.Match of Golang copy file* /data/playbook-?.yml /data/ # The copy instruction can retain the metadata information of the file, such as permission, timestamp, etc.
2.ADD
The features are basically the same as COPY, but with some more functions
1. The source file is a URL. At this time, the docker engine will download the link and put it into the target path, and the permission is automatically set to 600. If this is not the expected result, a RUN instruction must be added to modify the permission of the file.
2. The source file is a URL and a compressed package. It will not be decompressed automatically. It must also be decompressed separately using the RUN instruction.
3. When the source file is a compressed file and is gzip, bzip2,xz,tar, etc., the ADD instruction will automatically decompress the file to the target path.
ADD file.tgz /home RUN chmod a+x xxxx #You can modify the permissions of remote files through the RUN command
3.CMD
① CMD command introduction
CMD runs a command in the container to start the program
CMD ["Parameter 1" , "Parameter 2"]
The docker is not a virtual machine, and the container is a process. When the program starts, it needs to specify some running parameters, which is the function of the CMD instruction.
② Example
ps:
docker run -it centos cat /etc/os-release # CMD runs shell instructions and will also be converted to shell form CMD echo $PATH Will translate into CMD ["sh","-c","echo $PATH"]
Host command line docker run -it centos cat /etc/os-release Equivalent to dockerfile Medium CMD ["cat","/etc/os-release"]
4. In vessel operation procedure
Incorrect writing: CMD ["sh"."-c","systemctl start nginx" ] The main process of such a command is the interpreter, which ends immediately after execution, so the container exits Correct writing: CMD ["nginx","-g","daemon off;"]
5.ENV and ARG
① Setting environment variables
ENV NAME="ZHANGSAN" ENV AGE="18" ENV MYSQL_VERSION=5.6 # For all subsequent operations, you can directly obtain the variable value through $NAME
② Difference between ENV and ARG
ARG and ENV are environment variables
The difference is ENV. This variable can be used either when the image is built or when the container is running
ARG is only a variable that needs to be set when building an image, and the container disappears when it runs.
6.VOLUME
When the container is running, it should be ensured that no data is written in the storage layer. The data generated in the container is recommended to be mounted and written to the host computer. Perform maintenance.
① volume introduction
VOLUME /data # The / data folder in the container is automatically mounted as an anonymous volume when the container is running, Any data written to the directory will not be recorded by the container to ensure that the container storage layer is stateless.
② Using volume in Dockerfile
# Dockerfile FROM centos MAINTAINER ZHANGSAN VOLUME ["/data1","/data2"]
③ Generate image
[root@node1 docker]# docker build . Sending build context to Docker daemon 2.048kB Step 1/3 : FROM centos:7.8.2003 ---> afb6fca791e0 Step 2/3 : MAINTAINER ZHANGSAN ---> Running in 5023bed7a914 Removing intermediate container 5023bed7a914 ---> b2242678f857 Step 3/3 : VOLUME ["/data1","/data2"] ---> Running in 8a181e92a341 Removing intermediate container 8a181e92a341 ---> 6cc85e0cee71 Successfully built 6cc85e0cee71 [root@node1 docker]# docker tag 6cc85e0cee71 centos_volume [root@node1 docker]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE centos_volume latest 6cc85e0cee71 26 seconds ago 203MB centos_curl_new latest d61875c20211 34 minutes ago 471MB centos_curl latest ded6737bf511 53 minutes ago 471MB my_nginx latest ecda82f680dc 10 hours ago 133MB ittest/centos-vim-7.8.2003 latest 91e91af846d6 21 hours ago 386MB ubuntu latest c29284518f49 9 days ago 72.8MB nginx latest 4cdc5dd7eaad 2 weeks ago 133MB redis latest 08502081bff6 4 weeks ago 105MB fedora latest 055b2e5ebc94 2 months ago 178MB centos latest 300e315adb2f 7 months ago 209MB centos 7.8.2003 afb6fca791e0 14 months ago 203MB opensuse latest d9e50bf28896 2 years ago 111MB
④ Run the mirror
[root@node1 docker]# docker run centos_volume [root@node1 docker]#
⑤ View container records and related information
[root@node1 docker]# docker inspect 447041a55a0d
[
{
"Id": "447041a55a0d681c123fbd6286a05fb7ab9d499949bf80d3e2aac96091596afa",
"Created": "2021-07-23T13:25:43.107269297Z",
"Path": "/bin/bash",
"Args": [],
"State": {
"Status": "exited",
"Running": false,
"Paused": false,
"Restarting": false,
"OOMKilled": false,
"Dead": false,
"Pid": 0,
"ExitCode": 0,
"Error": "",
"StartedAt": "2021-07-23T13:25:43.373146025Z",
"FinishedAt": "2021-07-23T13:25:43.372437154Z"
},
"Image": "sha256:6cc85e0cee71b1927a79d9ca3a26b11323f5e88ee6bb9a2b878354f46f357e04",
"ResolvConfPath": "/var/lib/docker/containers/447041a55a0d681c123fbd6286a05fb7ab9d499949bf80d3e2aac96091596afa/resolv.conf",
"HostnamePath": "/var/lib/docker/containers/447041a55a0d681c123fbd6286a05fb7ab9d499949bf80d3e2aac96091596afa/hostname",
"HostsPath": "/var/lib/docker/containers/447041a55a0d681c123fbd6286a05fb7ab9d499949bf80d3e2aac96091596afa/hosts",
"LogPath": "/var/lib/docker/containers/447041a55a0d681c123fbd6286a05fb7ab9d499949bf80d3e2aac96091596afa/447041a55a0d681c123fbd6286a05fb7ab9d499949bf80d3e2aac96091596afa-json.log",
"Name": "/exciting_burnell",
"RestartCount": 0,
"Driver": "overlay2",
"Platform": "linux",
"MountLabel": "",
"ProcessLabel": "",
"AppArmorProfile": "",
"ExecIDs": null,
"HostConfig": {
"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/overlay2/78b450fd961317740de1225ce03c760b514623c7a089bfecb591a861ecfd3b15-init/diff:/var/lib/docker/overlay2/c4fc8645dba560891da2786efe974432eb221f63cc8986ecccb4a28a77176ce9/diff",
"MergedDir": "/var/lib/docker/overlay2/78b450fd961317740de1225ce03c760b514623c7a089bfecb591a861ecfd3b15/merged",
"UpperDir": "/var/lib/docker/overlay2/78b450fd961317740de1225ce03c760b514623c7a089bfecb591a861ecfd3b15/diff",
"WorkDir": "/var/lib/docker/overlay2/78b450fd961317740de1225ce03c760b514623c7a089bfecb591a861ecfd3b15/work"
},
"Name": "overlay2"
},
"Mounts": [
{
"Type": "volume",
"Name": "05ba887cb41240b61b9ae7ba36aeb5509535fb5c370abccad8a0059c200d0927",
"Source": "/var/lib/docker/volumes/05ba887cb41240b61b9ae7ba36aeb5509535fb5c370abccad8a0059c200d0927/_data",
"Destination": "/data1",
"Driver": "local",
"Mode": "",
"RW": true,
"Propagation": ""
},
{
"Type": "volume",
"Name": "6d8df1897042a46ce8c339fe462405771b43e2107034ddf9805f2ef79d9ebb9d",
"Source": "/var/lib/docker/volumes/6d8df1897042a46ce8c339fe462405771b43e2107034ddf9805f2ef79d9ebb9d/_data",
"Destination": "/data2",
"Driver": "local",
"Mode": "",
"RW": true,
"Propagation": ""
}
],
"Config": {
"Hostname": "447041a55a0d",
"Domainname": "",
"User": "",
"AttachStdin": false,
"AttachStdout": true,
"AttachStderr": true,
"Tty": false,
"OpenStdin": false,
"StdinOnce": false,
"Env": [
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
],
"Cmd": [
"/bin/bash"
],
"Image": "centos_volume",
"Volumes": {
"/data1": {},
"/data2": {}
},
"WorkingDir": "",
"Entrypoint": null,
"OnBuild": null,
"Labels": {
"org.label-schema.build-date": "20200504",
"org.label-schema.license": "GPLv2",
"org.label-schema.name": "CentOS Base Image",
"org.label-schema.schema-version": "1.0",
"org.label-schema.vendor": "CentOS",
"org.opencontainers.image.created": "2020-05-04 00:00:00+01:00",
"org.opencontainers.image.licenses": "GPL-2.0-only",
"org.opencontainers.image.title": "CentOS Base Image",
"org.opencontainers.image.vendor": "CentOS"
}
},
"NetworkSettings": {
"Bridge": "",
"SandboxID": "97f42a5aae093e45b987aeac823fe9fcebba9500c67dd4f41215d820fb0fe49f",
"HairpinMode": false,
"LinkLocalIPv6Address": "",
"LinkLocalIPv6PrefixLen": 0,
"Ports": {},
"SandboxKey": "/var/run/docker/netns/97f42a5aae09",
"SecondaryIPAddresses": null,
"SecondaryIPv6Addresses": null,
"EndpointID": "",
"Gateway": "",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"IPAddress": "",
"IPPrefixLen": 0,
"IPv6Gateway": "",
"MacAddress": "",
"Networks": {
"bridge": {
"IPAMConfig": null,
"Links": null,
"Aliases": null,
"NetworkID": "9d69c7098d163d0e7e02b1e6da0feed684de33bd6b5a6f16d75900d74fa3f91c",
"EndpointID": "",
"Gateway": "",
"IPAddress": "",
"IPPrefixLen": 0,
"IPv6Gateway": "",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"MacAddress": "",
"DriverOpts": null
}
}
}
}
]
⑥ . container record information filtering
⑦ . container data mounting method
① The container data is mounted by specifying the volume directory through dockerfile.
② Directly set the directory to be mapped and mounted through the docker run -v parameter.
7.EXPOSE
① Introduction to export
Specifies the external port services provided by the container runtime
Help users of the image to quickly understand one port service of the container
② Export related commands
docker port container docker run -p Host port:Container port docker run -P Random host port: container port
8.WORKDIR
Used to switch directories and change working directories in dockerfile
WORKDIR /opt
9.USER
It is used to change the environment and switch users
USER ROOT USER ZHANGSAN
5, ENTRTPOINT learning
1. Introduction to entrtpoint
The function is the same as CMD, which starts the program and parameters in the specified container.
However, when ENTRYPOINT is specified, the semantics of the CMD instruction changes. At this time, the CMD content is passed to the ENTRYPOINT instruction as a parameter.
The function is the same as CMD, which starts the program and parameters in the specified container.
However, when ENTRYPOINT is specified, the semantics of the CMD instruction changes. At this time, the CMD content is passed to the ENTRYPOINT instruction as a parameter.
2. Quickly edit dockerfile
① Prepare a dockerfile
FROM centos:7.8.2003
RUN rpm --rebuilddb && yum install epel-release -y
RUN rpm --rebuilddb && yum install curl -y
CMD ["curl","-s","cip.cc"]
② Build mirror
[root@node1 docker]# echo > Dockerfile [root@node1 docker]# vim Dockerfile [root@node1 docker]# cat Dockerfile FROM centos:7.8.2003 RUN rpm --rebuilddb && yum install epel-release -y RUN rpm --rebuilddb && yum install curl -y CMD ["curl","-s","cip.cc"] [root@node1 docker]# [root@node1 docker]# docker build . Sending build context to Docker daemon 2.048kB Step 1/4 : FROM centos:7.8.2003 ---> afb6fca791e0 Step 2/4 : RUN rpm --rebuilddb && yum install epel-release -y ---> Running in 158ebc6f1701 Loaded plugins: fastestmirror, ovl Determining fastest mirrors * base: mirrors.aliyun.com * extras: mirrors.aliyun.com * updates: mirrors.aliyun.com Resolving Dependencies --> Running transaction check ---> Package epel-release.noarch 0:7-11 will be installed --> Finished Dependency Resolution Dependencies Resolved ================================================================================ Package Arch Version Repository Size ================================================================================ Installing: epel-release noarch 7-11 extras 15 k Transaction Summary ================================================================================ Install 1 Package Total download size: 15 k Installed size: 24 k Downloading packages: warning: /var/cache/yum/x86_64/7/extras/packages/epel-release-7-11.noarch.rpm: Header V3 RSA/SHA256 Signature, key ID f4a80eb5: NOKEY Public key for epel-release-7-11.noarch.rpm is not installed Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7 Importing GPG key 0xF4A80EB5: Userid : "CentOS-7 Key (CentOS 7 Official Signing Key) <security@centos.org>" Fingerprint: 6341 ab27 53d7 8a78 a7c2 7bb1 24c6 a8a7 f4a8 0eb5 Package : centos-release-7-8.2003.0.el7.centos.x86_64 (@CentOS) From : /etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7 Running transaction check Running transaction test Transaction test succeeded Running transaction Installing : epel-release-7-11.noarch 1/1 Verifying : epel-release-7-11.noarch 1/1 Installed: epel-release.noarch 0:7-11 Complete! Removing intermediate container 158ebc6f1701 ---> 96ed23874ab7 Step 3/4 : RUN rpm --rebuilddb && yum install curl -y ---> Running in a7c0bfbbcd58 Loaded plugins: fastestmirror, ovl Loading mirror speeds from cached hostfile * base: mirrors.aliyun.com * epel: mirror.lzu.edu.cn * extras: mirrors.aliyun.com * updates: mirrors.aliyun.com Resolving Dependencies --> Running transaction check ---> Package curl.x86_64 0:7.29.0-57.el7 will be updated ---> Package curl.x86_64 0:7.29.0-59.el7_9.1 will be an update --> Processing Dependency: libcurl = 7.29.0-59.el7_9.1 for package: curl-7.29.0-59.el7_9.1.x86_64 --> Running transaction check ---> Package libcurl.x86_64 0:7.29.0-57.el7 will be updated ---> Package libcurl.x86_64 0:7.29.0-59.el7_9.1 will be an update --> Finished Dependency Resolution Dependencies Resolved ================================================================================ Package Arch Version Repository Size ================================================================================ Updating: curl x86_64 7.29.0-59.el7_9.1 updates 271 k Updating for dependencies: libcurl x86_64 7.29.0-59.el7_9.1 updates 223 k Transaction Summary ================================================================================ Upgrade 1 Package (+1 Dependent package) Total download size: 494 k Downloading packages: Delta RPMs disabled because /usr/bin/applydeltarpm not installed. -------------------------------------------------------------------------------- Total 1.7 MB/s | 494 kB 00:00 Running transaction check Running transaction test Transaction test succeeded Running transaction Updating : libcurl-7.29.0-59.el7_9.1.x86_64 1/4 Updating : curl-7.29.0-59.el7_9.1.x86_64 2/4 Cleanup : curl-7.29.0-57.el7.x86_64 3/4 Cleanup : libcurl-7.29.0-57.el7.x86_64 4/4 Verifying : curl-7.29.0-59.el7_9.1.x86_64 1/4 Verifying : libcurl-7.29.0-59.el7_9.1.x86_64 2/4 Verifying : curl-7.29.0-57.el7.x86_64 3/4 Verifying : libcurl-7.29.0-57.el7.x86_64 4/4 Updated: curl.x86_64 0:7.29.0-59.el7_9.1 Dependency Updated: libcurl.x86_64 0:7.29.0-59.el7_9.1 Complete! Removing intermediate container a7c0bfbbcd58 ---> 9a8cae434aa1 Step 4/4 : CMD ["curl","-s","cip.cc"] ---> Running in af92ee01da66 Removing intermediate container af92ee01da66 ---> ded6737bf511 Successfully built ded6737bf511
③ View mirror
[root@node1 docker]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE <none> <none> ded6737bf511 About a minute ago 471MB my_nginx latest ecda82f680dc 9 hours ago 133MB ittest/centos-vim-7.8.2003 latest 91e91af846d6 20 hours ago 386MB ubuntu latest c29284518f49 9 days ago 72.8MB nginx latest 4cdc5dd7eaad 2 weeks ago 133MB redis latest 08502081bff6 4 weeks ago 105MB fedora latest 055b2e5ebc94 2 months ago 178MB centos latest 300e315adb2f 7 months ago 209MB centos 7.8.2003 afb6fca791e0 14 months ago 203MB opensuse latest d9e50bf28896 2 years ago 111MB [root@node1 docker]# docker tag ded6737bf511 centos_curl [root@node1 docker]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE centos_curl latest ded6737bf511 About a minute ago 471MB my_nginx latest ecda82f680dc 9 hours ago 133MB ittest/centos-vim-7.8.2003 latest 91e91af846d6 20 hours ago 386MB ubuntu latest c29284518f49 9 days ago 72.8MB nginx latest 4cdc5dd7eaad 2 weeks ago 133MB redis latest 08502081bff6 4 weeks ago 105MB fedora latest 055b2e5ebc94 2 months ago 178MB centos latest 300e315adb2f 7 months ago 209MB centos 7.8.2003 afb6fca791e0 14 months ago 203MB opensuse latest d9e50bf28896 2 years ago 111MB
④ Run the image to generate container records
[root@node1 docker]# docker run centos_curl IP : xx.xx.xx.195 address : Ezhou, Hubei, China Operator : Unicom Data II : Xiangyang City, Hubei Province | Unicom Data three : Ezhou, Hubei, China | Unicom URL : http://www.cip.cc/xx.xx.xxx.195
⑤ Parameters cannot be passed in directly again
When tested, parameters cannot be directly passed in. This form is to overwrite the CMD in the image
[root@node1 docker]# docker run centos_curl -I docker: Error response from daemon: OCI runtime create failed: container_linux.go:380: starting container process caused: exec: "-I": executable file not found in $PATH: unknown. [root@node1 docker]# docker run centos_curl pwd /
3. Use entrypoint to pass in parameters to the container normally
Edit Dockerfile
① Modify Dockerfile
[root@node1 docker]# cat Dockerfile FROM centos:7.8.2003 RUN rpm --rebuilddb && yum install epel-release -y RUN rpm --rebuilddb && yum install curl -y CMD ["curl","-s","cip.cc"] ENTRYPOINT ["curl","-s","cip.cc"]
② Generate a new image
[root@node1 docker]# docker build . Sending build context to Docker daemon 2.048kB Step 1/5 : FROM centos:7.8.2003 ---> afb6fca791e0 Step 2/5 : RUN rpm --rebuilddb && yum install epel-release -y ---> Using cache ---> 96ed23874ab7 Step 3/5 : RUN rpm --rebuilddb && yum install curl -y ---> Using cache ---> 9a8cae434aa1 Step 4/5 : CMD ["curl","-s","cip.cc"] ---> Using cache ---> ded6737bf511 Step 5/5 : ENTRYPOINT ["curl","-s","cip.cc"] ---> Running in 02884a32cdc9 Removing intermediate container 02884a32cdc9 ---> d61875c20211 Successfully built d61875c20211 [root@node1 docker]# docker tag d61875c20211 centos_curl_new [root@node1 docker]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE centos_curl_new latest d61875c20211 32 seconds ago 471MB centos_curl latest ded6737bf511 20 minutes ago 471MB my_nginx latest ecda82f680dc 9 hours ago 133MB ittest/centos-vim-7.8.2003 latest 91e91af846d6 20 hours ago 386MB ubuntu latest c29284518f49 9 days ago 72.8MB nginx latest 4cdc5dd7eaad 2 weeks ago 133MB redis latest 08502081bff6 4 weeks ago 105MB fedora latest 055b2e5ebc94 2 months ago 178MB centos latest 300e315adb2f 7 months ago 209MB centos 7.8.2003 afb6fca791e0 14 months ago 203MB opensuse latest d9e50bf28896 2 years ago 111MB
③ Pass in parameters to the container normally
[root@node1 docker]# docker run centos_curl_new -I HTTP/1.1 200 OK Server: openresty Date: Fri, 23 Jul 2021 12:46:47 GMT Content-Type: text/html; charset=UTF-8 Connection: keep-alive Vary: Accept-Encoding X-cip-c: H [root@node1 docker]#
Note: the CMD instruction passed in is regarded as the parameter of ENTRYPOINT
The complete command executed in the container is curl - s cip.cc -I