To containerize we need a Dockerfile which is a text document that contains all the commands a user could call on the command line to assemble an image.
My Dockerfile looks like
vi Dockerfile
# we are using ‘centos’ base image
FROM centos:latest
#Author
MAINTAINER Emre
###Installing httpd web server
RUN yum clean all
RUN yum -y update
RUN yum install -y httpd
### Copying index.html
COPY ./index.html /var/www/html/
# Expose the default port
EXPOSE 80
# Start the service
CMD [“-D”, “FOREGROUND”]
ENTRYPOINT [“/usr/sbin/httpd”]
And I have got a index.html file.Its looks like:
<html>
<header><title>Hello Sysaix Fans</title></header>
<body>
Hello man!
</body>
</html>Instruction commands:
FROM -> It refers the base image from which we are going to build custom image. This instruction should be the first line in Dockerfile
MAINTAINER -> It refers author of the custom image
RUN -> it refers the set of commands which needs to be executed on image and commit it to image.
LABEL -> it refers the naming to image
CMD -> it refers the set of commands which needs to executed on container while bringing up contianer. There should be only one CMD entry in Dockerfile
ENTRYPOINT -> it refers the default command set of container during startup
EXPOSE -> it maps the container port and docker host port
ENV -> it refers the environmental variables and it is key value pair
ADD and COPY -> It is used to copy the files from context area to inside the container.
VOLUME -> it refers the mount point
USER -> it refers the username (user id) by which the above said RUN instruction should run
WORKDIR -> it refers the working directory location path where the above said RUN instructions should run.
[root@instance-4 dockerfolder]# docker build -t centos/new1 .
Sending build context to Docker daemon 3.072 kB
Step 1/9 : FROM centos:latest
Trying to pull repository registry.access.redhat.com/centos ...
Trying to pull repository docker.io/library/centos ...
latest: Pulling from docker.io/library/centos
256b176beaff: Pull complete
Digest: sha256:6f6d986d425aeabdc3a02cb61c02abb2e78e57357e92417d6d58332856024faf
Status: Downloaded newer image for docker.io/centos:latest
---> 5182e96772bf
Step 2/9 : MAINTAINER Emre
---> Running in c515e39bc20e
---> 6705887093bf
Removing intermediate container c515e39bc20e
Step 3/9 : RUN yum clean all
---> Running in b034450135b5
Loaded plugins: fastestmirror, ovl
Cleaning repos: base extras updates
Cleaning up everything
Maybe you want: rm -rf /var/cache/yum, to also free up space taken by orphaned data from disabled or removed repos
---> 8e80aaa07823
Removing intermediate container b034450135b5
Step 4/9 : RUN yum -y update
---> Running in 4740c9af6522
Loaded plugins: fastestmirror, ovl
Determining fastest mirrors
* base: mirror.vcu.edu
* extras: mirror.mojohost.com
* updates: mirror.mojohost.com
Resolving Dependencies
--> Running transaction check
---> Package audit-libs.x86_64 0:2.8.1-3.el7 will be updated
---> Package audit-libs.x86_64 0:2.8.1-3.el7_5.1 will be an update
---> Package centos-release.x86_64 0:7-5.1804.1.el7.centos will be updated
---> Package centos-release.x86_64 0:7-5.1804.4.el7.centos will be an update
---> Package dracut.x86_64 0:033-535.el7 will be updated
---> Package dracut.x86_64 0:033-535.el7_5.1 will be an update
---> Package kpartx.x86_64 0:0.4.9-119.el7 will be updated
---> Package kpartx.x86_64 0:0.4.9-119.el7_5.1 will be an update
---> Package libblkid.x86_64 0:2.23.2-52.el7 will be updated
---> Package libblkid.x86_64 0:2.23.2-52.el7_5.1 will be an update
---> Package libmount.x86_64 0:2.23.2-52.el7 will be updated
---> Package libmount.x86_64 0:2.23.2-52.el7_5.1 will be an update
---> Package libuuid.x86_64 0:2.23.2-52.el7 will be updated
---> Package libuuid.x86_64 0:2.23.2-52.el7_5.1 will be an update
---> Package systemd.x86_64 0:219-57.el7 will be updated
---> Package systemd.x86_64 0:219-57.el7_5.1 will be an update
---> Package systemd-libs.x86_64 0:219-57.el7 will be updated
---> Package systemd-libs.x86_64 0:219-57.el7_5.1 will be an update
---> Package util-linux.x86_64 0:2.23.2-52.el7 will be updated
---> Package util-linux.x86_64 0:2.23.2-52.el7_5.1 will be an update
--> Finished Dependency Resolution
Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Updating:
audit-libs x86_64 2.8.1-3.el7_5.1 updates 99 k
centos-release x86_64 7-5.1804.4.el7.centos updates 25 k
dracut x86_64 033-535.el7_5.1 updates 325 k
kpartx x86_64 0.4.9-119.el7_5.1 updates 76 k
libblkid x86_64 2.23.2-52.el7_5.1 updates 178 k
libmount x86_64 2.23.2-52.el7_5.1 updates 180 k
libuuid x86_64 2.23.2-52.el7_5.1 updates 81 k
systemd x86_64 219-57.el7_5.1 updates 5.0 M
systemd-libs x86_64 219-57.el7_5.1 updates 402 k
util-linux x86_64 2.23.2-52.el7_5.1 updates 2.0 M
Transaction Summary
================================================================================
Upgrade 10 Packages
Total download size: 8.4 M
Downloading packages:
Delta RPMs disabled because /usr/bin/applydeltarpm not installed.
Public key for centos-release-7-5.1804.4.el7.centos.x86_64.rpm is not installed
warning: /var/cache/yum/x86_64/7/updates/packages/centos-release-7-5.1804.4.el7.centos.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID f4a80eb5: NOKEY
--------------------------------------------------------------------------------
Total 8.3 MB/s | 8.4 MB 00:01
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-7-5.1804.1.el7.centos.x86_64 (@Updates)
From : /etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Updating : libuuid-2.23.2-52.el7_5.1.x86_64 1/20
Updating : libblkid-2.23.2-52.el7_5.1.x86_64 2/20
Updating : libmount-2.23.2-52.el7_5.1.x86_64 3/20
Updating : systemd-libs-219-57.el7_5.1.x86_64 4/20
Updating : audit-libs-2.8.1-3.el7_5.1.x86_64 5/20
Updating : util-linux-2.23.2-52.el7_5.1.x86_64 6/20
Updating : centos-release-7-5.1804.4.el7.centos.x86_64 7/20
Updating : systemd-219-57.el7_5.1.x86_64 8/20
Updating : kpartx-0.4.9-119.el7_5.1.x86_64 9/20
Updating : dracut-033-535.el7_5.1.x86_64 10/20
Cleanup : dracut-033-535.el7.x86_64 11/20
Cleanup : systemd-219-57.el7.x86_64 12/20
Cleanup : util-linux-2.23.2-52.el7.x86_64 13/20
Cleanup : centos-release-7-5.1804.1.el7.centos.x86_64 14/20
Cleanup : libmount-2.23.2-52.el7.x86_64 15/20
Cleanup : libblkid-2.23.2-52.el7.x86_64 16/20
Cleanup : libuuid-2.23.2-52.el7.x86_64 17/20
Cleanup : audit-libs-2.8.1-3.el7.x86_64 18/20
Cleanup : systemd-libs-219-57.el7.x86_64 19/20
Cleanup : kpartx-0.4.9-119.el7.x86_64 20/20
Verifying : systemd-219-57.el7_5.1.x86_64 1/20
Verifying : kpartx-0.4.9-119.el7_5.1.x86_64 2/20
Verifying : libuuid-2.23.2-52.el7_5.1.x86_64 3/20
Verifying : libblkid-2.23.2-52.el7_5.1.x86_64 4/20
Verifying : audit-libs-2.8.1-3.el7_5.1.x86_64 5/20
Verifying : util-linux-2.23.2-52.el7_5.1.x86_64 6/20
Verifying : systemd-libs-219-57.el7_5.1.x86_64 7/20
Verifying : libmount-2.23.2-52.el7_5.1.x86_64 8/20
Verifying : centos-release-7-5.1804.4.el7.centos.x86_64 9/20
Verifying : dracut-033-535.el7_5.1.x86_64 10/20
Verifying : kpartx-0.4.9-119.el7.x86_64 11/20
Verifying : util-linux-2.23.2-52.el7.x86_64 12/20
Verifying : systemd-libs-219-57.el7.x86_64 13/20
Verifying : libmount-2.23.2-52.el7.x86_64 14/20
Verifying : audit-libs-2.8.1-3.el7.x86_64 15/20
Verifying : libblkid-2.23.2-52.el7.x86_64 16/20
Verifying : centos-release-7-5.1804.1.el7.centos.x86_64 17/20
Verifying : libuuid-2.23.2-52.el7.x86_64 18/20
Verifying : systemd-219-57.el7.x86_64 19/20
Verifying : dracut-033-535.el7.x86_64 20/20
Updated:
audit-libs.x86_64 0:2.8.1-3.el7_5.1
centos-release.x86_64 0:7-5.1804.4.el7.centos
dracut.x86_64 0:033-535.el7_5.1
kpartx.x86_64 0:0.4.9-119.el7_5.1
libblkid.x86_64 0:2.23.2-52.el7_5.1
libmount.x86_64 0:2.23.2-52.el7_5.1
libuuid.x86_64 0:2.23.2-52.el7_5.1
systemd.x86_64 0:219-57.el7_5.1
systemd-libs.x86_64 0:219-57.el7_5.1
util-linux.x86_64 0:2.23.2-52.el7_5.1
Complete!
---> 09c71ca7b09b
Removing intermediate container 4740c9af6522
Step 5/9 : RUN yum install -y httpd
---> Running in cf2b719de843
Loaded plugins: fastestmirror, ovl
Loading mirror speeds from cached hostfile
* base: mirror.vcu.edu
* extras: mirror.mojohost.com
* updates: mirror.mojohost.com
Resolving Dependencies
--> Running transaction check
---> Package httpd.x86_64 0:2.4.6-80.el7.centos.1 will be installed
--> Processing Dependency: httpd-tools = 2.4.6-80.el7.centos.1 for package: httpd-2.4.6-80.el7.centos.1.x86_64
--> Processing Dependency: system-logos >= 7.92.1-1 for package: httpd-2.4.6-80.el7.centos.1.x86_64
--> Processing Dependency: /etc/mime.types for package: httpd-2.4.6-80.el7.centos.1.x86_64
--> Processing Dependency: libaprutil-1.so.0()(64bit) for package: httpd-2.4.6-80.el7.centos.1.x86_64
--> Processing Dependency: libapr-1.so.0()(64bit) for package: httpd-2.4.6-80.el7.centos.1.x86_64
--> Running transaction check
---> Package apr.x86_64 0:1.4.8-3.el7_4.1 will be installed
---> Package apr-util.x86_64 0:1.5.2-6.el7 will be installed
---> Package centos-logos.noarch 0:70.0.6-3.el7.centos will be installed
---> Package httpd-tools.x86_64 0:2.4.6-80.el7.centos.1 will be installed
---> Package mailcap.noarch 0:2.1.41-2.el7 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
httpd x86_64 2.4.6-80.el7.centos.1 updates 2.7 M
Installing for dependencies:
apr x86_64 1.4.8-3.el7_4.1 base 103 k
apr-util x86_64 1.5.2-6.el7 base 92 k
centos-logos noarch 70.0.6-3.el7.centos base 21 M
httpd-tools x86_64 2.4.6-80.el7.centos.1 updates 90 k
mailcap noarch 2.1.41-2.el7 base 31 k
Transaction Summary
================================================================================
Install 1 Package (+5 Dependent packages)
Total download size: 24 M
Installed size: 31 M
Downloading packages:
--------------------------------------------------------------------------------
Total 29 MB/s | 24 MB 00:00
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing : apr-1.4.8-3.el7_4.1.x86_64 1/6
Installing : apr-util-1.5.2-6.el7.x86_64 2/6
Installing : httpd-tools-2.4.6-80.el7.centos.1.x86_64 3/6
Installing : centos-logos-70.0.6-3.el7.centos.noarch 4/6
Installing : mailcap-2.1.41-2.el7.noarch 5/6
Installing : httpd-2.4.6-80.el7.centos.1.x86_64 6/6
Verifying : mailcap-2.1.41-2.el7.noarch 1/6
Verifying : httpd-tools-2.4.6-80.el7.centos.1.x86_64 2/6
Verifying : apr-util-1.5.2-6.el7.x86_64 3/6
Verifying : httpd-2.4.6-80.el7.centos.1.x86_64 4/6
Verifying : apr-1.4.8-3.el7_4.1.x86_64 5/6
Verifying : centos-logos-70.0.6-3.el7.centos.noarch 6/6
Installed:
httpd.x86_64 0:2.4.6-80.el7.centos.1
Dependency Installed:
apr.x86_64 0:1.4.8-3.el7_4.1
apr-util.x86_64 0:1.5.2-6.el7
centos-logos.noarch 0:70.0.6-3.el7.centos
httpd-tools.x86_64 0:2.4.6-80.el7.centos.1
mailcap.noarch 0:2.1.41-2.el7
Complete!
---> 8769b9bb9903
Removing intermediate container cf2b719de843
Step 6/9 : COPY ./index.html /var/www/html/
---> 6148fbcb6eb4
Removing intermediate container e22f4e40f061
Step 7/9 : EXPOSE 80
---> Running in e388c9d5a1ed
---> 8fb59f9d8e91
Removing intermediate container e388c9d5a1ed
Step 8/9 : CMD [“-D”, “FOREGROUND”]
---> Running in 2fea17f43992
---> 26f23f43f3af
Removing intermediate container 2fea17f43992
Step 9/9 : ENTRYPOINT [“/usr/sbin/httpd”]
---> Running in 85b08db9b615
---> d7489adf5f2f
Removing intermediate container 85b08db9b615
Successfully built d7489adf5f2f
[root@instance-4 dockerfolder]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
centos/firstweb latest d7489adf5f2f 36 seconds ago 476 MB
docker.io/centos latest 5182e96772bf 2 weeks ago 200 MB
[root@instance-4 dockerfolder]# root@instance-4 dockerfolder]# docker run -d -p 80:80 centos/new1
edaf3694003b302cdc8c713d6529f4440a4b7139bef5421c661884dba7301409root@instance-4 dockerfolder]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
1a121102d61f centos/new1 "/usr/sbin/httpd -D …" 10 minutes ago Up 10 minutes 0.0.0.0:80->80/tcp helloweb
