In Red Hat Enterprise Linux (RHEL) 8, the support for Docker has been removed. Whereas, a new containerization platform libpod (Podman's Container Management Library) has been introduced in RHEL 8. Being an upstream fork, CentOS 8 also follows the same path.
Therefore, to setup a containerization platform in CentOS 8, we have to install podman (Pod Manager tool) and relevant packages on our server. Following are the CLI tools used in this new container platform.
- podman - Client tool for managing containers.
- skopeo - Client tool for copying container images to/from registries.
- buildah - Client tool for building OCI (Open Container Initiative) complaince containers.
- runc - Container runtime client for running and working with OCI format containers.
In CentOS 8 yum repository, these tools are available separately in distinct packages as well as bundled in a common module:container-tools.
The best way to install all these tools is by using the container-tools module.
In this article, we are installing Podman containers on CentOS 8 and then create and run a test container using new podman tool.
Table of Contents:
- Environment Specification
- Installing Podman Containers on CentOS 8
- Using Podman Containers on CentOS 8
Environment Specification:
We have provisioned virtual machine with minimally installed CentOS 8 with following specification.
- CPU - 3.4 Ghz (2 cores)
- Memory - 2 GB
- Storage - 20 GB
- Operating System - CentOS 8.0
- Hostname - podman-01.recipes.com
- IP Address - 192.168.116.206 /24
Installing Podman Containers on CentOS 8:
Connect with podman-01.recipes.com using ssh as root user.
Build dnf cache using following command.
[root@podman-01 ~]# dnf makecache
CentOS-8 - AppStream 2.3 kB/s | 4.3 kB 00:01
CentOS-8 - Base 1.7 kB/s | 3.9 kB 00:02
CentOS-8 - Extras 649 B/s | 1.5 kB 00:02
Metadata cache created.
Install container-tools module using dnf command.
[root@podman-01 ~]# dnf install -y @container-tools
Last metadata expiration check: 0:03:35 ago on Mon 23 Dec 2019 09:41:36 PM PKT.
Dependencies resolved.
================================================================================
Package Arch Version Repository
Size
================================================================================
Installing group/module packages:
buildah x86_64 1.5-3.gite94b4f9.module_el8.0.0+58+91b614e7
AppStream 5.3 M
container-selinux noarch 2:2.94-1.git1e99f1d.module_el8.0.0+58+91b614e7
AppStream 43 k
containernetworking-plugins x86_64 0.7.4-3.git9ebe139.module_el8.0.0+58+91b614e7
AppStream 14 M
fuse-overlayfs x86_64 0.3-2.module_el8.0.0+58+91b614e7
AppStream 48 k
oci-systemd-hook x86_64 1:0.1.15-2.git2d0b8a3.module_el8.0.0+58+91b614e7
AppStream 39 k
oci-umount x86_64 2:2.3.4-2.git87f9237.module_el8.0.0+194+ac560166
AppStream 38 k
podman x86_64 1.0.5-1.gitf604175.module_el8.0.0+194+ac560166
AppStream 9.1 M
runc x86_64 1.0.0-55.rc5.dev.git2abd837.module_el8.0.0+58+91b614e7
AppStream 2.3 M
skopeo x86_64 1:0.1.32-3.git1715c90.module_el8.0.0+58+91b614e7
AppStream 4.8 M
slirp4netns x86_64 0.1-2.dev.gitc4e1bc5.module_el8.0.0+58+91b614e7
AppStream 55 k
Installing dependencies:
containers-common x86_64 1:0.1.32-3.git1715c90.module_el8.0.0+58+91b614e7
AppStream 31 k
criu x86_64 3.10-7.el8 AppStream 482 k
libnet x86_64 1.1.6-15.el8 AppStream 67 k
ostree-libs x86_64 2018.8-2.el8 AppStream 382 k
protobuf-c x86_64 1.3.0-4.el8 AppStream 37 k
yajl x86_64 2.1.0-10.el8 AppStream 41 k
checkpolicy x86_64 2.8-2.el8 BaseOS 338 k
fuse3-libs x86_64 3.2.1-12.el8 BaseOS 94 k
policycoreutils-python-utils noarch 2.8-16.1.el8 BaseOS 228 k
python3-audit x86_64 3.0-0.10.20180831git0047a6c.el8
BaseOS 85 k
python3-libsemanage x86_64 2.8-5.el8 BaseOS 127 k
python3-policycoreutils noarch 2.8-16.1.el8 BaseOS 2.2 M
python3-setools x86_64 4.2.0-2.el8 BaseOS 598 k
Installing module profiles:
container-tools/common
Enabling module streams:
container-tools rhel8
Transaction Summary
================================================================================
Install 23 Packages
Total download size: 40 M
Installed size: 146 M
Downloading Packages:
(1/23): container-selinux-2.94-1.git1e99f1d.mod 21 kB/s | 43 kB 00:02
(2/23): containers-common-0.1.32-3.git1715c90.m 67 kB/s | 31 kB 00:00
(3/23): criu-3.10-7.el8.x86_64.rpm 93 kB/s | 482 kB 00:05
(4/23): fuse-overlayfs-0.3-2.module_el8.0.0+58+ 83 kB/s | 48 kB 00:00
(5/23): libnet-1.1.6-15.el8.x86_64.rpm 63 kB/s | 67 kB 00:01
(6/23): oci-systemd-hook-0.1.15-2.git2d0b8a3.mo 69 kB/s | 39 kB 00:00
(7/23): oci-umount-2.3.4-2.git87f9237.module_el 65 kB/s | 38 kB 00:00
(8/23): ostree-libs-2018.8-2.el8.x86_64.rpm 120 kB/s | 382 kB 00:03
(9/23): podman-1.0.5-1.gitf604175.module_el8.0. 132 kB/s | 9.1 MB 01:10
(10/23): protobuf-c-1.3.0-4.el8.x86_64.rpm 34 kB/s | 37 kB 00:01
(11/23): buildah-1.5-3.gite94b4f9.module_el8.0. 60 kB/s | 5.3 MB 01:29
(12/23): runc-1.0.0-55.rc5.dev.git2abd837.modul 160 kB/s | 2.3 MB 00:15
(13/23): slirp4netns-0.1-2.dev.gitc4e1bc5.modul 106 kB/s | 55 kB 00:00
(14/23): yajl-2.1.0-10.el8.x86_64.rpm 39 kB/s | 41 kB 00:01
(15/23): checkpolicy-2.8-2.el8.x86_64.rpm 31 kB/s | 338 kB 00:11
(16/23): fuse3-libs-3.2.1-12.el8.x86_64.rpm 39 kB/s | 94 kB 00:02
(17/23): policycoreutils-python-utils-2.8-16.1. 37 kB/s | 228 kB 00:06
(18/23): python3-audit-3.0-0.10.20180831git0047 27 kB/s | 85 kB 00:03
(19/23): python3-libsemanage-2.8-5.el8.x86_64.r 38 kB/s | 127 kB 00:03
(20/23): python3-policycoreutils-2.8-16.1.el8.n 77 kB/s | 2.2 MB 00:29
(21/23): python3-setools-4.2.0-2.el8.x86_64.rpm 113 kB/s | 598 kB 00:05
(22/23): skopeo-0.1.32-3.git1715c90.module_el8. 67 kB/s | 4.8 MB 01:13
(23/23): containernetworking-plugins-0.7.4-3.gi 71 kB/s | 14 MB 03:18
--------------------------------------------------------------------------------
Total 203 kB/s | 40 MB 03:22
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
Preparing : 1/1
Installing : ostree-libs-2018.8-2.el8.x86_64 1/23
Installing : yajl-2.1.0-10.el8.x86_64 2/23
Installing : slirp4netns-0.1-2.dev.gitc4e1bc5.module_el8.0.0+58 3/23
Installing : oci-systemd-hook-1:0.1.15-2.git2d0b8a3.module_el8. 4/23
Installing : python3-setools-4.2.0-2.el8.x86_64 5/23
Installing : python3-libsemanage-2.8-5.el8.x86_64 6/23
Installing : python3-audit-3.0-0.10.20180831git0047a6c.el8.x86_ 7/23
Installing : fuse3-libs-3.2.1-12.el8.x86_64 8/23
Running scriptlet: fuse3-libs-3.2.1-12.el8.x86_64 8/23
Installing : fuse-overlayfs-0.3-2.module_el8.0.0+58+91b614e7.x8 9/23
Installing : containers-common-1:0.1.32-3.git1715c90.module_el8 10/23
Installing : checkpolicy-2.8-2.el8.x86_64 11/23
Installing : python3-policycoreutils-2.8-16.1.el8.noarch 12/23
Installing : policycoreutils-python-utils-2.8-16.1.el8.noarch 13/23
Installing : container-selinux-2:2.94-1.git1e99f1d.module_el8.0 14/23
Running scriptlet: container-selinux-2:2.94-1.git1e99f1d.module_el8.0 14/23
Installing : protobuf-c-1.3.0-4.el8.x86_64 15/23
Installing : libnet-1.1.6-15.el8.x86_64 16/23
Running scriptlet: libnet-1.1.6-15.el8.x86_64 16/23
Installing : criu-3.10-7.el8.x86_64 17/23
Installing : runc-1.0.0-55.rc5.dev.git2abd837.module_el8.0.0+58 18/23
Installing : containernetworking-plugins-0.7.4-3.git9ebe139.mod 19/23
Installing : podman-1.0.5-1.gitf604175.module_el8.0.0+194+ac560 20/23
Installing : buildah-1.5-3.gite94b4f9.module_el8.0.0+58+91b614e 21/23
Installing : skopeo-1:0.1.32-3.git1715c90.module_el8.0.0+58+91b 22/23
Installing : oci-umount-2:2.3.4-2.git87f9237.module_el8.0.0+194 23/23
Running scriptlet: oci-umount-2:2.3.4-2.git87f9237.module_el8.0.0+194 23/23
Verifying : buildah-1.5-3.gite94b4f9.module_el8.0.0+58+91b614e 1/23
Verifying : container-selinux-2:2.94-1.git1e99f1d.module_el8.0 2/23
Verifying : containernetworking-plugins-0.7.4-3.git9ebe139.mod 3/23
Verifying : containers-common-1:0.1.32-3.git1715c90.module_el8 4/23
Verifying : criu-3.10-7.el8.x86_64 5/23
Verifying : fuse-overlayfs-0.3-2.module_el8.0.0+58+91b614e7.x8 6/23
Verifying : libnet-1.1.6-15.el8.x86_64 7/23
Verifying : oci-systemd-hook-1:0.1.15-2.git2d0b8a3.module_el8. 8/23
Verifying : oci-umount-2:2.3.4-2.git87f9237.module_el8.0.0+194 9/23
Verifying : ostree-libs-2018.8-2.el8.x86_64 10/23
Verifying : podman-1.0.5-1.gitf604175.module_el8.0.0+194+ac560 11/23
Verifying : protobuf-c-1.3.0-4.el8.x86_64 12/23
Verifying : runc-1.0.0-55.rc5.dev.git2abd837.module_el8.0.0+58 13/23
Verifying : skopeo-1:0.1.32-3.git1715c90.module_el8.0.0+58+91b 14/23
Verifying : slirp4netns-0.1-2.dev.gitc4e1bc5.module_el8.0.0+58 15/23
Verifying : yajl-2.1.0-10.el8.x86_64 16/23
Verifying : checkpolicy-2.8-2.el8.x86_64 17/23
Verifying : fuse3-libs-3.2.1-12.el8.x86_64 18/23
Verifying : policycoreutils-python-utils-2.8-16.1.el8.noarch 19/23
Verifying : python3-audit-3.0-0.10.20180831git0047a6c.el8.x86_ 20/23
Verifying : python3-libsemanage-2.8-5.el8.x86_64 21/23
Verifying : python3-policycoreutils-2.8-16.1.el8.noarch 22/23
Verifying : python3-setools-4.2.0-2.el8.x86_64 23/23
Installed:
buildah-1.5-3.gite94b4f9.module_el8.0.0+58+91b614e7.x86_64
container-selinux-2:2.94-1.git1e99f1d.module_el8.0.0+58+91b614e7.noarch
containernetworking-plugins-0.7.4-3.git9ebe139.module_el8.0.0+58+91b614e7.x86_64
fuse-overlayfs-0.3-2.module_el8.0.0+58+91b614e7.x86_64
oci-systemd-hook-1:0.1.15-2.git2d0b8a3.module_el8.0.0+58+91b614e7.x86_64
oci-umount-2:2.3.4-2.git87f9237.module_el8.0.0+194+ac560166.x86_64
podman-1.0.5-1.gitf604175.module_el8.0.0+194+ac560166.x86_64
runc-1.0.0-55.rc5.dev.git2abd837.module_el8.0.0+58+91b614e7.x86_64
skopeo-1:0.1.32-3.git1715c90.module_el8.0.0+58+91b614e7.x86_64
slirp4netns-0.1-2.dev.gitc4e1bc5.module_el8.0.0+58+91b614e7.x86_64
containers-common-1:0.1.32-3.git1715c90.module_el8.0.0+58+91b614e7.x86_64
criu-3.10-7.el8.x86_64
libnet-1.1.6-15.el8.x86_64
ostree-libs-2018.8-2.el8.x86_64
protobuf-c-1.3.0-4.el8.x86_64
yajl-2.1.0-10.el8.x86_64
checkpolicy-2.8-2.el8.x86_64
fuse3-libs-3.2.1-12.el8.x86_64
policycoreutils-python-utils-2.8-16.1.el8.noarch
python3-audit-3.0-0.10.20180831git0047a6c.el8.x86_64
python3-libsemanage-2.8-5.el8.x86_64
python3-policycoreutils-2.8-16.1.el8.noarch
python3-setools-4.2.0-2.el8.x86_64
Complete!
Podman and related containerization tools has been installed on CentOS 8.
Using Podman Containers on CentOS 8:
Check Podman version.
[root@podman-01 ~]# podman version
Version: 1.0.5
Go Version: go1.11.6
OS/Arch: linux/amd64
Search for an image using podman command.
[root@podman-01 ~]# podman search alpine --filter is-official=true
INDEX NAME DESCRIPTION STARS OFFICIAL AUTOMATED
docker.io docker.io/library/alpine A minimal Docker image based on Alpine Linux... 5937 [OK]
Pull an image from online registry.
[root@podman-01 ~]# podman pull docker.io/library/alpine
Trying to pull docker.io/library/alpine...Getting image source signatures
Copying blob 63bc94deeb28: 2.65 MiB / 2.67 MiB [===============================]
Copying blob 63bc94deeb28: 2.67 MiB / 2.67 MiB [============================] 9s
Copying config c85b8f829d1f: 1.48 KiB / 1.48 KiB [==========================] 0s
Writing manifest to image destination
Storing signatures
c85b8f829d1f93a25fe91d2ce7dccf7ec723794873a77bb19623d38e926c788c
Show list of local podman images.
[root@podman-01 ~]# podman images
REPOSITORY TAG IMAGE ID CREATED SIZE
docker.io/library/alpine latest c85b8f829d1f 3 days ago 5.86 MB
Inspect the alpine Linux image for more details.
[root@podman-01 ~]# podman inspect alpine
[
{
"Id": "c85b8f829d1f93a25fe91d2ce7dccf7ec723794873a77bb19623d38e926c788c",
"Digest": "sha256:d371657a4f661a854ff050898003f4cb6c7f36d968a943c1d5cde0952bd93c80",
"RepoTags": [
"docker.io/library/alpine:latest"
],
"RepoDigests": [
"docker.io/library/alpine@sha256:d371657a4f661a854ff050898003f4cb6c7f36d968a943c1d5cde0952bd93c80"
],
"Parent": "",
"Comment": "",
"Created": "2019-12-19T23:21:54.894824922Z",
"Config": {
"Env": [
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
],
"Cmd": [
"/bin/sh"
]
},
"Version": "18.06.1-ce",
"Author": "",
"Architecture": "amd64",
"Os": "linux",
"Size": 5859848,
"VirtualSize": 5859848,
"GraphDriver": {
"Name": "overlay",
"Data": {
"MergedDir": "/var/lib/containers/storage/overlay/6bc83681f1baa18776614f386dee8811f0063fab656870291bd7751e74a830f4/merged",
"UpperDir": "/var/lib/containers/storage/overlay/6bc83681f1baa18776614f386dee8811f0063fab656870291bd7751e74a830f4/diff",
"WorkDir": "/var/lib/containers/storage/overlay/6bc83681f1baa18776614f386dee8811f0063fab656870291bd7751e74a830f4/work"
}
},
"RootFS": {
"Type": "layers",
"Layers": [
"sha256:6bc83681f1baa18776614f386dee8811f0063fab656870291bd7751e74a830f4"
]
},
"Labels": null,
"Annotations": {},
"ManifestType": "application/vnd.docker.distribution.manifest.v2+json",
"User": "",
"History": [
{
"created": "2019-12-19T23:21:54.731224548Z",
"created_by": "/bin/sh -c #(nop) ADD file:c7d28fcb71c026d7956b381180e4792c8219b04904e726a9266322ef5b256df8 in / "
},
{
"created": "2019-12-19T23:21:54.894824922Z",
"created_by": "/bin/sh -c #(nop) CMD [\"/bin/sh\"]",
"empty_layer": true
}
]
}
]
Create and run a container from alpine Linux image.
[root@podman-01 ~]# podman run -it --rm alpine /bin/sh
/ # uname -a
Linux 299572d7599a 4.18.0-80.el8.x86_64 #1 SMP Tue Jun 4 09:19:46 UTC 2019 x86_64 Linux
/ # cat /etc/os-release
NAME="Alpine Linux"
ID=alpine
VERSION_ID=3.11.0
PRETTY_NAME="Alpine Linux v3.11"
HOME_URL="https://alpinelinux.org/"
BUG_REPORT_URL="https://bugs.alpinelinux.org/"
/ # exit
Run the alpine Linux container in detach mode.
[root@podman-01 ~]# podman run -d alpine
85dcf6ee27b2ff57b480e6a9484d96129e775b4699390735ddc3f8366dd58737
Check list of recent containers.
[root@podman-01 ~]# podman ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f6cc375e3476 docker.io/library/alpine:latest /bin/sh 6 seconds ago Exited (0) 6 seconds ago heuristic_montalcini
f3de35c18d7d docker.io/library/alpine:latest /bin/sh About a minute ago Exited (0) About a minute ago stoic_goodall
85dcf6ee27b2 docker.io/library/alpine:latest /bin/sh 6 minutes ago Exited (0) 6 minutes ago sad_benz
Remove a container.
[root@podman-01 ~]# podman container rm f6cc375e3476
f6cc375e3476758431f2c7a9447b53c08fdaa0171f96bdd63212356b8eafb90c
Remove all containers.
[root@podman-01 ~]# podman container rm $(podman ps -a -q)
f3de35c18d7d54da9f97497db78e8a4f436b885b1c79765dcc1f847af2a0661a
85dcf6ee27b2ff57b480e6a9484d96129e775b4699390735ddc3f8366dd58737
Remove an image.
[root@podman-01 ~]# podman rmi docker.io/library/alpine
c85b8f829d1f93a25fe91d2ce7dccf7ec723794873a77bb19623d38e926c788c
If you have worked with Docker, you may have observed that the command syntax of podman is exactly same as of docker. Podman is also fully compatible with Docker images.
We have successfully installed podman containers on CentOS 8. We have only explored some of the most common commands here, if you want to learn more about containers you should read Docker in Action by Manning Publications.
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