Docker: Difference between revisions

From Alpine Linux
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  service docker start
  service docker start


{{Note|On older version of Alpine Linux with older version of docker you'll also need to disable some kernel security flags in order to build images:}}
{{Note|On older versions of Alpine Linux with older versions of docker you'll also need to disable some kernel security flags in order to build images:}}


  sysctl -w kernel.grsecurity.chroot_deny_chmod=0
  sysctl -w kernel.grsecurity.chroot_deny_chmod=0
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For more information, have a look at the [https://github.com/docker/docker/issues/20303 corresponding Github issue].
For more information, have a look at the [https://github.com/docker/docker/issues/20303 corresponding Github issue].


Anyway, this weakening of security is not necessary to do with Alpine 3.4.x and Docker 1.12 as of August 2016 anymore.
This weakening of security is not necessary to do with Alpine 3.4.x and Docker 1.12 as of August 2016.


=== Docker Compose ===
=== Docker Compose ===


'docker-compose' is in 'Community' repository since Alpine Linux >= 3.10.
'docker-compose' is in the 'Community' repository starting with Alpine Linux 3.10.


  apk add docker-compose
  apk add docker-compose


For older releases, do:
For older releases:


'''To install docker-compose, first install pip:'''
'''To install docker-compose, first install pip:'''
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</pre>
</pre>


and add in '''/etc/docker/daemon.json'''
add to '''/etc/docker/daemon.json'''


<pre>
<pre>
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         "no-new-privileges": false'''''
         "no-new-privileges": false'''''


You will find all possible configurations here[https://docs.docker.com/engine/reference/commandline/dockerd/#daemon-configuration-file].
You'll find all possible configurations here[https://docs.docker.com/engine/reference/commandline/dockerd/#daemon-configuration-file].


== Example: How to install docker from Arch ==
== Example: How to install docker from Arch ==
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== "WARNING: No {swap,memory} limit support" ==
== "WARNING: No {swap,memory} limit support" ==


You may, probably, encounter this message by executing <code>docker info</code>.
You might encounter this message when executing <code>docker info</code>.
To correct this situation we have to enable the <code>cgroup_enable=memory swapaccount=1</code>
To correct this situation, we have to enable the <code>cgroup_enable=memory swapaccount=1</code>


==== Alpine 3.8 ====
==== Alpine 3.8 ====
Well I'm not sure it wasn't the case before but for sure with Alpine 3.8 you must config cgroups properly
It may not have been the case before, but with Alpine 3.8, you must config cgroups properly


'''''Warning''''': This seems ''not'' to work with Alpine 3.9 and Docker 18.06. Follow the instructions for grub or extlinux below instead.
'''''Warning''''': This seems ''not'' to work with Alpine 3.9 and Docker 18.06. Follow the instructions for grub or extlinux below instead.
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=== Grub ===
=== Grub ===
Well; if you use Grub it is like any other linux and you just have to add the cgroup condition into <code>/etc/default/grub</code>, then upgrade your grub
If you use Grub, add the cgroup condition into <code>/etc/default/grub</code>, then upgrade your grub


<pre>GRUB_CMDLINE_LINUX_DEFAULT="... e=memory swapaccount=1"</pre>
<pre>GRUB_CMDLINE_LINUX_DEFAULT="... e=memory swapaccount=1"</pre>


=== Extlinux ===
=== Extlinux ===
With Extlinux you also add the cgroup condition but inside <code>/etc/update-extlinux.conf</code>
With Extlinux, you add the cgroup condition, but inside of <code>/etc/update-extlinux.conf</code>


<pre>default_kernel_opts="... cgroup_enable=memory swapaccount=1"</pre>
<pre>default_kernel_opts="... cgroup_enable=memory swapaccount=1"</pre>


than update the config and reboot
then update the config and reboot


<code>update-extlinux</code>
<code>update-extlinux</code>
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== '''How to use docker''' ==
== '''How to use docker''' ==


The best documentation for how to use Docker and create containers is at the main docker site.  Adding anything more to it here would be redundant.
The best documentation on using Docker and creating containers is at the main docker site.  Adding anything to it here would be redundant.


'''http://docs.docker.com/'''
'''http://docs.docker.com/'''


if you create an account at docker.com you can browse through other user's images and learn from the syntax in contributor's dockerfiles.
If you create an account at docker.com, you can browse through user images and learn from the syntax in contributed dockerfiles.


Official Docker image files are denoted by a blue ribon on the website.
Official Docker image files are denoted on the website by a blue ribbon.


== See also ==
== See also ==
* [https://www.erianna.com/creating-a-alpine-linux-repository/ Creating & Hosting an Alpine Linux Package Repository for Docker Packages]
* [https://www.erianna.com/creating-a-alpine-linux-repository/ Creating and Hosting an Alpine Linux Package Repository for Docker Packages]
* [[Running Alpine in a Docker Container]]
* [[Running Alpine in a Docker Container]]


[[Category:Virtualization]]
[[Category:Virtualization]]

Revision as of 17:16, 7 August 2021

Installation

The Docker package is in the 'Community' repository. See Alpine_Linux_package_management how to add a repository.

apk add docker

Connecting to the Docker daemon through its socket requires you to add yourself to the `docker` group.

addgroup username docker

To start the Docker daemon at boot, see Alpine_Linux_Init_System.

rc-update add docker boot
service docker start
Note: On older versions of Alpine Linux with older versions of docker you'll also need to disable some kernel security flags in order to build images:
sysctl -w kernel.grsecurity.chroot_deny_chmod=0
sysctl -w kernel.grsecurity.chroot_deny_mknod=0

For more information, have a look at the corresponding Github issue.

This weakening of security is not necessary to do with Alpine 3.4.x and Docker 1.12 as of August 2016.

Docker Compose

'docker-compose' is in the 'Community' repository starting with Alpine Linux 3.10.

apk add docker-compose

For older releases:

To install docker-compose, first install pip:

apk add py-pip python3-dev libffi-dev openssl-dev gcc libc-dev make
pip3 install docker-compose

Isolate containers with a user namespace

adduser -SDHs /sbin/nologin dockremap
addgroup -S dockremap
echo dockremap:$(cat /etc/passwd|grep dockremap|cut -d: -f3):65536 >> /etc/subuid
echo dockremap:$(cat /etc/passwd|grep dockremap|cut -d: -f4):65536 >> /etc/subgid

add to /etc/docker/daemon.json

{  
        "userns-remap": "dockremap"
}

You may also consider these options : '

       "experimental": false,
       "live-restore": true,
       "ipv6": false,
       "icc": false,
       "no-new-privileges": false

You'll find all possible configurations here[1].

Example: How to install docker from Arch

https://wiki.archlinux.org/index.php/Docker

"WARNING: No {swap,memory} limit support"

You might encounter this message when executing docker info. To correct this situation, we have to enable the cgroup_enable=memory swapaccount=1

Alpine 3.8

It may not have been the case before, but with Alpine 3.8, you must config cgroups properly

Warning: This seems not to work with Alpine 3.9 and Docker 18.06. Follow the instructions for grub or extlinux below instead.

echo "cgroup /sys/fs/cgroup cgroup defaults 0 0" >> /etc/fstab
cat >> /etc/cgconfig.conf <<EOF
mount {
cpuacct = /cgroup/cpuacct;
memory = /cgroup/memory;
devices = /cgroup/devices;
freezer = /cgroup/freezer;
net_cls = /cgroup/net_cls;
blkio = /cgroup/blkio;
cpuset = /cgroup/cpuset;
cpu = /cgroup/cpu;
}
EOF

Grub

If you use Grub, add the cgroup condition into /etc/default/grub, then upgrade your grub

GRUB_CMDLINE_LINUX_DEFAULT="... e=memory swapaccount=1"

Extlinux

With Extlinux, you add the cgroup condition, but inside of /etc/update-extlinux.conf

default_kernel_opts="... cgroup_enable=memory swapaccount=1"

then update the config and reboot

update-extlinux

How to use docker

The best documentation on using Docker and creating containers is at the main docker site. Adding anything to it here would be redundant.

http://docs.docker.com/

If you create an account at docker.com, you can browse through user images and learn from the syntax in contributed dockerfiles.

Official Docker image files are denoted on the website by a blue ribbon.

See also