Docker

2020-02-18T18:27:07Z

Alfa80: /* Grub */ Fix typo

Alpine makes a great docker container, because it is so small and optimized to be run in RAM.
It also might make a good controller for several docker containers with enough RAM. I haven't tested this yet
Docker's setup is easy to use from command line. Commands can be run from an interactive shell, or through a configuration file called a "Dockerfile".
docker.com has excellent walk-throughs on how to run, pull, setup a container, commit an image, and create a configuration file. hub.docker.com is a freemium setup, where the first private repository is free.

== Installation ==

Run <code>apk add docker</code> to install Docker on Alpine Linux.

The Docker package is in the 'Community' repository, so if the '''apk add''' fails with '''unsatisfiable constraints''', you need to edit the '''/etc/apk/repositories''' file to add (or uncomment) a line like:

<code>http://dl-cdn.alpinelinux.org/alpine/latest-stable/community</code>

then run <code>apk update</code> to index the repository.

'''To start the Docker daemon at boot, run:'''

<code>rc-update add docker boot</code>

'''Then to start the Docker daemon manually, run:'''

<code>service docker start</code>

{{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:}}

<code>sysctl -w kernel.grsecurity.chroot_deny_chmod=0</code>

<code>sysctl -w kernel.grsecurity.chroot_deny_mknod=0</code>

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.

=== Docker Compose ===

'''To install docker-compose, first install pip:'''

<code>apk add py-pip</code>

'''Since docker-compose version 1.24.0, you also need some dev dependencies:'''

<code>apk add python-dev libffi-dev openssl-dev gcc libc-dev make</code>

'''Then install docker-compose, run:'''

<code>pip install docker-compose</code>

== Isolate containers with a user namespace ==
<pre>
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
</pre>

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

<pre>
{
"userns-remap": "dockremap"
}
</pre>

''You may also consider these options : '''
"experimental": false,
"live-restore": true,
"ipv6": false,
"icc": false,
"no-new-privileges": false'''''

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

== Example: How to install docker from Arch ==

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

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

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

==== Alpine 3.8 ====
Well I'm not sure it was'nt the case before but for sure 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.

<pre>echo "cgroup /sys/fs/cgroup cgroup defaults 0 0" >> /etc/fstab</pre>
<pre>
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
</pre>

=== 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

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

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

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

than update the config and reboot

<code>update-extlinux</code>

== '''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.

'''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.

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

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

[[Category:Virtualization]]

Alpine Linux:FAQ

2020-02-17T14:47:13Z

Alfa80: /* Why don't I have man pages or where is the 'man' command? */ Fix markup

[[Image:filetypes.svg|64px|left|link=]]
This is a list of '''frequently asked questions''' about Alpine Linux. 
If your question is not answered on this page, use the search box above to find work in progress pages not linked here, or in case of no answer, edit this page and write down your question.
{{Tip| Prepare your question. Think it through. Make it simple and understandable.}}

=General=

To get oriented and learn what makes our distribution distinctive, see the [http://alpinelinux.org/about About page] or [[Alpine Linux:Overview|our more detailed overview]].

== I have found a bug, where can I report it? ==

You can report it on the '''https://gitlab.alpinelinux.org/groups/alpine/-/issues link of the bugtracker'''. But first search if was already reported.

== Are there any details about the releases available? ==
Yes, please check the [[Alpine Linux:Releases|Releases]] page.

== How can I contribute? ==
You can contribute by:
* Using the software and giving feedback.
* Documenting your [http://www.alpinelinux.org Alpine Linux] experiences on this [[Main_Page|wiki]].
* In many other ways.
Please visit [[Contribute|Contribute page]] to read more about this topic.

== Why don't I have man pages or where is the 'man' command? ==
The <code>man</code> command and man pages are not installed by default.

* First, install the {{pkg|man}} package:
<code>apk add man</code>
* Once that's done, install the documentation for the packages that you require man pages for:
<code>apk add ''package''-doc</code>

For example, say you installed {{Pkg|iptables}} and you now require its man pages:
<code>apk add iptables-doc</code> and then: <code>man iptables</code>. Keep in mind, not all packages will have a corresponding documentation package In our example above, we installed the man pages (and other documentation) for <code>iptables</code>

== What is the difference between edge and stable releases? ==
Stable releases are just what they sound like: initially a point-in-time snapshot of the package archives, but then maintained with bug-fixes only in order to keep a stable environment.

[[Edge]] is more of a rolling-release, with the latest and greatest packages available in the online repositories. 
Occasionally, snapshot ISO images of the then-current state of [[edge]] are made and are available for download. 
Typically these are made when there are major kernel upgrades or package upgrades that require initramfs rebuilds.

== What architectures does Alpine support? ==
As Alpine uses the Linux kernel, it supports:
* '''x86_64''': The popular AMD64 compatible 64-bit x86 based machines, i386 is not recommended for newer/latest hardware.
* '''s390x''': For the Super powered IBM mainframes, especially IBM Z and IBM LinuxONE servers.
* '''ppc64le''': For the PowerPC devices with pure little-endian mode, mostly for POWER8 and POWER9
* '''x86''': (i386 pc 32bit) and x86_64 (i686 pc 64bit and amd64)
* '''armhf''': The newer ARM hard-float for newer, more powerful 32-bit devices alongside 64-bit
* '''armv7''': The 32-bit ARM only execution state of the ARMv7 devices machines.
* '''aarch64''': The 64-bit ARM only execution state of the ARMv8 device machines.
* '''ppc64le''': for 64-bit big-endian PowerPC and Power ISA processors like some MAC computers.
* '''s390x''': for Server for IBM Z and LinuxONE mainframes.
'''Please check [https://alpinelinux.org/downloads Download] page for media availability on each one''' and check [[Alpine_Linux:Releases|Releases]] pages for latest.

== What kind of release of Alpine Linux are available? ==
Please check the [[Alpine_Linux:Releases|Releases]] page for more information.

=Setup=

== What is the difference between 'sys', 'data', and 'diskless' when running 'setup-alpine' or 'setup-disk'? ==
'''sys:''' This mode is a traditional disk install. The following partitions will be created on the disk: <nowiki>/boot</nowiki>, <nowiki>/</nowiki> (filesystem root) and <nowiki>swap</nowiki>. 
This mode may be used for development boxes, desktops, virtual servers, etc.

'''data:''' This mode uses your disk(s) for data storage, not for the operating system. Runs from the media and only <nowiki>/var</nowiki> is created on disk. The system itself will run from tmpfs (RAM). Use this mode if you only want to use the disk(s) for a mailspool, databases, logs, etc.

'''diskless:''' No disks are to be used. [[Alpine local backup]] may still be used in this mode.

These modes are explained further [[Installation#Overview_of_run_modes_for_Alpine_system|on the '''Installation''' page]].

== How do I upgrade Alpine? ==

To upgrade to a new stable release or edge:
<code>apk upgrade --available</code>

==My cron jobs don't run?==

Start service ''crond'' and add it to runlevel:

: {{cmd|rc-service crond start && rc-update add crond}}

After that the cron daemon is started automatically on system boot and executes the scripts placed in the folders under {{path|/etc/periodic}} - there's a {{path|15min}} folder, plus ones for {{path|hourly}}, {{path|daily}}, {{path|weekly}} and {{path|monthly}} scripts.

You can check whether your scripts are likely to run using the command:

: {{cmd|run-parts --test /etc/periodic/[foldername]}} - for example: ''run-parts --test /etc/periodic/15min''

This command will tell you what should run but will not actually execute the scripts.

If the results of the test are not as expected, check the following:

* Make sure the script is executable - if unsure, issue the command : {{cmd|chmod a+x [scriptname]}}
* Make sure the first line of your script is :<pre>#!/bin/sh</pre>
* Do not put file extensions on your script names - this stops them from working; for example: {{path|myscript}} will run, but {{path|myscript.sh}} won't

= Time and timezones =

== How do I set the local timezone? ==

Starting in Alpine 2.2, setting the timezone can be done through the [[Setup-alpine|setup-alpine]] script, and no manual settings should be necessary. 
If you wish to edit the timezone after installation, run the [[Alpine_setup_scripts|setup-timezone]] script.

= Packages =

== Can you build an apk package for ...? ==
Yes, we probably can. 
Please create an [https://gitlab.alpinelinux.org/alpine/aports/issues/new issue] in the [https://gitlab.alpinelinux.org bugtracker]. Prefix with "feat" in title and include a short description (one-line), an url for the home page, and an url for the source package.

== How can I build my own package? ==
Please see the [[Creating an Alpine package]] page.

== What does "required by: world[$pkgname]" mean? ==

It means that the package you try to install does not exist in the repositories you have configured in <code>/etc/apk/repositories</code>. Maybe you forgot to add community, testing or unmaintained to /etc/apk/repositories?

== How can i find out if a certain package exists in alpine? ==

If you want to only search repositories you have configured in /etc/apk/repositories, then <code>apk search $pkgname</code> should get you sorted. If you want to search all repositories have a look at the [https://pkgs.alpinelinux.org/ online pkg oracle]

== WARNING: Ignoring APKINDEX.xxxx.tar.gz ==
If you get <code>WARNING: Ignoring APKINDEX.xxxx.tar.gz: No such file or directory</code> while running package related tools, check your {{path|/etc/apk/repositories}} file if an entry points to {{path|.../v2.4/testing/}}. This directory is gone.

To check the content of the repositories file
{{Cmd|cat /etc/apk/repositories}}

or
{{Cmd|setup-apkrepos}}

= Dynamic DNS =
== How do I schedule a regular dynamic DNS update? ==
You'll want to install the {{pkg|ez-ipupdate}} package:
{{cmd|apk add ez-ipupdate}}

After that, create a new file at {{path|/etc/ez-ipupdate.conf}} with contents similar to:
service-type=dyndns
user=myusername:mypassword
interface=eth1
host=myhostname.dyndns.org

Make the new ip cache directory:
{{cmd|mkdir /var/cache/ez-ipupdate
lbu add /var/cache/ez-ipupdate}}

Then schedule a new cron job with this command:
{{cmd|echo >> /var/log/ez-ipupdate && \ /bin/date >> /var/log/ez-ipupdate && \ ez-ipupdate --config-file /etc/ez-ipupdate.conf -f -F /var/run/ez-ipupdate.pid \ --cache-file /var/cache/ez-ipupdate/ipcache --quiet >> /var/log/ez-ipupdate 2>&1}}

Don't forget to backup your settings!
{{cmd|lbu ci}}

= Terminal =

== How to enable/fix colors for git? ==

The problem is not in git itself or terminal, but in the <tt>less</tt> command.
Busybox’s <tt>less</tt> doesn’t support <tt>-r</tt> (<tt>--raw-control-chars</tt>) and <tt>-R</tt> (<tt>--RAW-CONTROL-CHARS</tt>) options.

The simplest (yet not ideal) solution is to install GNU less:

{{cmd|apk add less}}

= Old questions, no longer freqently asked =

== Alpine freezes during boot from Compact Flash, how can I fix? ==
Most Compact Flash card readers do not support proper DMA. 
You should append '''nodma''' to the ''append'' line in {{path|syslinux.cfg}}.

== How do I remove the CDROM? ==
Since the modloop loopback device is on CDROM you cannot just run <code>eject</code>. You need to unmount the modloop first. 
Unmounting both the modloop and the CDROM in one step can be done by executing:
{{Cmd|/etc/init.d/modloop stop}}

Then it's possible to eject the CDROM:
{{Cmd|eject}}

== How can I install a custom firmware in a diskless system? ==

The modules and firmware are both special images which are mounted as read-only. 
To fix this issue you can copy the firmware directory to your writeable media (cf/usb) and copy your custom firmware to it. 
After reboot Alpine should automatically use the directory on your local storage instead of the loopback device.

== How do I play my .ogg/.mp3 files? ==
First, the sound card should be recognized (you must have {{path|/dev/snd/*****}} files)

{{pkg|sox}}, {{pkg|mpg123}}, etc all use the oss sound driver, while Alpine uses ALSA drivers. 
So you need to load the snd-pcm-oss compatibility module. 
While you're at it, you might need {{pkg|aumix}} to turn up the sound volume
{{cmd|echo snd-pcm-oss >> /etc/modules
modprobe snd-pcm-oss
apk_add aumix sox
aumix (set volume settings)
play really_cool_song.mp3}}

== OpenNTPD reports an error with "adjtime" ==
Your log contains something like:
reply from 85.214.86.126: offset 865033148.784255 delay 0.055466, next query 32s
reply from 202.150.212.24: offset 865033148.779314 delay 0.400771, next query 3s
adjusting local clock by 865033148.779835s
adjtime failed: Invalid argument

{{pkg|openntpd}} is supposed to make small adjustments in the time without causing time jumps. 
If the adjustment is too big then something is clearly wrong and ntpd gives up. (its actually adjtime(3) that has a limit on how big adjustments are allowed)

You can make ntpd set the time at startup by adding ''-s'' option to ntpd. This is done by setting '''NTPD_OPTS="-s"''' in {{path|/etc/conf.d/ntpd}}.

== Using a cron job to keep the time in sync ==
Add the following to {{path|/etc/periodic/daily}} (or use another folder under the {{path|/etc/periodic}} heirarchy if you want to run the script more/less frequently)

Example: file called {{path|do-ntp}}
<pre>
#!/bin/sh
ntpd -d -q -n -p uk.pool.ntp.org</pre>

This queries the uk time server pool - you can modify this to suit your localisation, or just use ''pool.ntp.org''. More info here: [http://www.pool.ntp.org/zone/@ http://www.pool.ntp.org/zone/@]

== Windows clients reports an error when trying to sync ==
{{pkg|openntpd}} needs to run for a while before it is satisfied it is in sync.
Until then it will set a flag "clock not synchronized" and Windows will report an error while trying to sync with your {{pkg|openntpd}} server.

Only thing to do is wait, do something else for 15-20mins and then check.

[[Category:Newbie]]

Alpine Linux - User contributions [en]

Docker

Alpine Linux:FAQ