Alpine Linux - User contributions [en]

Initramfs init

2019-06-18T17:40:42Z

Jjott:

== initramfs init cmdline options (work in progress) ==

In addition to the [https://www.kernel.org/doc/html/v4.14/admin-guide/kernel-parameters.html kernel boot parameters] are a number of parameters that the init script understands.

Although you may specify your own init script when building an initramfs, these parameters allow for extensive control over the initial startup of an Alpine Linux system.

<code>quiet</code> : less verbose init script execution

<code>debug_init</code> : sets '-x' in the init script and -d for mdev

<code>chart</code> : Enables bootchartd for measuring system startup speed.

<code>ip=dhcp</code> : use DHCP for network configuration.

<code>ip=client-ip:server-ip:gw-ip:netmask:hostname:device:autoconf:dns1:dns2</code> : use static IP configuration, each field is separated by a colon <code>:</code>
* <code>client-ip</code> ip address of the guest VM where we are going to run the installer
* <code>server-ip</code> not used, leave blank or fill with <code>none</code>
* <code>gw-ip</code> the gateway ip address
* <code>netmask</code> the netmask
* <code>hostname</code> not used, leave blank or fill with <code>none</code>
* <code>device</code> the network interface of the guest VM, default is <code>eth0</code> if left blank
* <code>autoconf</code> not used, leave blank or fill with <code>none</code> or <code>off</code>
* <code>dns1</code> address of the DNS server
* <code>dns2</code> address of the 2nd DNS server

<code>modloop=URL</code> : the remote location of the image containing kernel's modules, required for LVM and raid setup.

:The remote location of the <code>modloop</code> image is the same as the kernel and initramfs (see below).

<code>blacklist=MODULE{,MODULE}</code> : This comma-separated list names kernel modules that modprobe will reject to load.

<code>alpine_repo=URL</code> : the location of the Alpine repository from which packages are downloaded.

:For stable release, use <code>http://dl-cdn.alpinelinux.org/alpine/v3.9/main</code>

:For rolling release, use <code>http://dl-cdn.alpinelinux.org/alpine/edge/main</code>

<code>ssh_key=URL</code> : the remote location of your SSH public key. It will be added to root's authorized_keys. Also triggers OpenSSH-server to be installed and started.

<code>apkovl=URL</code> : Unpack the APK Overlay file from this URL. Happens immediately after network is up . This option will set the default for service install and setup to false. (see .default_boot_services).

(work in progress)

* init=
* init_args=

* dasd=
* s390x_net=
* rootfstype=
* modules=
* crytptroot=
* cryptdm=
* cryptheader=
* cryptoffset=
* cryptokey=
* nbd=
* root=
* resume
* rootflags
* usbdelay
* pkgs=
* ssh_key=
* keep_apk_new
* splash=
*

Initramfs init

2019-06-18T17:40:19Z

Jjott: /* initramfs init cmdline options */

== initramfs init cmdline options ==

In addition to the [https://www.kernel.org/doc/html/v4.14/admin-guide/kernel-parameters.html kernel boot parameters] are a number of parameters that the init script understands.

Although you may specify your own init script when building an initramfs, these parameters allow for extensive control over the initial startup of an Alpine Linux system.

<code>quiet</code> : less verbose init script execution

<code>debug_init</code> : sets '-x' in the init script and -d for mdev

<code>chart</code> : Enables bootchartd for measuring system startup speed.

<code>ip=dhcp</code> : use DHCP for network configuration.

<code>ip=client-ip:server-ip:gw-ip:netmask:hostname:device:autoconf:dns1:dns2</code> : use static IP configuration, each field is separated by a colon <code>:</code>
* <code>client-ip</code> ip address of the guest VM where we are going to run the installer
* <code>server-ip</code> not used, leave blank or fill with <code>none</code>
* <code>gw-ip</code> the gateway ip address
* <code>netmask</code> the netmask
* <code>hostname</code> not used, leave blank or fill with <code>none</code>
* <code>device</code> the network interface of the guest VM, default is <code>eth0</code> if left blank
* <code>autoconf</code> not used, leave blank or fill with <code>none</code> or <code>off</code>
* <code>dns1</code> address of the DNS server
* <code>dns2</code> address of the 2nd DNS server

<code>modloop=URL</code> : the remote location of the image containing kernel's modules, required for LVM and raid setup.

:The remote location of the <code>modloop</code> image is the same as the kernel and initramfs (see below).

<code>blacklist=MODULE{,MODULE}</code> : This comma-separated list names kernel modules that modprobe will reject to load.

<code>alpine_repo=URL</code> : the location of the Alpine repository from which packages are downloaded.

:For stable release, use <code>http://dl-cdn.alpinelinux.org/alpine/v3.9/main</code>

:For rolling release, use <code>http://dl-cdn.alpinelinux.org/alpine/edge/main</code>

<code>ssh_key=URL</code> : the remote location of your SSH public key. It will be added to root's authorized_keys. Also triggers OpenSSH-server to be installed and started.

<code>apkovl=URL</code> : Unpack the APK Overlay file from this URL. Happens immediately after network is up . This option will set the default for service install and setup to false. (see .default_boot_services).

(work in progress)

* init=
* init_args=

* dasd=
* s390x_net=
* rootfstype=
* modules=
* crytptroot=
* cryptdm=
* cryptheader=
* cryptoffset=
* cryptokey=
* nbd=
* root=
* resume
* rootflags
* usbdelay
* pkgs=
* ssh_key=
* keep_apk_new
* splash=
*

Initramfs init

2019-06-14T05:26:21Z

Jjott:

== initramfs init cmdline options ==

The init script in the initramfs which is loaded by the kernel understands the following entires in your kernel command line:

<code>ip=dhcp</code> : use DHCP for network configuration.

<code>ip=client-ip:server-ip:gw-ip:netmask:hostname:device:autoconf:dns1:dns2</code> : use static IP configuration, each field is separated by a colon <code>:</code>
* <code>client-ip</code> ip address of the guest VM where we are going to run the installer
* <code>server-ip</code> not used, leave blank or fill with <code>none</code>
* <code>gw-ip</code> the gateway ip address
* <code>netmask</code> the netmask
* <code>hostname</code> not used, leave blank or fill with <code>none</code>
* <code>device</code> the network interface of the guest VM, default is <code>eth0</code> if left blank
* <code>autoconf</code> not used, leave blank or fill with <code>none</code> or <code>off</code>
* <code>dns1</code> address of the DNS server
* <code>dns2</code> address of the 2nd DNS server

<code>alpine_repo=</code> : the location of the Alpine repository from which packages are downloaded.

:For stable release, use <code>http://dl-cdn.alpinelinux.org/alpine/v3.9/main</code>

:For rolling release, use <code>http://dl-cdn.alpinelinux.org/alpine/edge/main</code>

<code>modloop=</code> : the remote location of the image containing kernel's modules, required for LVM and raid setup.

:The remote location of the <code>modloop</code> image is the same as the kernel and initramfs (see below).

<code>ssh_key=</code> : the remote location of your SSH public key which is used to allow SSH connection into the installer. It will be downloaded and copied into <code>/root/.ssh/authorized_keys</code> in the installer.

{{Note|Fetching public keys from HTTP, HTTPS and FTPS are supported. HTTP should only be used in local development network where you own the network.}}

{{Note|Alpine Linux security policies are against using passwords for root access via SSH as we consider using public-private key pairs is a much better approach.}}

<code>quiet</code> : less verbose init script execution

<code>debug_init</code> : sets '-x' in the init script and -d for mdev

* chart (flag)
* alpine_repo=
* blacklist=
* apkovl=URL load the apkovl file from URL
* dasd=
* s390x_net=
* rootfstype=
* modules=
* crytptroot=
* cryptdm=
* cryptheader=
* cryptoffset=
* cryptokey=
* nbd=
* root=
* resume
* rootflags
* init=
* init_args=
* usbdelay
* pkgs=
* ssh_key=
* keep_apk_new
* splash=
*

Initramfs init

2019-06-14T05:25:02Z

Jjott:

== initramfs init cmdline options ==

The init script in the initramfs which is loaded by the kernel understands the following entires in your kernel command line:

<code>ip=dhcp</code> : use DHCP for network configuration.

<code>ip=client-ip:server-ip:gw-ip:netmask:hostname:device:autoconf:dns1:dns2</code> : use static IP configuration, each field is separated by a colon <code>:</code>
* <code>client-ip</code> ip address of the guest VM where we are going to run the installer
* <code>server-ip</code> not used, leave blank or fill with <code>none</code>
* <code>gw-ip</code> the gateway ip address
* <code>netmask</code> the netmask
* <code>hostname</code> not used, leave blank or fill with <code>none</code>
* <code>device</code> the network interface of the guest VM, default is <code>eth0</code> if left blank
* <code>autoconf</code> not used, leave blank or fill with <code>none</code> or <code>off</code>
* <code>dns1</code> address of the DNS server
* <code>dns2</code> address of the 2nd DNS server

<code>alpine_repo=</code> : the location of the Alpine repository from which packages are downloaded.

:For stable release, use <code>http://dl-cdn.alpinelinux.org/alpine/v3.9/main</code>

:For rolling release, use <code>http://dl-cdn.alpinelinux.org/alpine/edge/main</code>

<code>modloop=</code> : the remote location of the image containing kernel's modules, required for LVM and raid setup.

:The remote location of the <code>modloop</code> image is the same as the kernel and initramfs (see below).

<code>ssh_key=</code> : the remote location of your SSH public key which is used to allow SSH connection into the installer. It will be downloaded and copied into <code>/root/.ssh/authorized_keys</code> in the installer.

{{Note|Fetching public keys from HTTP, HTTPS and FTPS are supported. HTTP should only be used in local development network where you own the network.}}

{{Note|Alpine Linux security policies are against using passwords for root access via SSH as we consider using public-private key pairs is a much better approach.}}

* quiet (flag) less verbose init script execution
* debug_init (flag) sets '-x' in the init script and -d for mdev
* chart (flag)
* alpine_repo=
* blacklist=
* apkovl=URL load the apkovl file from URL
* dasd=
* s390x_net=
* rootfstype=
* modules=
* crytptroot=
* cryptdm=
* cryptheader=
* cryptoffset=
* cryptokey=
* nbd=
* root=
* resume
* rootflags
* init=
* init_args=
* usbdelay
* pkgs=
* ssh_key=
* keep_apk_new
* splash=
*

Initramfs init

2019-06-14T03:13:59Z

Jjott: /* initramfs init cmdline options */

== initramfs init cmdline options ==

The init script in the initramfs which is loaded by the kernel understands the following entires in your kernel command line:

* quiet (flag) less verbose init script execution
* debug_init (flag) sets '-x' in the init script and -d for mdev
* chart (flag)
* alpine_repo=
* blacklist=
* apkovl=URL load the apkovl file from URL
* dasd=
* s390x_net=
* rootfstype=
* modules=
* crytptroot=
* cryptdm=
* cryptheader=
* cryptoffset=
* cryptokey=
* nbd=
* root=
* resume
* rootflags
* init=
* init_args=
* usbdelay
* pkgs=
* ssh_key=
* keep_apk_new
* splash=
*

Initramfs init

2019-06-12T18:49:14Z

Jjott: Created page with "== initramfs init cmdline options == The init script in the initramfs which is loaded by the kernel understands the following entires in your kernel command line: * quiet (f..."

== initramfs init cmdline options ==

The init script in the initramfs which is loaded by the kernel understands the following entires in your kernel command line:

* quiet (flag)
* chart (flag)
* alpine_repo=
* blacklist=
* apkovl=
* dasd=
* s390x_net=
* rootfstype=
* modules=
* crytptroot=
* cryptdm=
* cryptheader=
* cryptoffset=
* cryptokey=
* nbd=
* root=
* resume
* rootflags
* init=
* init_args=
* usbdelay
* pkgs=
* ssh_key=
* keep_apk_new
* splash=
*

Developer Documentation

2019-06-12T17:53:00Z

Jjott: /* Init system */

[[Image:package_system.svg|right|link=]]

== Package management ==

* [[Alpine Linux package management|Package Management (apk)]] ''(How to add/remove packages on your Alpine)''  
** [[Comparison with other distros]]
** [[apk spec]]
* [[Edge|Upgrading to Edge]]
* [[Alpine local backup|Alpine local backup (lbu)]] ''(Permanently store your modifications in case your box needs reboot)''
** [[Back Up a Flash Memory Installation]]
** [[Manually editing a existing apkovl]]

* [[How to setup a Alpine Linux mirror]]
* [[How to use xdelta and download only differential update files]]
* [[How to make a custom ISO image]]
** [[Burning ISOs]]

== Init system ==
* [[initramfs init]]
* [[Alpine Linux Init System|Init System (OpenRC)]] ''(Configure a service to automatically launch at next reboot)''
** [[Multiple Instances of Services]]
* [[Writing Init Scripts]]

== Development ==
=== Configuring your system ===
* [[Edge|Upgrading to Edge]] 


* [[Setting up the build environment on HDD]] 

** [[Creating_an_Alpine_package#Setup_your_system_and_account|Setup your system and account for building packages]]
** [[Abuild_and_Helpers#abuild-keygen|Abuild-keygen]]

* [[Installing Alpine Linux in a chroot]] 
** [[Buildlab]] ''(Tool for creating and managing chroots)''
* [[Install Alpine on LXC]]
* Install Alpine on [[Install Alpine on VirtualBox|VirtualBox]], [[Install Alpine on VMware|VMware]], [[Install Alpine on coLinux|coLinux]], [[Qemu]],  or [[Install Alpine on Amazon EC2|Amazon EC2]]

* [[Xen Dom0]] ''(Setting up Alpine as a dom0 for Xen hypervisor)''
** [[Xen Dom0 on USB or SD]]
** [[Create Alpine Linux PV DomU]]
** [[Xen LiveCD]]

* [[Setting up a basic vserver]] 
* [[Setting up a compile vserver]] for official or for [[Setting up a compile vserver for third party packages|third party]] packages 


=== Building from source and creating packages ===

* [[Aports tree]] 
* [[Abuild and Helpers]] ''(Scripts for packaging)''



* [[Creating an Alpine package]]



** [[Package policies]]
** [[Package Maintainers]]
* [[Custom Kernel]]
* [[APKBUILD Reference]]
* [[APKBUILD examples]]
* [[Alpine package format]]
* [[Apkindex format]]

* [[Development using git]] 
** [[Development using git:Basic usage|Basic usage]]
** [[Package Maintainers]]
** [[Creating patches]]
** [[Development using git:Developer repositories|Developer repositories]]
** [[Development using git:Cgit|Cgit]]
** [[Cgit|Another cgit page]]

=== Misc ===

* [[Alpine Package Testing Suite]] ''work in progress''
* [[Alpine Release Testing Checklist]]
* [[Running glibc programs]]
* [[Alpine Source Map by boot sequence]]

== Alpine Configuration Framework ==
{{Draft|Needs to be organized/consolidated.}}

* [[Alpine Configuration Framework Design]] (Why ACF is the way it is)
* [[Writing User Documentation for ACF]]
* [[ACF mvc.lua reference|mvc.lua reference]] - mvc.lua is the core of ACF
* [[ACF mvc.lua example|mvc.lua example]] - build a simple (command-line) application
* [[ACF acf www-controller.lua reference|acf www-controller reference]] - ACF www application functions
* [[ACF acf www example|acf www-controller example]] - webify the above examples
* [[ACF how to write]] - Step by step howto for writing acfs
* [[ACF core principles]] - Things that are standard across the application
* [[LuaPosix]] - Documentation for the Lua Posix functions
* [[ACF Libraries]] - Document the libraries and common functions
* [[Writing ACF Views]] - Guide for writing a view
* [[Writing ACF Controllers]] - Guide for writing a controller
* [[Writing ACF Models]] - Guide for writing a model

* [[ACF css]]
* [[ACF packages]]
* [[APKBUILD examples:ACF]]
* [[Apk.lua]]
* [[Changing passwords for ACF]]
* [[Generating SSL certs with ACF]]
* [[Generating SSL certs with ACF 1.9]]
* [[Getting started with ACF development]]
* [[Managing ACF]]

== Alpine-developed Utilities ==
* [[Alpine Wall]] - [[How-To Alpine Wall]] - [[Alpine Wall User's Guide]] ''(a new firewall management framework)''

== Alpine Design Docs ==
* [[Architecture]]
* [[File Formats]]

[[Category:Development]]

Running Alpine in a Docker Container

2019-06-12T17:38:58Z

Jjott: /* using mkinitfs */

Some things you might want to know if you're running Alpine in a Docker container.

== using mkinitfs ==

By default mkinitfs will use the running kernel to build the initfs. Since your Docker container is under some other kernel you need to specify this manually.

<code>apk add linux-vanilla</code>

<code>cat /usr/share/kernel/vanilla/kernel.release</code>

<code>mkinitfs 4.19.41-0-vanilla</code>

<code>mkinitfs `cat /usr/share/kernel/vanilla/kernel.release`</code>

== See also ==
* [[Docker]]

[[Category:Virtualization]]

Running Alpine in a Docker Container

2019-06-12T17:27:58Z

Jjott: /* using mkinitfs */

Some things you might want to know if you're running Alpine in a Docker container.

== using mkinitfs ==

By default mkinitfs will use the running kernel to build the initfs. Since your Docker container is under some other kernel you need to specify this manually.

<code>cat /usr/share/kernel/vanilla/kernel.release</code>

<code>mkinitfs 4.19.41-0-vanilla</code>

<code>mkinitfs `cat /usr/share/kernel/vanilla/kernel.release`</code>

== See also ==
* [[Docker]]

[[Category:Virtualization]]

Running Alpine in a Docker Container

2019-06-12T17:27:47Z

Jjott:

Some things you might want to know if you're running Alpine in a Docker container.

== using mkinitfs ==

By default mkinitfs will use the running kernel to build the initfs. Since your Docker container is under some other kernel you need to specify this manually.

<code>cat /usr/share/kernel/vanilla/kernel.release</code>
<code>mkinitfs 4.19.41-0-vanilla</code>
<code>mkinitfs `cat /usr/share/kernel/vanilla/kernel.release`</code>

== See also ==
* [[Docker]]

[[Category:Virtualization]]

Running Alpine in a Docker Container

2019-06-12T17:27:16Z

Jjott: /* using mkinitfs */

Some things you might want to know if you're running Alpine in a Docker container.

== using mkinitfs ==

By default mkinitfs will use the running kernel to build the initfs. Since your Docker container is under some other kernel you need to specify this manually.

<code>cat /usr/share/kernel/vanilla/kernel.release
mkinitfs 4.19.41-0-vanilla
mkinitfs `cat /usr/share/kernel/vanilla/kernel.release`
</code>

== See also ==
* [[Docker]]

[[Category:Virtualization]]

Running Alpine in a Docker Container

2019-06-12T17:26:24Z

Jjott:

Some things you might want to know if you're running Alpine in a Docker container.

== using mkinitfs ==

By default mkinitfs will use the running kernel to build the initfs. Since your Docker container is under some other kernel you need to specify this manually.

* cat /usr/share/kernel/vanilla/kernel.release
* mkinitfs 4.19.41-0-vanilla
* mkinitfs `cat /usr/share/kernel/vanilla/kernel.release`

== See also ==
* [[Docker]]

[[Category:Virtualization]]

Running Alpine in a Docker Container

2019-06-12T17:25:03Z

Jjott: Created page with "Some things you might want to know if you're running Alpine in a Docker container. == using mkinitfs == By default mkinitfs will use the running kernel to build the initfs...."

Some things you might want to know if you're running Alpine in a Docker container.

== using mkinitfs ==

By default mkinitfs will use the running kernel to build the initfs. Since your Docker container is under some other kernel you need to specify this manually.

* cat /usr/share/kernel/vanilla/kernel.release
* mkinitfs 4.19.41-0-vanilla
* mkinitfs `cat /usr/share/kernel/vanilla/kernel.release`

Docker

2019-06-12T17:20:09Z

Jjott:

Alpine makes a great docker container, because it is so small and optimized to be run in RAM.
It might 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
<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> than 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]]

Docker

2019-06-12T17:19:20Z

Jjott: /* See also */

Alpine makes a great docker container, because it is so small and optimized to be run in RAM.
It might 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
<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> than 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]]