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{{Subpages|Laptop Network Setup,GPU Acceleration,GPU Acceleration (NVIDIA),What are subuids and subgids?,Administration Tutorial,Features and Concepts}}
== Introduction ==

{{Important|Please note that if you plan to use LXD on a laptop, you are likely using WiFi and NetworkManager, and the steps below will ''not'' work for you bridge setup. Please see [[LXD/Laptop Network Setup]] for important differences to allow you to use LXD in 'dev mode' for local use of containers for development.}}

LXD is a container "hypervisor" designed to provide an easy set of tools to manage Linux containers, and its development is currently being led by employees at Canonical. You can learn more about the project in general at https://linuxcontainers.org/lxd/. 

LXD is currently used for container infrastructure for [[Special:MyLanguage/Funtoo Containers|Funtoo Containers]] and is also very well-supported under Funtoo Linux. For this reason, it's recommended that you check out LXD and see what it can do for you.

== Basic Setup on Funtoo ==

The following steps will show you how to set up a basic LXD environment under Funtoo Linux. This environment will essentially use the default LXD setup -- a will be created called {{c|lxdbr0}} which will use NAT to provide Internet access to your containers. In addition, a default storage pool will be created that will simply use your existing filesystem's storage, creating a directory at {{f|/var/lib/lxd/storage-pools/default}} to store any containers you create. More sophisticated configurations are possible that use dedicated network bridges connected to physical interfaces without NAT, as well as dedicated storage pools that use [[Special:MyLanguage/ZFS|ZFS]] and [[Special:MyLanguage/btrfs|btrfs]] -- however, these types of configurations are generally overkill for a developer workstation and should only be attempted by advanced users. So we won't cover them here.

=== Requirements ===

This section will guide you through setting up the basic requirements for creating an LXD environment.

The first step is to emerge LXD and its dependencies. Perform the following:

{{console|body=
# ##i##emerge -a lxd
}}

Once LXD is done emerging, we will want to enable it to start by default:

{{console|body=
# ##i##rc-update add lxd default
}}

In addition, we will want to set up the following files. {{f|/etc/security/limits.conf}} should be modified to have the following lines in it:

{{file|name=/etc/security/limits.conf|body=
*       soft    nofile  1048576
*       hard    nofile  1048576
root    soft    nofile  1048576
root    hard    nofile  1048576
*       soft    memlock unlimited
*       hard    memlock unlimited
# End of file
}}

Next, we come to the concept of "subuid" and "subgid". Typically, a user will get one user id and one group id. Subids and subgids allow us to assign additional UIDs and GIDs to a user for their own uses.
By default, LXD will allocate subuids for the root user, which is equivalent of creating the following files on the root filesystem:

{{file|name=/etc/subuid|body=
root:1000000:10000000000
}}

{{file|name=/etc/subgid|body=
root:1000000:10000000000
}}

The format of both of these files are "user":"start":"count". Meaning that the {{c|root}} user will be allocated "count" IDs starting at the position "start". The reason why LXD does this is because
these extra IDs will be used to isolate containers from the host processes and optionally from each other, by using different offsets so that their UID and GIDs will not overlap. Because LXD 5 now
has these settings "baked in", these files do not need to be created and exist here just for reference and understanding of default LXD behavior. For more information on subids and subgids, see [[LXD/What are subuids and subgids?|What are subuids and subgids?]].

==== LXD-in-LXD ====

The only time you will now need to set {{f|/etc/subuid}} and {{f|/etc/subgid}} now is if you are running "LXD-in-LXD". In this case, the inner LXD (within the container) will need to reduce these 
subuid and subgid mappings as the full range will not be available. This should be possible by simply using the following settings within your containerized LXD instance:

{{file|name=/etc/subuid|body=
root:65537:70000
}}

{{file|name=/etc/subgid|body=
root:65537:70000
}}

If you are not using advanced features of LXD, your LXD-in-LXD instance should now have sufficient id mappings to isolate container-containers from the host-container. The only remaining
step for LXD-in-LXD would be to allow the host-container to nest:

{{console|body=
# ##i##lxc config set host-container security.nesting true
}}

This will allow for host-container contain containers itself :)

=== Initialization ===

To configure LXD, first we will need to start LXD. This can be done as follows:

{{console|body=
# ##i##/etc/init.d/lxd start
}}

At this point, we can run {{c|lxd init}} to run a configuration wizard to set up LXD:

{{console|body=
# ##i##lxd init
Would you like to use LXD clustering? (yes/no) [default=no]: ##i##↵
Do you want to configure a new storage pool? (yes/no) [default=yes]: ##i##↵
Name of the new storage pool [default=default]: ##i##↵
Name of the storage backend to use (btrfs, dir, lvm) [default=btrfs]: ##i##dir ↵
Would you like to connect to a MAAS server? (yes/no) [default=no]: ##i##↵
Would you like to create a new local network bridge? (yes/no) [default=yes]: ##i##↵
What should the new bridge be called? [default=lxdbr0]: ##i##↵
What IPv4 address should be used? (CIDR subnet notation, “auto” or “none”) [default=auto]: ##i##↵
What IPv6 address should be used? (CIDR subnet notation, “auto” or “none”) [default=auto]: ##i##none ↵
Would you like LXD to be available over the network? (yes/no) [default=no]: ##i##↵
Would you like stale cached images to be updated automatically? (yes/no) [default=yes] ##i##↵
Would you like a YAML "lxd init" preseed to be printed? (yes/no) [default=no]: ##i##↵
#
}}

As you can see, we chose all the default ''except'' for:
;storage pool: We opted for using a directory-based container storage rather than [[Special:MyLanguage/btrfs|btrfs]] volumes.  Directory-based may be the default option during LXD configuration -- it depends if you have btrfs-tools installed or not.
;IPv6 address: It is recommended you turn this off unless you are specifically wanting to play with IPv6 in your containers. It may cause {{c|dhcpcd}} in your container to only retrieve an IPv6 address if you leave it enabled. This is great if you have IPv6 working -- otherwise, you'll get a dud IPv6 address and no IPv4 address, and thus no network.

{{Warning|As explained above, turn off IPv6 NAT in LXD unless you specifically intend to use it! It can confuse {{c|dhcpcd}}.}}

If you choose to output the ''YAML lxd init preseed'' configuration from the {{c|lxd init}} command above, here is a config example:

{{file|name=lxc_init_preseed.yaml|lang=YAML|desc=lxc init preseed config example|body=
config:
  images.auto_update_interval: "0"
networks:
- config:
    ipv4.address: auto
    ipv6.address: none
  description: ""
  name: lxdbr0
  type: ""
  project: default
storage_pools:
- config: {}
  description: ""
  name: default
  driver: dir
profiles:
- config: {}
  description: ""
  devices:
    eth0:
      name: eth0
      network: lxdbr0
      type: nic
    root:
      path: /
      pool: funtoo
      type: disk
  name: default
projects: []
cluster: null
}}

Now, we should be able to run {{c|lxc image list}} and get a response from the LXD daemon:

{{console|body=
# ##i##lxc image list
+-------+-------------+--------+-------------+------+------+-------------+
{{!}} ALIAS {{!}} FINGERPRINT {{!}} PUBLIC {{!}} DESCRIPTION {{!}} ARCH {{!}} SIZE {{!}} UPLOAD DATE {{!}}
+-------+-------------+--------+-------------+------+------+-------------+
#
}}
 
If you are able to do this, you have successfully set up the core parts of LXD! Note that we used the command {{c|lxc}} and not {{c|lxd}} like we did for {{c|lxd init}} -- from this point forward, you will use the {{c|lxc}} command. Don't let this
confuse you -- the {{c|lxc}} command is the primary command-line tool for working with LXD containers.

Above, you can see that no images are installed. Images are installable snapshots of containers that we can use to create new containers ourselves. So, as a first step, let's go ahead and grab an image we can use. You will want to browse https://build.funtoo.org for an LXD image that will work on your computer hardware. For example, I was able to download
the following file using {{c|wget}}:

{{console|body=
# ##i##wget https://build.funtoo.org/1.4-release-std/x86-64bit/amd64-zen2/2022-04-13/lxd-amd64-zen2-1.4-release-std-2022-04-13.tar.xz
}}

Once downloaded, this image can be installed using the following command:
{{console|body=
# ##i##lxc image import lxd-amd64-zen2-1.4-release-std-2022-04-13.tar.xz --alias funtoo
Image imported with fingerprint: fe4d27fb31bfaf3bd4f470e0ea43d26a6c05991de2a504b9e0a3b1a266dddc69
}}

Now you will see the image available in our image list:

{{console|body=
# ##i##lxc image list
+--------+--------------+--------+-----------------------------------------+--------------+-----------+----------+------------------------------+
| ALIAS  | FINGERPRINT  | PUBLIC |               DESCRIPTION               | ARCHITECTURE |   TYPE    |   SIZE   |         UPLOAD DATE          |
+--------+--------------+--------+-----------------------------------------+--------------+-----------+----------+------------------------------+
| funtoo | b8eaa7e30c14 | no     | 1.4 Release Zen2 64bit [std] 2022-04-13 | x86_64       | CONTAINER | 342.13MB | Apr 29, 2022 at 9:36pm (UTC) |
+--------+--------------+--------+-----------------------------------------+--------------+-----------+----------+------------------------------+
#
}}

=== First Container ===

It is now time to launch our first container. This can be done as follows:

{{console|body=
# ##i##lxc launch funtoo testcontainer
Creating testcontainer
Starting testcontainer
}}

We can now see the container running via {{c|lxc list}}:

{{console|body=
# ##i##lxc list
+---------------+---------+------+-----------------------------------------------+------------+-----------+
{{!}} NAME          {{!}}  STATE  {{!}} IPV4 {{!}}                     IPV6                      {{!}}    TYPE    {{!}} SNAPSHOTS {{!}}
+---------------+---------+------+-----------------------------------------------+------------+-----------+
{{!}} testcontainer {{!}} RUNNING {{!}}      {{!}} fd42:8063:81cb:988c:216:3eff:fe2a:f901 (eth0) {{!}} PERSISTENT {{!}}           {{!}}
+---------------+---------+------+-----------------------------------------------+------------+-----------+
#
}}
By default, our new container {{c|testcontainer}} will use the default profile, which will connect an {{c|eth0}} interface in the container to NAT, and will also use our directory-based LXD storage pool. We can now enter the container as follows:

{{console|body=
# ##i##lxc exec testcontainer -- su --login
%testcontainer%
}}

As you might have noticed, we do not yet have any IPv4 networking configured. While LXD has set up a bridge and NAT for us, along with a DHCP server to query, we actually need to use {{c|dhcpcd}} to query for an IP address, so let's get that set up:

{{console|body=
%testcontainer% ##i##echo "template=dhcpcd" > /etc/conf.d/netif.eth0
%testcontainer% ##i##cd /etc/init.d
%testcontainer% ##i##ln -s netif.tmpl netif.eth0
%testcontainer% ##i##rc-update add netif.eth0 default
 * service netif.eth0 added to runlevel default
%testcontainer% ##i##rc
 * rc is deprecated, please use openrc instead.
 * Caching service dependencies ...                             [ ##g##ok ##!g##]
 * Starting DHCP Client Daemon ...                              [ ##g##ok ##!g##]
 * Network dhcpcd eth0 up ...                                   [ ##g##ok ##!g##]
%testcontainer% ##i##
}}

You can now see that {{c|eth0}} has a valid IPv4 address:

{{console|body=
%testcontainer% ##i##ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.212.194.17  netmask 255.255.255.0  broadcast 10.212.194.255
        inet6 fd42:8063:81cb:988c:25ea:b5bd:603d:8b0d  prefixlen 64  scopeid 0x0<global>
        inet6 fe80::216:3eff:fe2a:f901  prefixlen 64  scopeid 0x20<link>
        ether 00:16:3e:2a:f9:01  txqueuelen 1000  (Ethernet)
        RX packets 45  bytes 5385 (5.2 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 20  bytes 2232 (2.1 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
}}

What happened is that LXD set up a DHCP server for us (dnsmasq) running on our private container network, and automatically offers IP addresses to our containers. It also configured iptables for us to NAT the connection so that outbound Internet access should magically work.
You should also be able to see this IPv4 address listed in the container list when you type {{c|lxc list}} on your host system.

=== Network Troubleshooting ===

{{warning|Proceed with caution. These are advanced LXC commands that can modify the state of your LXD local network setup. In extreme scenarios, all of your LXD containers' networks NAT routing can easily break all if the wrong LXC config key value is changed}}

Note that if you are having issues with your container getting an IPv4 address via DHCP, make sure that you turn IPv6 off in LXD. Do this
by running:

{{console|body=
###i## lxc network edit lxdbr0
}}

Then, change {{c|ipv6.nat}} YAML key value to {{c|"false"}} and restart LXD and the test container:

{{console|body=
###i## /etc/init.d/lxd restart
###i## lxc restart testcontainer
}}

This should resolve the issue.

{{important|If you have initialized your LXD cluster by turning off IPv6 with the ''What IPv6 address should be used?'' option set to {{c|none}}, then the {{c|ipv6.nat}} will not even be present in our LXC local network's {{c|lxdbr0}} bridge interface.

Be careful not to tamper with the {{c|ipv4.nat}} setting or all LXD container NAT routing will break, meaning no network traffic within running and new LXD containers will be able to route to external to the Internet!}}

Here is some example YAML of a default {{c|lxdbr0}} LXC local network bridge device for reference:

{{file|name=lxc_lxdbr0.yaml|lang=YAML|desc=lxc network edit lxdbr0|body=
config:
  ipv4.address: 10.239.139.1/24
  ipv4.nat: "true"
  ipv6.address: none
description: ""
name: lxdbr0
type: bridge
used_by:
- /1.0/profiles/default
- /1.0/instances/funtoo-livestream
managed: true
status: Created
locations:
- none
}}

=== Finishing Steps ===

Assuming your network is now working, you are ready to start using your new Funtoo container. Time to have some fun! Go ahead and run {{c|ego sync}} and then emerge your favorite things:
{{console|body=
%testcontainer% ##i##ego sync
\##g##Syncing meta-repo
Cloning into '/var/git/meta-repo'...

}}
[[Category:Containers]]
[[Category:LXD]]
[[Category:Official Documentation]]
[[Category:First Steps]]