AMINUL ISLAM SHAMIM

LXD containers get IP addresses from LAN DHCP Server & Static

By default, all containers run hidden in a private network on the host. The containers are not accessible from the local network, nor from the Internet. However, they have network access to the Internet through the host.

It would be great to have LXC containers getting from local DHCP server so that anyone from the network can connect to the container.

1. First we will create a bridge interface and add our physical interface (in the example it’s enp1s0) to the bridge:

sudo vi /etc/netplan/00-installer-config.yaml

network:

version: 2
renderer: networkd

ethernets:
  enp1s0:
    dhcp4: false
    dhcp6: false

bridges:
  bridge0:
    interfaces: [enp1s0]
    addresses: [192.168.99.252/24]
    gateway4: 192.168.99.1
    nameservers:
      addresses:
        - 1.1.1.1
        - 8.8.8.8
    parameters:
      stp: true
      forward-delay: 4
    dhcp4: no

Next apply the config

sudo netplan apply 2. Now install LXD

sudo apt install lxd 3. By default LXD will create a profile with name “default”. For us we will create a new profile name “bridgeprofile” and add the basic config:

sudo lxc profile create bridgeprofile Profile bridgeprofile created

sudo cat «EOF | lxc profile edit bridgeprofile

description: Bridged networking LXD profile
devices:
eth0:
name: eth0
nictype: bridged
parent: bridge0
type: nic
EOF

Verify the profile:

# lxc profile list
+—————+———+
| NAME | USED BY |
+—————+———+
| bridgeprofile | 0 |
+—————+———+
| default | 0 |
+—————+———+

4. Now generate lxd config using command “sudo lxd init” and select the appropriate options

r * oot@lxd-home:/home/fakrul# lxd init

Would you like to use LXD clustering? (yes/no) [default=no]:
Do you want to configure a new storage pool? (yes/no) [default=yes]:
Name of the new storage pool [default=default]:
Name of the storage backend to use (btrfs, dir, lvm, zfs, ceph) [default=zfs]:
Create a new ZFS pool? (yes/no) [default=yes]:
Would you like to use an existing block device? (yes/no) [default=no]:
Size in GB of the new loop device (1GB minimum) [default=46GB]:
Would you like to connect to a MAAS server? (yes/no) [default=no]:
Would you like to create a new local network bridge? (yes/no) [default=yes]: no
Would you like to configure LXD to use an existing bridge or host interface? (yes/no) [default=no]:
Would you like LXD to be available over the network? (yes/no) [default=no]:
Would you like stale cached images to be updated automatically? (yes/no) [default=yes]
Would you like a YAML “lxd init” preseed to be printed? (yes/no) [default=no]:

5. Edit the profile and add the storage pool. You can add any other cloud-init config if you want. For example I have added my ssh-public key and related information

sudo lxc profile show bridgeprofile config:

user.user-data: |
  #cloud-config
  users:
    - name: fakrul
      ssh_authorized_keys:
        - ssh-rsa    
 * *AAAAB3NzaC1yc2EAAAADAQABAAABAQCwkqkOEoYAolYMIkHozxc5eY6gjUhvqCbJj9BDRvsWL26Rm2Yg2aCcAGaiGo+a1ADX8Ty6Ed0s+jZtEaoTEKVCSlCPZ5BB03B80Wao1/RjjoVho12zf9r9lR5dz1n79fysCj43LRgJR7qb0Inpq4WyIx2mm4hq4kryWj5+cBm1LYnpIUf4LqCl3YzY2tKVXrpVqbrJ5SIdy7FD6FxZIdpdwGJ7b+uUv0R/zSfVMZuU1+DIxyO9la0ZhFL4I/5H9Tb348tLCjR7X//Tu+zSceTmg51ATWHvsSfRwOL/bUWRjMSr9swbXzwweGcw6k15VJ5sYiBFGDla5almjmXAfSxD aminul@rajshahionline.com
      sudo: ALL=(ALL) NOPASSWD:ALL
      groups: sudo
      shell: /bin/bash
      passwd: $1$hUDF3Apy$jJztHAqAE8qxMX3yl0rnK/
      gecos: Fakrul Alam
  # Update timezone
  locale: en_US.UTF-8
  timezone: Australia/Sydney
  # Update apt database on first boot (run 'apt-get update').
  package_update: true
  # Install required packages
  packages:
    - whois
    - inetutils-traceroute
    - traceroute
    - net-tools

description: Bridged networking LXD profile

devices:

eth0:
  name: eth0
  nictype: bridged
  parent: bridge0
  type: nic
root:
  path: /
  pool: default
  type: disk

name: bridgeprofile

6. Now you can deploy instances with “bridgeprofile”

lxc launch -p bridgeprofile ubuntu:18.04 graylog

7. The instance “graylog” will get IP address from the LAN DHCP server.

This is an issue with the name resolutions (DNS configuration) in the container.

Can you verify that you have tried the above with the container images ubuntu:18.04 or ubuntu:20.04? There are more container images in the images: repository, including Ubuntu images. If you have selected a Debian or Fedora container image, you would need to look above in this post the separate LXD profiles for them.

You can ping the Internet (the IP address for 1.1.1.1) but not hostnames (DNS issues). The cloud-config section above has a setting to enable DNS for you, and use one of the public DNS servers (8.8.8.8 is provided by Google).

First, can you run the following command in the container? It will try to make a name resolution using specifically the Google DNS server. If that works, then DNS resolutions are not blocked somehow. You should get the IP address of http://www.google.com in the output, both IPv4 and IPv6.

host www.google.com 8.8.8.8

Second, if the above works, verify that the cloud-init information managed to get parsed correctly, and can be found in the container.

$ cat /etc/netplan/50-cloud-init.yaml # This file is generated from information provided by the datasource. Changes # to it will not persist across an instance reboot. To disable cloud-init's # network configuration capabilities, write a file # /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following: # network: {config: disabled} network:

  ethernets:
      eth0:
          addresses:
          - 192.168.1.200/32
          nameservers:
              addresses:
              - 8.8.8.8
              search: []
          routes:
          -   on-link: true
              to: 0.0.0.0/0
              via: 169.254.0.1
  version: 2

$ Third, verify that the network manager (in the case of Ubuntu it is NetworkManager) is aware of the DNS server. The last lines mention the public Google DNS server, 8.8.8.8.

$ systemd-resolve –status … Link 2 (eth0)

    Current Scopes: DNS

DefaultRoute setting: yes

     LLMNR setting: yes

MulticastDNS setting: no

DNSOverTLS setting: no     
    DNSSEC setting: no     
  DNSSEC supported: no     
Current DNS Server: 8.8.8.8
       DNS Servers: 8.8.8.8

$

If need any changes

lxc profile edit bridgeprofile

New host create

lxc launch -p bridgeprofile ubuntu:20.04 zyx ( for ubuntu host )

lxc launch -p bridgeprofile images:debian/11/amd64 xyz ( for debian host )

login to lxc host

lxc exec xyz bash

Host Network conf host network » vi /etc/netplan/00-installer-config.yaml

network:

  ethernets:                            
      eth0:   
          addresses:                              
          - 103.16.74.7/27
          nameservers:                                 
              addresses:  
              - 8.8.8.8                                     
              search: []       
          routes:
          -   on-link: true         
              to: 0.0.0.0/0
              via: 103.16.74.1           
  version: 2

web GUI

/root/lxdui

python3 run.py start

create_lxc_container_inside_zfs-pool.pdf lxd_containers_get_ip_addresses_from_lan_dhcp_server_static_.pdf