How to deploy on LXD

This guide goes shows you how to deploy Charmed OpenSearch on LXD, Canonical’s lightweight container hypervisor.

Prerequisites

• Charmed OpenSearch VM Revision 108+
• Fulfil the system requirements

Summary

• Configure LXD
• Prepare Juju
• Deploy OpenSearch

Configure LXD

This subsection assumes you are running on a fresh Ubuntu installation. In this case, we need to either install or refresh the current LXD snap and initialize it.

Install

LXD is pre-installed on Ubuntu images. You can verify if you have it install with the command which lxd.

If not installed, the lxd package can be installed using

sudo snap install lxd --channel=latest/stable  # latest stable will settle for 5.21+ version

Refresh and initialize

Once installed, refresh the lxd snap:

sudo snap refresh lxd --channel=latest/stable  # latest stable will settle for 5.21+ version
lxd 5.21.1-2d13beb from Canonical✓ refreshed

Initialize your setup. In the steps below, LXD is initialized to the “dir” storage backend. We can keep that or selecting any other option. IPv6 is disabled.

sudo 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 (lvm, powerflex, zfs, btrfs, ceph, dir) [default=zfs]: dir
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]: 
What should the new bridge be called? [default=lxdbr0]: 
What IPv4 address should be used? (CIDR subnet notation, “auto” or “none”) [default=auto]: 
What IPv6 address should be used? (CIDR subnet notation, “auto” or “none”) [default=auto]: none
Would you like the LXD server 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]:

Prepare Juju

Once LXD is ready, we can move on and prepare Juju. First, install juju’s latest v3:

sudo snap install juju --classic --channel=3/stable

Make LXD accessible to your local user

Run the following commands to create a new group for LXD and add your current user to it:

sudo newgrp lxd
sudo usermod -a -G lxd $USER

Now, log out and log back in.

Sysctl configuration

Before bootstrapping Juju controllers, we need to enforce the sysconfigs that OpenSearch demands. Some of these settings must be applied within the container, others must be set directly on the host.

On the host machine, add the settings below to a config file:

sudo tee /etc/sysctl.d/opensearch.conf <<EOF
vm.swappiness = 0
vm.max_map_count = 262144
net.ipv4.tcp_retries2 = 5
EOF

Now, apply the new settings:

sudo sysctl -p /etc/sysctl.d/opensearch.conf

Bootstrap

Create the juju controller using the bootstrap command:

juju bootstrap localhost

Configure sysctl for each model

Configure cloud-init to set sysctl on each new container deployed. First, add the configurations to a cloud-init user data file:

cat <<EOF > cloudinit-userdata.yaml
cloudinit-userdata: |
  postruncmd:
    - [ 'echo', 'vm.max_map_count=262144', '>>', '/etc/sysctl.conf' ]
    - [ 'echo', 'vm.swappiness=0', '>>', '/etc/sysctl.conf' ]
    - [ 'echo', 'net.ipv4.tcp_retries2=5', '>>', '/etc/sysctl.conf' ]
    - [ 'echo', 'fs.file-max=1048576', '>>', '/etc/sysctl.conf' ]
    - [ 'sysctl', '-p' ]
EOF

Now, there are two options to set it as configuration: (1) set the cloud-init as a default and to be used by every new model created after that; or (2) set it as a model config for the target model. The latter will be explained in the next section.

To set the cloud-init script above as default, use the model-defaults command:

juju model-defaults --file=./cloudinit-userdata.yaml

Add model

Add a model for the OpenSearch deployment, for example:

juju add-model opensearch

Confirm the cloud-init script is configured on this new model:

juju model-config cloudinit-userdata
postruncmd:
  - [ 'echo', 'vm.max_map_count=262144', '>>', '/etc/sysctl.conf' ]
  - [ 'echo', 'vm.swappiness=0', '>>', '/etc/sysctl.conf' ]
  - [ 'echo', 'net.ipv4.tcp_retries2=5', '>>', '/etc/sysctl.conf' ]
  - [ 'echo', 'fs.file-max=1048576', '>>', '/etc/sysctl.conf' ]
  - [ 'sysctl', '-p' ]

If the script above is not available, follow section “Configure sysctl for each model” to create the cloud-init script correctly and set it for this model:

juju model-config --file=./cloudinit-userdata.yaml

Deploy OpenSearch

To deploy OpenSearch, run

juju deploy opensearch --channel 2/edge

For more information about deploying OpenSearch, see our tutorial.