How to deploy on LXD

This guide summarizes how to set up your machine and deploy Charmed OpenSearch on LXD, Canonical’s lightweight container hypervisor.

If you are a beginner to OpenSearch or Juju and are looking for a more comprehensive walkthrough of these steps, refer instead to the Tutorial.

Prerequisites

Juju v.3.5.3+: Install Juju, but do not bootstrap anything yet.

See also: How to install Juju

LXD v6.1+: Install and initialize LXD.

See also: FIrst steps with LXD

System requirements: Check that you fulfill the rest of the software and hardware requirements in the system requirements page.

Disable IPv6 on LXD

Juju does not support IPv6 addresses with LXD. To set the network bridge to have no IPv6 addresses, run the following command after initializing LXD:

lxc network set lxdbr0 ipv6.address none

See The LXD cloud and Juju for more information.

Sysctl configuration

Before bootstrapping Juju controllers, sysconfigs required by OpenSearch must be enforced. This entails modifying some kernel parameters on the host machine, and creating a configuration file to apply the same configuration in any new container that gets deployed.

sudo sysctl -a | grep -E 'swappiness|max_map_count|tcp_retries2'

Configure sysctl on the host machine

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

Then, apply the new settings:

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

Now you can bootstrap a Juju controller:

juju bootstrap localhost

Configure sysctl for new containers

Configure cloud-init to set sysctl on each new container that gets 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 apply this cloud-init configuration: set as the default config to be used by every new model created after that, or set it as a config for a target model.

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

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

To set the cloud-init script for a particular model, use the model-config command:

juju model-config --file=./cloudinit-userdata.yaml --model <model_name>

Deploy OpenSearch

Create a model if you haven’t already:

juju add-model <model_name>

In a single host deployment with LXD, we recommend using the testing profile, which will only consume 1G RAM per container.

To deploy OpenSearch with the testing profile, run

juju deploy opensearch --config profile=testing