Charmed MongoDB Tutorial (replica set) | 1. Set up the environment

Charmed MongoDB Tutorials > Deploy a replica set > 1. Set up the environment

Set up the environment

Charmed MongoDB is operated via Juju, a charm orchestration engine that makes them easy to operate. For this tutorial, we will set up the tools needed to deploy and use Charmed MongoDB.

Summary


Minimum requirements

Before we start, make sure your machine meets the following requirements:

  • Ubuntu 20.04 (Focal) or later.
  • 8GB of RAM.
  • 2 CPU threads.
  • At least 20GB of available storage.
  • Access to the internet for downloading the required snaps and charms.

Set up LXD

LXD is a system container and virtual machine manager. The simplest way to get started using the MongoDB charm is to set up a local LXD cloud, then running the charm in a LXD container.

Install

Verify if your Ubuntu system already has LXD installed by entering the command which lxd into the command line. If there is no output, then simply install LXD with

sudo snap install lxd

Configure

After installation, we need to run lxd init to perform post-installation tasks. For this tutorial, the default parameters are preferred and the network bridge should be set to have no IPv6 addresses, since Juju does not support IPv6 addresses with LXD:

lxd init --auto
lxc network set lxdbr0 ipv6.address none

You can list all LXD containers by entering the command lxc list. If you have not used any LXD containers before, the output will be blank at this stage in the tutorial:

+------+-------+------+------+------+-----------+
| NAME | STATE | IPV4 | IPV6 | TYPE | SNAPSHOTS |
+------+-------+------+------+------+-----------+

Set up Juju

Juju is an Operator Lifecycle Manager (OLM) for clouds, bare metal, LXD or Kubernetes. We will be using it to deploy and manage Charmed MongoDB.

Install

As with LXD, Juju is installed from a snap package:

sudo snap install juju --channel 3.1/stable

Juju already has a built-in knowledge of LXD and how it works, so there is no additional setup or configuration needed, however, because Juju 3.x is a a strictly confined snap, and is not allowed to create ~/.local/share we need to create it manually.

mkdir -p ~/.local/share

Bootstrap a controller

A controller will be used to deploy and control Charmed MongoDB. All we need to do is run the following command to bootstrap a Juju controller named ‘overlord’ to LXD. This bootstrapping processes can take several minutes depending on how provisioned (RAM, CPU, etc.) your machine is:

juju bootstrap localhost overlord  --agent-version 3.1.6

The Juju controller should exist within an LXD container. You can verify this by entering the command lxc list and you should see the following:

+---------------+---------+-----------------------+------+-----------+-----------+
|     NAME      |  STATE  |         IPV4          | IPV6 |   TYPE    | SNAPSHOTS |
+---------------+---------+-----------------------+------+-----------+-----------+
| juju-<id>     | RUNNING | 10.105.164.235 (eth0) |      | CONTAINER | 0         |
+---------------+---------+-----------------------+------+-----------+-----------+

where <id> is a unique combination of numbers and letters such as 9d7e4e-0

Add a model

The controller can work with different models; models host applications such as Charmed MongoDB.

Set up a specific model for Charmed MongoDB named tutorial:

juju add-model tutorial

You can now view the model you created above by entering the command juju status into the command line. You should see the following:

Model    Controller  Cloud/Region         Version  SLA          Timestamp
tutorial overlord    localhost/localhost  3.1.6   unsupported  23:20:53Z

Model "admin/tutorial" is empty.

Next step: 2. Deploy MongoDB