How to use a Manual cloud with Juju

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The purpose of the Manual cloud is to cater to the situation where you have machines (of any nature) at your disposal and you want to create a backing cloud out of them. If this collection of machines is composed solely of bare metal you might opt for a MAAS cloud. However, recall that such machines would also require IPMI hardware and a MAAS infrastructure. In contrast, the Manual cloud can make use of a collection of disparate hardware as well as of machines of varying natures (bare metal or virtual), all without any extra overhead/infrastructure.

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Limitations

With any other cloud, the Juju client can trigger the creation of a backing machine (e.g. a cloud instance) as they become necessary. In addition, the client can also cause charmed operators to be deployed automatically onto those newly-created machines. However, with a Manual cloud the machines must pre-exist and they must also be specifically targeted during charmed operator deployment.

A MAAS cloud must also have pre-existing backing machines. However, Juju, by default, can deploy charmed operators onto those machines, or add a machine to its pool of managed machines, without any extra effort.

Prerequisites

The following conditions must be met:

  • At least two machines are needed (one for the controller and one where charmed operators will be deployed).
  • The machines must have Ubuntu (or CentOS) installed.
  • The machines must be contactable over SSH with public key authentication using a user account with root privileges. On Ubuntu, sudo rights will suffice if this provides root access. If a password is required for sudo, juju will ask for it on the command line.
  • The machines must be able to ping each other.

Add a Manual cloud

Use the interactive add-cloud command to add your Manual cloud to Juju’s list of clouds. You will need to supply a name you wish to call your cloud, the IP address (or hostname) for the machine you intend to use as a controller, and what remote user account to connect to over SSH (prepend ‘user@’ to the address/hostname).

To interactively add a cloud definition to the local client cache, run:

juju add-cloud

An example user session looks as follows:

Cloud Types
  lxd
  maas
  manual
  openstack
  vsphere

Select cloud type: manual

Enter a name for your manual cloud: manual-cloud

Enter the controller's hostname or IP address: noah@10.143.211.93

Cloud "manual-cloud" successfully added
You may bootstrap with 'juju bootstrap manual-cloud'

We’ve called the new cloud ‘manual-cloud’, used an IP address of 10.143.211.93 for the intended controller, and added a user account of ‘noah’ to connect to.

Add credentials

Credentials should already have been set up via SSH. Nothing to do!

Create a controller

You are now ready to create a Juju controller for the cloud ‘manual-cloud’:

juju bootstrap manual-cloud

The machine that will be allocated to run the controller on is the one specified during the add-cloud step. In our example it is the machine with address 10.143.211.93.

For a detailed explanation and examples of the bootstrap command, see Create a controller and Configure a controller.

Add machines to a manual cloud

To add the machine with an IP address (and user) of bob@10.55.60.93 to the ‘default’ model in the Manual cloud (whose controller was named ‘manual-controller’):

juju add-machine ssh:bob@10.55.60.93

Unless you’re using passphraseless public key authentication, you may be prompted for a password a few times. The process takes a couple of minutes.

Once the command has returned, you can check that the machine is available:

juju machines

Sample output:

Machine  State    DNS          Inst id             Series  AZ  Message
0        started  10.55.60.93  manual:10.55.60.93  xenial      Manually provisioned machine

Additional Manual cloud notes

The following notes are pertinent to the Manual cloud:

  • Juju machines are always managed on a per-model basis. With a Manual cloud the add-machine process will need to be repeated if the model hosting those machines is destroyed.
  • To improve the performance of provisioning newly-added machines consider running an APT proxy or an APT mirror. See Offline mode strategies.

Additional CentOS notes

One of the requirements for the Manual cloud is that SSH is running on the participating machines, but for CentOS this may not be the case. To install SSH, run the following commands as the root user on the CentOS system:

yum install sudo openssh-server redhat-lsb-core
systemctl start sshd

Since you will be connecting to the root account during the add-machine step, also ensure that there is a root password set on the CentOS machine.

Set up your cloud
Juju OLM Documentation
List of supported clouds
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