SaltStack - Salt for Cloud Infrastructure

Salt provides a separate module, Salt Cloud to provide virtual machines of various cloud providers pke Amazon AWS, Google Compute, etc. Salt Cloud is a generic interface to configure and manage VMs of various cloud providers.

Cloud Config − The main configuration file for Salt Cloud is /etc/salt/cloud and it apppes to all the VMs. The main configuration file is called Cloud Config.

Cloud Providers − To target specific cloud providers, we can use specific configuration file and they are located in /etc/salt/cloud.providers.d/*.conf, these are called as Cloud Providers.

Cloud Profiles − To target a specific VM, we can also use a special configuration file, which apppes to that particular VM only and they are located at /etc/salt/cloud.profiles.d/*.conf, these are called as Cloud Profiles.

For a virtual machine, settings in the Cloud Config is appped first and then in the Cloud Providers and finally override is done by the Cloud Profiles.

Installation of Salt Cloud

By default, Salt Cloud is built into the Salt and is readily available. If it is not available, we can install it by using the command below.

pip install salt-cloud

Since Salt Cloud is a separate module and runs in its own process, it can be installed in the Salt Minion system as well instead of the Salt Master.

Provisioning a Virtual Machine

To provision a virtual machine, we need to define a cloud provider and a cloud profile. Once both are created, we can provision a new virtual machine for using it.

Cloud Provider

Cloud host information are configured in the Cloud provider configuration file. Normally, the basic information, which needs to be configured are cloud driver, username, password, private key, etc. Let us create a new cloud provider named as my-amazon-cloud.

Create a file, my-amazon-cloud.conf under /etc/salt/cloud.providers.d/

Add a new provider using the ec2 driver.

my-amazon-cloud:
   driver: ec2
   id:  <AWS_ID> 
   key:  <AWS_KEY> 
   private_key: /path/to/privatekey.pem
   keyname: <name of the key>
   securitygroup: default

   minion:
      master: <master server>

Salt provides drivers for various cloud host out of the box, such as GoGrid, HP Cloud, Google Compute Engine (GCE), Amazon AWS, Joyent, Linode, OpenNebula, ProfitBricks, Proxmox, Saltify, VexxHost, VMWare, etc.

Once the cloud providers are configured, we can query the available location of the provider, available machine images, and its various sizes.

salt-cloud --pst-location my-amazon-cloud
salt-cloud --pst-images my-amazon-cloud
salt-cloud --pst-sizes my-amazon-cloud

Cloud Profile

A Cloud profile specifies the virtual machine image and size. It can be configured under – /etc/salt/cloud.profiles.d/. Let us create a simple profile, simple.conf.

aws_micro:
   provider: my-amazon-cloud
   image: <image_id>
   size: <machine_id e.g. t1.micro>

Virtual Machine

Once the provider and profiles are configured, we can easily provide a virtual machine using the salt-cloud as shown below.

salt-cloud -p aws_micro master minion1 minion2

Where, p – Profile name master, minion1 and minion2 are the new virtual machines.

The details of the newly created virtual machine can be obtained by using the following command.

salt-cloud --query

The virtual machines can be destroyed using the following command −

slat-cloud -d master minion1

Cloud Map

A Cloud Map is a special format to create multiple virtual machines at once. The format of the map file is to specify the profile and then add a pst of the virtual machines under it.

A sample map file is as follows −

micro:
   - web1
   - web2
large:
   - db1
   - db2

The map file can be passed as an argument to the salt-cloud command to create the virtual machine as follows −

salt-cloud -m /path/to/mapfile