An image is a type of template for a virtual machine (VM).
You can launch an instance, custom install the software and files you want to use, then request an image of the instance. This will save all of the changes and updates within Atmosphere, but also make your custom changes available to yourself and collaborators. Saving instances as images helps leverage both your time and existing resources. The saved image can be used to launch a new child instance at any time. This allows you to discard non-active instances, thus saving resources.
After submitting the form, the Jetstream Atmosphere support staff will review and process the request. Future versions of Atmosphere will allow users to initiate the VM imaging process automatically.
Be sure to test launch any image created to validate that it behaves as expected BEFORE suspending or removing the current active instance, since only active instances can be imaged.
BEST PRACTICE: It is recommended to upgrade the operating system before imaging. For CentOS based systems, it's sudo yum update. For Ubuntu based systems, do sudo apt-get update and then sudo apt-get upgrade.
Creating an image on the SMALLEST possible size VM on which it will run will allow the image to be launched on VMs of the same size and larger.
For example, an image created on a Tiny size VM can be launched on a VM of any size; an image created on a Medium VM can only be launched on a Medium or larger size VM.
We cannot recommend strongly enough not using Atmosphere images on the API side of Jetstream or vice-versa.
The Atmosphere user interface is designed to be extremely easy to use, particularly for beginning users but the trade-off is that Atmosphere enforces certain practices behind the scenes.
The API user interface is close to raw openstack, makes almost no assumptions, requires advanced knowledge of Openstack and Linux, but is therefore much more flexible.
API and Atmosphere base images provided by Jetstream staff require SUBSTANTIAL work to make them CLEANLY work in the other environment.