Working with images

You can see a list of available images by clicking the Images link on the Grid web page after logging in or by executing the command gridcli images.

You may also use any image from the following remote sources if you use the --remote-image command-line flag when scheduling a reservation.

  1. The images: default remote. See here for a list.
  2. The ubuntu: default remote. See here for a list.
  3. The ubuntu-daily: default remote. See here for a list.

For example, you may specify ubuntu:22.04 to launch a bare Ubuntu 22.04 container. Images from these remote sources will not be listed by gridcli images.

Adding your own image

To use your own image, copy it to the images directory in your home directory. The image must be readable by all users. You can accomplish this by running chmod 0444 IMAGE at the terminal, where IMAGE is your image file. Although counter-intuitive, this will not allow other users to see or use your image. You can manage your images via the Images link in the web interface. Marking an image “public” will make it available to every Grid user.

Snapshotting a node

You can snapshot a running instance by typing gridcli node snapshot NODE SNAPSHOTNAME, where NODE is the node you wish to snapshot and SNAPSHOTNAME is the name of the snapshot you want to create. The snapshot will be written to the images directory in your home directory and will be named SNAPSHOTNAME.tar.gz. The node will be paused while a snapshot is taken, which can take several minutes depending on the size of the image.

If the images directory does not exist, the snapshot creates it, owned by you and the grid group, with permissions 0770. Your home directory must have a+x permissions so that the grid user can reach it, which you can provide with the command chmod a+x ~.

If you receive the error The grid user does not have permission to write to /home/USER/images., where USER is your username, your images directory exists but the grid user cannot write to it. If the directory belongs to the grid group, chmod 0770 ~/images fixes it. Otherwise, rename it with mv ~/images ~/images.old, take the snapshot, which creates a new images directory, and then move your images into the new directory. You may also contact support to have the directory fixed.