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Basic information about images

CSC provides a set of standard images that are well suited for cloud use. In most cases, you can use these images instead of creating your own. The images are created automatically using diskimage-builder. If you are interested in the details of how these images are created, see this GitHub page. The images are updated at regular intervals so that they contain the latest security updates at the time virtual machines are launched.

It is possible that for some use cases the automatically created images are not suitable. In this case, it is possible to create your own images and use them instead. However, there are some caveats to consider when creating your own images that you would not need to consider when using the default images. For more information,, see Advanced images

The main features of the images provided by CSC

The images provided by CSC are mostly the same as upstream.

  • Most of the images come with the pre-configured username cloud-user, though there are some exceptions to this rule.
  • We make sure that the images are updated before releasing them, so that we are sure that they work.
  • The -Cuda images come preinstalled with the latest CUDA drivers.
  • We enable automatic updates.
  • We disable password login.
  • We sometimes add some nice-to-have packages such as vim or ntp. We try to keep the additional packages at a minimum.


Image Username Modified
CentOS-8 cloud-user yes
CentOS-7 cloud-user yes
CentOS-7-cuda cloud-user yes
Ubuntu-20.04 ubuntu no
Ubuntu-18.04 ubuntu no


Currently in a tech preview because we have found some minor issues with it.

At the moment we are making these changes to it: - we change the username to "cloud-user" instead of centos - we have removed the resolver in /etc/resolv.conf

CentOS is the community version of Red Hat Enterprise Linux (RHEL).

Another difference is that this image does not have automatic updates enabled.


CentOS is the community version of Red Hat Enterprise Linux (RHEL). CentOS-7 is the distribution that the Pouta admins are the most accustomed to. This is the second-newest major release of CentOS.


This is the same as CentOS-7 but comes with preinstalled NVIDIA drivers. These are useful in combination with the GPU flavors since you do not need to download the drivers yourself. We try to always have the latest NVIDIA drivers installed, but sometimes we are lagging a bit behind. These images are huge, so you should use the normal CentOS-7 image if you are not using a GPU-flavor VM.

Ubuntu-20.04 LTS

Ubuntu-20.04 LTS image, included in Pouta, another one from Ubuntu image family for those who do not want to use CentOS. Note that like Ubuntu-18.04, Ubuntu 20.04 also has ubuntu as the default username instead of cloud-user. This is the another image type we started to provide directly from the upstream after Ubuntu-18.04.

Ubuntu-18.04 LTS

Some like chocolate, some like strawberry. This is the choice for those that do not want to use CentOS. Note that Ubuntu-18.04 has ubuntu as the default username instead of cloud-user, since it was the first image type we started to provide directly from the upstream.

Snowflake images

These images you should probably not use without a really good reason. You might be better off creating your own image

If there any images that you think we should add, do not hesitate to contact Service Desk.


This is a really small image which can be used to boot an instance really fast. This can be useful for doing tests in Pouta, such as testing if the network works or how fast you can launch an instance. You should not use this for persistent VMs, and you should always delete the instance when you are done with testing. There is very little reason for end-users using this image, and if you are unsure, CentOS and Ubuntu are better choices 99% of the time.