On Tue, Jun 09, 2020 at 02:57:14PM +0200, Thomas Goirand wrote: > In OpenStack, there's the possibility to rescue instances with a special > image made for it.
You mean this? https://docs.openstack.org/nova/latest/user/rescue.html According to the documentation, the default behaviour is to use a fresh copy of the the image already in use by the instance. So using a special rescue image is kind of a special case. > The only thing that changes is the cloud-init > configuration, so that it allows: > - ssh as root > - ssh using a password set by cloud-init (which can be seen with > "openstack server show" once the VM is in rescue mode). Where do those settings come from? Is this some kind of convention? If yes, please share them with us. > it's *not* reasonable to expect that: > - cloud users would use a normal image for rescue Using the normal image seems to be the default behaviour. Example of public documention from cloud providers who propose to just use the default image: https://help.switch.ch/engines/documentation/rescue-vm/ Red Hat describes possible problems with that approach: https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/16.0/html/instances_and_images_guide/ch-manage_instances#section-instance-rescue > - (which wouldn't be > adapted for the job) SWITCH for example describes the rescue mode to be used to fix the following problems: | - ssh key is lost → temporarily enable password login | - broken network configuration | - broken boot configuration | - interactive fsck needed None of those tasks require a special image, as the normal ones have everything on board to fix those problems. Please elaborate which problems you see. > Is there such a need in other clouds? How does it work in Azure/GCE/AWS? Nope. They don't have the concept of a rescue image or rescue mode. > Does the team has any idea of what kind of tool (ie: package names) that > we should install in such image? I thought about at least parted, mbr, > kpartx, dosfstools, e2fsprogs, qemu-utils, scrub, testdisk, scalpel, > gpart, gddrescue, foremost, ddrutility. > Anything else? Half of that list are recovery tools for hardware errors. Why would a cloud user care about hardware? Isn't that the providers job. > Therefore, IMO it'd be nice to also produce such image in our image-set. It might make sense to build such an image. But please make it into the form of a swiss army knife, so it can work of a thumb drive on a hardware machine as well. Kinda like grml. It would be more or less a hybrid of generic (includes cloud-init) and nocloud (can run without any infrastructure, but may require some fixes). Regards, Bastian -- Those who hate and fight must stop themselves -- otherwise it is not stopped. -- Spock, "Day of the Dove", stardate unknown
