On Wed, May 31, 2017 at 4:25 PM, Graham Leggett <[email protected]> wrote:
> On 31 May 2017, at 9:36 PM, Ryan Harper <[email protected]> wrote: > > Yes, the overlay module doesn't seem to have a way to find a default > workdir value by itself. =( > > > This is an unfortunate regression. > > What needs to happen is that after the fs_setup step that creates >> /mnt/postfix-overlay, but before the mounts section where the overlayfs is >> created, the workdir and upperdir directories need to be created on the >> /mnt/postfix-overlay disk as /mnt/postfix-overlay/upperdir and >> /mnt/postfix-overlay/workdir (or something) respectively. >> >> Is there something that can be done in cloud-init to make this possible? >> > > Surely it can; I think it's a matter of module timing: you need the > directory to be created prior to the mounts module running. > Looking at /etc/cloud/cloud.cfg, the cloud_init_modules list, shows that > 'bootcmd'[1] will run before the 'mounts' stage, so > it should be possible to include a command like this: > > bootcmd: > - mkdir -p /mnt/postfix-overlay-workdir > > And to update the overlayfs mount command to specify the workdir path. > > That's untested, but I think should do what you need. > > 1. http://cloudinit.readthedocs.io/en/latest/topics/modules.html#bootcmd > > > Alas, bootcmd also runs before the disk_setup stage, and as a result the > disk doesn’t exist yet that the directories need to be created on. > Yes, the workdir needs to be on the same filesystem as upper. > > # The modules that run in the 'config' stage > cloud_config_modules: > # Emit the cloud config ready event > # this can be used by upstart jobs for 'start on cloud-config'. > - emit_upstart > - disk_setup > - mounts > > “mounts” seems to be run directly after “disk_setup”, giving no option to > do anything in between. > > What is the cleanest way to fix this? > > Maybe something like this: > > fs_setup: > - label: postfix > device: /dev/xvde > filesystem: ext4 > mkdir: upperdir workdir > I think we will need to amend the mounts module; we cannot mkdir until the filesystem is mounted so adding config to fs_setup would mean we'd need to temp mount, mkdir, and umount. Looking at cc_mounts module, it already does mkdir on the mount point in the entry, I think it's reasonable to check for a list of lower,upper,workdir values if the fstype is overlay; and add this to the list of directories that cc_mounts creates. I've created https://bugs.launchpad.net/cloud-init/+bug/1695277 to track the work. > > Regards, > Graham > — > >
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