[Bug 1726855] [NEW] 17.10 installer has trouble with swap partitions

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Hi,

I just ran with both the graphical installer from 17.10 ubuntu desktop
and the console installer from 17.10 lubuntu alternate into a problem,
that I already had reported some time ago for an older release, but
which has now become a more severe problem. Before, it occasionally kept
ubuntu from booting, now it always keeps ubuntu from booting.

Problem:

I use that scheme to install machines with SSD:

/dev/sda1  small ext4 as /boot , not encrypted
/dev/sda2  luks-encrypted swap
/dev/sda3  luks-encrypted root (ext4 or btrfs)


both installers do create the swap partition, but do put the "swap" flag into /etc/crypttab. The system then fails to boot. 

The reason is that systemd can't deal with that and tries to create a
fresh plain or randomly generated swap partition, while at the same time
trying to decrypt the device with the given UUID. While this former UUID
as mentioned in /etc/crypttab does not exist anymore, systemd's task to
create and mount that waits forever.

Simple solution: take the swap flag from /etc/crypttab and recreate the
initramfs, without the swap flag systemd works well and just decrypts as
expected, then attaches as a swap device without trying to recreated
this.

That swap flag worked before the migration to systemd, and the
installers still use it, although systemd can't properly cope with it.


Only with the graphical installer, I ran into another, related problem.

When I create these partitions as described and in the order above, the
installer becomes unable to generate /dev/sda3. Reason: the installer
creates /dev/sda2 as described. But then, systemd immediately finds this
as a swap devices and uses it as a swap. After entering the
configuration for sda3, the installer checks, finds an "unencrypted
swap" (not sure whether the installer takes the encrypted as unencryptd
or whether systemd again misinterpretes /etc/crypttab and randomly
creates a plain swap in the raw device) and aborts with an error message
before finishing /dev/sda3.


However, if I change the order and configure in the order sda1 sda3 sda2 , thinks work normally. It's because the installer then does not perform the check again after creating the swap.

** Affects: debian-installer (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: bot-comment
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17.10 installer has trouble with swap partitions
https://bugs.launchpad.net/bugs/1726855
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