I was able to successfully use device mapper autoconfig feature
(commit 5ef07d79c) but it stopped working after a reboot.
Investigation shown that the dm device was not activated because of
a missing binary, that is not used during initial setup, but every
following time. Here's an error shown when trying to manually activate
the device:
> kir@kd:~/go/src/github.com/docker/docker$ sudo lvchange -a y /dev/docker/thinpool
> /usr/sbin/thin_check: execvp failed: No such file or directory
> Check of pool docker/thinpool failed (status:2). Manual repair required!
Surely, there is no solution to this other than to have a package that
provides the thin_check binary installed beforehand. Due to the fact
the issue revealed itself way later than DM setup was performed, it was
somewhat harder to investigate.
With this in mind, let's check for binary presense before setting up DM,
refusing to proceed if the binary is not there, saving a user from later
frustration.
While at it, eliminate repeated binary checking code. The downside is
that the binary lookup is happening more than once now -- I think the
clarity of code overweights this minor de-optimization.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
I tried using dm.directlvm_device but it ended up with the following
error:
> Error starting daemon: error initializing graphdriver: error
> writing docker thinp autoextend profile: open
> /etc/lvm/profile/docker-thinpool.profile: no such file or directory
The reason is /etc/lvm/profile directory does not exist. I think it is
better to try creating it beforehand.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Instead of forcing users to manually configure a block device to use
with devmapper, this gives the user the option to let the devmapper
driver configure a device for them.
Adds several new options to the devmapper storage-opts:
- dm.directlvm_device="" - path to the block device to configure for
direct-lvm
- dm.thinp_percent=95 - sets the percentage of space to use for
storage from the passed in block device
- dm.thinp_metapercent=1 - sets the percentage of space to for metadata
storage from the passed in block device
- dm.thinp_autoextend_threshold=80 - sets the threshold for when `lvm`
should automatically extend the thin pool as a percentage of the total
storage space
- dm.thinp_autoextend_percent=20 - sets the percentage to increase the
thin pool by when an autoextend is triggered.
Defaults are taken from
[here](https://docs.docker.com/engine/userguide/storagedriver/device-mapper-driver/#/configure-direct-lvm-mode-for-production)
The only option that is required is `dm.directlvm_device` for docker to
set everything up.
Changes to these settings are not currently supported and will error
out.
Future work could support allowing changes to these values.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
