Hetzner partitioning script #948

nh2 · 2018-05-08T18:59:18Z

This PR is based on top of PR #857 and thus includes its first commit; that PR should be merged before this one.

This PR modernises how the hetzner backend gets its inputs (using config instead of custom XML parsing), and then adds 3 options via which you can do custom partitioning. This is needed e.g. when you want to make an ext4 with external journal, using a combination of SSDs and HDDs that are common at Hetzner.

CC @aszlig @cleverca22

FRidh · 2018-05-10T06:56:12Z

nixops/backends/hetzner.py

-            setattr(self, var, xml_expr_to_python(node))
+
+        self.main_ipv4 = config["hetzner"]["mainIPv4"]
+        assert type(self.main_ipv4) is str


Use descriptors instead? Possibly http://traitlets.readthedocs.io.

These are nice ideas, but here I'm simply unifying the style to use the same as the other backends (such as the EC2 one,

nixops/nixops/backends/ec2.py

Line 39 in f10999a

self.access_key_id = config["ec2"]["accessKeyId"]

).

If we want to push for a change in style in general, we should probably tackle that separately for all backends and in coordination with whoever takes care of the those.

Regarding traitlets, I'm all for more type checking, but as far as I can tell it's an extra dependency so I can't tell whether or not we want to add it to nixops.

Apart from that, those types should already be checked by the NixOS module system, so I think most of those asserts aren't really needed.

nh2 · 2018-05-10T22:43:21Z

TODO for myself:

Fix example:

mkpart primary is misleading for GPT tables; as per https://www.gnu.org/software/parted/manual/html_node/mkpart.html#mkpart:

part-type is one of ‘primary’, ‘extended’ or ‘logical’, and may be specified only with ‘msdos’ or ‘dvh’ partition tables

Switch to MB instead of MiB, add note

      # Note we use "MB" instead of "MiB" because otherwise `--align optimal` has no effect;
      # as per documentation https://www.gnu.org/software/parted/manual/html_node/unit.html#unit:
      # > Note that as of parted-2.4, when you specify start and/or end values using IEC
      # > binary units like "MiB", "GiB", "TiB", etc., parted treats those values as exact

aszlig

I'd move most of the type and conflict checking to the module (for example via the assertions option) instead of within the Python part, as we can provide better error messages than a traceback from Python if we got an assertion.

Apart from that, it might be a good idea to fall back using nixos-generate-config (see _detect_hardware) with filesystem detection, so that providing fsInfo is optional.

aszlig · 2018-05-14T23:36:55Z

nix/hetzner.nix

      description = ''
        Specify layout of partitions and file systems using Anacondas Kickstart
        format. For possible options and commands, please have a look at:

        <link xlink:href="http://fedoraproject.org/wiki/Anaconda/Kickstart"/>
+
+        If the Kickstart is not sufficient for your partitioning needs,


Probably remove the the: If Kickstart is not sufficient...

aszlig · 2018-05-14T23:43:41Z

nix/hetzner.nix

+
+        Where possible, use the simpler "partitions" option instead of this option.
+
+        The "partitions" and "partitioningScript" options are mutually exclusive.


<option>partitions</option> and <option>partitioningScript</option>

aszlig · 2018-05-14T23:44:46Z

nix/hetzner.nix

+    filesystemInfo = mkOption {
+      type = types.nullOr types.attrs;
+      default = null;
+      example = {


Maybe use literalExample here, otherwise this ends up like this:

{ boot = { loader = { grub = { devices = [ "/dev/sda" "/dev/sdb" "/dev/sdc" "/dev/sdd" ] ; } ; } ; } ; fileSystems = { / = { fsType = "ext4"; label = "root"; options = [ "journal_path=/dev/disk/by-label/rootjournal" "data=journal" "errors=remount-ro" ] ; } ; } ; swapDevices = [ ] ; }

aszlig · 2018-05-14T23:45:05Z

nix/hetzner.nix

+      description = ''
+        Override the filesystem info obtained from the machine after partitioning.
+
+        This option is required when "partitioningScript" is used, but can also


Again, <option/>.

aszlig · 2018-05-14T23:48:24Z

nixops/backends/hetzner.py

-            setattr(self, var, xml_expr_to_python(node))
+
+        self.main_ipv4 = config["hetzner"]["mainIPv4"]
+        assert type(self.main_ipv4) is str


Apart from that, those types should already be checked by the NixOS module system, so I think most of those asserts aren't really needed.

aszlig · 2018-05-14T23:50:37Z

nixops/backends/hetzner.py

        """
        Bootstrap everything needed in order to get Nix and the partitioner
        usable in the rescue system. The keyword arguments are only for
        partitioning, see reboot_rescue() for description, if not given we will
        only mount based on information provided in self.partitions.
+
+        Exactly one of `partitions` and `partitioning_script` must be given as
+        non-None value.


I'd check this via the NixOS module system as well.

Yes, but not a reason not to merge, is it?

nh2 · 2018-05-26T03:02:55Z

Addressed a couple comments, some other ones still outstanding

…OS#856. The old approach, waiting for the machine to not having an open port, and then waiting for it to be open again, was insufficient, because of the race condition that the machine rebooted so quickly that the port was immediately open again without nixops noticing that it went down. I experienced this on a Hetzner cloud server. The new approach checks the `last reboot` on the remote side to change, which is not racy.

@aszlig

From @aszlig: > the Hetzner backend was written back then where there was > no config argument, so it's a good idea to switch to it

This allows for custom partitioning that Anaconda Kickstart / blivet cannot do.

coretemp · 2018-06-01T15:27:38Z

nixops/backends/__init__.py

+        self.reboot(hard=hard, reset=False)
+
+        self.log_start("waiting for reboot to complete...")
+        while True:


This doesn't look robust, because perhaps Hetzner did something wrong and it doesn't actually ever come up. I see lots of people who write while True: loops, but in reality, if it hasn't started after 3 minutes, you will start to wonder what's going on and you would have to manual work.

As such, this level of automation is an improvement over having nothing, but there is room for improvement.

coretemp · 2018-06-01T15:28:24Z

nixops/backends/__init__.py

+                break
+            self.log_continue(".")
+            time.sleep(1)
+        self.log_end("done.")


In a log it would be more useful see a line that says what actually was done.

@coretemp: This is done in log_start, which results in something like waiting for reboot to complete.....xxxx....done.. However I guess we could also refactor the logging mechanism to allow for context managers so this becomes more clear.

grahamc · 2020-03-26T19:23:12Z

Hello!

Thank you for this PR.

In the past several months, some major changes have taken place in
NixOps:

Backends have been removed, preferring a plugin-based architecture.
Here are some of them:
NixOps Core has been updated to be Python 3 only, and at the
same time, MyPy type hints have been added and are now strictly
required during CI.

This is all accumulating in to what I hope will be a NixOps 2.0
release. There is a tracking issue for that:
#1242 . It is possible that
more core changes will be made to NixOps for this release, with a
focus on simplifying NixOps core and making it easier to use and work
on.

My hope is that by adding types and more thorough automated testing,
it will be easier for contributors to make improvements, and for
contributions like this one to merge in the future.

However, because of the major changes, it has become likely that this
PR cannot merge right now as it is. The backlog of now-unmergable PRs
makes it hard to see which ones are being kept up to date.

If you would like to see this merge, please bring it up to date with
master and reopen it. If the or mypy type checking fails, please
correct any issues and then reopen it. I will be looking primarily at
open PRs whose tests are all green.

Thank you again for the work you've done here, I am sorry to be
closing it now.

Graham

This was referenced May 8, 2018

Don't use port open check to determine if reboot completed. Fixes #856. #857

Closed

Can't reformat machine when using LVM on RAID1 NixOS/nixpart#10

Open

nh2 force-pushed the hetzner-partitioning-script branch 2 times, most recently from e5f90bc to 85f720f Compare May 9, 2018 00:42

FRidh reviewed May 10, 2018

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aszlig requested changes May 15, 2018

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nh2 force-pushed the hetzner-partitioning-script branch 2 times, most recently from 161d512 to a794a4d Compare May 26, 2018 03:00

nh2 added 3 commits May 26, 2018 16:01

hetzner: Use config API instead of XML for extracting attributes.

7836009

From @aszlig: > the Hetzner backend was written back then where there was > no config argument, so it's a good idea to switch to it

hetzner: Add partitioningScript.

3ca62f2

This allows for custom partitioning that Anaconda Kickstart / blivet cannot do.

nh2 force-pushed the hetzner-partitioning-script branch from a794a4d to 3ca62f2 Compare May 26, 2018 14:01

coretemp reviewed Jun 1, 2018

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nh2 mentioned this pull request Jun 28, 2018

nixpart -p generates invalid syntax for my kickstart file NixOS/nixpart#11

Closed

grahamc closed this Mar 26, 2020

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Hetzner partitioning script #948

Hetzner partitioning script #948

nh2 commented May 8, 2018

FRidh May 10, 2018

nh2 May 10, 2018

aszlig May 14, 2018

nh2 commented May 10, 2018

aszlig left a comment

aszlig May 14, 2018

nh2 May 26, 2018

aszlig May 14, 2018

nh2 May 26, 2018

aszlig May 14, 2018

nh2 May 26, 2018

aszlig May 14, 2018

nh2 May 26, 2018

aszlig May 14, 2018

aszlig May 14, 2018

coretemp Jun 1, 2018

nh2 commented May 26, 2018

coretemp Jun 1, 2018

coretemp Jun 1, 2018

aszlig Jun 1, 2018

grahamc commented Mar 26, 2020


		Where possible, use the simpler "partitions" option instead of this option.

		The "partitions" and "partitioningScript" options are mutually exclusive.

Hetzner partitioning script #948

Hetzner partitioning script #948

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nh2 commented May 8, 2018

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grahamc commented Mar 26, 2020