[PVE-User] pve-firewall, clustering and HA gone bad

Thomas Lamprecht t.lamprecht at proxmox.com
Thu Jun 13 12:34:28 CEST 2019


Hi,

On 6/13/19 11:47 AM, Mark Schouten wrote:
> Let me start off with saying that I am not fingerpointing at anyone,
> merely looking for how to prevent sh*t from happening again!
> 
> Last month I emailed about issues with pve-firewall. I was told that
> there were fixes in the newest packages, so this maintenance I started
> with upgrading pve-firewall before anything else. Which went well for
> about all the clusters I upgraded.
> 
> Then I ended up at the last (biggest, 9 nodes) cluster, and stuff got
> pretty ugly. Here's what happened:
> 
> 1: I enabled IPv6 on the cluster interfaces in the last month. I've done
> this before on other clusters, nothing special there. So I added the
> IPv6 addresses on the interfaces and added all nodes in all the
> /etc/hosts files. I've had issues with not being able to start clusters
> because hostnames could not resolve, so all my nodes in all my clusters
> have all the hostnames and addresses of their respective peers in
> /etc/hosts.

Do your ringX_addr in corosync.conf use the hostnames or the resolved
addresses? As with nodes added on newer PVE (at least 5.1, IIRC) we try
to resolve the nodename and use the resolved address to exactly avoid
such issues. If it don't uses that I recommend changing that instead
of the all nodes in al /etc/hosts approach.

> 2: I upgraded pve-firewall on all the nodes, no issues there
> 3: I started dist-upgrading on proxmox01 and proxmox02, and restarting
> pve-firewall with `pve-firewall restart` because of [1] and noticed that
> pvecm status did not list any of the other nodes in list of peers. So we
> had:
>   proxmox01: proxmox01
>   proxmox02: proxmox02
>   proxmox03-proxmox09: proxmox03-proxmox09
> 
> Obviously, /etc/pve was readonly on proxmox01 and proxmox02, since they
> had no quorum.
> 4: HA is heavily used on this cluster. Just about all VM's have it
> enabled. So since 'I changed nothing', I restarted pve-cluster a few
> times on the broken nodes. Nothing helped.
> 4: I then restarted pve-cluster on proxmox03, and all of the sudden,
> proxmox01 looked happy again.
> 5: In the meantime, ha-manager had kicked in and started VM's on other
> nodes, but did not actually let proxmox01 fence itself, but I did not
> notice this.
> 6: I tried restarting pve-cluster on yet another node, and then all
> nodes except proxmox01 and proxmox02 fenced themselves, rebooting
> alltogether.
> 
> After rebooting, the cluster was not completely happy, because the
> firewall was still confused. So why was this firewall confused? Nothing
> changed, remember? Well, nothing except bullet 1.
> 
> It seems that pve-firewall tries to detect localnet, but failed to do so
> correct. localnet should be 192.168.1.0/24, but instead it detected the
> IPv6 addresses. Which isn't entirely incorrect, but IPv6 is not used for
> clustering, so I should open IPv4 in the firewall not IPv6. So it seems
> like nameresolving is used to define localnat, and not what corosync is
> actually using.

>From a quick look at the code: That seems true and is definitively the
wrong behavior :/

> 
> I fixed the current situation by adding the correct [ALIASES] in
> cluster.fw, and now all is well (except for the broken VM's that were
> running on two nodes and have broken images).
> 
> So I think there are two issues here:
> 1: pve-firewall should better detect the IP's used for essential
> services

Yes, granted, that should probably be. I'll try to take a look at this.

> 2: ha-manager should not be able to start the VM's when they are running
> elsewhere

This can only happen if fencing fails, and that fencing works is always
a base assumption we must take (as else no HA is possible at all).
So it would be interesting why fencing did not worked here (see below
for the reason I could not determine that yet as I did not have your logs
at hand)

> 
> Obviously, this is a faulty situation which causes unexpected results.
> Again, I'm not pointing fingers, I would like to discuss how we can
> improve these kind of faulty situations.
> 
> In the attachment, you can find a log with dpkg, pmxcfs, pve-ha-(lc)rm
> from all nodes. So maybe someone can better asses what went wrong.

The list trims attachments, could you please send them directly to my
address? I'd really like to see those.

> 
> [1]: https://bugzilla.proxmox.com/show_bug.cgi?id=1823
> 

[1] flew under my radar..



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