[pve-devel] [PATCH pve-manager v2 0/6] Fix #6816: Prevent ceph-exporter Daemon from Crashing on Startup - v2

[Max R. Carrara]

Fix #6816: Prevent ceph-exporter Daemon from Crashing on Startup - v2
=====================================================================

tl;dr: Stop ceph-exporter.service from ending up in a crash loop by
handing it a custom keyring file and setting its group to `www-data`,
similar to what we did for ceph-crash.service [0] before.

This is a refresh of a somewhat older series that has been rebased, with
the version guard in `debian/postinst` adapted. The description from the
previous version is provided here again for the reader's convenience.

Currently, the `ceph-exporter` daemon ends up in a short startup crash
loop before ultimately failing to start at all, because it tries to
access the keyring file at `/etc/pve/priv/ceph.client.admin.keyring`,
for which it doesn't have the permissions to do so.

Instead of giving it access to the admin ring, give it its own keyring
located at `/etc/pve/ceph/ceph.client.exporter.keyring`. This file and
its corresponding section in `/etc/pve/ceph.conf` is created when the
first MON is created via the API. If the cluster has already been set
up, a postinst hook creates the keyring file and adapts
`/etc/pve/ceph.conf` instead.

The core logic of all of this was already added for `ceph-crash` a while
ago [0] and is reused throughout the series, with some alterations to
the original code in order to make it a little more generic.

Testing
-------

Would appreciate if somebody could (smoke-)test this just to make sure I
didn't miss anything. In particular, ceph-exporter should start working
by itself if you upgrade pve-manager with this series applied on an
existing Ceph cluster (with `ceph-exporter` installed, of course).

The setup this series adds should also be done by the `pveceph` CLI for
new installations; installing Ceph on a single node should be sufficient
to test this.

*Important:* If you don't want to rebuild Ceph in order to test this,
you can override the systemd service for ceph-exporter as follows:

1. `mkdir -p /etc/systemd/system/ceph-exporter.service.d`

2. Create file `` with the following contents (inside ```):
```
[Service]
Environment="CEPH_KEYRING=/etc/pve/ceph/ceph.client.exporter.keyring"
ExecStart=
ExecStart=/usr/bin/ceph-exporter -f --id exporter --setuser ceph --setgroup www-data
```

3. `systemctl daemon-reload`

4. Install the pve-manager package from this series. See NOTE below.

Also, ensure you have `ceph-exporter` actually installed, of course.
Whether you install it before or after the above doesn't (shouldn't)
really matter.

Then, you should see the metrics become available at
http://your.node.tld:9926/metrics.

NOTE
----

Patch #03 adds a call to the helper in debian/postinst. The version
check there should be adapted after / while applying the series.
Right now, the version in the check is set to `9.1.5`.

Previous Versions
-----------------

v1: https://lore.proxmox.com/pve-devel/20250916172012.739807-1-m.carrara@proxmox.com/

References
----------

[0]: https://lore.proxmox.com/pve-devel/20240402145523.683008-11-m.carrara@proxmox.com/

Summary of Changes
------------------

pve-manager:

Max R. Carrara (5):
  ceph: tools: add helper sub for creating or updating keyring files
  fix #6816: api: ceph: create 'client.exporter' w/ keyring
  fix #6816: bin: add pve-ceph-keyring helper and call it in postinst
  ceph: tools: simplify helper sub for crash keyring file
  bin: make pve-init-ceph-crash call pve-ceph-keyring

 PVE/API2/Ceph/MON.pm    |   9 ++
 PVE/Ceph/Tools.pm       | 108 ++++++++++++---
 bin/Makefile            |   1 +
 bin/pve-ceph-keyring    | 286 ++++++++++++++++++++++++++++++++++++++++
 bin/pve-init-ceph-crash | 152 +--------------------
 debian/postinst         |  24 ++++
 6 files changed, 415 insertions(+), 165 deletions(-)
 create mode 100755 bin/pve-ceph-keyring


ceph:

Max R. Carrara (1):
  fix #6816: patches: make ceph-exporter use custom keyring

 ...orter-use-custom-keyring-and-set-gro.patch | 32 +++++++++++++++++++
 patches/series                                |  1 +
 2 files changed, 33 insertions(+)
 create mode 100644 patches/0042-systemd-ceph-exporter-use-custom-keyring-and-set-gro.patch

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2.47.3