Merge ~guoqiao/charm-prometheus-ceph-exporter:update-README into charm-prometheus-ceph-exporter:master

[Joe Guo]

Add deprecated notice in README for ceph >= Nautilus

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[🤖 prod-jenkaas-bootstack (prod-jenkaas-bootstack)]

A CI job is currently in progress. A follow up comment will be added when it completes.

[🤖 prod-jenkaas-bootstack (prod-jenkaas-bootstack)]

PASSED: Continuous integration, rev:bd74806979e65a78154b27e74008a18877e43f13
https://jenkins.canonical.com/bootstack/job/lp-charm-prometheus-ceph-exporter-ci/3/
Executed test runs:
    SUCCESS: https://jenkins.canonical.com/bootstack/job/lp-charm-test-unit/267/
    None: https://jenkins.canonical.com/bootstack/job/lp-update-mp/962/

Click here to trigger a rebuild:
https://jenkins.canonical.com/bootstack/job/lp-charm-prometheus-ceph-exporter-ci/3//rebuild

review: Approve (continuous-integration)

[Joe Guo (guoqiao)]

For bug LP#1931745, our original plan was to block prometheus-ceph-exporter if ceph >= Nautilus.

However, the effect to retrieve ceph version in p-c-e charm is more than it's worth, we have to create patches in following 3 repos to reach the goal:

https://review.opendev.org/c/openstack/charm-ceph-mon/+/805600
https://review.opendev.org/c/openstack/charm-interface-ceph-client/+/805582
https://code.launchpad.net/~ziyiwang/charm-prometheus-ceph-exporter/+git/charm-prometheus-ceph-exporter/+merge/407378

Also, we got questions and resistance from upstream team about:
- why we need to send ceph version over relation ? (we don't have better solution to get ceph version)
- why we don't have functional tests for this feature ? (3 repos are involved, we can not add func test when related changes are not in place yet)

The best place to add func test is in this charm itself when the other 2 patches are merged. However, this charm is going to be deprecated, so it's not worthy, again.

After discussion with elmo and Andrea, the decision is to add deprecated message in README of this charm, and drop above patches.

Review appreciated.

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change successfully merged at revision dff1ad8c3054045b97ef9b2282c3a3108be3a0d8

diff --git a/src/README.md b/src/README.md
index 50d92e8..eb29076 100644
--- a/src/README.md
+++ b/src/README.md
@@ -2,6 +2,11 @@
 
 This charm provides the [Prometheus Ceph exporter](https://github.com/digitalocean/ceph_exporter), part of the [Prometheus](https://prometheus.io/) monitoring system
 
+# IMPORTANT NOTICE
+
+This charm is deprecated since ceph Nautilus (14.0.0+), please use [charm-ceph-dashbaord](https://opendev.org/openstack/charm-ceph-dashboard) instead.
+Otherwise you will run into bug [LP#1931745](https://bugs.launchpad.net/charm-prometheus-ceph-exporter/+bug/1931745).
+
 # Introduction and Preparation
 
 The charm implements ceph-exporter functionality for Prometheus, it consumes the prometheus-ceph-exporter snap package,