ceph/doc/dev/mon-on-disk-formats.rst

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ON-DISK FORMAT
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UPGRADE PATH
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On-disk formats, or even data structure formats, may be changed during an
upgrade. Services wishing to do so, may so do it via the
`PaxosService::upgrade_format()` call path. There is no formalized, unified
format versioning; the `PaxosService` class keeps track of its
`format_version` through a key in the store, assumed an `unsigned int`, but
it will be the service's responsibility to give meaning to those versions.
AUTH MONITOR
============
versions
--------
versions are represented with a single `unsigned int`. By default, the value
zero represents the absence of a formal upgraded format. The first format
version was introduced in Dumpling; clusters upgrading to Dumpling saw their
format version being increased from zero to one::
0 to 1 - introduced in v0.65, dev release for v0.67 dumpling
1 to 2 - introduced in v12.0.2, dev release for luminous
2 to 3 - introduced in mimic
0 - all clusters pre-dumpling
1 - all clusters dumpling+ and pre-luminous
2 - all clusters luminous+ and pre-mimic
3 - all clusters mimic+
version 1: introduces new-style monitor caps (i.e., profiles)
version 2: introduces mgr caps and bootstrap-mgr key
version 3: creates all bootstrap and admin keys if they don't yet exist
callstack
---------
format_version set on `PaxosService::refresh()`::
- initially called from Monitor::refresh_from_paxos
- initially called from Monitor::init_paxos()
- initially called from Monitor::preinit()
AuthMonitor::upgrade_format() called by `PaxosService::_active()`::
- called from C_Committed callback, from PaxosService::propose_pending()
- called from C_Active callback, from PaxosService::_active()
- called from PaxosService::election_finished()
- on a freshly deployed cluster, upgrade_format() will be first called
*after* create_initial().
- on an existing cluster, upgrade_format() will be called after the first
election.
- upgrade_format() is irrelevant on a freshly deployed cluster, as there is
no format to upgrade at this point.
boil down
---------
* if `format_version >= current_version` then format is up-to-date, return.
* if `features doesn't contain LUMINOUS` then `current_version = 1`
* else if `features doesn't contain MIMIC` then `current_version = 2`
* else `current_version = 3`
if `format_version == 0`::
- upgrade to format version 1
- move to new-style monitor caps (i.e., profiles):
- set daemon profiles for existing entities
- set profile for existing bootstrap keys
if `format_version == 1`::
- upgrade to format version 2
- for existing entities:
- add new cap for mgr
- for existing 'mgr' entities, fix 'mon' caps due to bug from kraken
setting 'allow \*', and set 'allow profile mgr' instead.
- add bootstrap-mgr key.
if `format_version == 2`::
- upgrade to format version 3
- create all bootstrap keys if they don't currently exist