Tue Nov 21, 2017
repmgr 4.0 is an entirely new version of repmgr, implementing repmgr as a native PostgreSQL extension, adding new and improving existing features, and making repmgr more user-friendly and intuitive to use. The new code base will make it easier to add additional functionality for future releases.
With the new version, the opportunity has been taken to make some changes in the way repmgr is set up and configured. In particular changes have been made to some configuration file settings consistency for and clarity. Changes are covered in detail below
To standardise terminology, from this release primary
is used to
denote the read/write node in a streaming replication cluster. master
is still accepted as an alias for repmgr commands
(e.g. repmgr master register
).
For detailed instructions on upgrading from repmgr 3.x, see Upgrading from repmgr 3.x.
improved switchover:
the switchover
process has been improved and streamlined,
speeding up the switchover process and can also instruct other standbys
to follow the new primary once the switchover has completed. See
Performing a switchover with repmgr for more details.
"--dry-run" option: many repmgr commands now provide
a --dry-run
option which will execute the command as far
as possible without making any changes, which will enable possible issues
to be identified before the intended operation is actually carried out.
easier upgrades: repmgr is now implemented as a native PostgreSQL extension, which means future upgrades can be carried out by installing the upgraded package and issuing ALTER EXTENSION repmgr UPDATE.
improved logging output:
repmgr (and repmgrd) now provide more explicit
logging output giving a better picture of what is going on. Where appropriate,
DETAIL
and HINT
log lines provide additional
detail and suggestions for resolving problems. Additionally, repmgrd
now emits informational log lines at regular, configurable intervals
to confirm that it's running correctly and which node(s) it's monitoring.
automatic configuration file location in packages:
Many operating system packages place the repmgr configuration files
in a version-specific subdirectory, e.g. /etc/repmgr/9.6/repmgr.conf
;
repmgr now makes it easy for package maintainers to provide a patch
with the actual file location, meaning repmgr.conf
does not need to be provided explicitly. This is currently the case
for 2ndQuadrant-provided .deb
and .rpm
packages.
monitoring and status checks: New commands repmgr node check and repmgr node status providing information about a node's status and replication-related monitoring output.
node rejoin: New commands repmgr node rejoin enables a failed primary to be rejoined to a replication cluster, optionally using pg_rewind to synchronise its data, (note that pg_rewind may not be useable in some circumstances).
automatic failover: improved detection of node status; promotion decision based on a consensual model, with the promoted primary explicitly informing other standbys to follow it. The repmgrd daemon will continue functioning even if the monitored PostgreSQL instance is down, and resume monitoring if it reappears. Additionally, if the instance's role has changed (typically from a primary to a standby, e.g. following reintegration of a failed primary using repmgr node rejoin) repmgrd will automatically resume monitoring it as a standby.
new documentation: the existing documentation spread over multiple text files has been consolidated into DocBook format (as used by the main PostgreSQL project) and is now available online in HTML format.
The DocBook files can easily be used to create versions of the documentation in other formats such as PDF.
--dry-run
: repmgr will attempt to perform
the action as far as possible without making any changes to the
database
--upstream-node-id
: use to specify the upstream node
the standby will connect later stream from, when cloning
and registering a standby.
This replaces the configuration file parameter upstream_node
.
as the upstream node is set when the standby is initially cloned, but can change
over the lifetime of an installation (due to failovers, switchovers etc.) so it's
pointless/confusing keeping the original value around in repmgr.conf
.
repmgr
--replication-user
has been deprecated; it has been replaced
by the configuration file option replication_user
.
The value (which defaults to the user provided in the conninfo
string) will be stored in the repmgr metadata for use by
repmgr standby clone and repmgr standby follow.
--recovery-min-apply-delay
is now a configuration file parameter
recovery_min_apply_delay
, to ensure the setting does not get lost
when a standby follows a new upstream.
--no-conninfo-password
is deprecated; a password included in
the environment variable PGPASSWORD
will no longer be added
to primary_conninfo
by default; to force the inclusion
of a password (not recommended), use the new configuration file parameter
use_primary_conninfo_password
. For details, ee section
Managing passwords.
repmgrd
--monitoring-history
is deprecated and is replaced by the
configuration file option monitoring_history
.
This enables the setting to be changed without having to modify system service
files.
Required settings
The following 4 parameters are mandatory in repmgr.conf
:
Renamed settings
Some settings have been renamed for clarity and consistency:
node
is now node_id
name
is now node_name
barman_server
is now barman_host
master_reponse_timeout
is now
async_query_timeout
(to better indicate its purpose)
The following configuration file parameters have been renamed for consistency
with other parameters (and conform to the pattern used by PostgreSQL itself,
which uses the prefix log_
for logging parameters):
loglevel
is now log_level
logfile
is now log_file
logfacility
is now log_facility
Removed settings
cluster
has been removedupstream_node
- see note about
--upstream-node-id
aboveretry_promote_interval_secs
this is now redundant due
to changes in the failover/promotion mechanism; the new equivalent is
primary_notification_timeout
Logging changes
log_level
is INFO
rather than NOTICE
.
log_status_interval
, which causes
repmgrd to emit a status log
line at the specified interval
The shared library has been renamed from repmgr_funcs
to
repmgr
, meaning shared_preload_libraries
in postgresql.conf
needs to be updated to the new name:
shared_preload_libraries = 'repmgr'