* For consistency, use tclsh for the script as well
* Ignore leaked fds that originate from grandparent process, since we
only care about fds redis-sentinel itself is responsible for
* Check every test iteration to catch problems early
* Some cleanups, e.g. parameterization of file name, etc.
This commit fixes sentinel announces hostnames test error in certain linux environment
Before this commit, we only check localhost is resolved into 127.0.0.1, however in ubuntu
or some other linux environments "localhost" will be resolved into ::1 ipv6 address first if
the network stack is capable.
This is both a bugfix and an enhancement.
Internally, Sentinel relies entirely on IP addresses to identify
instances. When configured with a new master, it also requires users to
specify and IP and not hostname.
However, replicas may use the replica-announce-ip configuration to
announce a hostname. When that happens, Sentinel fails to match the
announced hostname with the expected IP and considers that a different
instance, triggering reconfiguration, etc.
Another use case is where TLS is used and clients are expected to match
the hostname to connect to with the certificate's SAN attribute. To
properly implement this configuration, it is necessary for Sentinel to
redirect clients to a hostname rather than an IP address.
The new 'resolve-hostnames' configuration parameter determines if
Sentinel is willing to accept hostnames. It is set by default to no,
which maintains backwards compatibility and avoids unexpected DNS
resolution delays on systems with DNS configuration issues.
Internally, Sentinel continues to identify instances by their resolved
IP address and will also report the IP by default. The new
'announce-hostnames' parameter determines if Sentinel should prefer to
announce a hostname, when available, rather than an IP address. This
applies to addresses returned to clients, as well as their
representation in the configuration file, REPLICAOF configuration
commands, etc.
This commit also introduces SENTINEL CONFIG GET and SENTINEL CONFIG SET
which can be used to introspect or configure global Sentinel
configuration that was previously was only possible by directly
accessing the configuration file and possibly restarting the instance.
Co-authored-by: myl1024 <myl92916@qq.com>
Co-authored-by: sundb <sundbcn@gmail.com>
This commit fixes a well known and an annoying issue in Sentinel mode.
Cause of this issue:
Currently, Redis rewrite process works well in server mode, however in sentinel mode,
the sentinel config has variant semantics for different configurations, in example configuration
https://github.com/redis/redis/blob/unstable/sentinel.conf, we put comments on these.
However the rewrite process only treat the sentinel config as a single option. During rewrite
process, it will mess up with the lines and comments.
Approaches:
In order to solve this issue, we need to differentiate different subconfig options in sentinel separately,
for example, sentinel monitor <master-name> <ip> <redis-port> <quorum>
we can treat it as sentinel monitor option, instead of the sentinel option.
This commit also fixes the dependency issue when putting configurations in sentinel.conf.
For example before this commit,we must put
`sentinel monitor <master-name> <ip> <redis-port> <quorum>` before
`sentinel auth-pass <master-name> <password>` for a single master,
otherwise the server cannot start and will return error. This commit fixes this issue, as long as
the monitoring master was configured, no matter the sequence is, the sentinel can start and run properly.
Sentinel uses execve to run scripts, so it needs to use FD_CLOEXEC
on all file descriptors, so that they're not accessible by the script it runs.
This commit includes a change to the sentinel tests, which verifies no
FDs are left opened when the script is executed.
* Introduce a connection abstraction layer for all socket operations and
integrate it across the code base.
* Provide an optional TLS connections implementation based on OpenSSL.
* Pull a newer version of hiredis with TLS support.
* Tests, redis-cli updates for TLS support.
During the initial handshake with the master a slave will report to have
a very high disconnection time from its master (since technically it was
disconnected since forever, so the current UNIX time in seconds is
reported).
However when the slave is connected again the Sentinel may re-scan the
INFO output again only after 10 seconds, which is a long time. During
this time Sentinels will consider this instance unable to failover, so
a useless delay is introduced.
Actaully this hardly happened in the practice because when a slave's
master is down, the INFO period for slaves changes to 1 second. However
when a manual failover is attempted immediately after adding slaves
(like in the case of the Sentinel unit test), this problem may happen.
This commit changes the INFO period to 1 second even in the case the
slave's master is not down, but the slave reported to be disconnected
from the master (by publishing, last time we checked, a master
disconnection time field in INFO).
This change is required as a result of an unrelated change in the
replication code that adds a small delay in the master-slave first
synchronization.
In the initialization test for each instance we used to unregister the
old master and register it again to clear the config.
However there is a race condition doing this: as soon as we unregister
and re-register "mymaster", another Sentinel can update the new
configuration with the old state because of gossip "hello" messages.
So the correct procedure is instead, unregister "mymaster" from all the
sentinel instances, and re-register it everywhere again.
The test now runs in a self-contained directory.
The general abstractions to run the tests in an environment where
mutliple instances are executed at the same time was extrapolated into
instances.tcl, that will be reused to test Redis Cluster.
