• Yossi Gottlieb's avatar
    Add hostname support in Sentinel. (#8282) · bb7cd974
    Yossi Gottlieb authored
    
    
    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: default avatarmyl1024 <myl92916@qq.com>
    Co-authored-by: default avatarsundb <sundbcn@gmail.com>
    bb7cd974
sentinel.conf 13.4 KB