The config sentinel starts and stops services - and restart failed services unless are manually stopped
All nodes in a Vespa system has at least these running services:
|config-proxy||proxies config requests between Vespa applications and the configserver node. All configuration is cached locally so that this node can maintain its current configuration, even if the configserver shuts down|
|config-sentinel||registers itself with the config-proxy and subscribes to and enforces node configuration, meaning the configuration of what services should be run locally, and with what parameters|
|vespa-logd||monitors $VESPA_HOME/logs/vespa/vespa.log, which is used by all other services, and relays everything to the log-server|
config-proxy is started.
The environment variables
VESPA_CONFIGSERVER_RPC_PORTare used to connect to the config-server(s). It will retry all config servers in case some are down.
- config-sentinel is started, and subscribes to node configuration (i.e. a service list) from config-proxy using its hostname as the config id. See Node and Network setup - Concepts and Requirements for details about how the hostname is detected and how to override it. The config for the config-sentinel (the service list) lists the processes to be started, along with the config id to assign to each, typically the logical name of that service instance.
- config-proxy subscribes to node configuration from config-server, caches it, and returns the result to config-sentinel
config-sentinel starts the services given in the node configuration,
with the config id as argument -
see example output below, like id="search/qrservers/qrserver.0". Each service:
- Subscribes to configuration from config-proxy
- config-proxy subscribes to configuration from config-server, caches it and returns result to the service
- The service runs according to its configuration, logging to $VESPA_HOME/logs/vespa/vespa.log. The processes instantiate internal components, each assigned the same or another config id, and instantiating further components.
The config sentinel runs a RPC service which can be used to list,
start and stop the services supposed to run on that node. This can
be useful for testing and debugging.
Use the vespa-sentinel-cmd
command line tool to trigger these actions.
Example output from
vespa-sentinel-cmd 'sentinel.ls' OK. container state=RUNNING mode=AUTO pid=27993 exitstatus=0 id="default/container.0" container-clustercontroller state=RUNNING mode=AUTO pid=27997 exitstatus=0 id="admin/cluster-controllers/0" distributor state=RUNNING mode=AUTO pid=27996 exitstatus=0 id="search/distributor/0" logd state=RUNNING mode=AUTO pid=5751 exitstatus=0 id="hosts/r6-3/logd" logserver state=RUNNING mode=AUTO pid=27994 exitstatus=0 id="admin/logserver" searchnode state=RUNNING mode=AUTO pid=27995 exitstatus=0 id="search/search/cluster.search/0" slobrok state=RUNNING mode=AUTO pid=28000 exitstatus=0 id="admin/slobrok.0"To learn more about the processes and services, see files and processes.