PGVIP

Description

When launched, the pgvip service (module pgvip.c) loads parameters from the pgvip.conf configuration file into global variables (global.h,global.c), generates final operating system commands based on templates with variables, starts the threads. All configuration file parameters and final commands correspond to global variables of the same name with the prefix g_.

Check threads with an interval of {time_check_interval} execute commands {command_db_state},{command_vip_state} and set the result to the global variable g_status. Only commands that were executed with an error are written to the system log.

Action thread with the interval {time_command_ssh_timeout_int+time_check_interval_int+1} sequentially executes actions from the list (array of procedures), which, if the condition from the g_status variable is successfully checked, OS commands are executed (usually one). The results of the actions are not analyzed, they will be obtained by checking on all web servers.
Written in the system log:

• action name: the actual name of the procedure (__func__)
• initial status: pgvip status
• condition: real C code fragment (#define action_condition_text(condition) #condition)
• operating system commands: command text, stdout/stderr output, exit code

Thread	Purpose	Module	Function
CHECKER_MASTER_DB	checking the status of master database	checker.c	checker_master_db_thread
CHECKER_STANDBY_DB	checking the status of standby database	checker.c	checker_standby_db_thread
CHECKER_MASTER_VIP	checking virtual IP address on the master server	checker.c	checker_master_vip_thread
CHECKER_STANDBY_VIP	checking virtual IP address on the standby server	checker.c	checker_standby_vip_thread
ACTION_EXECUTOR	performing actions	action.c	action_executor_thread
MONITORING	sending metric to the monitoring system, notification	monitoring.c	monitoring_thread
LOGGER	log rotation, checking for updates	util_log.c	_log_thread
ADMINISTRATION	processing of status, stop and show commands	util_admin.c	_admin_thread

The action table is generated from the action.c module.
To get the command text by the variable name, need to execute in the command line
pgvip show config | grep [var]

Action (procedure)	Condition (if)	Commands (vars)
action_master_vip_auto_down_execute	status.master_vip_auto_down==G_VIP_AUTO_DOWN_NOT_EXECUTING	command_master_vip_auto_down_execute
action_master_vip_up	status.standby_db_state!=G_DB_STATE_READ_WRITE && status.master_db_state==G_DB_STATE_READ_WRITE && status.master_vip_state==G_VIP_STATE_DOWN && status.master_vip_auto_down==G_VIP_AUTO_DOWN_EXECUTING	command_master_vip_up
action_master_vip_down	status.master_vip_state==G_VIP_STATE_UP && (status.master_db_state!=G_DB_STATE_READ_WRITE || status.standby_db_state==G_DB_STATE_READ_WRITE)	command_master_vip_down
action_standby_vip_auto_down_execute	status.standby_vip_auto_down==G_VIP_AUTO_DOWN_NOT_EXECUTING	command_standby_vip_auto_down_execute
action_standby_vip_up	status.master_vip_state!=G_VIP_STATE_UP && status.standby_db_state==G_DB_STATE_READ_WRITE && status.standby_vip_state==G_VIP_STATE_DOWN && status.standby_vip_auto_down==G_VIP_AUTO_DOWN_EXECUTING	command_standby_vip_up
action_standby_vip_down	status.standby_vip_state==G_VIP_STATE_UP && status.standby_db_state!=G_DB_STATE_READ_WRITE	command_standby_vip_down
action_standby_db_promote	status.master_db_state!=G_DB_STATE_READ_WRITE && status.standby_db_state==G_DB_STATE_IN_RECOVERY && (time_now()-status.value_time)>g_time_standby_promote_delay_int && status.standby_db_lag<=g_time_standby_allowable_lag_int	command_master_vip_down command_standby_db_promote command_standby_vip_up
action_master_db_break	status.master_db_state==G_DB_STATE_READ_WRITE && status.standby_db_state==G_DB_STATE_READ_WRITE	command_master_db_break

Command line parameters (after installation, can view them by executing pgvip --help)