x/valet

Tanvir Talukder e30684b0c3 Valet Documentation

Added REST API Documentation
Added Valet Plugins Documentation
Added Apache License info

2017-05-01 19:07:42 -05:00

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High Availability Valet Tools

This tool monitors one or more configured processes to maintain high availability.

$ python ./ha_valet.py [-p name]

ha_valet.cfg

The ha_valet configuration file contains a list of dictionaries. List keys are logical process names. List values are dictionaries representing a monitored Valet-related process.

Each dictionary must contain the following properties:

host
user
port
protocol
start_command
stop_command
test_command

Optional properties include:

order
priority
standy_by_list

Notes

The return value of test_command must not be 0 and should reflect the monitored process priority (see next section).
stand_by_list is an optional comma-delimited list of hosts used in conjunction with active/stand-by scenarios. ha_valet will attempt to restart the instance with the lower priority. If that instance fails to start, ha_valet will try restarting the process of the next host in the list.
priority is used to establish the primary/secondary hierarchy. It must be greater than 0. The lower the number, the higher the priority.

Monitored Process Priority

Monitored process priority is used in conjunction with active/stand-by scenarios. Unless a process is down, its priority must be greater than 0. The lower the number, the higher the priority.

For example, an instance returning 1 (in response to test_command) will take precedence over an instance returning 2. A priority of 0 means the process is down.

Examples

Host A

:Ostro
    host = Host_A
    stand_by_list = Host_A,Host_B
    user = stack
    port = 8091
    protocol = http
    priority = 1
    start_command="ssh %s@%s 'cd @OSTRO_SERVER_DIR@ ; sudo python ./ostro_daemon.py start'" % (user, host)
    stop_command="ssh %s@%s 'cd @OSTRO_SERVER_DIR@ ; sudo python ./ostro_daemon.py stop'" % (user, host)
    test_command="ssh %s@%s 'exit $(@OSTRO_SERVER_DIR@ ; sudo python ./ostro_daemon.py status ; echo $?)'" % (user, host)

:Allegro
    host = Host_A
    user = stack
    port = 8090
    protocol = http
    priority = 1
    start_command="sudo python @ALLEGRO_WSGI_DIR@/wsgi.py &"
    stop_command="sudo pkill -f wsgi"
    test_command="netstat -nap  | grep %s | grep LISTEN | wc -l | exit $(awk \'{print $1}\')" % (port)

Host B (172.20.90.130)

:Ostro
    host = Host_B
    stand_by_list = Host_A,Host_B
    user = stack
    port = 8091
    protocol = http
    priority = 2
    start_command="ssh %s@%s 'cd @OSTRO_SERVER_DIR@ ; sudo python ./ostro_daemon.py start'" % (user, host)
    stop_command="ssh %s@%s 'cd @OSTRO_SERVER_DIR@ ; sudo python ./ostro_daemon.py stop'" % (user, host)
    test_command="ssh %s@%s 'exit $(@OSTRO_SERVER_DIR@ ; sudo python ./ostro_daemon.py status ; echo $?)'" % (user, host)

:Allegro
    host = Host_B
    user = stack
    port = 8090
    protocol = http
    priority = 1
    start_command="sudo python @ALLEGRO_WSGI_DIR@/wsgi.py &"
    stop_command="sudo pkill -f wsgi"
    test_command="netstat -nap  | grep %s | grep LISTEN | wc -l | exit $(awk \'{print $1}\')" % (port)

Contact

Joe D'Andrea jdandrea@research.att.com

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