expression

A rate expression or a cron expression that defines how often the canary is to run. For a rate expression, The syntax is rate( *number unit* ) . unit can be minute , minutes , or hour . For example, rate(1 minute) runs the canary once a minute, rate(10 minutes) runs it once every 10 minutes, and rate(1 hour) runs it once every hour. You can specify a frequency between rate(1 minute) and rate(1 hour) . Specifying rate(0 minute) or rate(0 hour) is a special value that causes the canary to run only once when it is started. Use cron( *expression* ) to specify a cron expression. You can't schedule a canary to wait for more than a year before running. For information about the syntax for cron expressions, see Scheduling canary runs using cron .