Writing Expressions for KloudMate Alarms

alarm expressions allow you to manipulate query results using math and other operations kloudmate alarms can only be targeted on numeric data so, if a query returns time series data then it should be reduced using expressions before it can be used as an alarm target each individual expression or query is represented by a unique alphabetical notation such as a, b, and so on while writing an expression, one or more queries or other expressions can be passed as parameters using their notations expression operations kloudmate supports the following operations in alarm expressions math expression reduce condition expression math expression math expression takes time series or number data returned by a query or an expression and turns them into different time series and numbers using various mathematical operations or functions the following are the acceptable inputs for a math expression input any mathematical operation that is to be applied to the data returned from the other queries or expressions for math expressions, the queries or the expressions are as passed as parameters using their alphabetical notation prefixed with a dollar sign, for example, $a how does it work? kloudmate supports various mathematical operations and functions for math expressions mathematical operations for math expressions arithmetic operations ++ (increment) (decrement) + (addition) (subtraction) (multiplication) / (division) % (modulo) ^ (exponentiation) example ++$a, $a++, $a+1, $a 2, $a 2, $a/6, $a%$b, $a^2 boolean operations == (equal to) != (not equal to) < (less than) > (greater than) <= (less than or equal to) >= (greater than or equal to) example $a ==0, !$a !=0, $a<$b, $a>10, $a<=$d, $a>=$d logical operations && (and) || (or) ifnull (if nodata) example $a && $d, $a and $d, $a or $d, $a || $d, ifnull($a, 0) using expressions for multiple query conditions use the reduce function for all time series outputs (eg mean, max, last) use math expression ' ifnull ' logic with all reduced values, so that if any query returns 'nodata' it does not affect other queries' evaluation example ifnull($a, 0) > 50 || ifnull($b, 0) >90 here, ' ifnull ' checks for nodata and assigns given value '0' to that node if it is true '>' arithmetic operation 'greater than' checks the condition '||' logic operation 'or' evaluates both query nodes note that for the above mentioned operations when both $a and $b parameters are numbers, then the operation is performed between the two numbers if one parameter is a number, and the other is a time series, then the operation performed between the number and each value in the time series individually if both $a and $b parameters are time series data, then the operation performed between each value in the two series having the same time stamps the boolean and logical operations return 0 for false and 1 for true mathematical functions for math expressions abs returns the absolute value of its parameter which can be a number or a series e g , abs( 1) or abs($a) log returns the natural logarithm of its parameter which can be a number or a series if the value is less than 0, nan is returned e g , log( 1) or log($a) round returns a rounded integer value e g , round(3 123) or round($a) ceil rounds the number up to the nearest integer value e g , ceil(3 123) will return 4 floor rounds the number down to the nearest integer value e g , floor(3 123) will return 3 built in variables for math expressions to get any queried data in data per time range format (for example data/min), you can divide the respective data with the suitable time range variable you can choose from the following four time range variables that are built in $range\ m time range in minutes $range\ s time range in seconds $range\ h time range in hours $range\ d time range in days reduce reduce takes one or more time series or numbers of data returned from a query or an expression and turns them into a single number the following are the acceptable inputs for a reduced expression reduction function functions supported by reduce expression such as mean(), max(), min(), sum(), last(), count() query or expression data returned by a query or an expression is passed as a parameter using their respective alphabetical notation how does it work? the selected reduction function is used to aggregate the values of a query or an expression into a single value kloudmate supports various reduction functions for reduced expressions reduction functions for reduce expressions mean() get the average value max() get the maximum value min() get the minimum value sum() get the sum of all value last() get the last value count() get the total number of value condition expression condition expression takes one or more time series or numbers of data returned from queries or expressions and gives a boolean value as a result 0 (false) if the condition is not met or 1 (true) if the condition is met the following are the acceptable inputs for a condition expression reduction function functions supported by reduce expression such as mean(), max(), min(), sum(), last(), count() query or expression data returned by a query or an expression is passed as a parameter using their respective alphabetical notation condition string is above, is same or above, is below, is same or below value a number which will be used as the condition target how does it work? the selected reduction function will be applied to the selected query/expression to generate a single boolean value the generated value will be compared to the provided value according to the selected condition string when the input is a collection of time series or number data, the reduction function is applied to each element in the collection each of these reduced outputs is evaluated against the condition individually the outputs of the condition evaluation are then combined using the and operation you can add multiple conditions in a condition expression and choose how they work together using logical operators such as or & and related resources understanding kloudmate alarms setting up kloudmate