Hi Callum For what it's worth, I met the same issue, and I wrote a python lib that can split alert rules into multiple parts of expressions, based on grammar, so it can handles and/or/group_left/on, etc as well. The split_binary_op function takes a string expression and returns the parsed result in json format.
https://github.com/laixintao/promqlpy/ Also thanks Julius, your information helped a lot. ;D On Friday, June 4, 2021 at 1:37:29 AM UTC+8 [email protected] wrote: > Hi Callum, > > In general yes, the PromQL Go library lets you parse an expression and > then traverse its abstract syntax tree, using the types from the "ast" > package in > https://github.com/prometheus/prometheus/blob/main/promql/parser/ast.go. > You'd first use > https://pkg.go.dev/github.com/prometheus/prometheus/promql/parser#ParseExpr > to do the parsing, and that gives you back the AST to look at. > > For example, this is how PromLens shows the different sub-expressions of a > query (for your expression: https://demo.promlens.com/?l=eF6PYANAlbQ). > > However: Not every alerting query is of the shape "<something> <comp-op> > <number>". Comparison / filter operators are normal binary expressions that > may or may not occur at any part of a query (even deeply nested in a query > tree, not at the end), and you will also have alerting queries which do not > contain a filter operator at all. So you would have to apply certain > assumptions about the structure of a query to be able to extract just the > part you are interested in. > > Regards, > Julius > > On Thu, Jun 3, 2021 at 1:04 AM Callum Jones <[email protected]> wrote: > >> Hi, >> >> With alerting rules the Prometheus API (and templating language) has >> access to the "Value" of an alert which appears to be the first metric >> specified without the comparator. >> >> I was wondering if this is something that is easily accessible in the >> Prometheus Go packages such that I could give it the expression string and >> it would strip out the comparison part and return just the metric query. >> >> For example passing in: >> > sum by (instance) (rate(node_disk_read_bytes_total[2m])) / 1024 / 1024 >> > 50 >> would return >> > sum by (instance) (rate(node_disk_read_bytes_total[2m])) / 1024 / 1024 >> >> Thanks, >> Callum >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Prometheus Users" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/prometheus-users/a5b35b15-ebae-4030-8a9c-f67adb836eacn%40googlegroups.com >> >> <https://groups.google.com/d/msgid/prometheus-users/a5b35b15-ebae-4030-8a9c-f67adb836eacn%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > > > -- > Julius Volz > PromLabs - promlabs.com > -- You received this message because you are subscribed to the Google Groups "Prometheus Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/prometheus-users/62b48cf0-5acf-4eab-8cb8-e4c702938a44n%40googlegroups.com.
