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syntaxprometheusgrafana-templating

what does the 'up{}' syntax mean?

i've been working on some prometheus templating and whenever i look at other examples of templating i keep encountering this command:

$jobs = label_values(job)

$instance = up{job=~"$jobs"}

i understand that $jobs is a variable being created, but i have next to no clue what the up command is doing. I've looked online and i can't really narrow down the search enough for a generic word like 'up' haha

my best guess is that it makes the $instance variable equal only to cases where job is similar to jobs? i'm really not sure

any help would clarify a bunch. thanks!

Solution

  • According to the Jobs and instances Prometheus documentation:

    When Prometheus scrapes a target, it attaches some labels automatically to the scraped time series which serve to identify the scraped target:

    job: The configured job name that the target belongs to.
instance: The <host>:<port> part of the target's URL that was scraped.

    If either of these labels are already present in the scraped data, the behavior depends on the honor_labels configuration option.

    For each instance scrape, Prometheus stores a sample in the following time series:

    up{job="<job-name>", instance="<instance-id>"}: 1 if the instance is healthy, i.e. reachable, or 0 if the scrape failed.

    The up time series is useful for instance availability monitoring.