Data types

• Prometheus' is an expression language

Expressions

• The expressions can be evaluated to
• Instant vector
• Range vector
• Scalar
• String

Literals

• String literal

• Defined with quotes, double quotes or backticks

"this is a string"
'these are unescaped: \n \\ \t'
`these are not unescaped: \n ' " \t`

• Float literals

• Literal integer or floating-point numbers

23
-2.43
3.4e-9
0x8f
-Inf
NaN

Time Series Selectors

Instant Vector Selectors**

• Pick a selection from a a time series
• Uses the metric name as a function
• Label matching operators
• =: Select labels that are exactly equal to the provided string.
• !=: Select labels that are not equal to the provided string.
• =~: Select labels that regex-match the provided string. env=~"foo" is treated as env=~"^foo$".
• !~: Select labels that do not regex-match the provided string.

# all the time series
http_requests_total

# filter the time series
http_requests_total{job="prometheus", group="canary"}

# filter with regex
http_requests_total{environment=~"staging|testing|development", method!="GET"}
http_requests_total{environment=~"$ENVS"} # from list variable
http_requests_total{status!~"4.."}

# the time series to be used can be picked by a regex
{__name__=~"http_requests_total.*"}

Range Vector Selector

• Like instant vector, but it also select a range of samples
• Specify how far back in time the values should be fetched for each resulting range

http_requests_total{job="prometheus"}[5m]

Time Duration

• Specified by a number, following by a unit

ms # milliseconds
s # seconds
m # minutes
h # hours
d # days - assuming a day has always 24h
w # weeks - assuming a week has always 7d
y # years - assuming a year has always 365d

# concatenation
1h30m

Offset Modifier

• Changes the time offset for an instant

# request with the instant time past 1 week
http_requests_total{method="GET"} offset 1w
rate(http_requests_total[5m] offset 1w)

@ Modifier

• Specify the instant time

http_requests_total @ 1609746000
sum(http_requests_total{method="GET"} @ 1609746000)

# offset after @
http_requests_total @ 1609746000 offset 5m
# offset before @
http_requests_total offset 5m @ 1609746000