Impromptu is a tool that scrapes metrics from a Prometheus endpoint and continuously executes a user-provided PromQL query to visualize the metrics in the CLI.

You can use Impromptu to get an insight into the metrics of a service without deploying Prometheus and Grafana, mostly during development and testing.

impromptu.mov

Installation

Install using homebrew:

brew install lovromazgon/tap/impromptu

Or download the binary manually from the latest release.

Note

When downloading Impromptu manually on MacOS you will get a warning about a safety issue. That's because Impromptu is currently not a signed binary, you have to do some extra steps to make it run.

Once you have downloaded impromptu, you can try it out using this runnable example:

impromptu -t http://demo.do.prometheus.io:9100/metrics -q "rate(node_cpu_seconds_total{mode=\"idle\"}[5s])" -r 1m

Important

Impromptu embeds Prometheus under the hood to scrape metrics. Unfortunately, Prometheus currently has a hardcoded delay of 5 seconds before it starts scraping, so you need to wait before data starts to be displayed.

Usage

Usage:
    impromptu -t URL -q PROMQL_QUERY [-i DURATION] [-r DURATION]

Options:
    -t, --target-url URL               Fetch metrics from the specified URL
    -q, --query-string PROMQL_QUERY    Query to execute against the metrics
    -i, --query-interval DURATION      Interval to fetch metrics at [default: 1s]
    -r, --query-range DURATION         Range of the query [default: 5m]
    -v, --version                      Print version information

URL represents an endpoint that serves Prometheus metrics in text format.

PROMQL_QUERY is a Prometheus query language expression that returns a single
time series. The query is executed every second and the result is displayed
in a terminal chart. The query should return a single time series, e.g. a
rate or a sum of a counter. The query interval and range can be adjusted with
the -i and -r flags.

DURATION is a time duration string that can be parsed by Go's time.ParseDuration
function. It represents a time interval, e.g. "5m" for 5 minutes, "1h" for 1
hour, "30s" for 30 seconds, "1h 2m 3s" for 1 hour, 2 minutes and 3 seconds etc.

Example:
    $ impromptu -t http://demo.do.prometheus.io:9100/metrics -q "rate(node_cpu_seconds_total{mode=\"idle\"}[5s])" -r 1m

Roadmap

• Remove initial 5 second delay (PR: prometheus/prometheus#14073)
• Support for multiple time series
• Support for other charts (donut, bar chart)
• Display legend