Info

Updated on Apr 9, 2026

Info tracks key-value pairs that describe a target — build version, configuration, or environment metadata. The values are static: once set, the metric outputs a single time series with all key-value pairs as labels and a constant value of 1.

from prometheus_client import Info
i = Info('my_build_version', 'Description of info')
i.info({'version': '1.2.3', 'buildhost': 'foo@bar'})

Info exposes one time series per metric:

<name>_info{<key>="<value>", ...} — always 1; the key-value pairs become labels

Note: Info metrics do not work in multiprocess mode.

Constructor

Info(name, documentation, labelnames=(), namespace='', subsystem='', unit='', registry=REGISTRY)

Parameter	Type	Default	Description
`name`	`str`	required	Metric name. A `_info` suffix is appended automatically when exposing the time series.
`documentation`	`str`	required	Help text shown in the `/metrics` output and Prometheus UI.
`labelnames`	`Iterable[str]`	`()`	Names of labels for this metric. See Labels. Keys passed to `.info()` must not overlap with these label names.
`namespace`	`str`	`''`	Optional prefix.
`subsystem`	`str`	`''`	Optional middle component.
`unit`	`str`	`''`	Not supported — raises `ValueError`. Info metrics cannot have a unit.
`registry`	`CollectorRegistry`	`REGISTRY`	Registry to register with. Pass `None` to skip registration, which is useful in tests where you create metrics without wanting them in the global registry.

namespace, subsystem, and name are joined with underscores to form the full metric name:

# namespace='myapp', subsystem='http', name='build'
# produces: myapp_http_build_info
Info('build', 'Build information', namespace='myapp', subsystem='http')

Methods

`info(val)`

Set the key-value pairs for this metric. val must be a dict[str, str] — both keys and values must be strings. Keys must not overlap with the metric’s label names and values cannot be None. Calling info() again overwrites the previous value.

i.info({'version': '1.4.2', 'revision': 'abc123', 'branch': 'main'})

Labels

See Labels for how to use .labels(), .remove(), .remove_by_labels(), and .clear().

Real-world example

Exposing application build metadata so dashboards can join on version:

from prometheus_client import Info, start_http_server

BUILD_INFO = Info(
    'build',
    'Application build information',
    namespace='myapp',
)

BUILD_INFO.info({
    'version': '1.4.2',
    'revision': 'abc123def456',
    'branch': 'main',
    'build_date': '2024-01-15',
})

if __name__ == '__main__':
    start_http_server(8000)  # exposes metrics at http://localhost:8000/metrics
    # ... start your application ...

This produces:

myapp_build_info{branch="main",build_date="2024-01-15",revision="abc123def456",version="1.4.2"} 1.0