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Application metrics

Knowing an application's configuration isn’t enough to effectively operate and manage it. Consider that a well-designed application will have as few configurable parameters as possible. As an operator, you may find yourself wanting to know more about the resources that an application in your model consumes and provides -- resources such as:

  • Storage GiB used
  • Number of user accounts
  • Number of recently active users
  • Active database connections

Juju Metrics complete the operational picture with application observability; by modeling, sampling and collecting measurements of resources such as these. Juju collects application metrics at a cadence appropriate for taking a model-level assessment of application utilization and capacity planning.

There are many instrumentation and time-series data collection solutions supporting devops. Juju’s metrics complement these fine-grained, lower-level data sources with a model-level overview -- a starting point for deeper analysis.

Using metrics

View the most recent measurements from workloads that collect them with the juju metrics command.

View measurements for an entire model with:

juju metrics --all

Measurements from all metered workloads in the model are displayed:

UNIT                TIMESTAMP               METRIC      VALUE
webapp/0            2016-09-19T22:17:57Z    requests    11903
webapp/1            2016-09-19T22:17:52Z    requests    13719
ceph-mon/0          2016-09-19T22:15:36Z    gb-usage    5.2711902345
auth-sso/0          2016-09-19T22:14:29Z    users       28
auth-sso/0          2016-09-19T22:14:31Z    tokens      6

View measurements for specific units:

juju metrics webapp/0

Only webapp/0 measurements are shown:

UNIT                TIMESTAMP               METRIC      VALUE
webapp/0            2016-09-19T22:17:57Z    requests    13719

View measurements for applications as well:

juju metrics sso-auth

Measurements from all matching units are shown:

auth-sso/0          2016-09-19T22:14:29Z    users       28
auth-sso/0          2016-09-19T22:14:31Z    tokens      6

Machine readable formats are also supported:

juju metrics auth-sso --format yaml

Producing output ideal for integrating with data analysis and automation systems:

- unit: auth-sso/0
  timestamp: 2016-09-29T21:55:54.182Z
  metric: users
  value: "30"
- unit: auth-sso/0
  timestamp: 2016-09-29T21:55:53.319Z
  metric: tokens
  value: "7"

What does a charm measure?

The measurements collected by a charm are declared in its metrics.yaml. For example:

metrics:
  users:
    type: gauge
    description: Number of users
  tokens:
    type: gauge
    description: Number of active tokens

For a more detailed explanation of metrics.yaml, refer to the Metric types section in the developer documentation.

What else are metrics used for?

Measurements collected by Juju are also sent to Canonical, where they are aggregated across all deployments of the charm for analytics.

This information may be used to improve Juju, and may be shared with the charm developer to better support and improve the charm.

Canonical respects the privacy of its users and will not disclose the specific usage of individual users without prior consent.

You may opt-out of anonymous analytics at any time by setting the model configuration parameter transmit-vendor-metrics=false.