cached-metrics

Metrics exporter for Prometheus.

A small Flask app, designed to be run inside a docker container, that exposes a single /metrics endpoint returning metadata from a local cache file in a format that Prometheus can use for monitoring.

To get a minimal example working locally:

1. Clone with --recursive
2. cp cache-example metrics.json
3. cp config-example.json config.json
4. Edit the cache_volume property in config.json to the absolute path of this directory
5. Start the app by running:

   ./scripts/run config.json
   

6. To see the metrics change, change the utc_seconds value in metrics.json to a a value less than 5 minutes ago (convert current time to seconds here https://www.epochconverter.com/)

To run the current master from outside of DIDE, you can use:

./scripts/run config.json --public

Config

See config-example.json in this directory for an example config.

{
  "labels": {
    "db_name": "montagu"
  },
  "cache_volume": "barman_metrics",
  "cache_filename": "metrics.json",
  "port": 5000,
  "name": "barman-metrics",
  "max_age_seconds": 600
}

• labels are used by Prometheus to group metrics, and can be anything you like (see https://prometheus.io/docs/practices/naming/)
• cache_volume can be a named volume or absolute path, and is where the cache file will be found
• cache_filename is the name of the cache file
• port is the port the app will run on
• name is the name of the container the app will run as
• max_age_seconds is the threshold at which the app will consider cached data stale

Tests

To run tests inside a docker container, with config-example.json mounted as the config file:

./scripts/test.sh

To run tests not inside docker you would need to copy config-example.json to /etc/cm/config.json where the app expects to find its config, and cache-example to /app/cache/metrics.json where the app expects the cache file.

Teamcity

On Teamcity the script ./scripts/teamcity.sh is run, which runs tests and pushes the container to the montagu registry. To build the container locally, run

docker build \
       --tag $APP_DOCKER_COMMIT_TAG \
       --tag $APP_DOCKER_BRANCH_TAG \
       .