metrics-export-role

roles.metrics-export is a role for Tarantool 3. It allows to export metrics from Tarantool 3. For now only export via HTTP is supported.

Usage

1. Add the metrics-export-role package to dependencies in the .rockspec file.

dependencies = {
    ...
    'metrics-export-role == 0.2.0-1',
    ...
}

And re-build an application:

tt build

Be careful, it is better to use a latest release version.

2. Enable and configure the roles.metrics-export role for a Tarantool 3 instance. Use httpd role or listen field in to configure server instances. See below to get more detailed information about it.

groups:
  group-001:
    replicasets:
      replicaset-001:
        instances:
          master:
            roles: [roles.httpd, roles.metrics-export]
            roles_cfg:
              roles.httpd:
                default:
                  listen: '127.0.0.1:8083'
                additional:
                  listen: 8084
              roles.metrics-export:
                http:
                - endpoints:
                  - path: /metrics/json
                    format: json
                - server: 'additional'
                  endpoints:
                  - path: /metrics/prometheus
                    format: prometheus
                - listen: 8081
                  endpoints:
                  - path: /metrics/json
                    format: json
                  - path: /metrics/prometheus/
                    format: prometheus
                - listen: 'my_host:8082'
                  endpoints:
                  - path: /metrics/prometheus
                    format: prometheus
                  - path: /metrics/json/
                    format: json

In the example above, we configure four HTTP servers. There are serveral server fields:

• first with server field which refers to an additional server in the httpd role;
• the next one, with no info about server, is configured with default name in httpd config;
• and the last two listen fields (0.0.0.0:8081 and my_host:8082) that are listed directly.

The servers will be running on the master Tarantool instance.

Each server has two endpoints:

• /metrics/json exports metrics with JSON format.
• /metrics/prometheus exports metrics with Prometheus-compatible format.

Configuration

The role configuration at the top level could be described as:

export_target: opts

http target

For now only http target is supported. The target allows to export metrics via HTTP-servers. The target could be configured as an array of servers.

Each server must have listen param that could be a port (number) or a string in the format host:port. The address will be used by HTTP server to listen requests.

Each server could have endpoints param as an array of endpoints to process incoming requests. An individual endpoint can be described as:

- path: /path/to/export/on/the/server
  format: format_to_export

Optionally, you can enable http metrics for each endpoint. For this you should set metrics.enabled to true:

- path: /path/to/export/on/the/server
  format: format_to_export
  metrics:
    enabled: true

For now only json and prometheus formats are supported.

Integration with httpd role

Use httpd role as well. To enable it, you need to fill server field with name that was configured in roles.httpd block instead of listen like it was earlier. To configure httpd role you need to write block in roles_cfg section:

roles_cfg:
  roles.httpd:
    default:
      listen: 8081
    additional:
      listen: '127.0.0.1:8082'

After it you can use server name in roles.metrics-export block. If server and listen names wasn't provided, the default server from httpd role configuration will be used:

roles.metrics-export:
  http:
  - server: 'additional'
    endpoints:
    ...
  - endpoints:
    ...

So now it is possible to mix server and listen parameteres.

Let's put it all together now:

roles_cfg:
  roles.httpd:
    default:
      listen: 8081
    additional:
      listen: '127.0.0.1:8082'
  roles.metrics-export:
    http:
    - listen: 8081
      endpoints:
      - path: /metrics
        format: json
      - path: /metrics/prometheus/
        format: prometheus
    - listen: '127.0.0.1:8082'
      endpoints:
      - path: /metrics/
        format: json
        metrics:
          enabled: true
    - server: 'additional'
      endpoints:
      - path: /metrics
        format: json
    - endpoints:
      - path: /metrics
        format: prometheus
        metrics:
          enabled: true

With this configuration, metrics can be obtained on this machine with the Tarantool instance as follows:

curl -XGET 127.0.0.1:8081/metrics
# Metrics will be returned in JSON format.
curl -XGET 127.0.0.1:8081/metrics/prometheus
# Metrics will be returned in Prometheus-compatible format.
curl -XGET 127.0.0.1:8082/metrics
# Metrics will be returned in JSON format.

Development

First you need to clone the repository:

git clone https://github.com/tarantool/metrics-export-role
cd metrics-export-role

After that you need to install dependencies (tt is required). To do it, run:

make deps

It's possible to install requirements only for running tests or linter check. To install only tests requirements, run:

make deps depname=test

To install tests with coverage requirements, run:

make deps depname=coverage

To install linter checks, run:

make deps depname=lint

At this point you could run tests (tarantool 3 is required):

make test

And a linter:

make luacheck