feat(metrics): add opt-in BEAM runtime metrics collector

[solnic]

Adds automatic BEAM runtime metrics. It must be enabled in your config:

config :sentry,
  metrics: [
    runtime: [
      # Enable auto-metrics - this is `false` by default
      enabled: true
    ],
    # Attach `elixir_version` and `otp_version` to the default attributes if you want.
    #
    # This is `false` by default.
    version_attributes: true
  ]

Once enabled, memory usage is reported as gauges, in bytes:

• elixir.runtime.mem.total
• elixir.runtime.mem.processes
• elixir.runtime.mem.processes_used
• elixir.runtime.mem.system
• elixir.runtime.mem.atom
• elixir.runtime.mem.atom_used
• elixir.runtime.mem.binary
• elixir.runtime.mem.code
• elixir.runtime.mem.ets

Collection frequency

The SDK handles telemetry_poller's events to get the data, the interval can be adjusted using the following config:

config :telemetry_poller, default: [period: 30_000]

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[whatyouhide]

Have we considered doing this via the extremely well-established https://github.com/beam-telemetry/telemetry_poller under the hood?

[solnic]

Have we considered doing this via the extremely well-established https://github.com/beam-telemetry/telemetry_poller under the hood?

@whatyouhide yeah we could but custom plumbing would still be needed. Do you think it'd still be better? I'm all for having less code over here of course.

[whatyouhide]

@solnic yes I think it's worth it. telemetry_poller actually emits VM-metric events already so Sentry could also just register a telemetry handler for those to clean up things a bit more.

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[cursor]

Startup crash without telemetry present

Medium Severity

Enabling metrics.runtime calls :telemetry.attach_many/4 during application start with no check that :telemetry (or telemetry_poller) is loaded. Both are optional dependencies, so a boot with runtime: [enabled: true] and no telemetry raises UndefinedFunctionError and takes down the :sentry app. Tracing already warns and disables itself when its optional stack is missing; this path does not. If telemetry is present but telemetry_poller is not, the handler still attaches and the feature silently never reports.

Additional Locations (1)

• lib/sentry/application.ex#L102-L109

 

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Boot crash without telemetry loaded

High Severity

Enabling metrics.runtime.enabled calls :telemetry.attach_many from maybe_attach_runtime_metrics during application start with no check that :telemetry is available. Both :telemetry and :telemetry_poller are optional, so that call raises and fails host-app boot when the library is not on the path or not started yet.

Additional Locations (1)

• lib/sentry/metrics/runtime.ex#L24-L32

 

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