(submitting-customping)=

# Submitting custom pings (deprecated)

:::{important}
Legacy Telemetry collection APIs are now deprecated.
Please use Glean instead.
:::

Custom pings can be submitted from JavaScript using:

```js
TelemetryController.submitExternalPing(type, payload, options)
```

- `type` - a `string` that is the type of the ping, limited to `/^[a-z0-9][a-z0-9-]+[a-z0-9]$/i`.
- `payload` - the actual payload data for the ping, has to be a JSON style object.
- `options` - optional, an object containing additional options:
  : - `addClientId`- whether to add the client id and profile group id to the ping, defaults to `false`
  - `addEnvironment` - whether to add the environment data to the ping, defaults to `false`
  - `overrideEnvironment` - a JSON style object that overrides the environment data

`TelemetryController` will assemble a ping with the passed payload and the specified options.
That ping will be archived locally for use with Shield and inspection in `about:telemetry`.
If preferences allow the upload of Telemetry pings, the ping will be uploaded at the next opportunity (this is subject to throttling, retry-on-failure, etc.).

:::{important}
Every new or changed data collection in Firefox needs a [data collection review](https://wiki.mozilla.org/Firefox/Data_Collection) from a Data Steward.
:::

## Submission constraints

When submitting pings on shutdown, they should not be submitted after Telemetry shutdown.
Pings should be submitted at the latest within:

- the [observer notification](https://developer.mozilla.org/docs/Observer_Notifications#Application_shutdown) `"profile-before-change"`
- the {ref}`AsyncShutdown phase <AsyncShutdown_phases>` `sendTelemetry`

There are other constraints that can lead to a ping submission getting dropped:

- invalid ping type strings.
- invalid payload types: E.g. strings instead of objects.
- oversized payloads: We currently only drop pings >1MB, but targeting sizes of \<=10KB is recommended.

### Tools

Helpful tools for designing new pings include:

- [gzipServer](https://github.com/mozilla/gzipServer) - a Python script that can run locally and receives and saves Telemetry pings. Making Firefox send to it allows inspecting outgoing pings easily.
- `about:telemetry` - allows inspecting submitted pings from the local archive, including all custom ones.

### Designing custom pings

In general, creating a new custom ping means you don't benefit automatically from the existing tooling. Further work is needed to make data show up in re:dash or other analysis tools.

In addition to the [data collection review](https://wiki.mozilla.org/Firefox/Data_Collection), questions to guide a new ping design are:

- Submission interval & triggers:
  : - What events trigger ping submission?
  - What interval is the ping submitted in?
  - Is there a throttling mechanism?
  - What is the desired latency? (submitting "at least daily" still leads to certain latency tails)
  - Are pings submitted on a clock schedule? Or based on "time since session start", "time since last ping" etc.? (I.e. will we get sharp spikes in submission volume?)
- Size and volume:
  : - What’s the size of the submitted payload?
  - What's the full ping size including metadata in the pipeline?
  - What’s the target population?
  - What's the overall estimated volume?
- Dataset:
  : - Is it opt-out?
  - Does it need to be opt-out?
  - Does it need to be in a separate ping? (why can’t the data live in probes?)
- Privacy:
  : - Is there risk to leak PII?
  - How is that risk mitigated?
- Data contents:
  : - Does the submitted data answer the posed product questions?
  - Does the shape of the data allow to answer the questions efficiently?
  - Is the data limited to what's needed to answer the questions?
  - Does the data use common formats? (i.e. can we reuse tooling or analysis know-how)
