# `DdDataStreams.Transport`
[🔗](https://github.com/rockneurotiko/dd_data_streams/blob/main/lib/dd_data_streams/transport.ex#L1)

How a payload reaches the Datadog Agent.

The aggregator knows only this behaviour, so an application can reuse an
existing HTTP pool instead of the default. `DdDataStreams.Transport.Req` is the
default and is compiled only when the optional `Req` dependency is available.

An implementation posts the body to the agent's `/v0.1/pipeline_stats`
endpoint and reports the HTTP status, or the reason the request did not
complete. The agent adds the API key itself, so no authentication header is
passed.

`post/3` must return promptly: the aggregator waits for it while handling
casts and flushes, so a transport that never returns blocks aggregation and
lets the mailbox grow. A transport is expected to enforce its own connect,
receive and request timeouts.

# `post`

```elixir
@callback post(url :: String.t(), headers :: [{String.t(), String.t()}], body :: iodata()) ::
  {:ok, non_neg_integer()} | {:error, term()}
```

Posts a request body and returns the response status or the transport error.

---

*Consult [api-reference.md](api-reference.md) for complete listing*