> ## Documentation Index
> Fetch the complete documentation index at: https://docs.telophasehq.com/llms.txt
> Use this file to discover all available pages before exploring further.

# S3

> Write processed records to an Amazon S3 bucket.

The **S3 sink** uploads objects to S3 with durability via a local **write-ahead log (WAL)**.\
Encoding, compression, object sizing, and concurrency are configured via common sink options.

***

## Schema

<ParamField path="type" type="string" required>
  Must be set to `s3`.
</ParamField>

<ParamField path="bucket_name" type="string" required>
  Name of the destination S3 bucket (do **not** prefix with `s3://`).
</ParamField>

<ParamField path="region" type="string">
  AWS region for the bucket (optional).\
  If omitted, the AWS SDK’s default resolution is used (env vars, instance metadata, etc.).
</ParamField>

<ParamField path="wal_path" type="string">
  Filesystem path for the sink’s write-ahead log (WAL).\
  Defaults to `/tmp/wal`.
</ParamField>

<ParamField path="max_file_age_seconds" type="int">
  Maximum age (in seconds) before a WAL file is rotated and flushed to S3.\
  Defaults to `60`.
</ParamField>

<ParamField path="encoding" type="object">
  Controls how Tangent serializes records emitted by this source. See [Encoding](/configuration/sinks/encoding).
</ParamField>

<ParamField path="compression" type="object">
  Controls how Tangent compresses payloads emitted by this source. See [Compression](/configuration/sinks/compression).
</ParamField>

***

## Example (NDJSON + Zstd)

```yaml tangent.yaml icon=upload theme={null}
sinks:
  s3_staging:
    type: s3
    bucket_name: my-bucket
    region: us-west-2
    # common options
    encoding: ndjson         # default
    compression:             # default shown explicitly
      type: zstd
      level: 3
    wal_path: /tmp/wal
    max_file_age_seconds: 60
```

## Example (Parquet + Gzip, Arrow schema)

```yaml tangent.yaml icon=upload theme={null}
sinks:
  s3_parquet:
    type: s3
    bucket_name: analytics-data
    region: us-east-1
    encoding:
      type: parquet
      schema: ./schemas/arrow_schema.json
    compression:
      type: gzip
      level: 6
    wal_path: /var/lib/tangent/wal
    max_file_age_seconds: 120
```

***

## Durability & Delivery

* **At-least-once delivery**: records are appended to a local **WAL** before upload.
* On restart or failure, the WAL is replayed and any incomplete objects are retried.
* Rotation is triggered by **size** (`object_max_bytes`) or **time** (`max_file_age_seconds`).

***

## See also

* [`File` sink](/configuration/sinks/file) for local files
* [`Blackhole` sink](/configuration/sinks/blackhole) for testing
* [DAG configuration](/configuration/dag)