---
title: "otelcol.receiver.tcplog | Grafana Alloy documentation"
description: "Learn about otelcol.receiver.tcplog"
---

# `otelcol.receiver.tcplog`

> **EXPERIMENTAL**: This is an [experimental](/docs/release-life-cycle/) component. Experimental components are subject to frequent breaking changes, and may be removed with no equivalent replacement. To enable and use an experimental component, you must set the `stability.level` [flag](/docs/alloy/latest/reference/cli/run/) to `experimental`.

`otelcol.receiver.tcplog` accepts log messages over a TCP connection and forwards them as logs to other `otelcol.*` components.

> Note
> 
> `otelcol.receiver.tcplog` is a wrapper over the upstream OpenTelemetry Collector [`tcplog`](https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/v0.147.0/receiver/tcplogreceiver) receiver. Bug reports or feature requests will be redirected to the upstream repository, if necessary.

You can specify multiple `otelcol.receiver.tcplog` components by giving them different labels.

## Usage

Alloy ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```alloy
otelcol.receiver.tcplog "<LABEL>" {
  listen_address = "<IP_ADDRESS:PORT>"

  output {
    logs    = [...]
  }
}
```

## Arguments

You can use the following arguments with `otelcol.receiver.tcplog`:

Expand table

| Name                 | Type     | Description                                                                                                                                                                                                        | Default   | Required |
|----------------------|----------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------|----------|
| `listen_address`     | `string` | The `<HOST:PORT>` address to listen to for logs messages.                                                                                                                                                          |           | yes      |
| `add_attributes`     | `bool`   | Add `net.*` attributes to log messages according to [OpenTelemetry semantic conventions](https://github.com/open-telemetry/semantic-conventions/blob/main/docs/attributes-registry/network.md#network-attributes). | `false`   | no       |
| `encoding`           | `string` | The encoding of the log messages.                                                                                                                                                                                  | `"utf-8"` | no       |
| `max_log_size`       | `string` | The maximum size of a log entry to read before failing.                                                                                                                                                            | `"1MiB"`  | no       |
| `one_log_per_packet` | `bool`   | Skip log tokenization, improving performance when messages always contain one log and multiline isn’t used.                                                                                                        | `false`   | no       |

The `encoding` argument specifies the encoding of the incoming log messages. `encoding` must be one of `utf-8`, `utf-16le`, `utf-16be`, `ascii`, `big5`, or `nop`. Refer to the upstream receiver [documentation](https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/main/receiver/tcplogreceiver/README.md#supported-encodings) for more details.

The `max_log_size` argument has a minimum value of `64KiB`.

## Blocks

You can use the following blocks with `otelcol.receiver.tcplog`:

No valid configuration blocks found.

### `output`

Required

The `output` block configures a set of components to forward resulting telemetry data to.

The following arguments are supported:

Expand table

| Name   | Type                     | Description                        | Default | Required |
|--------|--------------------------|------------------------------------|---------|----------|
| `logs` | `list(otelcol.Consumer)` | List of consumers to send logs to. | `[]`    | no       |

You must specify the `output` block, but all its arguments are optional. By default, telemetry data is dropped. Configure the `logs` argument accordingly to send telemetry data to other components, .

### `debug_metrics`

The `debug_metrics` block configures the metrics that this component generates to monitor its state.

The following arguments are supported:

Expand table

| Name                               | Type      | Description                                          | Default | Required |
|------------------------------------|-----------|------------------------------------------------------|---------|----------|
| `disable_high_cardinality_metrics` | `boolean` | Whether to disable certain high cardinality metrics. | `true`  | no       |

`disable_high_cardinality_metrics` is the Alloy equivalent to the `telemetry.disableHighCardinalityMetrics` feature gate in the OpenTelemetry Collector. It removes attributes that could cause high cardinality metrics. For example, attributes with IP addresses and port numbers in metrics about HTTP and gRPC connections are removed.

> Note
> 
> If configured, `disable_high_cardinality_metrics` only applies to `otelcol.exporter.*` and `otelcol.receiver.*` components.

### `multiline`

The `multiline` block configures logic for splitting incoming log entries. The following arguments are supported:

Expand table

| Name                 | Type     | Description                                                     | Default | Required |
|----------------------|----------|-----------------------------------------------------------------|---------|----------|
| `line_end_pattern`   | `string` | A regular expression that matches the end of a log entry.       |         | no       |
| `line_start_pattern` | `string` | A regular expression that matches the beginning of a log entry. |         | no       |
| `omit_pattern`       | `bool`   | Omit the start/end pattern from the split log entries.          | `false` | no       |

A `multiline` block must contain either `line_start_pattern` or `line_end_pattern`.

If a `multiline` block isn’t set, log entries won’t be split.

### `retry_on_failure`

The `retry_on_failure` block configures the retry behavior when the receiver encounters an error downstream in the pipeline. A backoff algorithm is used to delay the retry upon subsequent failures. The following arguments are supported:

Expand table

| Name               | Type       | Description                                                                                                               | Default | Required |
|--------------------|------------|---------------------------------------------------------------------------------------------------------------------------|---------|----------|
| `enabled`          | `bool`     | If set to `true` and an error occurs, the receiver will pause reading the log files and resend the current batch of logs. | `false` | no       |
| `initial_interval` | `duration` | The time to wait after first failure to retry.                                                                            | `"1s"`  | no       |
| `max_elapsed_time` | `duration` | The maximum age of a message before the data is discarded.                                                                | `"5m"`  | no       |
| `max_interval`     | `duration` | The maximum time to wait after applying backoff logic.                                                                    | `"30s"` | no       |

If `max_elapsed_time` is set to `0` data is never discarded.

### `tls`

The `tls` block configures TLS settings used for a server. If the `tls` block isn’t provided, TLS won’t be used for connections to the server.

The following arguments are supported:

Expand table

| Name                           | Type           | Description                                                                                  | Default     | Required |
|--------------------------------|----------------|----------------------------------------------------------------------------------------------|-------------|----------|
| `ca_file`                      | `string`       | Path to the CA file.                                                                         |             | no       |
| `ca_pem`                       | `string`       | CA PEM-encoded text to validate the server with.                                             |             | no       |
| `cert_file`                    | `string`       | Path to the TLS certificate.                                                                 |             | no       |
| `cert_pem`                     | `string`       | Certificate PEM-encoded text for client authentication.                                      |             | no       |
| `cipher_suites`                | `list(string)` | A list of TLS cipher suites that the TLS transport can use.                                  | `[]`        | no       |
| `client_ca_file`               | `string`       | Path to the TLS cert to use by the server to verify a client certificate.                    |             | no       |
| `curve_preferences`            | `list(string)` | Set of elliptic curves to use in a handshake.                                                | `[]`        | no       |
| `include_system_ca_certs_pool` | `boolean`      | Whether to load the system certificate authorities pool alongside the certificate authority. | `false`     | no       |
| `key_file`                     | `string`       | Path to the TLS certificate key.                                                             |             | no       |
| `key_pem`                      | `secret`       | Key PEM-encoded text for client authentication.                                              |             | no       |
| `max_version`                  | `string`       | Maximum acceptable TLS version for connections.                                              | `"TLS 1.3"` | no       |
| `min_version`                  | `string`       | Minimum acceptable TLS version for connections.                                              | `"TLS 1.2"` | no       |
| `reload_interval`              | `duration`     | The duration after which the certificate is reloaded.                                        | `"0s"`      | no       |

If `reload_interval` is set to `"0s"`, the certificate never reloaded.

The following pairs of arguments are mutually exclusive and can’t both be set simultaneously:

- `ca_pem` and `ca_file`
- `cert_pem` and `cert_file`
- `key_pem` and `key_file`

If `cipher_suites` is left blank, a safe default list is used. Refer to the [Go Cipher Suites documentation](https://go.dev/src/crypto/tls/cipher_suites.go) for a list of supported cipher suites.

`client_ca_file` sets the `ClientCA` and `ClientAuth` to `RequireAndVerifyClientCert` in the `TLSConfig`. Refer to the [Go TLS documentation](https://godoc.org/crypto/tls#Config) for more information.

The `curve_preferences` argument determines the set of elliptic curves to prefer during a handshake in preference order. If not provided, a default list is used. The set of elliptic curves available are `X25519`, `P521`, `P256`, and `P384`.

### `tpm`

The `tpm` block configures retrieving the TLS `key_file` from a trusted device.

The following arguments are supported:

Expand table

| Name         | Type     | Description                                                        | Default | Required |
|--------------|----------|--------------------------------------------------------------------|---------|----------|
| `auth`       | `string` | The authorization value used to authenticate the TPM device.       | `""`    | no       |
| `enabled`    | `bool`   | Load the `tls.key_file` from TPM.                                  | `false` | no       |
| `owner_auth` | `string` | The owner authorization value used to authenticate the TPM device. | `""`    | no       |
| `path`       | `string` | Path to the TPM device or Unix domain socket.                      | `""`    | no       |

The [trusted platform module](https://trustedcomputinggroup.org/resource/trusted-platform-module-tpm-summary/) (TPM) configuration can be used for loading TLS key from TPM. Currently only TSS2 format is supported.

The `path` attribute is not supported on Windows.

In the following example, the private key `my-tss2-key.key` in TSS2 format is loaded from the TPM device `/dev/tmprm0`:

Alloy ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```alloy
otelcol.example.component "<LABEL>" {
    ...
    tls {
        ...
        key_file = "my-tss2-key.key"
        tpm {
            enabled = true
            path = "/dev/tpmrm0"
        }
    }
}
```

## Exported fields

`otelcol.receiver.tcplog` doesn’t export any fields.

## Component health

`otelcol.receiver.tcplog` is only reported as unhealthy if given an invalid configuration.

## Debug information

`otelcol.receiver.tcplog` doesn’t expose any component-specific debug information.

## Debug metrics

`otelcol.receiver.tcplog` doesn’t expose any component-specific debug metrics.

## Example

This example receives log messages from TCP and logs them.

Alloy ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```alloy
otelcol.receiver.tcplog "default" {
    listen_address = "localhost:1515"
    output {
        logs = [otelcol.exporter.debug.default.input]
    }
}

otelcol.exporter.debug "default" {}
```

## Compatible components

`otelcol.receiver.tcplog` can accept arguments from the following components:

- Components that export [OpenTelemetry `otelcol.Consumer`](../../../compatibility/#opentelemetry-otelcolconsumer-exporters)

> Note
> 
> Connecting some components may not be sensible or components may require further configuration to make the connection work correctly. Refer to the linked documentation for more details.