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arc

Writes data to an Arc database via the msgpack ingestion endpoint.

Introduced in version 4.88.0.

This output sends data to an Arc columnar analytical database using its high-performance MessagePack ingestion endpoint.

Arc supports two payload formats:

columnar (default): Transposes batched messages into column arrays. This is the recommended format, offering significantly faster ingestion.
row: Sends each message as an individual row record with fields and optional tags.

Data is encoded as MessagePack and optionally compressed with zstd (recommended) or gzip before being sent to the Arc endpoint.

In columnar mode, all messages within a single batch must have the same set of fields. Arc validates that all column arrays have equal length and rejects batches with mismatched columns. Schema evolution across separate batches is fully supported. Use row format if messages within a batch have varying schemas.

Performance

This output benefits from sending multiple messages in flight in parallel for improved performance. You can tune the max number of in flight messages (or message batches) with the field max_in_flight.

This output benefits from sending messages as a batch for improved performance. Batches can be formed at both the input and output level. You can find out more in this doc.

Common
Advanced

output:
  label: ""
  arc:
    base_url: "" # No default (required)
    timeout: 5s
    token: "" # No default (optional)
    database: default
    measurement: "" # No default (required)
    format: columnar
    tags_mapping: "" # No default (optional)
    compression: zstd
    max_in_flight: 64
    batching:
      count: 0
      byte_size: 0
      period: ""
      check: ""

output:
  label: ""
  arc:
    base_url: "" # No default (required)
    timeout: 5s
    tls:
      enabled: false
      skip_cert_verify: false
      enable_renegotiation: false
      root_cas: ""
      root_cas_file: ""
      client_certs: []
    proxy_url: ""
    disable_http2: false
    tps_limit: 0
    tps_burst: 1
    backoff:
      initial_interval: 1s
      max_interval: 30s
      max_retries: 3
    tcp:
      connect_timeout: 0s
      keep_alive:
        idle: 15s
        interval: 15s
        count: 9
      tcp_user_timeout: 0s
    http:
      max_idle_conns: 100
      max_idle_conns_per_host: 0
      max_conns_per_host: 64
      idle_conn_timeout: 1m30s
      tls_handshake_timeout: 10s
      expect_continue_timeout: 1s
      response_header_timeout: 0s
      disable_keep_alives: false
      disable_compression: false
      max_response_header_bytes: 1048576
      max_response_body_bytes: 10485760
      write_buffer_size: 4096
      read_buffer_size: 4096
      h2:
        strict_max_concurrent_requests: false
        max_decoder_header_table_size: 4096
        max_encoder_header_table_size: 4096
        max_read_frame_size: 16384
        max_receive_buffer_per_connection: 1048576
        max_receive_buffer_per_stream: 1048576
        send_ping_timeout: 0s
        ping_timeout: 15s
        write_byte_timeout: 0s
    access_log_level: ""
    access_log_body_limit: 0
    token: "" # No default (optional)
    database: default
    measurement: "" # No default (required)
    format: columnar
    timestamp_field: ""
    timestamp_unit: auto
    tags_mapping: "" # No default (optional)
    compression: zstd
    max_in_flight: 64
    batching:
      count: 0
      byte_size: 0
      period: ""
      check: ""
      processors: [] # No default (optional)

Fields

`access_log_body_limit`

Maximum bytes of request/response body to include in logs. 0 to skip body logging.

Type: int

Default: 0

`access_log_level`

Log level for HTTP request/response logging. Empty disables logging.

Type: string

Default: ""

Options: "", TRACE, DEBUG, INFO, WARN, ERROR

`backoff`

Adaptive backoff configuration for 429 (Too Many Requests) responses. Always active.

Type: object

`backoff.initial_interval`

Initial interval between retries on 429 responses.

Type: string

Default: 1s

`backoff.max_interval`

Maximum interval between retries on 429 responses.

Type: string

Default: 30s

`backoff.max_retries`

Maximum number of retries on 429 responses.

Type: int

Default: 3

`base_url`

The base URL of the target service (for example, https://api.example.com). TLS is enabled automatically for https URLs.

Type: string

`batching`

Configure a batching policy.

Type: object

# Examples:
batching:
  byte_size: 5000
  count: 0
  period: 1s

# ---

batching:
  count: 10
  period: 1s

# ---

batching:
  check: this.contains("END BATCH")
  count: 0
  period: 1m

`batching.byte_size`

The maximum total size (in bytes) that a batch can reach before it is flushed. When the combined size of all messages in the batch reaches or exceeds this limit, the batch is immediately sent to the next stage (such as a processor or output).

Set to 0 to disable size-based batching. When disabled, messages are flushed based on other conditions (such as count or period).

Type: int

Default: 0

`batching.check`

A Bloblang query that returns a boolean value indicating whether a message should end a batch.

Type: string

Default: ""

# Examples:
check: this.type == "end_of_transaction"

`batching.count`

The number of messages at which the batch is flushed. Set to 0 to disable count-based batching.

Type: int

Default: 0

`batching.period`

The length of time after which an incomplete batch is flushed regardless of its size. This field accepts Go duration format strings such as 100ms, 1s, or 5s. Supported time units are ns, us, ms, s, m, and h.

Type: string

Default: ""

# Examples:
period: 1s

# ---

period: 1m

# ---

period: 500ms

`batching.processors[]`

A list of processors to apply to a batch as it is flushed. This allows you to aggregate and archive the batch however you see fit. All resulting messages are flushed as a single batch, so splitting the batch into smaller batches with these processors has no effect.

Type: array<processor>

# Examples:
processors:
  - archive:
      format: concatenate


# ---

processors:
  - archive:
      format: lines


# ---

processors:
  - archive:
      format: json_array

`compression`

Compression algorithm for the request body. zstd is recommended for best decompression performance in Arc.

Type: string

Default: zstd

Options: zstd, gzip, none

`database`

The target database name.

Type: string

Default: default

`disable_http2`

Disable HTTP/2 and force HTTP/1.1.

Type: bool

Default: false

`format`

The payload format. columnar transposes batch messages into column arrays for best performance. row sends each message as an individual record.

Type: string

Default: columnar

Options: columnar, row

`http`

HTTP transport settings controlling connection pooling, timeouts, and HTTP/2.

Type: object

`http.disable_compression`

Disable automatic decompression of gzip responses.

Type: bool

Default: false

`http.disable_keep_alives`

Disable HTTP keep-alive connections; each request uses a new connection.

Type: bool

Default: false

`http.expect_continue_timeout`

Maximum time to wait for a server’s 100-continue response before sending the body. 0 means the body is sent immediately.

Type: string

Default: 1s

`http.h2`

HTTP/2-specific transport settings. Only applied when HTTP/2 is enabled.

Type: object

`http.h2.max_decoder_header_table_size`

Upper limit in bytes for the HPACK header table used to decode headers from the peer. Must be less than 4 MiB.

Type: int

Default: 4096

`http.h2.max_encoder_header_table_size`

Upper limit in bytes for the HPACK header table used to encode headers sent to the peer. Must be less than 4 MiB.

Type: int

Default: 4096

`http.h2.max_read_frame_size`

Largest HTTP/2 frame this endpoint will read. Valid range: 16 KiB to 16 MiB.

Type: int

Default: 16384

`http.h2.max_receive_buffer_per_connection`

Maximum flow-control window size in bytes for data received on a connection. Must be at least 64 KiB and less than 4 MiB.

Type: int

Default: 1048576

`http.h2.max_receive_buffer_per_stream`

Maximum flow-control window size in bytes for data received on a single stream. Must be less than 4 MiB.

Type: int

Default: 1048576

`http.h2.ping_timeout`

Timeout waiting for a PING response before closing the connection.

Type: string

Default: 15s

`http.h2.send_ping_timeout`

Idle timeout after which a PING frame is sent to verify connection health. 0 disables health checks.

Type: string

Default: 0s

`http.h2.strict_max_concurrent_requests`

When true, new requests block when a connection’s concurrency limit is reached instead of opening a new connection.

Type: bool

Default: false

`http.h2.write_byte_timeout`

Timeout for writing data to a connection. The timer resets whenever bytes are written. 0 disables the timeout.

Type: string

Default: 0s

`http.idle_conn_timeout`

How long an idle connection remains in the pool before being closed. 0 disables the timeout.

Type: string

Default: 1m30s

`http.max_conns_per_host`

Maximum total connections (active + idle) per host. 0 means unlimited.

Type: int

Default: 64

`http.max_idle_conns`

Maximum total number of idle (keep-alive) connections across all hosts. 0 means unlimited.

Type: int

Default: 100

`http.max_idle_conns_per_host`

Maximum idle connections to keep per host. 0 (the default) uses GOMAXPROCS+1.

Type: int

Default: 0

`http.max_response_body_bytes`

Maximum bytes of response body the client will read. The response body is wrapped with a limit reader; reads beyond this cap return EOF. 0 disables the limit.

Type: int

Default: 10485760

`http.max_response_header_bytes`

Maximum bytes of response headers to allow.

Type: int

Default: 1048576

`http.read_buffer_size`

Size in bytes of the per-connection read buffer.

Type: int

Default: 4096

`http.response_header_timeout`

Maximum time to wait for response headers after writing the full request. 0 disables the timeout.

Type: string

Default: 0s

`http.tls_handshake_timeout`

Maximum time to wait for a TLS handshake to complete. 0 disables the timeout.

Type: string

Default: 10s

`http.write_buffer_size`

Size in bytes of the per-connection write buffer.

Type: int

Default: 4096

`max_in_flight`

The maximum number of messages to have in flight at a given time. For outputs that send messages in batches, this limit applies to message batches. Increase this value to improve throughput.

Type: int

Default: 64

`measurement`

The measurement (table) name. Supports interpolation functions.

Type: string

# Examples:
measurement: cpu_metrics

# ---

measurement: ${!metadata("measurement")}

# ---

measurement: ${!json("type")}

`proxy_url`

HTTP proxy URL. Empty string disables proxying.

Type: string

Default: ""

`tags_mapping`

An optional Bloblang mapping to extract tags from each message. Only used in row format. The result must be a map[string]string.

Type: string

# Examples:
tags_mapping: 'root = {"host": this.hostname, "region": this.region}'

`tcp`

Configure TCP socket-level settings to optimize network performance and reliability. These low-level controls are useful for:

Unresponsive hosts: Set connect_timeout to limit how long a connection attempt can take (the default 0s sets no limit)
Long-lived connections: Configure keep_alive settings to detect and recover from stale connections
Unstable networks: Tune keep-alive probes to balance between quick failure detection and avoiding false positives
Linux systems with specific requirements: Use tcp_user_timeout (Linux 2.6.37+) to control data acknowledgment timeouts

Most users should keep the default values. Only modify these settings if you’re experiencing connection stability issues or have specific network requirements.

Type: object

`tcp.connect_timeout`

Maximum amount of time a dial will wait for a connect to complete. Zero disables.

Type: string

Default: 0s

`tcp.keep_alive`

TCP keep-alive probe configuration.

Type: object

`tcp.keep_alive.count`

Maximum unanswered keep-alive probes before dropping the connection. Zero defaults to 9.

Type: int

Default: 9

`tcp.keep_alive.idle`

Duration the connection must be idle before sending the first keep-alive probe. Zero defaults to 15s. Negative values disable keep-alive probes.

Type: string

Default: 15s

`tcp.keep_alive.interval`

Duration between keep-alive probes. Zero defaults to 15s.

Type: string

Default: 15s

`tcp.tcp_user_timeout`

Maximum time to wait for acknowledgment of transmitted data before killing the connection. Linux-only (kernel 2.6.37+), ignored on other platforms. When enabled, keep_alive.idle must be greater than this value per RFC 5482. Zero disables.

Type: string

Default: 0s

`timeout`

HTTP request timeout.

Type: string

Default: 5s

`timestamp_field`

The field name within each message containing the timestamp. If empty, the current time is used. Supports Unix timestamps and RFC3339 strings.

Type: string

Default: ""

`timestamp_unit`

The unit of a numeric timestamp field. auto detects the unit based on magnitude. Ignored when timestamp_field is empty.

Type: string

Default: auto

Options: us, ms, s, ns, auto

`tls`

Configure Transport Layer Security (TLS) settings to secure network connections. This includes options for standard TLS as well as mutual TLS (mTLS) authentication where both client and server authenticate each other using certificates. Key configuration options include enabled to enable TLS, client_certs for mTLS authentication, root_cas/root_cas_file for custom certificate authorities, and skip_cert_verify for development environments.

Type: object

`tls.client_certs[]`

A list of client certificates for mutual TLS (mTLS) authentication. Configure this field to enable mTLS, authenticating the client to the server with these certificates.

You must set tls.enabled: true for the client certificates to take effect.

Certificate pairing rules: For each certificate item, provide either:

Inline PEM data using both cert and key or
File paths using both cert_file and key_file.

Mixing inline and file-based values within the same item is not supported.

Type: array<object>

Default: []

# Examples:
client_certs:
  - cert: foo
    key: bar


# ---

client_certs:
  - cert_file: ./example.pem
    key_file: ./example.key

`tls.client_certs[].cert`

The plaintext certificate to use for TLS authentication. Must be paired with the corresponding private key in the key field when using inline PEM data for mTLS client certificates.

Type: string

Default: ""

`tls.client_certs[].cert_file`

The path to a file containing the certificate to use for TLS authentication. Must be paired with the corresponding private key file in the key_file field when using file-based configuration for mTLS client certificates.

Type: string

Default: ""

`tls.client_certs[].key`

Private key for mTLS client certificate as inline PEM data. Must correspond to the client certificate specified in the cert field. Use this field together with cert when providing certificate data inline rather than through files.

This field contains sensitive information that usually shouldn’t be added to a configuration directly. For more information, see Secrets.

Type: string

Default: ""

`tls.client_certs[].key_file`

Path to private key file for mTLS client certificate in PEM format. Must correspond to the client certificate specified in the cert_file field. Use this field together with cert_file when loading certificate data from files.

Type: string

Default: ""

`tls.client_certs[].password`

The password to use for the private key (specified in the key or key_file fields), if it is password-protected. The PKCS#1 and PKCS#8 formats are supported. Supports environment variable interpolation for secure password management.

The pbeWithMD5AndDES-CBC algorithm is obsolete and not supported for the PKCS#8 format. This algorithm does not authenticate the ciphertext, making it vulnerable to padding oracle attacks that can let an attacker recover the plaintext.

This field contains sensitive information that usually shouldn’t be added to a configuration directly. For more information, see Secrets.

Type: string

Default: ""

# Examples:
password: foo

# ---

password: ${KEY_PASSWORD}

`tls.enable_renegotiation`

Whether to allow the remote server to repeatedly request renegotiation. Enable this option if you’re seeing the error message local error: tls: no renegotiation.

Type: bool

Default: false

`tls.enabled`

Whether to enable TLS for secure connections. Set to true to enable TLS encryption. Required to be true for other TLS options (like client_certs, root_cas, etc.) to take effect.

Type: bool

Default: false

`tls.root_cas`

Specify a root certificate authority to use (optional). This is a string that represents a certificate chain from the parent-trusted root certificate, through possible intermediate signing certificates, to the host certificate. Use either this field for inline certificate data or root_cas_file for file-based certificate loading.

This field contains sensitive information that usually shouldn’t be added to a configuration directly. For more information, see Secrets.

Type: string

Default: ""

# Examples:
root_cas: |-
  -----BEGIN CERTIFICATE-----
  ...
  -----END CERTIFICATE-----

`tls.root_cas_file`

Specify the path to a root certificate authority file (optional). This is a file, often with a .pem extension, which contains a certificate chain from the parent-trusted root certificate, through possible intermediate signing certificates, to the host certificate. Use either this field for file-based certificate loading or root_cas for inline certificate data.

Type: string

Default: ""

# Examples:
root_cas_file: ./root_cas.pem

`tls.skip_cert_verify`

Whether to skip server-side certificate verification. Set to true only for testing environments as this reduces security by disabling certificate validation. When using self-signed certificates or in development, this may be necessary, but should never be used in production. Consider using root_cas or root_cas_file to specify trusted certificates instead of disabling verification entirely.

Type: bool

Default: false

`token`

Bearer token for authentication.

This field contains sensitive information that usually shouldn’t be added to a configuration directly. For more information, see Secrets.

Type: string

`tps_burst`

Maximum burst size for rate limiting.

Type: int

Default: 1

`tps_limit`

Rate limit in requests per second. 0 disables rate limiting.

Type: float

Default: 0

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arc

Performance

Fields

access_log_body_limit

access_log_level

backoff

backoff.initial_interval

backoff.max_interval

backoff.max_retries

base_url

batching

batching.byte_size

batching.check

batching.count

batching.period

batching.processors[]

compression

database

disable_http2

format

http

http.disable_compression

http.disable_keep_alives

http.expect_continue_timeout

http.h2

http.h2.max_decoder_header_table_size

http.h2.max_encoder_header_table_size

http.h2.max_read_frame_size

http.h2.max_receive_buffer_per_connection

http.h2.max_receive_buffer_per_stream

http.h2.ping_timeout

http.h2.send_ping_timeout

http.h2.strict_max_concurrent_requests

http.h2.write_byte_timeout

http.idle_conn_timeout

http.max_conns_per_host

http.max_idle_conns

http.max_idle_conns_per_host

http.max_response_body_bytes

http.max_response_header_bytes

http.read_buffer_size

http.response_header_timeout

http.tls_handshake_timeout

http.write_buffer_size

max_in_flight

measurement

proxy_url

tags_mapping

tcp

tcp.connect_timeout

tcp.keep_alive

tcp.keep_alive.count

tcp.keep_alive.idle

tcp.keep_alive.interval

tcp.tcp_user_timeout

timeout

timestamp_field

timestamp_unit

tls

tls.client_certs[]

tls.client_certs[].cert

tls.client_certs[].cert_file

tls.client_certs[].key

tls.client_certs[].key_file

tls.client_certs[].password

tls.enable_renegotiation

tls.enabled

tls.root_cas

tls.root_cas_file

tls.skip_cert_verify

token

tps_burst

tps_limit

`access_log_body_limit`

`access_log_level`

`backoff`

`backoff.initial_interval`

`backoff.max_interval`

`backoff.max_retries`

`base_url`

`batching`

`batching.byte_size`

`batching.check`

`batching.count`

`batching.period`

`batching.processors[]`

`compression`

`database`

`disable_http2`

`format`

`http`

`http.disable_compression`

`http.disable_keep_alives`

`http.expect_continue_timeout`

`http.h2`

`http.h2.max_decoder_header_table_size`

`http.h2.max_encoder_header_table_size`

`http.h2.max_read_frame_size`

`http.h2.max_receive_buffer_per_connection`

`http.h2.max_receive_buffer_per_stream`

`http.h2.ping_timeout`

`http.h2.send_ping_timeout`

`http.h2.strict_max_concurrent_requests`

`http.h2.write_byte_timeout`

`http.idle_conn_timeout`

`http.max_conns_per_host`

`http.max_idle_conns`

`http.max_idle_conns_per_host`

`http.max_response_body_bytes`

`http.max_response_header_bytes`

`http.read_buffer_size`

`http.response_header_timeout`

`http.tls_handshake_timeout`

`http.write_buffer_size`

`max_in_flight`

`measurement`

`proxy_url`

`tags_mapping`

`tcp`

`tcp.connect_timeout`

`tcp.keep_alive`

`tcp.keep_alive.count`

`tcp.keep_alive.idle`

`tcp.keep_alive.interval`

`tcp.tcp_user_timeout`

`timeout`

`timestamp_field`

`timestamp_unit`

`tls`

`tls.client_certs[]`

`tls.client_certs[].cert`

`tls.client_certs[].cert_file`

`tls.client_certs[].key`

`tls.client_certs[].key_file`

`tls.client_certs[].password`

`tls.enable_renegotiation`

`tls.enabled`

`tls.root_cas`

`tls.root_cas_file`

`tls.skip_cert_verify`

`token`

`tps_burst`

`tps_limit`