Splunk HEC logs

Deliver log data to Splunk’s HTTP Event Collector

status: stable delivery: at-least-once acknowledgements: yes egress: batch state: stateless previously known as: splunk_hec
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Alias

This component was previously called the splunk_hec sink. Make sure to update your Vector configuration to accommodate the name change:

[sinks.my_splunk_hec_logs_sink]
+type = "splunk_hec_logs"
-type = "splunk_hec"

Configuration

Example configurations 

{
  "sinks": {
    "my_sink_id": {
      "type": "splunk_hec_logs",
      "inputs": [
        "my-source-or-transform-id"
      ],
      "acknowledgements": null,
      "endpoint": "https://http-inputs-hec.splunkcloud.com",
      "host_key": "hostname",
      "indexed_fields": [
        "field1"
      ],
      "compression": "none",
      "encoding": {
        "codec": "json"
      },
      "healthcheck": null,
      "default_token": "${SPLUNK_HEC_TOKEN}"
    }
  }
}
[sinks.my_sink_id]
type = "splunk_hec_logs"
inputs = [ "my-source-or-transform-id" ]
endpoint = "https://http-inputs-hec.splunkcloud.com"
host_key = "hostname"
indexed_fields = [ "field1" ]
compression = "none"
default_token = "${SPLUNK_HEC_TOKEN}"

  [sinks.my_sink_id.encoding]
  codec = "json"

---
sinks:
  my_sink_id:
    type: splunk_hec_logs
    inputs:
      - my-source-or-transform-id
    acknowledgements: null
    endpoint: https://http-inputs-hec.splunkcloud.com
    host_key: hostname
    indexed_fields:
      - field1
    compression: none
    encoding:
      codec: json
    healthcheck: null
    default_token: ${SPLUNK_HEC_TOKEN}

{
  "sinks": {
    "my_sink_id": {
      "type": "splunk_hec_logs",
      "inputs": [
        "my-source-or-transform-id"
      ],
      "acknowledgements": null,
      "endpoint": "https://http-inputs-hec.splunkcloud.com",
      "host_key": "hostname",
      "index": "{{ host }}",
      "indexed_fields": [
        "field1"
      ],
      "source": "{{ file }}",
      "buffer": null,
      "batch": null,
      "compression": "none",
      "encoding": {
        "codec": "json"
      },
      "healthcheck": null,
      "request": null,
      "tls": null,
      "proxy": null,
      "default_token": "${SPLUNK_HEC_TOKEN}",
      "sourcetype": "{{ sourcetype }}"
    }
  }
}
[sinks.my_sink_id]
type = "splunk_hec_logs"
inputs = [ "my-source-or-transform-id" ]
endpoint = "https://http-inputs-hec.splunkcloud.com"
host_key = "hostname"
index = "{{ host }}"
indexed_fields = [ "field1" ]
source = "{{ file }}"
compression = "none"
default_token = "${SPLUNK_HEC_TOKEN}"
sourcetype = "{{ sourcetype }}"

  [sinks.my_sink_id.encoding]
  codec = "json"

---
sinks:
  my_sink_id:
    type: splunk_hec_logs
    inputs:
      - my-source-or-transform-id
    acknowledgements: null
    endpoint: https://http-inputs-hec.splunkcloud.com
    host_key: hostname
    index: "{{ host }}"
    indexed_fields:
      - field1
    source: "{{ file }}"
    buffer: null
    batch: null
    compression: none
    encoding:
      codec: json
    healthcheck: null
    request: null
    tls: null
    proxy: null
    default_token: ${SPLUNK_HEC_TOKEN}
    sourcetype: "{{ sourcetype }}"

acknowledgements

common optional object
Controls how acknowledgements are handled by this sink. When enabled, all connected sources that support end-to-end acknowledgements will wait for the destination of this sink to acknowledge receipt of events before providing acknowledgement to the sending source. These settings override the global acknowledgement settings.

acknowledgements.enabled

common optional bool
Controls if all connected sources will wait for this sink to deliver the events before acknowledging receipt.
default: false

acknowledgements.indexer_acknowledgements_enabled

optional bool
Controls if the sink will integrate with Splunk HEC indexer acknowledgements for end-to-end acknowledgements.
default: true

acknowledgements.max_pending_acks

optional uint
The maximum number of ack ids pending query. Once reached, the sink will begin applying backpressure.
default: 1e+06

acknowledgements.query_interval

optional uint
The amount of time to wait in between queries to the Splunk HEC indexer acknowledgement endpoint. Minimum of 1.
default: 10 (seconds)

acknowledgements.retry_limit

optional uint
The maximum number of times an ack id will be queried for its status. Minimum of 1.
default: 30

batch

optional object
Configures the sink batching behavior.

batch.max_bytes

common optional uint
The maximum size of a batch, in bytes, before it is flushed.

batch.max_events

common optional uint
The maximum size of a batch, in events, before it is flushed.

batch.timeout_secs

common optional float
The maximum age of a batch before it is flushed.
default: 1 (seconds)

buffer

optional object
Configures the sink specific buffer behavior.

buffer.max_events

common optional uint
The maximum number of events allowed in the buffer.
Relevant when: type = "memory"
default: 500 (events)

buffer.max_size

required uint

The maximum size of the buffer on the disk. Must be at least 128 megabytes (134217728 bytes).

Note that during normal disk buffer operation, the disk buffer can create one additional 128 megabyte block so the minimum disk space required is actually 256 megabytes.

Relevant when: type = "disk"
Examples 
104900000

buffer.type

common optional string literal enum
The buffer’s type and storage mechanism.
Enum options
OptionDescription
diskStores the sink’s buffer on disk. This is less performant, but durable. Data will not be lost between restarts. Will also hold data in memory to enhance performance. WARNING: This may stall the sink if disk performance isn’t on par with the throughput. For comparison, AWS gp2 volumes are usually too slow for common cases.
memoryStores the sink’s buffer in memory. This is more performant, but less durable. Data will be lost if Vector is restarted forcefully.
default: memory

buffer.when_full

optional string literal enum
The behavior when the buffer becomes full.
Enum options
OptionDescription
blockApplies back pressure when the buffer is full. This prevents data loss, but will cause data to pile up on the edge.
drop_newestDrops new data as it’s received. This data is lost. This should be used when performance is the highest priority.
default: block

compression

common optional string literal enum

The compression strategy used to compress the encoded event data before transmission.

Some cloud storage API clients and browsers will handle decompression transparently, so files may not always appear to be compressed depending how they are accessed.

Enum options string literal
OptionDescription
gzipGzip standard DEFLATE compression.
default: none

default_token

required string literal
Default Splunk HEC token. If an event has a token set in its metadata, it will prevail over the one set here.
Examples 
"${SPLUNK_HEC_TOKEN}"
"A94A8FE5CCB19BA61C4C08"

encoding

required object

Configures the encoding specific sink behavior.

Note: When data in encoding is malformed, currently only a very generic error “data did not match any variant of untagged enum EncodingConfig” is reported. Follow this issue to track progress on improving these error messages.

encoding.codec

required string literal enum
The encoding codec used to serialize the events before outputting.
Enum options
OptionDescription
jsonJSON encoded event.
textThe message field from the event.
Examples 
"json"
"text"

encoding.except_fields

optional [string]
Prevent the sink from encoding the specified fields.

encoding.only_fields

optional [string]
Makes the sink encode only the specified fields.

encoding.timestamp_format

optional string literal enum
How to format event timestamps.
Enum options
OptionDescription
rfc3339Formats as a RFC3339 string
unixFormats as a unix timestamp
default: rfc3339

endpoint

required string literal
The base URL of the Splunk instance.
Examples 
"https://http-inputs-hec.splunkcloud.com"
"https://hec.splunk.com:8088"
"http://example.com"

healthcheck

common optional object
Health check options for the sink.

healthcheck.enabled

common optional bool
Enables/disables the healthcheck upon Vector boot.
default: true

host_key

common optional string literal
The name of the log field to be used as the hostname sent to Splunk HEC. This overrides the global host_key option.
Examples 
"hostname"

index

optional string template
The name of the index where to send the events to. If not specified, the default index is used.
Note: This parameter supports Vector's template syntax, which enables you to use dynamic per-event values.
Examples 
"{{ host }}"
"custom_index"

indexed_fields

common optional [string]
Fields to be added to Splunk index.
Array string field_path
Examples 
[
  "field1",
  "field2"
]

inputs

required [string]

A list of upstream source or transform IDs. Wildcards (*) are supported.

See configuration for more info.

Array string literal
Examples 
[
  "my-source-or-transform-id",
  "prefix-*"
]

proxy

optional object
Configures an HTTP(S) proxy for Vector to use. By default, the globally configured proxy is used.

proxy.enabled

optional bool
If false the proxy will be disabled.
default: true

proxy.http

optional string literal
The URL to proxy HTTP requests through.
Examples 
"http://foo.bar:3128"

proxy.https

optional string literal
The URL to proxy HTTPS requests through.
Examples 
"http://foo.bar:3128"

proxy.no_proxy

optional [string]

A list of hosts to avoid proxying. Allowed patterns here include:

PatternExample match
Domain namesexample.com matches requests to example.com
Wildcard domains.example.com matches requests to example.com and its subdomains
IP addresses127.0.0.1 matches requests to 127.0.0.1
CIDR blocks192.168.0.0./16 matches requests to any IP addresses in this range
Splat* matches all hosts

request

optional object
Configures the sink request behavior.

request.adaptive_concurrency

optional object
Configure the adaptive concurrency algorithms. These values have been tuned by optimizing simulated results. In general you should not need to adjust these.
request.adaptive_concurrency.decrease_ratio
optional float
The fraction of the current value to set the new concurrency limit when decreasing the limit. Valid values are greater than 0 and less than 1. Smaller values cause the algorithm to scale back rapidly when latency increases. Note that the new limit is rounded down after applying this ratio.
default: 0.9
request.adaptive_concurrency.ewma_alpha
optional float
The adaptive concurrency algorithm uses an exponentially weighted moving average (EWMA) of past RTT measurements as a reference to compare with the current RTT. This value controls how heavily new measurements are weighted compared to older ones. Valid values are greater than 0 and less than 1. Smaller values cause this reference to adjust more slowly, which may be useful if a service has unusually high response variability.
default: 0.7
request.adaptive_concurrency.rtt_deviation_scale
optional float
When calculating the past RTT average, we also compute a secondary “deviation” value that indicates how variable those values are. We use that deviation when comparing the past RTT average to the current measurements, so we can ignore increases in RTT that are within an expected range. This factor is used to scale up the deviation to an appropriate range. Valid values are greater than or equal to 0, and we expect reasonable values to range from 1.0 to 3.0. Larger values cause the algorithm to ignore larger increases in the RTT.
default: 2

request.concurrency

common optional uint
The maximum number of in-flight requests allowed at any given time, or “adaptive” to allow Vector to automatically set the limit based on current network and service conditions.

request.rate_limit_duration_secs

common optional uint
The time window, in seconds, used for the rate_limit_num option.
default: 1 (seconds)

request.rate_limit_num

common optional uint
The maximum number of requests allowed within the rate_limit_duration_secs time window.
default: 9.223372036854776e+18

request.retry_attempts

optional uint
The maximum number of retries to make for failed requests. The default, for all intents and purposes, represents an infinite number of retries.
default: 1.8446744073709552e+19

request.retry_initial_backoff_secs

optional uint
The amount of time to wait before attempting the first retry for a failed request. Once, the first retry has failed the fibonacci sequence will be used to select future backoffs.
default: 1 (seconds)

request.retry_max_duration_secs

optional uint
The maximum amount of time, in seconds, to wait between retries.
default: 3600 (seconds)

request.timeout_secs

common optional uint
The maximum time a request can take before being aborted. It is highly recommended that you do not lower this value below the service’s internal timeout, as this could create orphaned requests, pile on retries, and result in duplicate data downstream.
default: 60 (seconds)

source

optional string template
The source of events sent to this sink. Typically the filename the logs originated from. If unset, the Splunk collector will set it.
Note: This parameter supports Vector's template syntax, which enables you to use dynamic per-event values.
Examples 
"{{ file }}"
"/var/log/syslog"
"UDP:514"

sourcetype

optional string template
The sourcetype of events sent to this sink. If unset, Splunk will default to httpevent.
Note: This parameter supports Vector's template syntax, which enables you to use dynamic per-event values.
Examples 
"{{ sourcetype }}"
"_json"
"httpevent"

tls

optional object
Configures the TLS options for outgoing connections.

tls.ca_file

optional string literal
Absolute path to an additional CA certificate file, in DER or PEM format (X.509), or an inline CA certificate in PEM format.
Examples 
"/path/to/certificate_authority.crt"

tls.crt_file

common optional string literal
Absolute path to a certificate file used to identify this connection, in DER or PEM format (X.509) or PKCS#12, or an inline certificate in PEM format. If this is set and is not a PKCS#12 archive, key_file must also be set.
Examples 
"/path/to/host_certificate.crt"

tls.enabled

common optional bool
Enable TLS during connections to the remote.
default: false

tls.key_file

common optional string literal
Absolute path to a private key file used to identify this connection, in DER or PEM format (PKCS#8), or an inline private key in PEM format. If this is set, crt_file must also be set.
Examples 
"/path/to/host_certificate.key"

tls.key_pass

optional string literal
Pass phrase used to unlock the encrypted key file. This has no effect unless key_file is set.
Examples 
"${KEY_PASS_ENV_VAR}"
"PassWord1"

tls.verify_certificate

optional bool
If true (the default), Vector will validate the TLS certificate of the remote host.
default: true

tls.verify_hostname

optional bool
If true (the default), Vector will validate the configured remote host name against the remote host’s TLS certificate. Do NOT set this to false unless you understand the risks of not verifying the remote hostname.
default: true

Telemetry

Metrics

link

buffer_byte_size

gauge
The number of bytes current in the buffer.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

buffer_discarded_events_total

counter
The number of events dropped by this non-blocking buffer.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

buffer_events

gauge
The number of events currently in the buffer.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

buffer_received_event_bytes_total

counter
The number of bytes received by this buffer.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

buffer_received_events_total

counter
The number of events received by this buffer.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

buffer_sent_event_bytes_total

counter
The number of bytes sent by this buffer.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

buffer_sent_events_total

counter
The number of events sent by this buffer.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

component_discarded_events_total

counter
The number of events dropped by this component.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

component_errors_total

counter
The total number of errors encountered by this component.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
error_type required
The type of the error
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.
stage required
The stage within the component at which the error occurred.

component_received_event_bytes_total

counter
The number of event bytes accepted by this component either from tagged origins like file and uri, or cumulatively from other origins.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
container_name optional
The name of the container from which the data originated.
file optional
The file from which the data originated.
host optional
The hostname of the system Vector is running on.
mode optional
The connection mode used by the component.
peer_addr optional
The IP from which the data originated.
peer_path optional
The pathname from which the data originated.
pid optional
The process ID of the Vector instance.
pod_name optional
The name of the pod from which the data originated.
uri optional
The sanitized URI from which the data originated.

component_received_events_count

histogram
A histogram of Vector the number of events passed in each internal batch in Vector’s internal topology. Note that this is separate than sink-level batching. It is mostly useful for low level debugging performance issues in Vector due to small internal batches.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
container_name optional
The name of the container from which the data originated.
file optional
The file from which the data originated.
host optional
The hostname of the system Vector is running on.
mode optional
The connection mode used by the component.
peer_addr optional
The IP from which the data originated.
peer_path optional
The pathname from which the data originated.
pid optional
The process ID of the Vector instance.
pod_name optional
The name of the pod from which the data originated.
uri optional
The sanitized URI from which the data originated.

component_received_events_total

counter
The number of events accepted by this component either from tagged origins like file and uri, or cumulatively from other origins.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
container_name optional
The name of the container from which the data originated.
file optional
The file from which the data originated.
host optional
The hostname of the system Vector is running on.
mode optional
The connection mode used by the component.
peer_addr optional
The IP from which the data originated.
peer_path optional
The pathname from which the data originated.
pid optional
The process ID of the Vector instance.
pod_name optional
The name of the pod from which the data originated.
uri optional
The sanitized URI from which the data originated.

component_sent_bytes_total

counter
The number of raw bytes sent by this component to destination sinks.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
endpoint optional
The endpoint to which the bytes were sent. For HTTP, this will be the host and path only, excluding the query string.
file optional
The absolute path of the destination file.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.
protocol required
The protocol used to send the bytes.
region optional
The AWS region name to which the bytes were sent. In some configurations, this may be a literal hostname.

component_sent_event_bytes_total

counter
The total number of event bytes emitted by this component.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
host optional
The hostname of the system Vector is running on.
output optional
The specific output of the component.
pid optional
The process ID of the Vector instance.

component_sent_events_total

counter
The total number of events emitted by this component.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
host optional
The hostname of the system Vector is running on.
output optional
The specific output of the component.
pid optional
The process ID of the Vector instance.

events_in_total

counter
The number of events accepted by this component either from tagged origins like file and uri, or cumulatively from other origins. This metric is deprecated and will be removed in a future version. Use component_received_events_total instead.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
container_name optional
The name of the container from which the data originated.
file optional
The file from which the data originated.
host optional
The hostname of the system Vector is running on.
mode optional
The connection mode used by the component.
peer_addr optional
The IP from which the data originated.
peer_path optional
The pathname from which the data originated.
pid optional
The process ID of the Vector instance.
pod_name optional
The name of the pod from which the data originated.
uri optional
The sanitized URI from which the data originated.

events_out_total

counter
The total number of events emitted by this component. This metric is deprecated and will be removed in a future version. Use component_sent_events_total instead.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
host optional
The hostname of the system Vector is running on.
output optional
The specific output of the component.
pid optional
The process ID of the Vector instance.

http_request_errors_total

counter
The total number of HTTP request errors for this component.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

processed_events_total

counter
The total number of events processed by this component. This metric is deprecated in place of using component_received_events_total and component_sent_events_total metrics.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

requests_received_total

counter
The total number of requests received by this component.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

utilization

gauge
A ratio from 0 to 1 of the load on a component. A value of 0 would indicate a completely idle component that is simply waiting for input. A value of 1 would indicate a that is never idle. This value is updated every 5 seconds.
component_id required
The Vector component ID.
component_kind required
The Vector component kind.
component_name required
Deprecated, use component_id instead. The value is the same as component_id.
component_type required
The Vector component type.
host optional
The hostname of the system Vector is running on.
pid optional
The process ID of the Vector instance.

How it works

Buffers and batches

This component buffers & batches data as shown in the diagram above. You’ll notice that Vector treats these concepts differently, instead of treating them as global concepts, Vector treats them as sink specific concepts. This isolates sinks, ensuring services disruptions are contained and delivery guarantees are honored.

Batches are flushed when 1 of 2 conditions are met:

  1. The batch age meets or exceeds the configured timeout_secs.
  2. The batch size meets or exceeds the configured max_bytes or max_events.

Buffers are controlled via the buffer.* options.

Health checks

Health checks ensure that the downstream service is accessible and ready to accept data. This check is performed upon sink initialization. If the health check fails an error will be logged and Vector will proceed to start.

Require health checks

If you’d like to exit immediately upon a health check failure, you can pass the --require-healthy flag:

vector --config /etc/vector/vector.toml --require-healthy

Disable health checks

If you’d like to disable health checks for this sink you can set the healthcheck option to false.

Indexer Acknowledgements

To provide more accurate end-to-end acknowledgements, this sink will automatically integrate (unless explicitly disabled) with Splunk HEC indexer acknowledgements if the provided Splunk HEC token has the feature enabled. In other words, if ackID’s are present in Splunk HEC responses, this sink will store and query for the status of said ackID’s to confirm that data has been successfully delivered. Upstream sources with the Vector end-to-end acknowledgements feature enabled will wait for this sink to confirm delivery of events before acknowledging receipt.

The Splunk channel required for indexer acknowledgements is created using a randomly generated UUID. By default, this sink uses the recommended Splunk indexer acknowledgements client behavior: querying for ack statuses every 10 seconds for a maximum of 30 attempts (5 minutes) per ackID.

Partitioning

Vector supports dynamic configuration values through a simple template syntax. If an option supports templating, it will be noted with a badge and you can use event fields to create dynamic values. For example:

[sinks.my-sink]
dynamic_option = "application={{ application_id }}"

In the above example, the application_id for each event will be used to partition outgoing data.

Rate limits & adaptive concurrency

Adaptive Request Concurrency (ARC)

Adaptive Request Concurrency is a feature of Vector that does away with static concurrency limits and automatically optimizes HTTP concurrency based on downstream service responses. The underlying mechanism is a feedback loop inspired by TCP congestion control algorithms. Checkout the announcement blog post,

We highly recommend enabling this feature as it improves performance and reliability of Vector and the systems it communicates with. As such, we have made it the default, and no further configuration is required.

Static concurrency

If Adaptive Request Concurrency is not for you, you can manually set static concurrency limits by specifying an integer for request.concurrency:

[sinks.my-sink]
  request.concurrency = 10

Rate limits

In addition to limiting request concurrency, you can also limit the overall request throughput via the request.rate_limit_duration_secs and request.rate_limit_num options.

[sinks.my-sink]
  request.rate_limit_duration_secs = 1
  request.rate_limit_num = 10

These will apply to both adaptive and fixed request.concurrency values.

Retry policy

Vector will retry failed requests (status == 429, >= 500, and != 501). Other responses will not be retried. You can control the number of retry attempts and backoff rate with the request.retry_attempts and request.retry_backoff_secs options.

Splunk HEC Channel Header

Splunk HEC requests will include the X-Splunk-Request-Channel header with a randomly generated UUID as the channel value. Splunk requires a channel value when using indexer acknowledgements, but also accepts channel values when indexer acknowledgements is disabled. Thus, this channel value is included regardless of indexer acknowledgement settings.

State

This component is stateless, meaning its behavior is consistent across each input.

Transport Layer Security (TLS)

Vector uses OpenSSL for TLS protocols due to OpenSSL’s maturity. You can enable and adjust TLS behavior using the tls.* options.
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