AWS Cloudwatch Logs Sink

The Vector aws_cloudwatch_logs sink sends logs to AWS Cloudwatch logs.

Configuration

[sinks.my_sink_id]
# General
type = "aws_cloudwatch_logs" # required
inputs = ["my-source-or-transform-id"] # required
compression = "none" # optional, default
create_missing_group = true # optional, default
create_missing_stream = true # optional, default
group_name = "group-name" # required
healthcheck = true # optional, default
region = "us-east-1" # required, required when endpoint = null
stream_name = "{{ host }}" # required
# Encoding
encoding.codec = "json" # required
  • optionalstring

    assume_role

    The ARN of an IAM role to assume at startup. See AWS Authentication for more info.

    • View examples
  • optionaltable

    batch

    Configures the sink batching behavior.

    • commonoptionaluint

      max_bytes

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

      • Default: 1048576 (bytes)
    • commonoptionaluint

      max_events

      The maximum size of a batch, in events, before it is flushed. See Buffers & batches for more info.

      • Default: 10000 (events)
    • commonoptionaluint

      timeout_secs

      The maximum age of a batch before it is flushed. See Buffers & batches for more info.

      • Default: 1 (seconds)
  • optionaltable

    buffer

    Configures the sink specific buffer behavior.

    • commonoptionaluint

      max_events

      The maximum number of events allowed in the buffer. See Buffers & batches for more info.

      • Only relevant when: type = "memory"
      • Default: 500 (events)
    • commonrequired*uint

      max_size

      The maximum size of the buffer on the disk. See Buffers & batches for more info.

      • Only required when: type = "disk"
      • View examples
    • enumcommonoptionalstring

      type

      The buffer's type and storage mechanism.

      • Default: "memory"
      • Enum, must be one of: "memory" "disk"
      • View examples
    • enumoptionalstring

      when_full

      The behavior when the buffer becomes full.

      • Default: "block"
      • Enum, must be one of: "block" "drop_newest"
      • View examples
  • enumcommonoptionalstring

    compression

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

    • Default: "none"
    • Enum, must be one of: "none" "gzip"
    • View examples
  • commonoptionalbool

    create_missing_group

    Dynamically create a log group if it does not already exist. This will ignore create_missing_stream directly after creating the group and will create the first stream.

    • Default: true
    • View examples
  • commonoptionalbool

    create_missing_stream

    Dynamically create a log stream if it does not already exist.

    • Default: true
    • View examples
  • commonrequiredtable

    encoding

    Configures the encoding specific sink behavior.

    • commonrequiredstring

      codec

      The encoding codec used to serialize the events before outputting.

      • View examples
    • optional[string]

      except_fields

      Prevent the sink from encoding the specified labels.

      • View examples
    • optional[string]

      only_fields

      Prevent the sink from encoding the specified labels.

      • View examples
    • enumoptionalstring

      timestamp_format

      How to format event timestamps.

      • Default: "rfc3339"
      • Enum, must be one of: "rfc3339" "unix"
      • View examples
  • optionalstring

    endpoint

    Custom endpoint for use with AWS-compatible services. Providing a value for this option will make region moot.

    • Only relevant when: region = null
    • View examples
  • templateablecommonrequiredstring

    group_name

    The group name of the target CloudWatch Logs stream.

    • View examples
  • commonoptionalbool

    healthcheck

    Enables/disables the sink healthcheck upon Vector boot. See Health checks for more info.

    • Default: true
    • View examples
  • commonrequired*string

    region

    The AWS region of the target service. If endpoint is provided it will override this value since the endpoint includes the region.

    • Only required when: endpoint = null
    • View examples
  • optionaltable

    request

    Configures the sink request behavior.

    • optionaltable

      adaptive_concurrency

      Configure the adaptive concurrency algorithms. These values have been tuned by optimizing simulated results. In general you should not need to adjust these.

      • optionalfloat
        decrease_ratio

        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
      • optionalfloat
        ewma_alpha

        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
      • optionalfloat
        rtt_threshold_ratio

        When comparing the past RTT average to the current measurements, we ignore changes that are less than this ratio higher than the past RTT. Valid values are greater than or equal to 0. Larger values cause the algorithm to ignore larger increases in the RTT.

        • Default: 0.05
    • commonoptionaluint

      concurrency

      The maximum number of in-flight requests allowed at any given time.

      • Default: 5 (requests)
    • commonoptionaluint

      rate_limit_duration_secs

      The time window, in seconds, used for the rate_limit_num option.

      • Default: 1 (seconds)
    • commonoptionaluint

      rate_limit_num

      The maximum number of requests allowed within the rate_limit_duration_secs time window.

      • Default: 5
    • optionaluint

      retry_attempts

      The maximum number of retries to make for failed requests. The default, for all intents and purposes, represents an infinite number of retries.

      • Default: 18446744073709552000
    • optionaluint

      retry_initial_backoff_secs

      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)
    • optionaluint

      retry_max_duration_secs

      The maximum amount of time, in seconds, to wait between retries.

      • Default: 10 (seconds)
    • commonoptionaluint

      timeout_secs

      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. See Buffers & batches for more info.

      • Default: 30 (seconds)
  • templateablecommonrequiredstring

    stream_name

    The stream name of the target CloudWatch Logs stream.

    • View examples

Env Vars

  • commonoptionalstring

    AWS_ACCESS_KEY_ID

    The AWS access key id. Used for AWS authentication when communicating with AWS services. See AWS Authentication for more info.

    • View examples
  • commonoptionalstring

    AWS_CONFIG_FILE

    Specifies the location of the file that the AWS CLI uses to store configuration profiles.

    • Default: "~/.aws/config"
  • commonoptionalstring

    AWS_CREDENTIAL_EXPIRATION

    Expiration time in RFC 3339 format. If unset, credentials won't expire.

    • View examples
  • commonoptionalstring

    AWS_DEFAULT_REGION

    The default AWS region.

    • Only relevant when: endpoint = null
    • View examples
  • commonoptionalstring

    AWS_PROFILE

    Specifies the name of the CLI profile with the credentials and options to use. This can be the name of a profile stored in a credentials or config file.

    • Default: "default"
    • View examples
  • commonoptionalstring

    AWS_ROLE_SESSION_NAME

    Specifies a name to associate with the role session. This value appears in CloudTrail logs for commands performed by the user of this profile.

    • View examples
  • commonoptionalstring

    AWS_SECRET_ACCESS_KEY

    The AWS secret access key. Used for AWS authentication when communicating with AWS services. See AWS Authentication for more info.

    • View examples
  • commonoptionalstring

    AWS_SESSION_TOKEN

    The AWS session token. Used for AWS authentication when communicating with AWS services.

    • View examples
  • commonoptionalstring

    AWS_SHARED_CREDENTIALS_FILE

    Specifies the location of the file that the AWS CLI uses to store access keys.

    • Default: "~/.aws/credentials"

Telemetry

This component provides the following metrics that can be retrieved through the internal_metrics source. See the metrics section in the monitoring page for more info.

  • counter

    processing_errors_total

    The total number of processing errors encountered by this component. This metric includes the following tags:

    • component_kind - The Vector component kind.

    • component_name - The Vector component ID.

    • component_type - The Vector component type.

    • error_type - The type of the error

    • instance - The Vector instance identified by host and port.

    • job - The name of the job producing Vector metrics.

  • counter

    processed_events_total

    The total number of events processed by this component. This metric includes the following tags:

    • component_kind - The Vector component kind.

    • component_name - The Vector component ID.

    • component_type - The Vector component type.

    • file - The file that produced the error

    • instance - The Vector instance identified by host and port.

    • job - The name of the job producing Vector metrics.

  • counter

    processed_bytes_total

    The total number of bytes processed by the component. This metric includes the following tags:

    • component_kind - The Vector component kind.

    • component_name - The Vector component ID.

    • component_type - The Vector component type.

    • instance - The Vector instance identified by host and port.

    • job - The name of the job producing Vector metrics.

How It Works

AWS Authentication

Vector checks for AWS credentials in the following order:

  1. Environment variables AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY.
  2. The credential_process command in the AWS config file. (usually located at ~/.aws/config)
  3. The AWS credentials file. (usually located at ~/.aws/credentials)
  4. The IAM instance profile. (will only work if running on an EC2 instance with an instance profile/role)

If credentials are not found the healtcheck will fail and an error will be logged.

Obtaining an access key

In general, we recommend using instance profiles/roles whenever possible. In cases where this is not possible you can generate an AWS access key for any user within your AWS account. AWS provides a detailed guide on how to do this.

Assuming roles

Vector can assume an AWS IAM role via the assume_role option. This is an optional setting that is helpful for a variety of use cases, such as cross account access.

Buffers & 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 <% if component.options.batch.children.respond_to?(:max_size) %>max_size<% else %>max_events<% end %>.

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.

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:

vector.toml
[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 & adapative concurrency

Adaptive Request Concurrency (ARC)

Adaptive Requst Concurrency is a feature of Vector that does away with static rate limits and automatically optimizes HTTP concurrency limits 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.

To enable, set the request.concurrency option to adaptive:

vector.toml
[sinks.my-sink]
request.concurrency = "adaptive"

Static rate limits

If Adaptive Request Concurrency is not for you, you can manually set static rate limits with the request.rate_limit_duration_secs, request.rate_limit_num, and request.concurrency options:

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

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.