vector/transforms/sample/config.rs
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use snafu::Snafu;
use vector_lib::config::{LegacyKey, LogNamespace};
use vector_lib::configurable::configurable_component;
use vector_lib::lookup::{lookup_v2::OptionalValuePath, owned_value_path};
use vrl::value::Kind;
use crate::{
conditions::AnyCondition,
config::{
DataType, GenerateConfig, Input, OutputId, TransformConfig, TransformContext,
TransformOutput,
},
schema,
template::Template,
transforms::Transform,
};
use super::transform::{Sample, SampleMode};
#[derive(Debug, Snafu)]
pub enum SampleError {
// Errors from `determine_sample_mode`
#[snafu(display(
"Only positive, non-zero numbers are allowed values for `ratio`, value: {ratio}"
))]
InvalidRatio { ratio: f64 },
#[snafu(display("Only non-zero numbers are allowed values for `rate`"))]
InvalidRate,
#[snafu(display(
"Exactly one value must be provided for either 'rate' or 'ratio', but not both"
))]
InvalidConfiguration,
}
/// Configuration for the `sample` transform.
#[configurable_component(transform(
"sample",
"Sample events from an event stream based on supplied criteria and at a configurable rate."
))]
#[derive(Clone, Debug)]
#[serde(deny_unknown_fields)]
pub struct SampleConfig {
/// The rate at which events are forwarded, expressed as `1/N`.
///
/// For example, `rate = 1500` means 1 out of every 1500 events are forwarded and the rest are
/// dropped. This differs from `ratio` which allows more precise control over the number of events
/// retained and values greater than 1/2. It is an error to provide a value for both `rate` and `ratio`.
#[configurable(metadata(docs::examples = 1500))]
pub rate: Option<u64>,
/// The rate at which events are forwarded, expressed as a percentage
///
/// For example, `ratio = .13` means that 13% out of all events on the stream are forwarded and
/// the rest are dropped. This differs from `rate` allowing the configuration of a higher
/// precision value and also the ability to retain values of greater than 50% of all events. It is
/// an error to provide a value for both `rate` and `ratio`.
#[configurable(metadata(docs::examples = 0.13))]
#[configurable(validation(range(min = 0.0, max = 1.0)))]
pub ratio: Option<f64>,
/// The name of the field whose value is hashed to determine if the event should be
/// sampled.
///
/// Each unique value for the key creates a bucket of related events to be sampled together
/// and the rate is applied to the buckets themselves to sample `1/N` buckets. The overall rate
/// of sampling may differ from the configured one if values in the field are not uniformly
/// distributed. If left unspecified, or if the event doesn’t have `key_field`, then the
/// event is sampled independently.
///
/// This can be useful to, for example, ensure that all logs for a given transaction are
/// sampled together, but that overall `1/N` transactions are sampled.
#[configurable(metadata(docs::examples = "message"))]
pub key_field: Option<String>,
/// The event key in which the sample rate is stored. If set to an empty string, the sample rate will not be added to the event.
#[configurable(metadata(docs::examples = "sample_rate"))]
#[serde(default = "default_sample_rate_key")]
pub sample_rate_key: OptionalValuePath,
/// The value to group events into separate buckets to be sampled independently.
///
/// If left unspecified, or if the event doesn't have `group_by`, then the event is not
/// sampled separately.
#[configurable(metadata(
docs::examples = "{{ service }}",
docs::examples = "{{ hostname }}-{{ service }}"
))]
pub group_by: Option<Template>,
/// A logical condition used to exclude events from sampling.
pub exclude: Option<AnyCondition>,
}
impl SampleConfig {
fn sample_rate(&self) -> Result<SampleMode, SampleError> {
match (self.rate, self.ratio) {
(None, Some(ratio)) => {
if ratio <= 0.0 {
Err(SampleError::InvalidRatio { ratio })
} else {
Ok(SampleMode::new_ratio(ratio))
}
}
(Some(rate), None) => {
if rate == 0 {
Err(SampleError::InvalidRate)
} else {
Ok(SampleMode::new_rate(rate))
}
}
_ => Err(SampleError::InvalidConfiguration),
}
}
}
impl GenerateConfig for SampleConfig {
fn generate_config() -> toml::Value {
toml::Value::try_from(Self {
rate: None,
ratio: Some(0.1),
key_field: None,
group_by: None,
exclude: None::<AnyCondition>,
sample_rate_key: default_sample_rate_key(),
})
.unwrap()
}
}
#[async_trait::async_trait]
#[typetag::serde(name = "sample")]
impl TransformConfig for SampleConfig {
async fn build(&self, context: &TransformContext) -> crate::Result<Transform> {
Ok(Transform::function(Sample::new(
Self::NAME.to_string(),
self.sample_rate()?,
self.key_field.clone(),
self.group_by.clone(),
self.exclude
.as_ref()
.map(|condition| condition.build(&context.enrichment_tables))
.transpose()?,
self.sample_rate_key.clone(),
)))
}
fn input(&self) -> Input {
Input::new(DataType::Log | DataType::Trace)
}
fn validate(&self, _: &schema::Definition) -> Result<(), Vec<String>> {
self.sample_rate()
.map(|_| ())
.map_err(|e| vec![e.to_string()])
}
fn outputs(
&self,
_: vector_lib::enrichment::TableRegistry,
input_definitions: &[(OutputId, schema::Definition)],
_: LogNamespace,
) -> Vec<TransformOutput> {
vec![TransformOutput::new(
DataType::Log | DataType::Trace,
input_definitions
.iter()
.map(|(output, definition)| {
(
output.clone(),
definition.clone().with_source_metadata(
SampleConfig::NAME,
Some(LegacyKey::Overwrite(owned_value_path!("sample_rate"))),
&owned_value_path!("sample_rate"),
Kind::bytes(),
None,
),
)
})
.collect(),
)]
}
}
pub fn default_sample_rate_key() -> OptionalValuePath {
OptionalValuePath::from(owned_value_path!("sample_rate"))
}
#[cfg(test)]
mod tests {
use crate::transforms::sample::config::SampleConfig;
#[test]
fn generate_config() {
crate::test_util::test_generate_config::<SampleConfig>();
}
}