1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140

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;

/// 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.
    #[configurable(metadata(docs::examples = 1500))]
    pub rate: u64,

    /// 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 GenerateConfig for SampleConfig {
    fn generate_config() -> toml::Value {
        toml::Value::try_from(Self {
            rate: 10,
            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.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 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>();
    }
}