fix(datadog_metrics sink): Revert to using v1 endpoint by default

docs/DEPRECATIONS.md

@@ -18,5 +18,4 @@ For example:
 
 ## To be removed
 
-- datadog_v1_metrics v0.35.0 Support for `v1` series endpoint in the `datadog_metrics` sink should be removed.
 - http_internal_metrics v0.35.0 `requests_completed_total`, `request_duration_seconds`, and `requests_received_total` internal metrics should be removed.

src/sinks/datadog/metrics/config.rs

@@ -22,18 +22,15 @@ use crate::{
     tls::{MaybeTlsSettings, TlsEnableableConfig},
 };
 
+#[derive(Clone, Copy, Debug, Default)]
+pub struct DatadogMetricsDefaultBatchSettings;
+
 // This default is centered around "series" data, which should be the lion's share of what we
 // process.  Given that a single series, when encoded, is in the 150-300 byte range, we can fit a
 // lot of these into a single request, something like 150-200K series.  Simply to be a little more
 // conservative, though, we use 100K here.  This will also get a little more tricky when it comes to
 // distributions and sketches, but we're going to have to implement incremental encoding to handle
 // "we've exceeded our maximum payload size, split this batch" scenarios anyways.
-pub const MAXIMUM_PAYLOAD_COMPRESSED_SIZE: usize = 3_200_000;
-pub const MAXIMUM_PAYLOAD_SIZE: usize = 62_914_560;
-
-#[derive(Clone, Copy, Debug, Default)]
-pub struct DatadogMetricsDefaultBatchSettings;
-
 impl SinkBatchSettings for DatadogMetricsDefaultBatchSettings {
     const MAX_EVENTS: Option<usize> = Some(100_000);
     const MAX_BYTES: Option<usize> = None;
@@ -44,9 +41,6 @@ pub(super) const SERIES_V1_PATH: &str = "/api/v1/series";
 pub(super) const SERIES_V2_PATH: &str = "/api/v2/series";
 pub(super) const SKETCHES_PATH: &str = "/api/beta/sketches";
 
-// TODO: the series V1 endpoint support is considered deprecated and should be removed in a future release.
-// At that time when the V1 support is removed, the SeriesApiVersion stops being useful and can be removed.
-
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum SeriesApiVersion {
     V1,
@@ -60,12 +54,12 @@ impl SeriesApiVersion {
             Self::V2 => SERIES_V2_PATH,
         }
     }
-    fn get_api_version_backwards_compatible() -> Self {
+    fn get_api_version() -> Self {
         static API_VERSION: OnceLock<SeriesApiVersion> = OnceLock::new();
         *API_VERSION.get_or_init(|| {
-            match std::env::var("VECTOR_TEMP_USE_DD_METRICS_SERIES_V1_API") {
-                Ok(_) => Self::V1,
-                Err(_) => Self::V2,
+            match std::env::var("VECTOR_TEMP_USE_DD_METRICS_SERIES_V2_API") {
+                Ok(_) => Self::V2,
+                Err(_) => Self::V1,
             }
         })
     }
@@ -80,6 +74,12 @@ pub enum DatadogMetricsEndpoint {
     Sketches,
 }
 
+/// Payload limits for metrics are endpoint-dependent.
+pub(super) struct DatadogMetricsPayloadLimits {
+    pub(super) uncompressed: usize,
+    pub(super) compressed: usize,
+}
+
 impl DatadogMetricsEndpoint {
     /// Gets the content type associated with the specific encoder for a given metric endpoint.
     pub const fn content_type(self) -> &'static str {
@@ -96,7 +96,29 @@ impl DatadogMetricsEndpoint {
 
     // Creates an instance of the `Series` variant with the default API version.
     pub fn series() -> Self {
-        Self::Series(SeriesApiVersion::get_api_version_backwards_compatible())
+        Self::Series(SeriesApiVersion::get_api_version())
+    }
+
+    pub(super) const fn payload_limits(self) -> DatadogMetricsPayloadLimits {
+        // from https://docs.datadoghq.com/api/latest/metrics/#submit-metrics
+
+        let (uncompressed, compressed) = match self {
+            // Sketches use the same payload size limits as v1 series
+            DatadogMetricsEndpoint::Series(SeriesApiVersion::V1)
+            | DatadogMetricsEndpoint::Sketches => (
+                62_914_560, // 60 MiB
+                3_200_000,  // 3.2 MB
+            ),
+            DatadogMetricsEndpoint::Series(SeriesApiVersion::V2) => (
+                5_242_880, // 5 MiB
+                512_000,   // 512 KB
+            ),
+        };
+
+        DatadogMetricsPayloadLimits {
+            uncompressed,
+            compressed,
+        }
     }
 }
 
@@ -197,12 +219,7 @@ impl DatadogMetricsConfig {
     ) -> crate::Result<DatadogMetricsEndpointConfiguration> {
         let base_uri = self.get_base_agent_endpoint();
 
-        // TODO: the V1 endpoint support is considered deprecated and should be removed in a future release.
-        // At that time, the get_api_version_backwards_compatible() should be replaced with statically using the v2.
-        let series_endpoint = build_uri(
-            &base_uri,
-            SeriesApiVersion::get_api_version_backwards_compatible().get_path(),
-        )?;
+        let series_endpoint = build_uri(&base_uri, SeriesApiVersion::get_api_version().get_path())?;
         let sketches_endpoint = build_uri(&base_uri, SKETCHES_PATH)?;
 
         Ok(DatadogMetricsEndpointConfiguration::new(

src/sinks/datadog/metrics/encoder.rs

@@ -17,9 +17,7 @@ use vector_lib::{
     EstimatedJsonEncodedSizeOf,
 };
 
-use super::config::{
-    DatadogMetricsEndpoint, SeriesApiVersion, MAXIMUM_PAYLOAD_COMPRESSED_SIZE, MAXIMUM_PAYLOAD_SIZE,
-};
+use super::config::{DatadogMetricsEndpoint, SeriesApiVersion};
 use crate::{
     common::datadog::{
         DatadogMetricType, DatadogPoint, DatadogSeriesMetric, DatadogSeriesMetricMetadata,
@@ -171,13 +169,12 @@ impl DatadogMetricsEncoder {
         endpoint: DatadogMetricsEndpoint,
         default_namespace: Option<String>,
     ) -> Result<Self, CreateError> {
-        // According to the datadog-agent code, sketches use the same payload size limits as series
-        // data. We're just gonna go with that for now.
+        let payload_limits = endpoint.payload_limits();
         Self::with_payload_limits(
             endpoint,
             default_namespace,
-            MAXIMUM_PAYLOAD_SIZE,
-            MAXIMUM_PAYLOAD_COMPRESSED_SIZE,
+            payload_limits.uncompressed,
+            payload_limits.compressed,
         )
     }