extend Log; histogram -> DDSketch, openmetrics histogram bucket; add init_config

extend Log:
 - Add fields to the Log message to support all the metadata the agent
   and ADP support
 - The fields map 1:1 onto ADP's internal Log struct

Histogram / sketch:
 - Renamed histogram.proto to sketch.proto and replaced its contents
   with the DDSketch wire format used by the agent's SketchPayload
 - CheckData oneof slot 5 is repurposed to carry pre-aggregated sketches

Note: lib/saluki-components/src/sources/checks_ipc/mod.rs is left
broken — it still imports the old Checks service.

init_config:
 - The check API has both `config` and `init_config`, and many
   integrations rely on the init_config block for shared defaults
 - The previous CheckInstance message only carried the
   per-instance config, so an ACR-scheduled check would receive an
   empty init_config

openmetrics:
 - Add support for the new openmetrics histogram bucket type

Author: nathan-b

lib/protos/datadog/build.rs

@@ -157,8 +157,9 @@ fn main() {
                 "proto/checks/v1/log.proto",
                 "proto/checks/v1/service_check.proto",
                 "proto/checks/v1/event.proto",
-                "proto/checks/v1/histogram.proto",
+                "proto/checks/v1/sketch.proto",
                 "proto/checks/v1/event_platform_event.proto",
+                "proto/checks/v1/histogram_bucket.proto",
             ],
             &["proto"],
         )

lib/protos/datadog/proto/checks/v1/acr_ipc.proto

@@ -45,7 +45,14 @@ message CheckInstance {
   string check_name = 1;
   string instance_name = 2;
   string id = 3;
+  // The per-instance YAML/JSON block (a single entry from the
+  // integration's `instances:` list).
   bytes config = 4;
+  // The integration-level YAML/JSON `init_config:` block, shared
+  // across every instance of this integration. Required for any check
+  // that reads defaults at Configure time (credentials, base URLs,
+  // shared tags, etc.).
+  bytes init_config = 5;
 }
 
 // Check data: client -> server (batched)

lib/protos/datadog/proto/checks/v1/checks.proto

@@ -4,18 +4,25 @@ package datadog.checks.v1;
 
 import "checks/v1/event.proto";
 import "checks/v1/event_platform_event.proto";
-import "checks/v1/histogram.proto";
+import "checks/v1/histogram_bucket.proto";
 import "checks/v1/log.proto";
 import "checks/v1/metric.proto";
 import "checks/v1/service_check.proto";
+import "checks/v1/sketch.proto";
 
 message CheckData {
     oneof data {
         datadog.checks.v1.metric.Metric metric = 1;
         datadog.checks.v1.log.Log log = 2;
         datadog.checks.v1.service_check.ServiceCheck service_check = 3;
         datadog.checks.v1.event.Event event = 4;
-        datadog.checks.v1.histogram.Histogram histogram = 5;
+        // Slot 5 was previously `histogram` (an unused stub). Repurposed
+        // to carry pre-aggregated DDSketches; the wire bytes from any
+        // legacy producer of the old Histogram message would be
+        // mis-parsed here, so don't rely on cross-version compatibility
+        // for slot 5 specifically.
+        datadog.checks.v1.sketch.Sketch sketch = 5;
         datadog.checks.v1.event_platform_event.EventPlatformEvent event_platform_event = 6;
+        datadog.checks.v1.histogram_bucket.HistogramBucket histogram_bucket = 7;
     }
 }

lib/protos/datadog/proto/checks/v1/histogram.proto

@@ -0,0 +1,49 @@
+syntax = "proto3";
+
+package datadog.checks.v1.histogram_bucket;
+
+// HistogramBucket carries a pre-aggregated histogram bucket produced
+// by an OpenMetrics / Prometheus-style integration. It is the wire
+// shape for both the agent's `Sender.HistogramBucket` and
+// `Sender.OpenmetricsBucket` upcalls (see
+// pkg/aggregator/sender/sender.go on the receiving side); the two
+// differ only in whether the producer is emitting many buckets per
+// (name, tags) context (`HistogramBucket`, multiple_buckets=true) or
+// exactly one (`OpenmetricsBucket`, multiple_buckets=false, the
+// default for Python `aggregator.submit_histogram_bucket`).
+message HistogramBucket {
+    // Metric name (e.g. "http.request.duration.count").
+    string name = 1;
+
+    // Number of observations counted by this bucket.
+    int64 value = 2;
+
+    // Bucket bounds. For point observations (single-value buckets),
+    // both bounds carry the same value.
+    double lower_bound = 3;
+    double upper_bound = 4;
+
+    // True when value increases monotonically across calls and the
+    // receiver should compute per-bucket deltas client-side. False
+    // when the producer already emits deltas.
+    bool monotonic = 5;
+
+    // Hostname this bucket was produced on. Empty means "use the
+    // receiving agent's default hostname".
+    string hostname = 6;
+
+    // Tags in `key:value` form.
+    repeated string tags = 7;
+
+    // When `monotonic=true`, indicates the receiver should emit the
+    // first observed value rather than wait for a second to compute a
+    // delta. Producers set this when they know the bucket started from
+    // zero recently (e.g. a freshly-scraped target).
+    bool flush_first_value = 8;
+
+    // Distinguishes the two sender upcalls. False (the default)
+    // routes to `Sender.OpenmetricsBucket`; true routes to
+    // `Sender.HistogramBucket`. Python `submit_histogram_bucket`
+    // always lands as false.
+    bool multiple_buckets = 9;
+}

lib/protos/datadog/proto/checks/v1/histogram_bucket.proto

@@ -12,7 +12,37 @@ enum LogLevel {
     LOG_LEVEL_CRITICAL = 50;
 }
 
+// Log carries a single log record produced by an integration check.
+//
+// Fields 1 and 2 mirror the original minimal shape and stay for backward
+// compatibility. Fields 3-8 are additive: proto3 default-empty values are
+// wire-compatible with peers that don't populate them.
 message Log {
     string message = 1;
     LogLevel level = 2;
+
+    // Integration source name (e.g. "mysql", "http_check"). Used by the
+    // logs intake to route and tag.
+    string source = 3;
+
+    // Hostname the log was produced on. Empty means "use the receiving
+    // agent's default hostname".
+    string hostname = 4;
+
+    // Service the log relates to. Surfaces as `service` in the intake.
+    string service = 5;
+
+    // Log-level tags, in `key:value` form (matches the agent's wire
+    // format used elsewhere). Combined with host / integration tags
+    // downstream.
+    repeated string tags = 6;
+
+    // Unix-nanosecond timestamp at which the producer believes the log
+    // event happened. Zero means "stamp at receive time".
+    int64 timestamp = 7;
+
+    // Free-form additional structured fields. Each value is a JSON-encoded
+    // string so producers can convey arbitrary scalar / array / object
+    // shapes through a stable wire type.
+    map<string, string> additional_properties = 8;
 }

lib/protos/datadog/proto/checks/v1/log.proto

@@ -0,0 +1,46 @@
+syntax = "proto3";
+
+package datadog.checks.v1.sketch;
+
+// Sketch carries a pre-aggregated DDSketch produced by a check.
+//
+// The wire format is aligned with the Datadog Agent's sketch_payload
+// format (see DataDog/agent-payload v5 SketchPayload.Sketch.Dogsketch)
+// so receivers can convert directly to the agent's internal Sketch
+// type without a separate sketches-go round-trip.
+message Sketch {
+    // Metric name (e.g. "http.request.duration").
+    string name = 1;
+
+    // Tags in `key:value` form.
+    repeated string tags = 2;
+
+    // Hostname this sketch was produced on. Empty means "use the
+    // receiving agent's default hostname".
+    string hostname = 3;
+
+    // Unix-second timestamp at which the producer flushed the sketch.
+    int64 timestamp = 4;
+
+    // Flush interval the producer used; informational only — the
+    // receiving aggregator stamps its own flush boundary.
+    uint64 interval_secs = 5;
+
+    // The DDSketch body itself, in the agent's bin-encoded shape.
+    Dogsketch dogsketch = 6;
+}
+
+// Dogsketch is the bin-encoded DDSketch payload. Bin keys (k) and
+// counts (n) are parallel arrays — k[i] is the bin index and n[i] the
+// number of observations in that bin. This matches the Datadog Agent's
+// SketchPayload.Sketch.Dogsketch definition exactly.
+message Dogsketch {
+    int64 ts = 1;
+    int64 cnt = 2;
+    double min = 3;
+    double max = 4;
+    double avg = 5;
+    double sum = 6;
+    repeated sint32 k = 7;
+    repeated uint32 n = 8;
+}