chore(log_to_metric transform): Add Cargo feature for the transform (vectordotdev#18337)

The `log_to_metric` transform was missing a corresponding Cargo feature. Therefore, when compiling
Vector with a reduced set of features, this transform was always included even if not requested.

This is the only transform that was still missing a Cargo feature.

The previous attempt incorrectly tried to feature-gate the `parser` module in `internal_events`.
Instead, this commit allows for the `parser` module imports to be left unused when not required.

The test configuration in the `api` module was also missing a dependency on `transforms-log_to_metric`.

Signed-off-by: Hugo Hromic <[email protected]>

Author: hhromic

Cargo.toml

@@ -580,6 +580,7 @@ transforms-logs = [
   "transforms-aws_ec2_metadata",
   "transforms-dedupe",
   "transforms-filter",
+  "transforms-log_to_metric",
   "transforms-lua",
   "transforms-metric_to_log",
   "transforms-pipelines",
@@ -592,6 +593,7 @@ transforms-logs = [
 transforms-metrics = [
   "transforms-aggregate",
   "transforms-filter",
+  "transforms-log_to_metric",
   "transforms-lua",
   "transforms-metric_to_log",
   "transforms-pipelines",
@@ -604,6 +606,7 @@ transforms-aggregate = []
 transforms-aws_ec2_metadata = ["dep:arc-swap"]
 transforms-dedupe = ["dep:lru"]
 transforms-filter = []
+transforms-log_to_metric = []
 transforms-lua = ["dep:mlua", "vector-core/lua"]
 transforms-metric_to_log = []
 transforms-pipelines = ["transforms-filter", "transforms-route"]
@@ -848,6 +851,7 @@ shutdown-tests = ["api", "sinks-blackhole", "sinks-console", "sinks-prometheus",
 cli-tests = ["sinks-blackhole", "sinks-socket", "sources-demo_logs", "sources-file"]
 vector-api-tests = [
   "sources-demo_logs",
+  "transforms-log_to_metric",
   "transforms-remap",
   "sinks-blackhole"
 ]

src/api/tap.rs

@@ -415,6 +415,7 @@ async fn tap_handler(
     test,
     feature = "sinks-blackhole",
     feature = "sources-demo_logs",
+    feature = "transforms-log_to_metric",
     feature = "transforms-remap",
 ))]
 mod tests {

src/internal_events/mod.rs

@@ -76,6 +76,7 @@ mod journald;
 mod kafka;
 #[cfg(feature = "sources-kubernetes_logs")]
 mod kubernetes_logs;
+#[cfg(feature = "transforms-log_to_metric")]
 mod log_to_metric;
 mod logplex;
 #[cfg(feature = "sinks-loki")]
@@ -213,6 +214,7 @@ pub(crate) use self::journald::*;
 pub(crate) use self::kafka::*;
 #[cfg(feature = "sources-kubernetes_logs")]
 pub(crate) use self::kubernetes_logs::*;
+#[cfg(feature = "transforms-log_to_metric")]
 pub(crate) use self::log_to_metric::*;
 #[cfg(feature = "sources-heroku_logs")]
 pub(crate) use self::logplex::*;
@@ -224,6 +226,7 @@ pub(crate) use self::lua::*;
 pub(crate) use self::metric_to_log::*;
 #[cfg(feature = "sources-nginx_metrics")]
 pub(crate) use self::nginx_metrics::*;
+#[allow(unused_imports)]
 pub(crate) use self::parser::*;
 #[cfg(feature = "sources-postgresql_metrics")]
 pub(crate) use self::postgresql_metrics::*;

src/transforms/mod.rs

@@ -12,6 +12,7 @@ pub mod aws_ec2_metadata;
 pub mod dedupe;
 #[cfg(feature = "transforms-filter")]
 pub mod filter;
+#[cfg(feature = "transforms-log_to_metric")]
 pub mod log_to_metric;
 #[cfg(feature = "transforms-lua")]
 pub mod lua;