Remove serialize feature (#738)

Removes non-spec serialization support to reduce public API surface
area.

.github/workflows/ci.yml

@@ -72,7 +72,7 @@ jobs:
         override: true
     - name: Run tests
       run: cargo --version &&
-        cargo test --verbose --manifest-path=opentelemetry/Cargo.toml --features trace,metrics,serialize,rt-tokio,testing &&
+        cargo test --verbose --manifest-path=opentelemetry/Cargo.toml --features trace,metrics,rt-tokio,testing &&
         cargo test --manifest-path=opentelemetry-jaeger/Cargo.toml --features rt-tokio &&
         cargo test --manifest-path=opentelemetry-zipkin/Cargo.toml
   cargo-deny:

examples/basic-otlp-http/Cargo.toml

@@ -5,6 +5,6 @@ edition = "2018"
 publish = false
 
 [dependencies]
-opentelemetry = { path = "../../opentelemetry", features = ["rt-tokio", "metrics", "serialize"] }
+opentelemetry = { path = "../../opentelemetry", features = ["rt-tokio", "metrics"] }
 opentelemetry-otlp = { path = "../../opentelemetry-otlp", features = ["http-proto", "reqwest-client"] }
 tokio = { version = "1.0", features = ["full"] }

examples/basic-otlp-with-selector/Cargo.toml

@@ -7,7 +7,7 @@ publish = false
 [dependencies]
 futures-util = { version = "0.3", default-features = false, features = ["std"] }
 lazy_static = "1.4"
-opentelemetry = { path = "../../opentelemetry", features = ["rt-tokio", "metrics", "serialize"] }
+opentelemetry = { path = "../../opentelemetry", features = ["rt-tokio", "metrics"] }
 opentelemetry-otlp = { path = "../../opentelemetry-otlp", features = ["tonic", "metrics"] }
 serde_json = "1.0"
 tokio = { version = "1.0", features = ["full"] }

examples/basic-otlp/Cargo.toml

@@ -7,7 +7,7 @@ publish = false
 [dependencies]
 futures-util = { version = "0.3", default-features = false, features = ["std"] }
 lazy_static = "1.4"
-opentelemetry = { path = "../../opentelemetry", features = ["rt-tokio", "metrics", "serialize"] }
+opentelemetry = { path = "../../opentelemetry", features = ["rt-tokio", "metrics"] }
 opentelemetry-otlp = { path = "../../opentelemetry-otlp", features = ["tonic", "metrics"] }
 serde_json = "1.0"
 tokio = { version = "1.0", features = ["full"] }

examples/basic/Cargo.toml

@@ -7,8 +7,7 @@ publish = false
 [dependencies]
 futures-util = { version = "0.3", default-features = false, features = ["std"] }
 lazy_static = "1.4"
-opentelemetry = { path = "../../opentelemetry", features = ["serialize", "rt-tokio", "metrics"] }
+opentelemetry = { path = "../../opentelemetry", features = ["rt-tokio", "metrics"] }
 opentelemetry-jaeger = { path = "../../opentelemetry-jaeger", features = ["rt-tokio"] }
-serde_json = "1.0"
 thrift = "0.13"
 tokio = { version = "1.0", features = ["full"] }

examples/basic/src/main.rs

@@ -6,7 +6,7 @@ use opentelemetry::sdk::{metrics::PushController, trace as sdktrace, Resource};
 use opentelemetry::trace::TraceError;
 use opentelemetry::{
     baggage::BaggageExt,
-    metrics::{MetricsError, ObserverResult},
+    metrics::ObserverResult,
     trace::{TraceContextExt, Tracer},
     Context, Key, KeyValue,
 };
@@ -29,13 +29,7 @@ fn delayed_interval(duration: Duration) -> impl Stream<Item = tokio::time::Insta
 }
 
 fn init_meter() -> PushController {
-    opentelemetry::sdk::export::metrics::stdout(tokio::spawn, delayed_interval)
-        .with_formatter(|batch| {
-            serde_json::to_value(batch)
-                .map(|value| value.to_string())
-                .map_err(|err| MetricsError::Other(err.to_string()))
-        })
-        .init()
+    opentelemetry::sdk::export::metrics::stdout(tokio::spawn, delayed_interval).init()
 }
 
 const FOO_KEY: Key = Key::from_static_str("ex.com/foo");

examples/dynatrace/Cargo.toml

@@ -8,7 +8,7 @@ publish = false
 futures = "0.3"
 http = "0.2"
 lazy_static = "1.4"
-opentelemetry = { path = "../../opentelemetry", default-features = false, features = ["trace", "serialize"] }
+opentelemetry = { path = "../../opentelemetry", default-features = false, features = ["trace"] }
 opentelemetry-dynatrace = { path = "../../opentelemetry-dynatrace" }
 opentelemetry-http = { path = "../../opentelemetry-http", default-features = false }
 opentelemetry-otlp = { path = "../../opentelemetry-otlp", default-features = false, features = ["http-proto", "reqwest-client"] }

examples/external-otlp-grpcio-async-std/Cargo.toml

@@ -7,10 +7,7 @@ publish = false
 [dependencies]
 async-std = { version = "1.9.0", features = ["attributes"] }
 env_logger = "0.8.2"
-opentelemetry = { path = "../../opentelemetry", features = [
-    "rt-async-std",
-    "serialize"
-] }
+opentelemetry = { path = "../../opentelemetry", features = ["rt-async-std"] }
 opentelemetry-otlp = { path = "../../opentelemetry-otlp", features = [
     "grpc-sys",
     "trace",

examples/external-otlp-tonic-tokio/Cargo.toml

@@ -5,7 +5,7 @@ edition = "2018"
 publish = false
 
 [dependencies]
-opentelemetry = { path = "../../opentelemetry", features = ["rt-tokio", "metrics", "serialize"] }
+opentelemetry = { path = "../../opentelemetry", features = ["rt-tokio", "metrics"] }
 opentelemetry-otlp = { path = "../../opentelemetry-otlp", features = ["tonic", "tls", "tls-roots"] }
 serde_json = "1.0"
 tokio = { version = "1.0", features = ["full"] }

opentelemetry-api/Cargo.toml

@@ -9,7 +9,6 @@ futures-channel = "0.3"
 futures-util = { version = "0.3", default-features = false, features = ["std", "sink"] }
 lazy_static = "1.4"
 pin-project = { version = "1.0.2", optional = true }
-serde = { version = "1.0", features = ["derive", "rc"], optional = true }
 thiserror = "1"
 tokio-stream = { version = "0.1", optional = true }
 
@@ -24,5 +23,4 @@ js-sys = "0.3"
 default = ["trace"]
 trace = ["pin-project"]
 metrics = ["fnv"]
-serialize = ["serde"]
 testing = ["trace"]

opentelemetry-api/src/baggage.rs

@@ -6,14 +6,11 @@
 //!   information to metrics, traces, and logs.
 //! * [`BaggageExt`]: Extensions for managing `Baggage` in a [`Context`].
 //!
-//! Baggage can be sent between systems using the [`BaggagePropagator`] in
+//! Baggage can be sent between systems using a baggage propagator in
 //! accordance with the [W3C Baggage] specification.
 //!
-//! [`BaggagePropagator`]: crate::sdk::propagation::BaggagePropagator
 //! [W3C Baggage]: https://w3c.github.io/baggage
 use crate::{Context, Key, KeyValue, Value};
-#[cfg(feature = "serialize")]
-use serde::{Deserialize, Serialize};
 use std::collections::{hash_map, HashMap};
 use std::iter::FromIterator;
 
@@ -375,7 +372,6 @@ impl BaggageExt for Context {
 /// `BaggageMetadata` can be added to values in the form of a property set,
 /// represented as semi-colon `;` delimited list of names and/or name-value
 /// pairs, e.g. `;k1=v1;k2;k3=v3`.
-#[cfg_attr(feature = "serialize", derive(Deserialize, Serialize))]
 #[derive(Clone, Debug, PartialOrd, PartialEq, Default)]
 pub struct BaggageMetadata(String);
 
@@ -399,7 +395,6 @@ impl From<&str> for BaggageMetadata {
 }
 
 /// [`Baggage`] name-value pairs with their associated metadata.
-#[cfg_attr(feature = "serialize", derive(Deserialize, Serialize))]
 #[derive(Clone, Debug, PartialEq)]
 pub struct KeyValueMetadata {
     /// Dimension or event key

opentelemetry-api/src/common.rs

@@ -1,10 +1,7 @@
-#[cfg(feature = "serialize")]
-use serde::{Deserialize, Serialize};
 use std::borrow::Cow;
 use std::fmt;
 
 /// Key used for metric `AttributeSet`s and trace `Span` attributes.
-#[cfg_attr(feature = "serialize", derive(Deserialize, Serialize))]
 #[derive(Clone, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
 pub struct Key(Cow<'static, str>);
 
@@ -93,7 +90,6 @@ impl fmt::Display for Key {
 }
 
 /// Array of homogeneous values
-#[cfg_attr(feature = "serialize", derive(Deserialize, Serialize))]
 #[derive(Clone, Debug, PartialEq)]
 pub enum Array {
     /// Array of bools
@@ -157,7 +153,6 @@ into_array!(
 );
 
 /// Value types for use in `KeyValue` pairs.
-#[cfg_attr(feature = "serialize", derive(Deserialize, Serialize))]
 #[derive(Clone, Debug, PartialEq)]
 pub enum Value {
     /// bool values
@@ -237,7 +232,6 @@ impl fmt::Display for Value {
 }
 
 /// `KeyValue` pairs are used by `AttributeSet`s and `Span` attributes.
-#[cfg_attr(feature = "serialize", derive(Deserialize, Serialize))]
 #[derive(Clone, Debug, PartialEq)]
 pub struct KeyValue {
     /// Dimension or event key

opentelemetry-api/src/global/mod.rs

@@ -12,7 +12,7 @@
 //!
 //! ### Usage in Applications
 //!
-//! Applications configure their tracer either by [installing a trace pipeline],
+//! Applications configure their tracer either by installing a trace pipeline,
 //! or calling [`set_tracer_provider`].
 //!
 //! ```
@@ -68,7 +68,6 @@
 //! # }
 //! ```
 //!
-//! [installing a trace pipeline]: crate::sdk::export::trace::stdout::PipelineBuilder::install_simple
 //! [`TracerProvider`]: crate::trace::TracerProvider
 //! [`Span`]: crate::trace::Span
 //!
@@ -84,7 +83,7 @@
 //!
 //! ### Usage in Applications
 //!
-//! Applications configure their meter either by [installing a metrics pipeline],
+//! Applications configure their meter either by installing a metrics pipeline,
 //! or calling [`set_meter_provider`].
 //!
 //! ```
@@ -135,7 +134,6 @@
 //! # }
 //! ```
 //!
-//! [installing a metrics pipeline]: crate::sdk::export::metrics::stdout::StdoutExporterBuilder::init
 //! [`MeterProvider`]: crate::metrics::MeterProvider
 //! [`set_meter_provider`]: crate::global::set_meter_provider
 

opentelemetry-api/src/lib.rs

@@ -3,9 +3,24 @@
 //! can analyze them using [Prometheus], [Jaeger], and other observability tools.
 //!
 //! *Compiler support: [requires `rustc` 1.46+][msrv]*
+//!
 //! [Prometheus]: https://prometheus.io
 //! [Jaeger]: https://www.jaegertracing.io
 //! [msrv]: #supported-rust-versions
+//!
+//! ## Supported Rust Versions
+//!
+//! OpenTelemetry is built against the latest stable release. The minimum
+//! supported version is 1.46. The current OpenTelemetry version is not
+//! guaranteed to build on Rust versions earlier than the minimum supported
+//! version.
+//!
+//! The current stable Rust compiler and the three most recent minor versions
+//! before it will always be supported. For example, if the current stable
+//! compiler version is 1.49, the minimum supported version will not be
+//! increased past 1.46, three minor versions prior. Increasing the minimum
+//! supported compiler version is not considered a semver breaking change as
+//! long as doing so complies with this policy.
 #![warn(
     future_incompatible,
     missing_debug_implementations,

opentelemetry-api/src/trace/mod.rs

@@ -53,11 +53,10 @@
 //! Exporting spans often involves sending data over a network or performing
 //! other I/O tasks. OpenTelemetry allows you to schedule these tasks using
 //! whichever runtime you area already using such as [Tokio] or [async-std].
-//! When using an async runtime it's best to use the [`BatchSpanProcessor`]
+//! When using an async runtime it's best to use the batch span processor
 //! where the spans will be sent in batches as opposed to being sent once ended,
 //! which often ends up being more efficient.
 //!
-//! [`BatchSpanProcessor`]: crate::sdk::trace::BatchSpanProcessor
 //! [Tokio]: https://tokio.rs
 //! [async-std]: https://async.rs
 //!
@@ -150,8 +149,6 @@
 //! ```
 
 use futures_channel::{mpsc::TrySendError, oneshot::Canceled};
-#[cfg(feature = "serialize")]
-use serde::{Deserialize, Serialize};
 use std::borrow::Cow;
 use std::fmt;
 use std::time;
@@ -242,7 +239,6 @@ pub trait IdGenerator: Send + Sync + fmt::Debug {
 
 /// A `Span` has the ability to add events. Events have a time associated
 /// with the moment when they are added to the `Span`.
-#[cfg_attr(feature = "serialize", derive(Deserialize, Serialize))]
 #[derive(Clone, Debug, PartialEq)]
 pub struct Event {
     /// Event name
@@ -284,7 +280,6 @@ impl Event {
 
 /// During the `Span` creation user MUST have the ability to record links to other `Span`s. Linked
 /// `Span`s can be from the same or a different trace.
-#[cfg_attr(feature = "serialize", derive(Deserialize, Serialize))]
 #[derive(Clone, Debug, PartialEq)]
 pub struct Link {
     span_context: SpanContext,

opentelemetry-api/src/trace/span.rs

@@ -16,8 +16,6 @@
 //! implementations MUST NOT allow callers to create Spans directly. All `Span`s MUST be created
 //! via a Tracer.
 use crate::{trace::SpanContext, KeyValue};
-#[cfg(feature = "serialize")]
-use serde::{Deserialize, Serialize};
 use std::borrow::Cow;
 use std::error::Error;
 use std::fmt;
@@ -212,7 +210,6 @@ pub trait Span {
 /// | `Producer` |     | yes |     | yes |
 /// | `Consumer` |     | yes | yes |     |
 /// | `Internal` |     |     |     |     |
-#[cfg_attr(feature = "serialize", derive(Deserialize, Serialize))]
 #[derive(Clone, Debug, PartialEq)]
 pub enum SpanKind {
     /// Indicates that the span describes a synchronous request to
@@ -254,7 +251,6 @@ impl fmt::Display for SpanKind {
 /// The `StatusCode` interface represents the status of a finished `Span`.
 /// It's composed of a canonical code in conjunction with an optional
 /// descriptive message.
-#[cfg_attr(feature = "serialize", derive(Deserialize, Serialize))]
 #[derive(Clone, Debug, PartialEq, Copy)]
 pub enum StatusCode {
     /// The default status.

opentelemetry-api/src/trace/span_context.rs

@@ -10,8 +10,6 @@
 //! The spec can be viewed here: <https://github.com/open-telemetry/opentelemetry-specification/blob/v1.3.0/specification/trace/api.md#spancontext>
 //!
 //! [w3c TraceContext specification]: https://www.w3.org/TR/trace-context/
-#[cfg(feature = "serialize")]
-use serde::{Deserialize, Serialize};
 use std::collections::VecDeque;
 use std::fmt;
 use std::hash::Hash;
@@ -27,7 +25,6 @@ use thiserror::Error;
 /// See the W3C TraceContext specification's [trace-flags] section for more details.
 ///
 /// [trace-flags]: https://www.w3.org/TR/trace-context/#trace-flags
-#[cfg_attr(feature = "serialize", derive(Deserialize, Serialize))]
 #[derive(Clone, Debug, Default, PartialEq, Eq, Copy, Hash)]
 pub struct TraceFlags(u8);
 
@@ -98,7 +95,6 @@ impl fmt::LowerHex for TraceFlags {
 /// A 16-byte value which identifies a given trace.
 ///
 /// The id is valid if it contains at least one non-zero byte.
-#[cfg_attr(feature = "serialize", derive(Deserialize, Serialize))]
 #[derive(Clone, PartialEq, Eq, Copy, Hash)]
 pub struct TraceId(pub(crate) u128);
 
@@ -160,7 +156,6 @@ impl fmt::LowerHex for TraceId {
 /// An 8-byte value which identifies a given span.
 ///
 /// The id is valid if it contains at least one non-zero byte.
-#[cfg_attr(feature = "serialize", derive(Deserialize, Serialize))]
 #[derive(Clone, PartialEq, Eq, Copy, Hash)]
 pub struct SpanId(pub(crate) u64);
 
@@ -226,7 +221,6 @@ impl fmt::LowerHex for SpanId {
 /// Please review the [W3C specification] for details on this field.
 ///
 /// [W3C specification]: https://www.w3.org/TR/trace-context/#tracestate-header
-#[cfg_attr(feature = "serialize", derive(Deserialize, Serialize))]
 #[derive(Clone, Debug, Default, Eq, PartialEq, Hash)]
 pub struct TraceState(Option<VecDeque<(String, String)>>);
 
@@ -445,7 +439,6 @@ pub enum TraceStateError {
 ///
 /// Spans that do not have the `sampled` flag set in their [`TraceFlags`] will
 /// be ignored by most tracing tools.
-#[cfg_attr(feature = "serialize", derive(Deserialize, Serialize))]
 #[derive(Clone, Debug, PartialEq, Hash, Eq)]
 pub struct SpanContext {
     trace_id: TraceId,

opentelemetry-sdk/Cargo.toml

@@ -35,7 +35,6 @@ rand_distr = "0.4.0"
 default = ["trace"]
 trace = ["opentelemetry-api/trace", "crossbeam-channel", "rand", "pin-project", "async-trait", "percent-encoding"]
 metrics = ["opentelemetry-api/metrics", "dashmap", "fnv"]
-serialize = ["opentelemetry-api/serialize", "serde"]
 testing = ["opentelemetry-api/testing", "trace", "metrics", "rt-async-std", "rt-tokio", "rt-tokio-current-thread", "tokio/macros", "tokio/rt-multi-thread"]
 rt-tokio = ["tokio", "tokio-stream"]
 rt-tokio-current-thread = ["tokio", "tokio-stream"]