Added

• Added resource.Default() for use with meter and tracer providers. (#1507)
• AttributePerEventCountLimit and AttributePerLinkCountLimit for SpanLimits. (#1535)
• Added Keys() method to propagation.TextMapCarrier and propagation.HeaderCarrier to adapt http.Header to this interface. (#1544)
• Added code attributes to go.opentelemetry.io/otel/semconv package. (#1558)
• Compatibility testing suite in the CI system for the following systems. (#1567)

  OS	Go Version	Architecture
  Ubuntu	1.15	amd64
  Ubuntu	1.14	amd64
  Ubuntu	1.15	386
  Ubuntu	1.14	386
  MacOS	1.15	amd64
  MacOS	1.14	amd64
  Windows	1.15	amd64
  Windows	1.14	amd64
  Windows	1.15	386
  Windows	1.14	386

Changed

• Replaced interface oteltest.SpanRecorder with its existing implementation
  StandardSpanRecorder (#1542).
• Default span limit values to 128. (#1535)
• Rename MaxEventsPerSpan, MaxAttributesPerSpan and MaxLinksPerSpan to EventCountLimit, AttributeCountLimit and LinkCountLimit, and move these fields into SpanLimits. (#1535)
• Renamed the otel/label package to otel/attribute. (#1541)
• Vendor the Jaeger exporter's dependency on Apache Thrift. (#1551)
• Parallelize the CI linting and testing. (#1567)
• Stagger timestamps in exact aggregator tests. (#1569)
• Changed all examples to use WithBatchTimeout(5 * time.Second) rather than WithBatchTimeout(5). (#1621)
• Prevent end-users from implementing some interfaces (#1575)

      "otel/exporters/otlp/otlphttp".Option
      "otel/exporters/stdout".Option
      "otel/oteltest".Option
      "otel/trace".TracerOption
      "otel/trace".SpanOption
      "otel/trace".EventOption
      "otel/trace".LifeCycleOption
      "otel/trace".InstrumentationOption
      "otel/sdk/resource".Option
      "otel/sdk/trace".ParentBasedSamplerOption
      "otel/sdk/trace".ReadOnlySpan
      "otel/sdk/trace".ReadWriteSpan

Removed

• Removed attempt to resample spans upon changing the span name with span.SetName(). (#1545)
• The test-benchmark is no longer a dependency of the precommit make target. (#1567)
• Removed the test-386 make target.
  This was replaced with a full compatibility testing suite (i.e. multi OS/arch) in the CI system. (#1567)

Fixed

• The sequential timing check of timestamps in the stdout exporter are now setup explicitly to be sequential (#1571). (#1572)
• Windows build of Jaeger tests now compiles with OS specific functions (#1576). (#1577)
• The sequential timing check of timestamps of go.opentelemetry.io/otel/sdk/metric/aggregator/lastvalue are now setup explicitly to be sequential (#1578). (#1579)
• Validate tracestate header keys with vedors according to the W3C TraceContext specification (#1475). (#1581)
• The OTLP exporter includes related labels for translations of a GaugeArray (#1563). (#1570)

Raw changes made between v0.17.0 and v0.18.0

bb4c297 Pre release v0.18.0 (#1635)
712c3dc Fix makefile ci target and coverage test packages (#1634)
841d2a5 Rename local var new to not collide with builtin (#1610)
13938ab Update SpanProcessor docs (#1611)
e25503a Add compatibility tests to CI (#1567)
1519d95 Use reasonable interval in sdktrace.WithBatchTimeout (#1621)
7d4496e Pass metric labels when transforming to gaugeArray (#1570)
6d4a5e0 Bump google.golang.org/grpc from 1.35.0 to 1.36.0 in /exporters/otlp (#1619)
a93393a Bump google.golang.org/grpc in /example/prom-collector (#1620)
e499ca8 Fix validation for tracestate with vendor and add tests (#1581)
43886e5 Make timestamps sequential in lastvalue agg check (#1579)
37688ef revent end-users from implementing some interfaces (#1575)
85e696d Updating documentation with an working example for creating NewExporter (#1513)
562eb28 Unify the Added sections of the unreleased changes (#1580)
c4cf1af Fix Windows build of Jaeger tests (#1577)
4a163be Fix stdout TestStdoutTimestamp failure with sleep (#1572)
bd4701e Stagger timestamps in exact aggregator tests (#1569)
b94cd4b add code attributes to semconv package (#1558)
78c06ce Update docs from gitter to slack for communication (#1554)
1307c91 Remove vendor exclude from license-check (#1552)
5d2636e Bump github.com/golangci/golangci-lint in /internal/tools (#1565)
d7aff47 Vendor Thrift dependency (#1551)
298c5a1 Update span limits to conform with OpenTelemetry specification (#1535)
ecf65d7 Rename otel/label -> otel/attribute (#1541)
1b5b662 Remove resampling on span.SetName (#1545)
8da5299 fix: grpc reconnection (#1521)
3bce9c9 Add Keys() method to propagation.TextMapCarrier (#1544)
0b1a1c7 Make oteltest.SpanRecorder into a concrete type (#1542)
7d0e3e5 SDK span no modification after ended (#1543)
7de3b58 Remove extra labels types (#1314)
73194e4 Bump google.golang.org/api from 0.39.0 to 0.40.0 in /exporters/trace/jaeger (#1536)
8fae0a6 Create resource.Default() with required attributes/default values (#1507)