Trait-based initialization and other utilities

Adds the concept of a 'platform', a centralized place in which
environment-specific information will be managed, and provides common
initialization logic for most "standard" apps.

As part of the common initialization, other parts of core have also
been reworked:

- HTTP-related unmarshallers and path matchers have been factored out
  from core.json to a new core.rest.directives package (core.json
  extends those unmarshallers and matchers for backwards
  compatibility)

- CORS handling has also been moved to a dedicated utility trait

- Some custom headers have been moved from raw headers to typed ones
  in core.rest.headers

- The concept of a "reporter" has been introduced. A reporter is a
  context-aware combination of tracing and logging. It is intended to
  issue diagnostic messages that can be traced across service
  boundaries.

Closes #192
Closes #195

1 files changed, 18 insertions, 0 deletions

diff --git a/src/main/scala/xyz/driver/core/reporting/NoTraceReporter.scala b/src/main/scala/xyz/driver/core/reporting/NoTraceReporter.scala
new file mode 100644
index 0000000..9179f42
--- /dev/null
+++ b/src/main/scala/xyz/driver/core/reporting/NoTraceReporter.scala
@@ -0,0 +1,18 @@
+package xyz.driver.core
+package reporting
+
+import com.typesafe.scalalogging.Logger
+
+import scala.concurrent.Future
+
+class NoTraceReporter(val logger: Logger) extends Reporter with ScalaLoggerLike {
+  override def traceWithOptionalParent[A](
+      name: String,
+      tags: Map[String, String],
+      parent: Option[(SpanContext, Reporter.CausalRelation)])(op: SpanContext => A): A = op(SpanContext.fresh())
+  override def traceWithOptionalParentAsync[A](
+      name: String,
+      tags: Map[String, String],
+      parent: Option[(SpanContext, Reporter.CausalRelation)])(op: SpanContext => Future[A]): Future[A] =
+    op(SpanContext.fresh())
+}