feat: add otelsql instrumentation

otelsql/README.md

@@ -0,0 +1,61 @@
+[![PkgGoDev](https://pkg.go.dev/badge/github.com/uptrace/opentelemetry-go-extra/otelsql)](https://pkg.go.dev/github.com/uptrace/opentelemetry-go-extra/otelsql)
+
+# OpenTelemetry Go instrumentation for database/sql package
+
+otelsql instrumentation records database queries (including `Tx` and `Stmt` queries) and reports
+`DBStats` metrics.
+
+## Installation
+
+```shell
+go get github.com/uptrace/opentelemetry-go-extra/otelsql
+```
+
+## Usage
+
+To instrument database/sql, you need to connect to a database using the API provided by this
+package:
+
+- `sql.Open(driverName, dsn)` becomes `otelsql.Open(driverName, dsn)`.
+- `sql.OpenDB(connector)` becomes `otelsql.OpenDB(connector)`.
+
+```go
+import (
+	"github.com/uptrace/opentelemetry-go-extra/otelsql"
+	semconv "go.opentelemetry.io/otel/semconv/v1.4.0"
+)
+
+db, err := otelsql.Open("sqlite", "file::memory:?cache=shared",
+	otelsql.WithAttributes(semconv.DBSystemSqlite),
+	otelsql.WithDBName("mydb"))
+if err != nil {
+	panic(err)
+}
+```
+
+And then use context-aware API to propagate the active span via
+[context](https://docs.uptrace.dev/guide/go.html#context):
+
+```go
+var num int
+if err := db.QueryRowContext(ctx, "SELECT 42").Scan(&num); err != nil {
+	panic(err)
+}
+```
+
+See [example](/example/) for details.
+
+## Options
+
+Both [otelsql.Open](https://pkg.go.dev/github.com/uptrace/opentelemetry-go-extra/otelsql#Open) and
+[otelsql.OpenDB](https://pkg.go.dev/github.com/uptrace/opentelemetry-go-extra/otelsql#OpenDB) accept
+the same [options](https://pkg.go.dev/github.com/uptrace/opentelemetry-go-extra/otelsql#Option):
+
+- [WithAttributes](https://pkg.go.dev/github.com/uptrace/opentelemetry-go-extra/otelsql#WithAttributes)
+  configures attributes that are used to create a span.
+- [WithDBName](https://pkg.go.dev/github.com/uptrace/opentelemetry-go-extra/otelsql#WithDBName)
+  configures a `db.name` attribute.
+- [WithDBSystem](https://pkg.go.dev/github.com/uptrace/opentelemetry-go-extra/otelsql#WithDBSystem)
+  configures a `db.system` attribute. When possible, you should prefer using WithAttributes and
+  [semconv](https://pkg.go.dev/go.opentelemetry.io/otel/semconv/v1.4.0), for example,
+  `otelsql.WithAttributes(semconv.DBSystemSqlite)`.