global: move to context (#1699)

* global: move to context

Move from golang.org/x/net/context to std lib's context.

Change done with:

for i in $(grep -l '/context' **/*.go); do sed -e 's|golang.org/x/net/context|context|' -i $i; echo $i; done
for i in **/*.go; do goimports -w $i; done

* drop from dns.pb.go as well

plugin/proxy/dns.go

@@ -6,8 +6,9 @@ import (
 
 	"github.com/coredns/coredns/request"
 
+	"context"
+
 	"github.com/miekg/dns"
-	"golang.org/x/net/context"
 )
 
 type dnsEx struct {

plugin/proxy/dnstap.go

@@ -7,9 +7,10 @@ import (
 	"github.com/coredns/coredns/plugin/dnstap/msg"
 	"github.com/coredns/coredns/request"
 
+	"context"
+
 	tap "github.com/dnstap/golang-dnstap"
 	"github.com/miekg/dns"
-	"golang.org/x/net/context"
 )
 
 func toDnstap(ctx context.Context, host string, ex Exchanger, state request.Request, reply *dns.Msg, start time.Time) error {

plugin/proxy/dnstap_test.go

@@ -9,9 +9,10 @@ import (
 	mwtest "github.com/coredns/coredns/plugin/test"
 	"github.com/coredns/coredns/request"
 
+	"context"
+
 	tap "github.com/dnstap/golang-dnstap"
 	"github.com/miekg/dns"
-	"golang.org/x/net/context"
 )
 
 func testCase(t *testing.T, ex Exchanger, q, r *dns.Msg, datq, datr *msg.Builder) {

plugin/proxy/exchanger.go

@@ -3,8 +3,9 @@ package proxy
 import (
 	"github.com/coredns/coredns/request"
 
+	"context"
+
 	"github.com/miekg/dns"
-	"golang.org/x/net/context"
 )
 
 // Exchanger is an interface that specifies a type implementing a DNS resolver that

plugin/proxy/google.go

@@ -14,8 +14,9 @@ import (
 	"github.com/coredns/coredns/plugin/pkg/log"
 	"github.com/coredns/coredns/request"
 
+	"context"
+
 	"github.com/miekg/dns"
-	"golang.org/x/net/context"
 )
 
 type google struct {

plugin/proxy/grpc.go

@@ -9,10 +9,11 @@ import (
 	"github.com/coredns/coredns/plugin/pkg/trace"
 	"github.com/coredns/coredns/request"
 
+	"context"
+
 	"github.com/grpc-ecosystem/grpc-opentracing/go/otgrpc"
 	"github.com/miekg/dns"
 	opentracing "github.com/opentracing/opentracing-go"
-	"golang.org/x/net/context"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
 )

plugin/proxy/grpc_test.go

@@ -9,8 +9,9 @@ import (
 	"github.com/coredns/coredns/plugin/test"
 	"github.com/coredns/coredns/request"
 
+	"context"
+
 	"github.com/miekg/dns"
-	"golang.org/x/net/context"
 	"google.golang.org/grpc/grpclog"
 )
 

plugin/proxy/lookup.go

@@ -11,8 +11,9 @@ import (
 	"github.com/coredns/coredns/plugin/pkg/healthcheck"
 	"github.com/coredns/coredns/request"
 
+	"context"
+
 	"github.com/miekg/dns"
-	"golang.org/x/net/context"
 )
 
 // NewLookup create a new proxy with the hosts in host and a Random policy.

plugin/proxy/proxy.go

@@ -13,9 +13,10 @@ import (
 	"github.com/coredns/coredns/plugin/pkg/healthcheck"
 	"github.com/coredns/coredns/request"
 
+	"context"
+
 	"github.com/miekg/dns"
 	ot "github.com/opentracing/opentracing-go"
-	"golang.org/x/net/context"
 )
 
 var (