Kitchen: Generate LogDog prefix from Swarming.

go/src/infra/tools/kitchen/kitchen.go

Index: go/src/infra/tools/kitchen/kitchen.go
diff --git a/go/src/infra/tools/kitchen/kitchen.go b/go/src/infra/tools/kitchen/kitchen.go
index 69b16dcc623dff50892826a041c1b25f5c071843..68bd7d31dd9d6ec93f262482f8895e50a153db41 100644
--- a/go/src/infra/tools/kitchen/kitchen.go
+++ b/go/src/infra/tools/kitchen/kitchen.go
@@ -13,6 +13,7 @@ import (
 	"golang.org/x/net/context"
 
 	"github.com/luci/luci-go/common/cli"
+	"github.com/luci/luci-go/common/environ"
 	"github.com/luci/luci-go/common/errors"
 	log "github.com/luci/luci-go/common/logging"
 	"github.com/luci/luci-go/common/logging/gologger"
@@ -68,3 +69,18 @@ func logAnnotatedErr(ctx context.Context, err error) {
 
 	log.Errorf(ctx, "Annotated error stack:\n%s", buf.String())
 }
+
+// getSwarmingTaskParameters retrieves the Swarming task parameters from the
+// environment.
+func getSwarmingTaskParameters(env environ.Env) (host, taskID string, err error) {
+	if host, _ = env.Get("SWARMING_SERVER"); host == "" {
+		err = errors.Reason("missing or empty SWARMING_SERVER").Err()
+		return
+	}
+	if taskID, _ = env.Get("SWARMING_TASK_ID"); taskID == "" {
+		err = errors.Reason("missing SWARMING_TASK_ID").Err()
+		return
+	}
+
+	return
+}