api: Use a Logger instead of an io.Writer in api.Watch

So that we can pass around only a Logger, not a LogOutput

agent/agent.go

@@ -1263,7 +1263,7 @@ func (a *Agent) reloadWatches(cfg *config.RuntimeConfig) error {
 				httpConfig := wp.Exempt["http_handler_config"].(*watch.HttpHandlerConfig)
 				wp.Handler = makeHTTPWatchHandler(a.logger, httpConfig)
 			}
-			wp.LogOutput = a.LogOutput
+			wp.Logger = a.logger.Named("watch")
 
 			addr := config.Address
 			if config.Scheme == "https" {

api/watch/plan.go

@@ -31,8 +31,10 @@ func (p *Plan) Run(address string) error {
 
 // Run is used to run a watch plan
 func (p *Plan) RunWithConfig(address string, conf *consulapi.Config) error {
-	// Create the logger
-	logger := newWatchLogger(p.LogOutput)
+	logger := p.Logger
+	if logger == nil {
+		logger = newWatchLogger(p.LogOutput)
+	}
 
 	// Setup the client
 	p.address = address

api/watch/watch.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	consulapi "github.com/hashicorp/consul/api"
+	"github.com/hashicorp/go-hclog"
 	"github.com/mitchellh/mapstructure"
 )
 
@@ -29,7 +30,10 @@ type Plan struct {
 	// on index param. To support hash based watches, set HybridHandler instead.
 	Handler       HandlerFunc
 	HybridHandler HybridHandlerFunc
-	LogOutput     io.Writer
+
+	Logger hclog.Logger
+	// Deprecated: use Logger
+	LogOutput io.Writer
 
 	address      string
 	client       *consulapi.Client