Resolves Issue jaegertracing#5168: Adding the print-config subcommand

Signed-off-by: Guilherme Mafra da Costa <g.mafra.costa@gmail.com>

cmd/all-in-one/main.go

@@ -33,6 +33,7 @@ import (
 	"github.com/jaegertracing/jaeger/cmd/all-in-one/setupcontext"
 	collectorApp "github.com/jaegertracing/jaeger/cmd/collector/app"
 	collectorFlags "github.com/jaegertracing/jaeger/cmd/collector/app/flags"
+	print_config "github.com/jaegertracing/jaeger/cmd/internal/config"
 	"github.com/jaegertracing/jaeger/cmd/internal/docs"
 	"github.com/jaegertracing/jaeger/cmd/internal/env"
 	"github.com/jaegertracing/jaeger/cmd/internal/flags"
@@ -229,6 +230,7 @@ by default uses only in-memory database.`,
 	command.AddCommand(env.Command())
 	command.AddCommand(docs.Command(v))
 	command.AddCommand(status.Command(v, ports.CollectorAdminHTTP))
+	command.AddCommand(print_config.Command(v))
 
 	config.AddFlags(
 		v,

cmd/collector/main.go

@@ -28,6 +28,7 @@ import (
 
 	"github.com/jaegertracing/jaeger/cmd/collector/app"
 	"github.com/jaegertracing/jaeger/cmd/collector/app/flags"
+	printConfig "github.com/jaegertracing/jaeger/cmd/internal/config"
 	"github.com/jaegertracing/jaeger/cmd/internal/docs"
 	"github.com/jaegertracing/jaeger/cmd/internal/env"
 	cmdFlags "github.com/jaegertracing/jaeger/cmd/internal/flags"
@@ -142,6 +143,7 @@ func main() {
 	command.AddCommand(env.Command())
 	command.AddCommand(docs.Command(v))
 	command.AddCommand(status.Command(v, ports.CollectorAdminHTTP))
+	command.AddCommand(printConfig.Command(v))
 
 	config.AddFlags(
 		v,

cmd/internal/config/config.go

@@ -0,0 +1,41 @@
+// Copyright (c) 2018 The Jaeger Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package print_config
+
+import (
+	"fmt"
+	"sort"
+
+	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+)
+
+func Command(v *viper.Viper) *cobra.Command {
+	c := &cobra.Command{
+		Use:   "print-config",
+		Short: "Print configurations",
+		Long:  `Iterates through the environment variables and prints them out`,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			keys := v.AllKeys()
+			sort.Strings(keys)
+
+			for _, env := range keys {
+				value := v.Get(env)
+				fmt.Printf("%s=%v\n", env, value)
+			}
+			return nil
+		},
+	}
+	return c
+}