Implement file watching

cmd/file.go

@@ -1,6 +1,8 @@
 package cmd
 
 import (
+	"strconv"
+
 	"github.com/ldez/traefik-certs-dumper/v2/dumper"
 	"github.com/ldez/traefik-certs-dumper/v2/dumper/file"
 	"github.com/spf13/cobra"
@@ -13,8 +15,13 @@ var fileCmd = &cobra.Command{
 	Long:  `Dump the content of the "acme.json" file from Traefik to certificates.`,
 	RunE: runE(func(baseConfig *dumper.BaseConfig, cmd *cobra.Command) error {
 		acmeFile := cmd.Flag("source").Value.String()
+		watch, _ := strconv.ParseBool(cmd.Flag("watch").Value.String())
 
-		return file.Dump(acmeFile, baseConfig)
+		config := &file.Config{
+			AcmeFile: acmeFile,
+			Watch:    watch,
+		}
+		return file.Dump(config, baseConfig)
 	}),
 }
 
@@ -22,4 +29,5 @@ func init() {
 	rootCmd.AddCommand(fileCmd)
 
 	fileCmd.Flags().String("source", "./acme.json", "Path to 'acme.json' file.")
+	fileCmd.PersistentFlags().Bool("watch", false, "Enable watching changes.")
 }

dumper/file/config.go

@@ -0,0 +1,7 @@
+package file
+
+// Config file configuration.
+type Config struct {
+	AcmeFile string
+	Watch    bool
+}

dumper/file/file.go

@@ -2,14 +2,20 @@ package file
 
 import (
 	"encoding/json"
+	"log"
 	"os"
 
 	"github.com/ldez/traefik-certs-dumper/v2/dumper"
+	"github.com/rjeczalik/notify"
 )
 
 // Dump Dumps "acme.json" file to certificates.
-func Dump(acmeFile string, baseConfig *dumper.BaseConfig) error {
-	data, err := readFile(acmeFile)
+func Dump(config *Config, baseConfig *dumper.BaseConfig) error {
+	if config.Watch {
+		return watch(config.AcmeFile, baseConfig)
+	}
+
+	data, err := readFile(config.AcmeFile)
 	if err != nil {
 		return err
 	}
@@ -17,6 +23,31 @@ func Dump(acmeFile string, baseConfig *dumper.BaseConfig) error {
 	return dumper.Dump(data, baseConfig)
 }
 
+func watch(acmeFile string, baseConfig *dumper.BaseConfig) error {
+	events := make(chan notify.EventInfo, 1)
+
+	if err := notify.Watch(acmeFile, events, notify.Create, notify.Write, notify.Remove); err != nil {
+		return err
+	}
+	defer notify.Stop(events)
+
+	for {
+		// wait for filesystem event
+		<-events
+
+		data, err := readFile(acmeFile)
+		if err != nil {
+			return err
+		}
+
+		if err := dumper.Dump(data, baseConfig); err != nil {
+			return err
+		}
+
+		log.Println("Dumped new certificate data.")
+	}
+}
+
 func readFile(acmeFile string) (*dumper.StoredData, error) {
 	source, err := os.Open(acmeFile)
 	if err != nil {

go.mod

@@ -28,6 +28,7 @@ require (
 	github.com/pkg/errors v0.8.1 // indirect
 	github.com/prometheus/client_golang v0.9.2 // indirect
 	github.com/prometheus/client_model v0.0.0-20190129233127-fd36f4220a90 // indirect
+	github.com/rjeczalik/notify v0.9.2
 	github.com/sirupsen/logrus v1.4.1 // indirect
 	github.com/soheilhy/cmux v0.1.4 // indirect
 	github.com/spf13/cobra v0.0.3

go.sum

@@ -90,6 +90,8 @@ github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910/go.mod h1:
 github.com/prometheus/client_model v0.0.0-20190129233127-fd36f4220a90/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
 github.com/prometheus/common v0.0.0-20181126121408-4724e9255275/go.mod h1:daVV7qP5qjZbuso7PdcryaAu0sAZbrN9i7WWcTMWvro=
 github.com/prometheus/procfs v0.0.0-20181204211112-1dc9a6cbc91a/go.mod h1:c3At6R/oaqEKCNdg8wHV1ftS6bRYblBhIjjI8uT2IGk=
+github.com/rjeczalik/notify v0.9.2 h1:MiTWrPj55mNDHEiIX5YUSKefw/+lCQVoAFmD6oQm5w8=
+github.com/rjeczalik/notify v0.9.2/go.mod h1:aErll2f0sUX9PXZnVNyeiObbmTlk5jnMoCa4QEjJeqM=
 github.com/rogpeppe/fastuuid v0.0.0-20150106093220-6724a57986af/go.mod h1:XWv6SoW27p1b0cqNHllgS5HIMJraePCO15w5zCzIWYg=
 github.com/russross/blackfriday v1.5.2 h1:HyvC0ARfnZBqnXwABFeSZHpKvJHJJfPz81GNueLj0oo=
 github.com/russross/blackfriday v1.5.2/go.mod h1:JO/DiYxRf+HjHt06OyowR9PTA263kcR/rfWxYHBV53g=
@@ -143,6 +145,7 @@ golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20180926160741-c2ed4eda69e7/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20181026203630-95b1ffbd15a5/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20181107165924-66b7b1311ac8/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20181205085412-a5c9d58dba9a h1:1n5lsVfiQW3yfsRGu98756EH1YthsFqr/5mxHduZW2A=