fix(flags): detect schedule set from env (#1373)

internal/flags/flags.go

@@ -19,6 +19,8 @@ import (
 // use watchtower
 const DockerAPIMinVersion string = "1.25"
 
+var defaultInterval = int((time.Hour * 24).Seconds())
+
 // RegisterDockerFlags that are used directly by the docker api client
 func RegisterDockerFlags(rootCmd *cobra.Command) {
 	flags := rootCmd.PersistentFlags()
@@ -362,11 +364,10 @@ Should only be used for testing.`)
 
 // SetDefaults provides default values for environment variables
 func SetDefaults() {
-	day := (time.Hour * 24).Seconds()
 	viper.AutomaticEnv()
 	viper.SetDefault("DOCKER_HOST", "unix:///var/run/docker.sock")
 	viper.SetDefault("DOCKER_API_VERSION", DockerAPIMinVersion)
-	viper.SetDefault("WATCHTOWER_POLL_INTERVAL", day)
+	viper.SetDefault("WATCHTOWER_POLL_INTERVAL", defaultInterval)
 	viper.SetDefault("WATCHTOWER_TIMEOUT", time.Second*10)
 	viper.SetDefault("WATCHTOWER_NOTIFICATIONS", []string{})
 	viper.SetDefault("WATCHTOWER_NOTIFICATIONS_LEVEL", "info")
@@ -540,12 +541,23 @@ func ProcessFlagAliases(flags *pflag.FlagSet) {
 		setFlagIfDefault(flags, `notification-template`, tpl)
 	}
 
-	if flags.Changed(`interval`) && flags.Changed(`schedule`) {
+	scheduleChanged := flags.Changed(`schedule`)
+	intervalChanged := flags.Changed(`interval`)
+	// FIXME: snakeswap
+	// due to how viper is integrated by swapping the defaults for the flags, we need this hack:
+	if val, _ := flags.GetString(`schedule`); val != `` {
+		scheduleChanged = true
+	}
+	if val, _ := flags.GetInt(`interval`); val != defaultInterval {
+		intervalChanged = true
+	}
+
+	if intervalChanged && scheduleChanged {
 		log.Fatal(`Only schedule or interval can be defined, not both.`)
 	}
 
 	// update schedule flag to match interval if it's set, or to the default if none of them are
-	if flags.Changed(`interval`) || !flags.Changed(`schedule`) {
+	if intervalChanged || !scheduleChanged {
 		interval, _ := flags.GetInt(`interval`)
 		flags.Set(`schedule`, fmt.Sprintf(`@every %ds`, interval))
 	}

internal/flags/flags_test.go

@@ -173,7 +173,7 @@ func TestProcessFlagAliasesSchedAndInterval(t *testing.T) {
 	RegisterSystemFlags(cmd)
 	RegisterNotificationFlags(cmd)
 
-	require.NoError(t, cmd.ParseFlags([]string{`--schedule`, `@now`, `--interval`, `10`}))
+	require.NoError(t, cmd.ParseFlags([]string{`--schedule`, `@hourly`, `--interval`, `10`}))
 	flags := cmd.Flags()
 
 	assert.PanicsWithValue(t, `FATAL`, func() {
@@ -181,6 +181,26 @@ func TestProcessFlagAliasesSchedAndInterval(t *testing.T) {
 	})
 }
 
+func TestProcessFlagAliasesScheduleFromEnvironment(t *testing.T) {
+	cmd := new(cobra.Command)
+
+	err := os.Setenv("WATCHTOWER_SCHEDULE", `@hourly`)
+	require.NoError(t, err)
+	defer os.Unsetenv("WATCHTOWER_SCHEDULE")
+
+	SetDefaults()
+	RegisterDockerFlags(cmd)
+	RegisterSystemFlags(cmd)
+	RegisterNotificationFlags(cmd)
+
+	require.NoError(t, cmd.ParseFlags([]string{}))
+	flags := cmd.Flags()
+	ProcessFlagAliases(flags)
+
+	sched, _ := flags.GetString(`schedule`)
+	assert.Equal(t, `@hourly`, sched)
+}
+
 func TestProcessFlagAliasesInvalidPorcelaineVersion(t *testing.T) {
 	logrus.StandardLogger().ExitFunc = func(_ int) { panic(`FATAL`) }
 	cmd := new(cobra.Command)