Opt in to private channel support explicitly

README.md

@@ -21,6 +21,8 @@ You will need to create a Slack app with the following scopes:
 
 For private channels and when the `channels:join` scope is not assigned, the Slack app needs to be joined to the target channel manually. (One easy to do this is to select the app from a channel where it already exists and use the context menu to add it to another channel.)
 
+Support for private channels also needs the `--include-private-channels` flag to be explicitly set.
+
 Next up, one or more _slack syncs_ must be configured, preferrably through a YAML configuration file. Here is an [example file](config.example.yaml):
 
 ```yaml

main.go

@@ -18,6 +18,7 @@ var (
 	slToken                  string
 	notAlphaNumRE            = regexp.MustCompile(`[^[:alnum:]]`)
 	minDaemonUpdateFrequency = 1 * time.Minute
+	includePrivateChannels   bool
 )
 
 func main() {
@@ -97,6 +98,11 @@ By default, the program will terminate after a single run. Use the --daemon flag
 				Usage:       "how often on-call schedules should be checked for changes (minimum is 1 minute)",
 				Destination: &p.daemonUpdateFrequency,
 			},
+			&cli.BoolFlag{
+				Name:        "include-private-channels",
+				Usage:       "update topics from rivate channels as well",
+				Destination: &includePrivateChannels,
+			},
 			&cli.BoolFlag{
 				Name:        "dry-run",
 				Usage:       "do not update topic",
@@ -132,7 +138,7 @@ func realMain(p params) error {
 
 	sp := syncerParams{
 		pdClient: newPagerDutyClient(pdToken),
-		slClient: newSlackMetaClient(slToken),
+		slClient: newSlackMetaClient(slToken, includePrivateChannels),
 	}
 
 	ctx := context.Background()

slack.go

@@ -54,12 +54,19 @@ func (cl channelList) find(id, name string) *slack.Channel {
 }
 
 type slackMetaClient struct {
-	slackClient *slack.Client
+	slackClient  *slack.Client
+	channelTypes []string
 }
 
-func newSlackMetaClient(token string) *slackMetaClient {
+func newSlackMetaClient(token string, includePrivateChannels bool) *slackMetaClient {
+	channelTypes := []string{"public_channel"}
+	if includePrivateChannels {
+		channelTypes = append(channelTypes, "private_channel")
+	}
+
 	return &slackMetaClient{
-		slackClient: slack.New(token),
+		slackClient:  slack.New(token),
+		channelTypes: channelTypes,
 	}
 }
 
@@ -100,7 +107,7 @@ func (metaClient *slackMetaClient) getChannels(ctx context.Context) (channelList
 				Cursor:          cursor,
 				ExcludeArchived: "true",
 				Limit:           200,
-				Types:           []string{"public_channel", "private_channel"},
+				Types:           metaClient.channelTypes,
 			})
 			return err
 		})