Add support for slack application tokens

Author: L0RD-ZER0

README.md

@@ -56,6 +56,7 @@ SLACK_FOOTER         | Powered By rtCamp's GitHub Actions Library            | S
 MSG_MINIMAL          | -                                                     | If set to `true`, removes: `Ref`, `Event`,  `Actions URL` and `Commit` from the message. You can optionally whitelist any of these 4 removed values by passing it comma separated to the variable instead of `true`. (ex: `MSG_MINIMAL: event` or `MSG_MINIMAL: ref,actions url`, etc.)
 SLACKIFY_MARKDOWN    | -                                                     | If set to `true`, it will convert markdown to slack format. (ex: `*bold*` to `bold`) Note: This only works for custom messages and not for the default message generated by the action. Credits: [slackify-markdown-action](https://github.com/marketplace/actions/slack-markdown-converter)
 SLACK_THREAD_TS      | -                                                     | If you want to send message in a thread, you can pass the timestamp of the parent message to this variable. You can get the timestamp of the parent message from the message URL in Slack. (ex: `SLACK_THREAD_TS: 1586130833.000100`)
+SLACK_TOKEN          | -                                                     | If you want to send message to a channel using a slack token. You will need to pass a channel in order to send messages using token, requiring a value for ``SLACK_CHANNEL``. Note that in case both webhook url and token are provided, webhook url will be prioritized.
 SLACK_ON_SUCCESS     | -                                                     | If set, will send the provided message instead of the default message when the passed status (through ``SLACK_COLOR``) is `success`.
 SLACK_ON_FAILURE     | -                                                     | If set, will send the provided message instead of the default message when the passed status (through ``SLACK_COLOR``) is `failure`.
 SLACK_ON_CANCEL      | -                                                     | If set, will send the provided message instead of the default message when the passed status (through ``SLACK_COLOR``) is `cancelled`.

entrypoint.sh

@@ -2,6 +2,7 @@
 
 # Check required env variables
 flag=0
+mode="WEBHOOK"
 if [[ -z "$SLACK_WEBHOOK" ]]; then
     flag=1
     missing_secret="SLACK_WEBHOOK"
@@ -13,11 +14,19 @@ if [[ -z "$SLACK_WEBHOOK" ]]; then
     fi
 fi
 
+if [[ "$flag" -eq 1 ]] && [[ -n "$SLACK_TOKEN" || -n "$SLACK_CHANNEL" ]] ; then
+    # Basically, if both SLACK_TOKEN and SLACK_CHANNEL are provided, then it's a token mode
+    flag=0
+    mode="TOKEN"
+fi
+
 if [[ "$flag" -eq 1 ]]; then
-    printf "[\e[0;31mERROR\e[0m] Secret \`$missing_secret\` is missing. Please add it to this action for proper execution.\nRefer https://github.com/rtCamp/action-slack-notify for more information.\n"
+    echo -e "[\e[0;31mERROR\e[0m] Secret \`$missing_secret\` is missing. Alternatively, a pair of \`SLACK_TOKEN\` and \`SLACK_CHANNEL\` can be provided. Please add it to this action for proper execution.\nRefer https://github.com/rtCamp/action-slack-notify for more information.\n"
     exit 1
 fi
 
+export MSG_MODE="$mode"
+
 # custom path for files to override default files
 custom_path="$GITHUB_WORKSPACE/.github/slack"
 main_script="/main.sh"

main.go

@@ -30,6 +30,7 @@ const (
 	EnvMinimal        = "MSG_MINIMAL"
 	EnvSlackLinkNames = "SLACK_LINK_NAMES"
 	EnvThreadTs       = "SLACK_THREAD_TS"
+	EnvMessageMode    = "MSG_MODE"
 )
 
 type Webhook struct {
@@ -64,16 +65,24 @@ type Field struct {
 func main() {
 	endpoint := os.Getenv(EnvSlackWebhook)
 	custom_payload := envOr(EnvSlackCustom, "")
+	if endpoint == "" {
+		if os.Getenv(EnvSlackChannel) == "" {
+			fmt.Fprintln(os.Stderr, "Channel is required for sending message using a token")
+			os.Exit(1)
+		}
+		if os.Getenv(EnvMessageMode) == "TOKEN" {
+			endpoint = "https://slack.com/api/chat.postMessage"
+		} else {
+			fmt.Fprintln(os.Stderr, "URL is required")
+			os.Exit(2)
+		}
+	}
 	if custom_payload != "" {
 		if err := send_raw(endpoint, []byte(custom_payload)); err != nil {
 			fmt.Fprintf(os.Stderr, "Error sending message: %s\n", err)
 			os.Exit(2)
 		}
 	} else {
-		if endpoint == "" {
-			fmt.Fprintln(os.Stderr, "URL is required")
-			os.Exit(2)
-		}
 		text := os.Getenv(EnvSlackMessage)
 		if text == "" {
 			fmt.Fprintln(os.Stderr, "Message is required")
@@ -262,7 +271,27 @@ func send(endpoint string, msg Webhook) error {
 
 func send_raw(endpoint string, payload []byte) error {
 	b := bytes.NewBuffer(payload)
-	res, err := http.Post(endpoint, "application/json", b)
+
+	var res *http.Response
+	var err error
+
+	switch os.Getenv(EnvMessageMode) {
+	case "WEBHOOK":
+		res, err = http.Post(endpoint, "application/json", b)
+	case "TOKEN":
+		req, err := http.NewRequest("POST", endpoint, b)
+		if err != nil {
+			return fmt.Errorf("Error creating request: %s\n", err)
+		}
+		req.Header.Set("Content-Type", "application/json")
+		req.Header.Set("Authorization", "Bearer "+os.Getenv("SLACK_TOKEN"))
+		client := &http.Client{}
+		res, err = client.Do(req)
+	default:
+		fmt.Fprintf(os.Stderr, "Invalid message mode: %s\n", os.Getenv(EnvMessageMode))
+		os.Exit(6)
+	}
+
 	if err != nil {
 		return err
 	}

main.sh

@@ -37,6 +37,10 @@ if [[ -z "$SLACK_WEBHOOK" ]]; then
 	fi
 fi
 
+if [[ -z "$SLACK_WEBHOOK" ]]; then
+  printf "[\e[0;31mERROR\e[0m] Secret \`SLACK_WEBHOOK\` is missing. Falling back to using \`SLACK_TOKEN\` and \`SLACK_CHANNEL\`.\n"
+fi
+
 if [[ -f "$hosts_file" ]]; then
 	hostname=$(cat "$hosts_file" | shyaml get-value "$GITHUB_BRANCH.hostname")
 	user=$(cat "$hosts_file" | shyaml get-value "$GITHUB_BRANCH.user")