Workflow Operator on LINE

Workflow Operator on LINE connects LINE one-on-one chats, groups, and rooms to the built-in Dagu agent through the LINE Messaging API webhook. Each allowed source keeps its own running context, so follow-up questions and DAG-run notifications stay in the same LINE conversation.

Prerequisites

Before setting up Workflow Operator on LINE, configure AI agent in the Web UI. Go to AI agent Settings (/agent-settings) and set up the model, tool policy, and other defaults first. The LINE bot forwards messages to the built-in steward, so it must be configured before LINE can use it.

You also need a public HTTPS URL for the Dagu server. LINE requires the webhook URL to use HTTPS with a certificate trusted by common browsers.

Deployment requirement

LINE delivers user messages by sending webhook requests to Dagu. For self-hosted Dagu, the LINE webhook endpoint must be reachable from the public internet over HTTPS, either by exposing the Dagu server through a reverse proxy or by using a tunnel such as Tailscale Funnel, Cloudflare Tunnel, or ngrok.

If you do not want to operate the public endpoint yourself, use a managed instance instead. Dagu Cloud runs a full managed Dagu server with a public HTTPS endpoint, while private workers can still run workflows inside your own infrastructure when needed. See the Dagu pricing page for the current managed-instance options.

Creating a LINE Bot

Before configuring Dagu, create a LINE Messaging API channel for the bot.

1. Open the LINE Developers Console.

2. Create or select a provider.

3. Create a Messaging API channel for the bot.

4. In the channel's Messaging API tab, issue a channel access token. This is the value for bots.line.channel_access_token.

5. In the channel's Basic settings tab, copy the channel secret. This is the value for bots.line.channel_secret.

6. In the Messaging API tab, set the webhook URL to your Dagu server:

   https://<your-dagu-host>/api/v1/bots/line/webhook

   If Dagu is served under a base path, include it before /api/v1.

7. Click Verify. LINE sends a webhook with an empty events array; Dagu returns HTTP 200 when the signature is valid.

8. Enable Use webhook.

9. Add the LINE Official Account as a friend, or invite it to the group or room where you want to use it.

LINE's own greeting and auto-response messages can make it hard to tell whether a reply came from Dagu or from LINE Official Account Manager. For first-time setup, turn those off in LINE Official Account Manager.

Finding Source IDs

Dagu authorizes LINE conversations with allowed_source_ids. These are LINE user IDs, group IDs, or room IDs from webhook event sources.

To find a source ID, temporarily start Dagu with the LINE bot configured but without the desired source in allowed_source_ids, then send a message from that LINE chat. Dagu logs the rejected source ID and source type. Add that ID to allowed_source_ids and restart.

Running

The LINE connector for Workflow Operator starts automatically when bots.provider is set to line and you run either:

dagu server

or

dagu start-all

In both modes, the connector shares the server's agent API instance and registers the LINE webhook route on the same HTTP server.

Configuration

Set provider: line under bots and configure the LINE-specific fields. Only one connector can be active at a time.

bots:
  provider: line
  safe_mode: true
  line:
    channel_access_token: "your-line-channel-access-token"
    channel_secret: "your-line-channel-secret"
    allowed_source_ids:
      - "U1234567890abcdef"
      - "C1234567890abcdef"
    respond_to_all: true

bots fields

Field	Type	Default	Description
provider	string	"" (disabled)	Which connector to run. Set to "line" for LINE. If empty, no bot starts.
safe_mode	bool	true	Passed to the agent's ChatRequest.SafeMode field. Applies to all bot connectors.

bots.line fields

Field	Type	Default	Description
channel_access_token	string	(required)	LINE Messaging API channel access token.
channel_secret	string	(required)	LINE Messaging API channel secret used to verify x-line-signature.
allowed_source_ids	[]string	(required)	LINE user, group, or room IDs authorized to use the bot. Messages from other sources are rejected.
respond_to_all	bool	true	When true, the bot responds to every message in allowed groups and rooms. When false, group and room messages must mention the bot. One-on-one chats always respond.

Environment variables

Variable	Config equivalent
DAGU_BOTS_PROVIDER	bots.provider
DAGU_BOTS_SAFE_MODE	bots.safe_mode
DAGU_BOTS_LINE_CHANNEL_ACCESS_TOKEN	bots.line.channel_access_token
DAGU_BOTS_LINE_CHANNEL_SECRET	bots.line.channel_secret
DAGU_BOTS_LINE_ALLOWED_SOURCE_IDS	bots.line.allowed_source_ids
DAGU_BOTS_LINE_RESPOND_TO_ALL	bots.line.respond_to_all

For allowed_source_ids, use a comma-separated string:

export DAGU_BOTS_LINE_ALLOWED_SOURCE_IDS=U1234567890abcdef,C1234567890abcdef

Event Handling

LINE sends webhook events to Dagu. Dagu verifies the x-line-signature header with HMAC-SHA256 before processing the body.

Messages

• One-on-one chats: handled when the user ID is listed in allowed_source_ids.
• Groups and rooms: handled when the group ID or room ID is listed in allowed_source_ids.
• With respond_to_all: false, group and room messages are handled only when the message mentions the bot or when the chat is answering a pending prompt.

Only text messages are forwarded to the agent. Other LINE message types are ignored.

Text Commands

Type these as plain messages:

Text	Behavior
new or /new	Starts a fresh conversation in the current LINE source
cancel or /cancel	Cancels the currently active agent session
start or /start	Prints a short welcome message

All other text is forwarded to the agent.

Agent Prompts

When the agent asks the user a question, the LINE bot sends the question as text. If the prompt has options, Dagu lists each option as <option_id>: <label>. Reply with the option ID or label to submit that option. If the prompt allows free text, a normal text reply is also accepted.

DAG Run Notifications

When event tracking is available, the bot can send DAG-run notifications into each allowed LINE source. If event tracking is unavailable, LINE chat still works; only automatic run notifications are skipped.

Notifications follow the same batching model as the other Workflow Operator connectors:

1. Dagu checks for new run events every 10 seconds and remembers what it has already delivered.
2. On first startup, existing LINE sources only receive future events.
3. For each destination, it batches pending DAG-run notifications. Urgent single-run batches try to generate the message with the agent; all other delivered batches use deterministic formatting.
4. Delivered entries are retained for 2 hours to suppress duplicate event replays, while failed deliveries remain pending and are retried.

Message Length

LINE text messages are split at paragraph boundaries when they exceed 5,000 characters, falling back to line boundaries when needed.