Special Environment Variables

Dagu injects a small set of read-only environment variables whenever it runs a workflow. These variables carry metadata about the current DAG run (name, run identifier, log locations, status) and are available for interpolation inside commands, arguments, lifecycle handlers, and most other places where you can reference environment variables.

Availability

• Step execution – Every step receives the run-level variables plus a step-specific name and log file paths while it executes.
• Lifecycle handlers – onExit, onSuccess, onFailure, onCancel, and onWait handlers inherit the same variables. They additionally receive the final DAG_RUN_STATUS so that post-run automation can branch on success or failure. The onWait handler receives DAG_WAITING_STEPS with step names waiting for approval.
• Nested contexts – When a step launches a sub DAG through the dagu CLI, the sub run gets its own identifiers and log locations; the parent identifiers remain accessible in the parent process for chaining or notifications.

Values are refreshed for each step, so DAG_RUN_STEP_NAME, DAG_RUN_STEP_STDOUT_FILE, and DAG_RUN_STEP_STDERR_FILE always point at whichever step (or handler) is currently running.

Reference

Variable	Provided In	Description	Example
DAG_NAME	All steps & handlers	Name of the DAG definition being executed.	daily-backup
DAG_RUN_ID	All steps & handlers	Unique identifier for the current run. Combines timestamp and a short suffix.	20241012_040000_c1f4b2
DAG_RUN_LOG_FILE	All steps & handlers	Absolute path to the aggregated DAG run log. Useful for attaching to alerts.	/var/log/dagu/daily-backup/20241012_040000.log
DAG_RUN_STEP_NAME	Current step or handler only	Name field of the step that is currently executing.	upload-artifacts
DAG_RUN_STEP_STDOUT_FILE	Current step or handler only	File path backing the step's captured stdout stream.	/var/log/dagu/daily-backup/upload-artifacts.stdout.log
DAG_RUN_STEP_STDERR_FILE	Current step or handler only	File path backing the step's captured stderr stream.	/var/log/dagu/daily-backup/upload-artifacts.stderr.log
DAG_RUN_STATUS	Lifecycle handlers only	Canonical completion status (succeeded, partially_succeeded, failed, aborted).	failed
DAG_WAITING_STEPS	Wait handler only	Comma-separated list of step names currently waiting for human approval (HITL).	approval-step,review-step
PWD	Current step only	Working directory for the step. Defaults to DAG's workingDir or the DAG file's directory.	/home/user/project
DAGU_PARAMS_JSON	All steps & handlers	JSON string containing the resolved parameter map. If the run was started with JSON parameters, the original payload is preserved.	{"ENVIRONMENT":"prod","batchSize":1000}
WEBHOOK_PAYLOAD	Webhook-triggered runs only	JSON string containing the payload from the webhook request body. Only available when the DAG was triggered via a webhook.	{"branch":"main","commit":"abc123"}

Parameter Payload (DAGU_PARAMS_JSON)

Dagu always computes the effective parameter set before each run. The scheduler then serializes that map into the DAGU_PARAMS_JSON environment variable so steps can read the entire payload—without reconstructing it from params strings.

• Defaults declared in the DAG plus CLI/API overrides are merged into a single JSON object.
• When the run was started with raw JSON parameters (e.g., dagu start dag.yaml -- '{"foo":"bar"}'), the original JSON string is preserved verbatim.
• The variable is empty only when the DAG defines no parameters and none were supplied at runtime.

Example usage inside a shell step:

steps:
  - name: inspect params
    command: echo "Full payload: ${DAGU_PARAMS_JSON}"
  - name: read environment
    type: jq
    config:
      raw: true
    script: ${DAGU_PARAMS_JSON}
    command: '"Environment: \(.ENVIRONMENT // "dev")"'

This is particularly useful when downstream scripts expect structured data. Treat the JSON as read-only metadata—mutating it inside a step will not affect subsequent steps.

Webhook Payload

When a DAG is triggered via a webhook, the request payload is made available through the WEBHOOK_PAYLOAD environment variable. This allows your DAG steps to receive and process data from the triggering system.

Example Usage

Access payload fields directly using Dagu's JSON field access syntax:

name: webhook-triggered-dag
steps:
  - name: deploy
    command: |
      echo "Deploying branch ${WEBHOOK_PAYLOAD.branch}"
      echo "Commit: ${WEBHOOK_PAYLOAD.commit}"
      ./scripts/deploy.sh

  - name: notify
    command: echo "Deployed by ${WEBHOOK_PAYLOAD.sender.login}"
    depends:
      - deploy

For complex payloads with nested structures:

steps:
  - name: process-github-push
    command: |
      echo "Repository: ${WEBHOOK_PAYLOAD.repository.full_name}"
      echo "Pusher: ${WEBHOOK_PAYLOAD.pusher.name}"
      echo "First commit message: ${WEBHOOK_PAYLOAD.commits.0.message}"

Notes

• Dagu automatically parses the JSON payload and allows direct field access using dot notation.
• For arrays, use numeric indices (e.g., ${WEBHOOK_PAYLOAD.commits.0} for the first element).
• Maximum payload size is 1MB.
• The variable is empty when the DAG is triggered by other means (scheduler, API, CLI).
• Always validate the payload contents in your DAG before processing.