Parameters

Make workflows dynamic and reusable with runtime parameters.

Parameter Definition

# Named parameters
params:
  - ENVIRONMENT: dev
  - PORT: 8080
  - DEBUG: false

# Positional parameters (accessed as $1, $2, ...)
params: first second third

steps:
  - echo $1 --env=${ENVIRONMENT} --port=${PORT}

Passing Parameters

# Named parameters
dagu start workflow.yaml -- ENVIRONMENT=prod PORT=80

# Positional parameters  
dagu start workflow.yaml -- input.csv output.json

# Mixed
dagu start workflow.yaml -- config.json ENVIRONMENT=prod

# With spaces
dagu start workflow.yaml -- MESSAGE="Hello World"

Dynamic Parameters

params:
  # Command substitution
  - DATE: "`date +%Y-%m-%d`"
  - GIT_COMMIT: "`git rev-parse --short HEAD`"
  
  # Environment variables
  - USER: ${USER}
  - LOG_PATH: ${LOG_DIR:-/var/log}  # With default

steps:
  - backup-${DATE}-${GIT_COMMIT}.tar.gz

Using Parameters

params:
  - INPUT: data.csv
  - THREADS: 4
  - SKIP_TESTS: false

steps:
  # In commands
  - python processor.py --input ${INPUT} --threads ${THREADS}
    
  # In conditions
  - command: npm test
    preconditions:
      - condition: "${SKIP_TESTS}"
        expected: "false"
        
  # In environment
  - env:
      - API_VERSION: ${VERSION:-v1}
    command: ./app

Enforcing Fixed Parameters

Prevent users from modifying critical parameters:

runConfig:
  disableParamEdit: true  # Parameters cannot be changed
  disableRunIdEdit: false # Custom run IDs still allowed

params:
  - ENVIRONMENT: production  # Always production
  - DB_HOST: prod.db.example.com
  - SAFETY_MODE: enabled

steps:
  - echo "Deploying to ${ENVIRONMENT} with DB ${DB_HOST}"

Enforcing Run ID Format

Ensure consistent run ID naming:

runConfig:
  disableParamEdit: false  # Parameters can be changed
  disableRunIdEdit: true   # Must use auto-generated run IDs

steps:
  - echo "Auditing run ${DAG_RUN_ID}"