Development workflow

Hammerkit isn't only for CI — the same build file drives a fast local loop. This guide combines watch, services and needs into a develop-on-save setup.

Watch a taskCopy Anchor Link

--watch re-runs a task when its src changes, and — because hammerkit knows the graph — re-runs anything downstream too, reusing cached results for everything unchanged. A short debounce coalesces a burst of saves into one restart.

tasks:
  api:
    image: node:24-alpine
    src:
      - src
    cmds:
      - node src/index.js

hammerkit api --watch

Let the tool watch itselfCopy Anchor Link

Some tools already do incremental rebuilds faster than a full task restart (tsc -w, ng serve, vite, nodemon). Mark those continuous: true so hammerkit starts them once and does not restart them on file changes in watch mode:

tasks:
  serve:
    image: node:24-alpine
    continuous: true
    src:
      - src
    cmds:
      - npm run dev

Keep services up while you workCopy Anchor Link

A task that needs a service starts and stops it around each run. During development you usually want the database to stay up across many runs — start the services once in the background and leave them:

hammerkit up --daemon     # start services, return immediately
hammerkit api --watch     # iterate; the db keeps running
hammerkit down            # stop services when you're done

up --watch also restarts services whose mounted config changes. Attach a volume so the database keeps its data between restarts.

Putting it togetherCopy Anchor Link

A typical loop for an API with a database and a frontend:

services:
  postgres:
    image: postgres:16-alpine
    healthcheck:
      cmd: "pg_isready -U dev"
    volumes:
      - "dev-db:/var/lib/postgresql/data"
    ports:
      - 5432

tasks:
  api:
    image: node:24-alpine
    needs: [postgres]
    labels:
      stage: dev
    src:
      - src
    cmds:
      - npm run dev

  web:
    image: node:24-alpine
    continuous: true
    labels:
      stage: dev
    src:
      - web
    cmds:
      - npm run dev --prefix web

hammerkit up --daemon       # postgres in the background
hammerkit -f stage=dev --watch

Group the dev tasks with a label (stage: dev) so a single filtered command starts exactly the watch loop you want. See labels for the grouping pattern.