**Tags:** "Hello World" Examples · Bun # Bun Hello World A [Bun](https://bun.sh) application connected to [PostgreSQL](https://www.postgresql.org/), running on [Zerops](https://zerops.io) with six ready-made environment configurations — from AI agent and remote development to stage and highly-available production. ### Available Environments - [AI Agent](https://app.zerops.io/recipes/bun-hello-world.md?environment=ai-agent) - [Remote (CDE)](https://app.zerops.io/recipes/bun-hello-world.md?environment=remote-cde) - [Local](https://app.zerops.io/recipes/bun-hello-world.md?environment=local) - [Stage](https://app.zerops.io/recipes/bun-hello-world.md?environment=stage) - **Small Production** ← current - [Highly-available Production](https://app.zerops.io/recipes/bun-hello-world.md?environment=highly-available-production) ### Services in this Environment **Services:** - **core** (core@1) - Containers: 1 × Shared Core, 0.00 GB RAM, 0 GB Disk - **app** (bun@1.2) :3000 - Containers: 2 × Shared Core, 0.38 GB RAM, 1 GB Disk - Repository: [zerops-recipe-apps/bun-hello-world-app](https://github.com/zerops-recipe-apps/bun-hello-world-app) - **db** (postgresql@18) :5432, :6432 - Containers: 1 × Shared Core, 0.38 GB RAM, 1 GB Disk **Total Resources:** 4 containers, 1.12 GB RAM, 3 GB Disk ### One-Click Deploy (Import YAML) Use this YAML with `zcli project import` to deploy this environment: ```yaml # Small production environment offers a production-ready setup optimized for moderate throughput. project: name: bun-hello-world-small-prod services: # Production app — Zerops pulls source from the 'buildFromGit' repo and uses the 'prod' # zeropsSetup to bundle TypeScript into standalone files (~300 KB artifact, no node_modules). # minContainers: 2 ensures at least two containers run at all times — spreading load # and keeping the service available if one container is replaced during a deploy. # Zerops autoscales vertically within the bounds set below. - hostname: app type: bun@1.2 zeropsSetup: prod buildFromGit: https://github.com/zerops-recipe-apps/bun-hello-world-app enableSubdomainAccess: true # Zerops subdomain — map your custom domain in the UI minContainers: 2 verticalAutoscaling: minRam: 0.25 minFreeRamGB: 0.125 # ~50% reserve — headroom for traffic spikes and Bun's runtime # PostgreSQL single-node database. Zerops encrypts and backs up data automatically. # For high-traffic production, consider upgrading to HA mode (see Environment 5) # or configuring your own backup export strategy via the Zerops UI. # Priority 10 starts the database before the app — prevents connection errors on deploy. - hostname: db type: postgresql@18 mode: NON_HA priority: 10 verticalAutoscaling: minRam: 0.25 minFreeRamGB: 0.125 ``` --- ## Next Steps After deploying one of the environments and getting to know Zerops, you have two paths to choose from: 1. **Template Flow** — Clone our GitHub repositories and use the whole recipe as a template 2. **Integrate Flow** — If you already have an existing application on a similar stack, integrate the recipe setup with your application Select a flow: [Template Flow](https://app.zerops.io/recipes/bun-hello-world.md?environment=small-production&guideFlow=template) or [Integrate Flow](https://app.zerops.io/recipes/bun-hello-world.md?environment=small-production&guideFlow=integrate) Both flows are shown below: ## How to take over the Small Production environment ### 📦 Clone the template repositories Fork or clone the following repositories to your local machine or GitHub account: - [zerops-recipe-apps/bun-hello-world-app](https://github.com/zerops-recipe-apps/bun-hello-world-app) ### 1. Find your service name Many commands and configurations need the exact name of your service. You can find it in the Zerops Dashboard. - Open your project in the Zerops Dashboard. - In the project overview, find the service you want to manage. - Use this exact name whenever a command or pipeline configuration asks for ``. Zerops GUI: Locating the Service Name ### 2. Configure deployment pipeline Go to Service Settings > Pipelines & CI/CD Settings in the Zerops Dashboard and connect your repository. For production, use a trigger on new tags. This keeps deployments intentional and tied to a specific version. You can also add a regex filter, such as `^v[0-9]+\.[0-9]+\.[0-9]+$`, if you want to allow only semantic version tags. Zerops GUI: Triggers Alternatively, add `zcli push` to your existing CI/CD pipeline if you want full control over when deployments happen. Learn more about pipeline triggers: https://docs.zerops.io/features/pipeline ### 3. Deploy to production Create and push a new Git tag to deploy a specific version of your app: ```bash git tag -a v1.0.0 -m "Release version 1.0.0" git push origin v1.0.0 ``` > [!TIP] > Open the pipeline detail in the Zerops Dashboard to check the build progress and verify that all steps finish successfully. ### 4. Configure autoscaling Review the autoscaling settings for your runtime services and databases in Service Settings > Automatic Scaling Configuration in the Zerops Dashboard. Zerops GUI: Autoscaling configuration The most important settings are: ```yaml verticalAutoscaling: minRam: 1 minFreeRamGB: 0.5 minFreeRamPercent: 20 ``` > [!CAUTION] > Pay attention to `minFreeRamGB`. This value tells Zerops when to scale RAM vertically. Adjust it based on your app’s real memory needs. RAM scales up immediately, while CPU scales after two consecutive measurements below the threshold. > [!TIP] > Run a quick stress test with a tool like hey before real users arrive. This helps you see how your app behaves under load and tune the autoscaling settings. ### 5. Set up your domain To send real traffic to your app, configure public HTTP access in Service Settings > Public Access & Internal Ports in the Zerops Dashboard. Add your custom domain and point your DNS records to the Zerops IPs shown in the dashboard: Zerops GUI: Public access and custom domain ```text Type Name Content TTL A example.com Auto AAAA example.com Auto ``` For wildcard domains, add a CNAME record for SSL validation. Check the public access documentation: https://docs.zerops.io/features/access > [!TIP] > When changing DNS records for production, start with a low TTL value. Make sure SSL certificates are active before you disable the fallback Zerops subdomain. Once everything works, you can disable the Zerops subdomain so all traffic goes through your custom domain. --- ### 🎉 You are good to go! Your application is live in production and the core setup is complete. The following sections are optional. They cover extra production features such as log forwarding, backups, and diagnostic access. You can stop here and come back later when you need them. --- ### 6. Set up log forwarding (Optional) To send logs to an external service, go to Project Settings > Log Forwarding & Logs Overview in the Zerops Dashboard. You can forward logs to services like Better Stack, Papertrail, or your own self-hosted solution. Learn more about log forwarding: https://docs.zerops.io/references/logging ### 7. Configure database backups (Optional) Manage automated encrypted backups in Service Settings > Backups in the Zerops Dashboard. By default, backups run daily between 00:00 and 01:00 UTC. Before a major deployment, create a manual protected backup: ```bash zcli backup create --tags pre-deploy,protected ``` Read the backup documentation for more options: https://docs.zerops.io/features/backup ### 8. Set up diagnostic access (Optional) Use zCLI and VPN access when you need to inspect or maintain services directly. For runtime services: ```bash zcli vpn up ssh .zerops ``` For databases, connect through the VPN to reach the project’s private network, or set up secure direct IP access for your database admin tools. Check the VPN documentation: https://docs.zerops.io/references/cli/commands#vpn-up ## How to integrate app with Zerops ### 1. Adding `zerops.yaml` The main application configuration file you place at the root of your repository, it tells Zerops how to build, deploy and run your application. ```yaml zerops: # Production setup — bundle TypeScript into standalone files, deploy minimal artifacts. # bun build --target bun inlines all dependencies: no node_modules at runtime. - setup: prod build: base: bun@1.2 envVariables: # Redirect bun's install cache into the project tree so Zerops can cache it # between builds. Default ~/.bun is outside the project and cannot be cached. BUN_INSTALL: ./.bun buildCommands: # --frozen-lockfile: fail if bun.lock would change — reproducible builds - bun install --frozen-lockfile # Bundle app and migration into standalone files; all pg imports are inlined - bun build src/index.ts --outfile dist/index.js --target bun - bun build migrate.ts --outfile dist/migrate.js --target bun deployFiles: # Only bundled artifacts — no node_modules, no source. 156 KB total. - dist cache: - node_modules - .bun/install/cache # Matches BUN_INSTALL path above # Readiness check: Zerops verifies each new runtime container responds before the # project balancer routes traffic to it — prevents deploying a broken build. deploy: readinessCheck: httpGet: port: 3000 path: / run: base: bun@1.2 # initCommands run on every container start, before the start command. # zsc execOnce runs migration exactly once per version across all containers — # prevents race conditions when scaling to multiple containers. # In initCommands (not buildCommands) so migration and code deploy atomically. initCommands: - zsc execOnce ${appVersionId} -- bun dist/migrate.js ports: - port: 3000 httpSupport: true envVariables: NODE_ENV: production DB_NAME: db # Zerops generates connection variables per service using {hostname}_{key} pattern DB_HOST: ${db_hostname} DB_PORT: ${db_port} DB_USER: ${db_user} DB_PASS: ${db_password} start: bun dist/index.js healthCheck: httpGet: port: 3000 path: / # Development setup — deploy full source so developers can work via SSH immediately. # Bun is pre-installed; run 'bun --hot src/index.ts' to start with hot reload. - setup: dev build: base: bun@1.2 envVariables: BUN_INSTALL: ./.bun buildCommands: # Install all dependencies including devDependencies — no compilation. # Developer runs the app themselves via SSH. - bun install deployFiles: # Deploy entire working directory: source, node_modules, and bun's package cache - ./ cache: - node_modules - .bun/install/cache run: base: bun@1.2 initCommands: # Migration runs at deploy time — DB is ready when developer SSHs in - zsc execOnce ${appVersionId} -- bun migrate.ts ports: - port: 3000 httpSupport: true envVariables: NODE_ENV: development DB_NAME: db DB_HOST: ${db_hostname} DB_PORT: ${db_port} DB_USER: ${db_user} DB_PASS: ${db_password} # Lets developer use 'bun add' via SSH — reuses the cached packages shipped in ./ BUN_INSTALL: /var/www/.bun # Zerops starts nothing — developer drives via SSH: 'bun --hot src/index.ts' start: zsc noop --silent ``` ### 🎯 What's next? **Deploy other environments** — Ready to scale? Deploy additional environments for different stages of your workflow: - [AI Agent](https://app.zerops.io/recipes/bun-hello-world.md?environment=ai-agent) - [Remote (CDE)](https://app.zerops.io/recipes/bun-hello-world.md?environment=remote-cde) - [Local](https://app.zerops.io/recipes/bun-hello-world.md?environment=local) - [Stage](https://app.zerops.io/recipes/bun-hello-world.md?environment=stage) - [Highly-available Production](https://app.zerops.io/recipes/bun-hello-world.md?environment=highly-available-production) ## Knowledge Base ### Platform Reference - [Routing & Domains](https://docs.zerops.io/features/access) - [Scaling](https://docs.zerops.io/features/scaling) - [Environment Variables](https://docs.zerops.io/features/env-variables) - [CLI (zcli)](https://docs.zerops.io/references/cli) ### Service Type Reference **Bun** - [Build & Deploy](https://docs.zerops.io/bun/how-to/build-pipeline) - [Customize Runtime](https://docs.zerops.io/bun/how-to/customize-runtime) **PostgreSQL** - [Connect](https://docs.zerops.io/postgresql/how-to/connect) - [Backup & Restore](https://docs.zerops.io/postgresql/how-to/backup) - [Manage](https://docs.zerops.io/postgresql/how-to/manage) - [Scale](https://docs.zerops.io/postgresql/how-to/scale) ### Application Reference #### app Knowledge Base ### Base Image Includes: Bun, `npm`, `yarn`, `git`, `bunx`. NOT included: `pnpm`. ### Gotchas - **`BUN_INSTALL: ./.bun` for build caching** — Zerops can only cache paths inside the project tree. Default `~/.bun` is outside it and gets lost between builds. - **Use `bunx` instead of `npx`** — `npx` may not resolve correctly in the Bun runtime. - **`bun build --target bun` only works with pure-JS dependencies** — The prod setup bundles with `bun build` which inlines all imports. This works for pure-JS packages (e.g. `pg`) but silently produces broken bundles for native addons (`mysql2`, `bcrypt`, `sharp`, `canvas`, etc.). The build exits 0 but the bundle fails at runtime or is empty. If your app uses native dependencies, skip bundling: use `deployFiles: [./]` and `start: bun src/index.ts` for both dev and prod setups. --- ## Related Recipes - [Zerops showcase](https://app.zerops.io/recipes/zerops-showcase.md) - [Go Hello World](https://app.zerops.io/recipes/go-hello-world.md) - [Java Hello World](https://app.zerops.io/recipes/java-hello-world.md) - [Deno Hello World](https://app.zerops.io/recipes/deno-hello-world.md)