**Tags:** "Hello World" Examples · Gleam # Gleam Hello World A [Gleam](https://gleam.run) web application with a PostgreSQL database, showcasing Gleam's type-safe Erlang/OTP ecosystem on [Zerops](https://zerops.io) — from AI agent workspaces through local and remote development to staged and highly-available production deployments. ### Available Environments - [AI Agent](https://app.zerops.io/recipes/gleam-hello-world.md?environment=ai-agent) - [Remote (CDE)](https://app.zerops.io/recipes/gleam-hello-world.md?environment=remote-cde) - [Local](https://app.zerops.io/recipes/gleam-hello-world.md?environment=local) - [Stage](https://app.zerops.io/recipes/gleam-hello-world.md?environment=stage) - **Small Production** ← current - [Highly-available Production](https://app.zerops.io/recipes/gleam-hello-world.md?environment=highly-available-production) ### Services in this Environment **Services:** - **core** (core:single@2) - Containers: 1 × Shared Core, 0.00 GB RAM, 0 GB Disk - **app** (ubuntu/gleam@1.5.1) :3000 - Containers: 2 × Shared Core, 0.38 GB RAM, 1 GB Disk - Repository: [zerops-recipe-apps/gleam-hello-world-app](https://github.com/zerops-recipe-apps/gleam-hello-world-app) - **db** (postgresql:single@18) :5432, :6432 - Containers: 1 × Shared Core, 4.50 GB RAM, 1 GB Disk **Total Resources:** 4 containers, 5.25 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: gleam-hello-world-small-prod services: # Deploy the production app — Zerops pulls source and zerops.yaml # from the 'buildFromGit' repo and uses the 'prod' zeropsSetup to # compile a self-contained Erlang shipment and deploy it. The 'prod' # setup runs the database migration atomically via initCommands # before traffic reaches the new containers. # Subdomain access gives a public HTTPS URL; add a custom domain # in the Zerops dashboard for production traffic. - hostname: app type: gleam@1.5 zeropsSetup: prod buildFromGit: https://github.com/zerops-recipe-apps/gleam-hello-world-app enableSubdomainAccess: true # minContainers: 2 keeps two containers running at all times for # availability and zero-downtime deploys. Zerops autoscales # RAM within the verticalAutoscaling bounds as load changes. minContainers: 2 verticalAutoscaling: minRam: 0.25 # Reserve free RAM for OTP scheduler and request spikes. # Production services should always have headroom (30-50% of # minRam) to absorb traffic bursts without OOM kills. minFreeRamGB: 0.125 # PostgreSQL single-node database. Automatic encrypted backups are # on by default. For production traffic, consider HA mode or a # dedicated backup strategy. Priority 10 ensures the database starts # before app containers. - hostname: db type: postgresql:single@18 profile: oltp-production priority: 10 ``` --- ## 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/gleam-hello-world.md?environment=small-production&guideFlow=template) or [Integrate Flow](https://app.zerops.io/recipes/gleam-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/gleam-hello-world-app](https://github.com/zerops-recipe-apps/gleam-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 — compiles an Erlang shipment and deploys the # optimized artifact. Gleam compiles to BEAM bytecode; the shipment # bundles all compiled modules with a launch script. - setup: prod build: os: ubuntu base: gleam@1.5 buildCommands: # Export a self-contained Erlang/OTP shipment — compiled BEAM # files for the app and all dependencies, with entrypoint.sh. - gleam export erlang-shipment # Bundle the migration script with the shipment so initCommands # can run it without access to source code. - cp migrate.sh build/erlang-shipment/migrate.sh deployFiles: # ~ strips the path prefix: build/erlang-shipment/* lands at # /var/www/* in the runtime container (entrypoint.sh, all # package ebin dirs, and migrate.sh at the same level). - build/erlang-shipment/~ cache: # Gleam downloads Hex packages to build/packages/ — cache this # in-tree folder to skip network fetches on subsequent builds. - build/packages # Readiness check: verifies containers are healthy before the # project balancer routes traffic to them (zero-downtime deploys). deploy: readinessCheck: httpGet: port: 3000 path: / run: # Gleam's Erlang shipment requires an OTP runtime on the host — # the BEAM files are not statically linked. gleam@1.5 includes # Erlang/OTP 26, matching the build container exactly. os: ubuntu base: gleam@1.5 # Run migration once per deploy using execOnce — prevents race # conditions when multiple containers start simultaneously. # In initCommands (not buildCommands) so migration and code # deploy atomically. retryUntilSuccessful handles transient # DB startup delays on fresh deploys. initCommands: - zsc execOnce ${appVersionId} --retryUntilSuccessful -- sh /var/www/migrate.sh ports: - port: 3000 httpSupport: true envVariables: DB_HOST: ${db_hostname} DB_PORT: ${db_port} # DB_NAME matches the PostgreSQL service hostname ('db'). DB_NAME: db DB_USER: ${db_user} DB_PASS: ${db_password} start: ./entrypoint.sh run # Development setup — deploys source for live SSH development. # Gleam is installed on the runtime; developers run 'gleam run' # interactively after SSH. - setup: dev build: os: ubuntu base: gleam@1.5 buildCommands: # Source-only deployment. Gleam packages are downloaded in # initCommands rather than here, avoiding build-container # permission issues when cached build/ directories are restored. - "true" deployFiles: # Deploy source and config files. zerops.yaml included so # 'zcli push' works when SSHed into the dev container. - src - gleam.toml - manifest.toml - zerops.yaml - migrate.sh run: os: ubuntu base: gleam@1.5 # Download Hex packages and run migration once per deploy. # 'gleam deps download' populates build/packages/ so 'gleam run' # works offline in the container. execOnce prevents repeated # compilation (30+ packages) on restart or scale events. initCommands: - zsc execOnce ${appVersionId} --retryUntilSuccessful -- sh -c "gleam deps download && gleam run -m migrate" ports: - port: 3000 httpSupport: true envVariables: # rebar3 (Erlang build tool used by Gleam's package compiler) # requires HOME to locate its global config. Without it, # rebar_dir:home_dir/0 crashes when 'gleam run' compiles deps. HOME: /home/zerops DB_HOST: ${db_hostname} DB_PORT: ${db_port} DB_NAME: db DB_USER: ${db_user} DB_PASS: ${db_password} # Zerops starts the container and leaves it idle. SSH in and # run 'gleam run' to start the development server on port 3000. # Note: after a container restart, re-run 'gleam deps download' # to restore the build/packages/ directory before 'gleam run'. 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/gleam-hello-world.md?environment=ai-agent) - [Remote (CDE)](https://app.zerops.io/recipes/gleam-hello-world.md?environment=remote-cde) - [Local](https://app.zerops.io/recipes/gleam-hello-world.md?environment=local) - [Stage](https://app.zerops.io/recipes/gleam-hello-world.md?environment=stage) - [Highly-available Production](https://app.zerops.io/recipes/gleam-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 **Gleam** - [Build & Deploy Pipeline](https://docs.zerops.io/ubuntu/how-to/build-pipeline) - [Customize runtime](https://docs.zerops.io/ubuntu/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) --- ## Related Recipes - [Go Hello World](https://app.zerops.io/recipes/go-hello-world.md) - [Java Hello World](https://app.zerops.io/recipes/java-hello-world.md) - [SolidStart SSR Hello World](https://app.zerops.io/recipes/solidstart-ssr-hello-world.md) - [Astro SSR Hello World](https://app.zerops.io/recipes/astro-ssr-hello-world.md)