Deploy Go applications

A Go web server runs on Sevalla as an application: Sevalla builds an image from your Git repository, compiles your main package into a binary, and runs it as processes. The web process runs the binary that serves HTTP, background workers and cron jobs can run other binaries from the same module, and jobs run migrations before each deployment.

Framework guides

net/http

Deploy a JSON API on the standard library, with Go 1.22 routing patterns and a graceful shutdown.

Gin

Deploy Gin in release mode, with the visitor’s IP address from Cloudflare’s header.

Echo

Deploy Echo v5, which shuts down gracefully on its own.

Fiber

Deploy Fiber v3, with the proxy settings that make c.IP() and c.Scheme() right.

How Go applications run on Sevalla

Part	On Sevalla
Build	Ingot, Sevalla’s builder, by default. It recognizes a Go project by `go.mod` or `go.work`, downloads the modules from `go.mod` and `go.sum`, then compiles each `main` package at the module’s root and in `cmd/<name>` into `/usr/local/bin`, with `-trimpath -ldflags="-s -w"`. With a `vendor/modules.txt`, it builds from the vendored modules instead.
Modules	Go modules. When `go.mod` requires modules, commit `go.sum`: without it, the build fails with `go.mod requires modules, but go.sum is missing`.
Go version	Go 1.27, Ingot’s default line, as long as the `toolchain` or `go` line in `go.mod` allows it. See Pin the Go version. The build never downloads another Go: Ingot sets `GOTOOLCHAIN=local`.
cgo	Off, so binaries are static and need no C library. Ingot turns it on when a package in your module imports `"C"`, or when `go.mod` requires `github.com/mattn/go-sqlite3` or `github.com/confluentinc/confluent-kafka-go`. Set `CGO_ENABLED=1` as a build-time variable to turn it on yourself.
Start command	The binary of the `main` package at the module’s root, such as `/usr/local/bin/storefront`, named after the last part of the module path. With no root package and one package in `cmd/`, that one. With several and none at the root, set the start command: Ingot builds every one of them into `/usr/local/bin`. See Set the start command.
Port	Sevalla sets the `PORT` environment variable to the web process’s port, `8080` by default. The server must listen on it, on all network interfaces, as `http.Server{Addr: ":" + os.Getenv("PORT")}` does.
Concurrency	One process serves every request on goroutines. For a module whose `go` line is 1.25 or later, Go sizes `GOMAXPROCS` to the instance’s CPU limit. To serve more traffic, choose a larger size or add instances. See Scaling.
Shutdown	Sevalla sends `SIGTERM` to stop an instance. Handle it with `signal.NotifyContext` and `http.Server.Shutdown`, as in the net/http guide, so requests in progress finish. Ingot’s image runs the binary under `tini`, which passes the signal on.
Image	Ingot builds on `golang:1.27-trixie` and runs the binary on `debian:trixie-slim`, with CA certificates and time zone data, as user `1000:1000`.
Runtime files	The binary runs from `/app`. Ingot copies the folders a Go server usually reads at runtime, `assets`, `locales`, `migrations`, `public`, `static`, `templates` and `views`, and `config` when it holds no Go code, from the module’s root into `/app`, so relative paths such as `templates/index.html` work. Files you embed with `//go:embed` are part of the binary.
Migrations	A job with the start policy Before deployment that runs a migration binary or tool from the image. If it fails, the deployment fails and the previous version keeps running.
Workers	A background worker that runs another binary of the module, such as `/usr/local/bin/worker` built from `cmd/worker`. See Run workers and jobs.
Scheduled tasks	A cron job that runs a binary on a schedule.
Databases	PostgreSQL, MySQL, MariaDB, Redis or Valkey on Sevalla, reached over an internal connection that adds the connection details as environment variables.
Files	The filesystem resets on every deployment. Keep uploads in object storage, or attach a disk.
Dockerfile	Switch the build strategy to Dockerfile on the application’s Settings tab. See Build with a Dockerfile.

Every process (web, worker, cron job and job) runs from the same image, each with its own start command. See Processes for every process type and its settings.

Pin the Go version

The go line in go.mod is the oldest Go release that builds the module, and go mod init sets it to the release you run, such as go 1.27.1. Ingot builds on Go 1.27, its default line, whenever the module allows it, and on the newest maintained line that satisfies the module otherwise. A new Ingot release can move the default to a newer Go line, which Go’s compatibility promise covers. Ingot takes the version from the first of these that’s set:

The INGOT_GO_VERSION environment variable, marked Available during buildtime, such as 1.26.
versions.go in ingot.json, such as { "versions": { "go": "1.26" } }.
The toolchain line, then the go line, of go.work when the repository has one, otherwise of go.mod. Both are minimums.

To stay on one Go line, set it in ingot.json or with INGOT_GO_VERSION: 1.26 builds on the newest Go 1.26 release. The build plan’s Go row shows the version and where it came from, for example go.mod "go 1.27.1" or ingot.json "1.26". A go line newer than every Go release Ingot knows fails the build with no go version in this Ingot release satisfies ">=1.28.0" (newest known: 1.27.3). Set the line to a release Ingot knows with go mod edit -go=1.27.0. See Set the language version.

Build with a Dockerfile

Ingot needs no Dockerfile, but you can write your own for full control of the image. A Dockerfile for Go on Sevalla builds in a golang image of the line go.mod asks for, copies go.mod and go.sum and runs go mod download before it copies the code, so a code change reuses the downloaded modules, and builds with CGO_ENABLED=0. The final stage needs the binary, /bin/sh for the web terminal and custom start commands, and CA certificates, which alpine has, and runs as a user other than root. A server that handles SIGTERM itself needs no init process. Each guide has one: see Gin for a module with dependencies, and net/http for one without.

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.NET

Elixir

Static site generators

Framework guides

net/http

Gin

Echo

Fiber

How Go applications run on Sevalla

Pin the Go version

Build with a Dockerfile

​Framework guides

net/http

Gin

Echo

Fiber

​How Go applications run on Sevalla

​Pin the Go version

​Build with a Dockerfile

Framework guides

How Go applications run on Sevalla

Pin the Go version

Build with a Dockerfile