Gleam has no workspaces.Trellis adds them.

gleam build, gleam test, and gleam publish each operate on a single package directory. Trellis is one binary that fans them across every package in the repository, then adds changelogs, versioning, and publishing on top. Everything it knows comes from the gleam.toml files you already have.

Read the docs Install

$curl --proto '=https' --tlsv1.2 -LsSf https://github.com/tylerbutler/trellis/releases/latest/download/trellis-gleam-installer.sh | sh

$trellis graph

lat_core (1.2.0)
lat_mid (0.5.1)
  └─ lat_core
lat_cli (0.4.3)
  ├─ lat_core
  └─ lat_mid
lat_example (0.0.0)
  └─ lat_cli

Real output. Trellis computes the graph from path dependencies.

Opinionated, but modular.

Trellis has one way of doing each job — TOML change fragments, a tag per package, bumps derived from fragment kinds. But the jobs are independent: nothing requires the piece above it, so you adopt a layer at a time and keep whatever already works.

Just the task runner
run, exec, list, and graph need no configuration at all — members are auto-discovered from git. Your changelog tool and CI stay untouched.
Add changelogs and versioning
Fragments, version plan, and version apply manage bumps and changelogs without trellis owning your release workflow — or any CI at all.
Add publishing
tag and publish push to Hex in dependency order, from your own scripts or workflows.
The full pipeline
ci, changelog check, and release pr turn GitHub Actions workflows into thin triggers around trellis commands.

The glue this replaces.

Without a workspace concept, a multi-package repository builds one by hand — bash loops, YAML blocks, duplicated config. Every row below is something a Gleam repository has to maintain itself, and every row can go quietly wrong:

Where it lives	What's maintained by hand	What can drift
`justfile`	The package list, in topological order, as a space-separated string	A new package is silently excluded from every recipe
`justfile`	~15 near-identical `for pkg in …` bash loops	Copy-paste drift between recipes; strictly serial execution
`.changie.yaml`	One config block per package: label, key, changelog path, version regex	A forgotten block means a package can't be versioned or released
`publish.yml`	A hand-written mirror of the path_dependency graph	Nothing verifies it when a package gains a dependency
`release.yml`	25 lines of inline `sed`/`grep` patching locked versions	Untestable regex logic living inside CI YAML

Trellis derives the information behind each row from gleam.toml, a file format the ecosystem already uses.

Configure nothing that can be derived.
Verify anything that must be duplicated.

# The table's presence marks the workspace root.
# Every key is optional — members auto-discover from git.
[tools.trellis]
members = ["packages/*", "examples/*"]
# Exclusions are scoped by task. `@release` covers changelog,
# versioning, tagging, publishing, and release CI.
exclude = { docs = ["examples/*"], "@release" = ["examples/*"] }

[tools.trellis.tasks.lint]
command = "gleam run -m glinter"

[tools.trellis.publish]
tag_format = "{name}-v{version}"

From that, trellis computes:

The member set and its topological order — new packages join every command the moment their directory matches a glob.
Change impact — --since origin/main maps a diff to owning packages, plus the reverse-dependency closure. Only test what a PR touched.
Publish order and path-dep rewrites — dependencies publish first, path references become Hex versions automatically.
A tag per releasable package — and a doctor that fails loudly when anything drifts.

One workspace. Different task sets.

Examples, benchmarks, and internal tools can remain workspace members for builds, tests, and graphing without needing generated docs or a release on Hex.

exclude gives each built-in or custom task its own member-path globs. The reserved @release key covers changelogs, versioning, tags, publishing, and release CI.

Configure package exclusions →

Member	build / test	docs	release
`packages/*`	included	included	included
`examples/*`	included	excluded	excluded

$trellis list --releasable

lat_core  hex
lat_mid   hex
lat_cli   hex

lat_example — the examples/ member — still appears in trellis list, graph, exec, and tasks that do not exclude it. Only the configured task sets change.

One binary across the lifecycle.

The same tool runs locally and in CI. Commands work from anywhere in the workspace — the root is found by walking up, like git or cargo.

Every day
init
Write the workspace table; only needed to configure something
run
Run a task across packages, graph-parallel by default
list
Packages in topological order — dependencies first
graph
The dependency graph, as text, DOT, Mermaid, or JSON
exec
Any command, in each package directory
doctor
Validate workspace invariants; non-zero exit on any error
Cut a release
changelog
Native fragment engine — no second tool to install
version
Plan and apply bumps from unreleased fragments
tag
Compare versions against git tags; create what's missing
publish
To Hex, in dependency order, path deps rewritten
lockfile
Patch locked versions without touching the network
In CI
ci
Structured JSON for GitHub Actions matrices and outputs
changelog check
Fail a PR that changes a package without logging it
release pr
Open the release pull request, versions applied

Checks for drift.

Some things can't be derived — locked versions, changelogs, tags, toolchain pins. For those, trellis doctor checks the invariants that remain explicit and exits non-zero when one breaks.

$trellis doctor

checked: member globs resolve and every package has a parseable gleam.toml
checked: path dependencies stay inside the workspace; graph is acyclic
checked: task exclusion globs match members; no package depends on one unavailable at its release lifecycle
checked: tag format produces a unique tag per releasable package
checked: manifest.toml locked versions match workspace-internal gleam.toml versions
checked: each releasable package's version is not behind its CHANGELOG
checked: unreleased changelog fragments parse and reference valid packages, kinds, and categories
checked: [tools.trellis] carries no unrecognized or deprecated keys
checked: packages agree on the external dependencies they share
checked: gleam on PATH matches the .tool-versions pin (advisory)

ok: 4 package(s) (1 workspace, 0 git_only, 3 hex), 0 warning(s)

Install a prebuilt binary.

Trellis has no runtime dependencies and includes SLSA build provenance. Its shell installer typically completes in about a second in CI.

Shell (Linux, macOS): $curl --proto '=https' --tlsv1.2 -LsSf https://github.com/tylerbutler/trellis/releases/latest/download/trellis-gleam-installer.sh | sh
Homebrew: $brew install tylerbutler/tap/trellis
mise / asdf (pin it in .tool-versions): $mise use "github:tylerbutler/trellis@0.10.3"
From source: $cargo install --git https://github.com/tylerbutler/trellis

Windows installer and pinned-version URLs are on thereleases page. From there, trellis doctor works immediately — no setup. Run trellis init only when you want to configure something; the configuration guide covers what it writes.

Gleam has no workspaces.Trellis adds them.

Opinionated, but modular.

Just the task runner

Add changelogs and versioning

Add publishing

The full pipeline

The glue this replaces.

From that, trellis computes:

One workspace. Different task sets.

One binary across the lifecycle.

1Every day

2Cut a release

3In CI

Checks for drift.

Install a prebuilt binary.

Every day

Cut a release

In CI