gantry

README

gantry

gantry is a non-Kubernetes release orchestrator. It reads the latest published release of each of your components from a forge (GitLab today), writes the resolved immutable image references into a per-environment dotenv pin file (committing only when something actually changed), and reconciles the running environment with docker compose pull && up -d over SSH.

The gap it fills

Plenty of teams run their services with Docker Compose on plain hosts rather than Kubernetes. They still want the things Kubernetes-style GitOps gives you: a single declarative description of which version runs where, an auditable history of every version bump, and a one-command path from "a new release exists" to "it is running in the test environment." gantry provides exactly that for the Compose-over-SSH world — config-driven, with no system-specific logic baked in.

Current capabilities

• Consume the latest GitLab Release of each component and parse its embedded release-metadata block (repository:tag, digest, commit, changelog). When the metadata carries a digest, the pin is written as repository:tag@sha256:… so the pulled image cannot drift if the tag is later re-pushed.
• Pin the resolved image references into a per-environment dotenv file and commit the change to git — but only when the pin actually differs (commit-on-diff; re-runs are no-ops).
• Deploy the environment over SSH: write the env file on the host, docker login any referenced private registries, then docker compose pull and up -d.
• Inspect before acting: plan shows pending pin changes without writing, and status shows current pins vs. the latest available releases.

Everything I/O — GitLab HTTP, SSH, git commits — sits behind interfaces, so the core logic is tested without live infrastructure. gantry never shells out at runtime: it uses go-git and golang.org/x/crypto/ssh directly.

Quickstart

# Build the binary
task build            # or: go build -o gantry ./cmd/gantry

export GANTRY_FORGE_TOKEN=glpat-xxxxxxxxxxxxxxxxxxxx

# See what would change, then apply it
./gantry plan   --env test --config gantry.yaml
./gantry sync   --env test --config gantry.yaml

# Compare current pins against the latest releases
./gantry status --env test --config gantry.yaml

A complete, runnable configuration lives in examples/demo — a generic two-component setup that is intentionally unrelated to any specific system, to show that gantry is driven entirely by gantry.yaml.

See docs/getting-started.md for a full walkthrough and docs/configuration.md for the complete config reference.

Roadmap

Current version covers consume → pin → deploy for a single track-mode environment. Planned next:

• Promotion — execute the promote_from env model (copy pins from an upstream environment instead of tracking the forge directly).
• Rollback and drift detection.
• More forges — GitHub releases adapter alongside GitLab.
• More executors — symlink/blue-green deploy strategies.
• Health verification after deploy, notifications, and a status matrix across environments.

License

Released under the MIT License.