devvm

One frontend for persistent dev boxes, whatever the transport — a local smolvm microVM or a remote host reached over ssh. A Go rewrite of the old bin/devvm bash script.

Module: github.com/smweber/devvm.

A machine's backend says who owns it and how it's reached:

Managed backends (smol, remote-managed) are devvm's to shape — it installs prereqs, can harden, and manages known_hosts. Unmanaged (remote-unmanaged) is an adopted host: devvm never modifies its OS, only checks prereqs and edits the user's own ~/.ssh/authorized_keys. Old confs with backend = "ssh" (+ optional unmanaged) migrate on load. (hetzner, an API-provisioned managed backend over the ssh transport, is the planned next backend.)

• devvm create NAME — create/adopt any backend. Flags drive it non-interactively (--backend, --memory, --ssh-host, --transport, …); a terminal prompts (via huh) for whatever's unset.
• devvm attach NAME — join the persistent dev tmux session.
• devvm shell NAME — a raw login shell, no tmux.
• Both take --transport ssh|mosh for remote machines (default from the conf's transport field); smol ignores it. (There is no separate ssh/mosh command.)

go build ./...            # everything
go test ./...             # unit tests (forwards, daemon, keys, config, auth)
go build -o ~/.local/bin/devvm ./cmd/devvm   # install the host CLI

bootstrap.sh (host profile) does the last step for you.

cmd/devvm/          host CLI entrypoint
cmd/devvm-agent/    guest agent: serve (forwards+rpc+events) | open-url
internal/cli/       cobra command tree (+ create's huh form)
internal/config/    TOML machine registry (~/.config/devvm/machines/<name>.toml)
internal/backend/   Backend interface + smol.go + ssh.go (both remote-* backends)
internal/session/   per-machine forward daemon (owns the one exec) + client
internal/agentrpc/  yamux stream protocol (forward / rpc / event) shared host+guest
internal/agentbin/  embedded, cross-compiled guest agent binaries (go:embed)
internal/keys/      authorized_keys logic (dedup / revoke / list), host-side, was awk
internal/auth/      login orchestration, URL bridge, callback-as-forward
internal/bootstrap/ prereqs (install on managed / check on adopt) + bootstrap-hook + hardening
internal/hostbrowser/ open guest login URLs on the host (sanitized)

smolvm has poor concurrency across separate machine exec sessions, so every forward, rpc, and auth event for a machine rides a single persistent devvm-agent serve exec, multiplexed with yamux. This is why the session daemon exists (it owns that exec for the machine's lifetime) and why forwards are yamux streams for smol. ssh has no such limit, so its forwards are native -L on a ControlMaster; only the agent's rpc/events ride the exec. authorized_keys management runs host-side (internal/keys over one plain exec), so it needs no agent — which is what lets keys work on an adopt host with zero footprint.

internal/agentbin/bin/devvm-agent-linux-{amd64,arm64} are cross-compiled and committed, then go:embed-ed into the host binary so go install …@latest yields a self-contained artifact. Guests must be Linux: anything needing the agent (auth, smol forwards) fails early with a clear error on other OSes, while agent-free commands (shell, attach, exec, keys, ssh forwards) work on any remote with an sshd. Regenerate after changing cmd/devvm-agent:

./build.sh

go install github.com/smweber/devvm/cmd/devvm@latest resolves the module from the repo named by its module path (go.mod), at the repo root. Publishing is just tagging a release:

git tag v0.1.0 && git push --tags