Skill Installer (SkillsStore)

Module: ovos_core.skill_installer.SkillsStore

SkillsStore provides runtime skill and package management via the MessageBus. It is enabled by default in ovos-core but can be disabled with --disable-installer.

pip Backend

SkillsStore uses uv pip if uv is on $PATH (default in raspOVOS); otherwise falls back to pip. A named lock (ovos_pip.lock) prevents concurrent installs.

SkillsStore.UV = shutil.which("uv")  # None if not available

Constraints

All installs use a constraints file to avoid dependency conflicts. The default constraints file is fetched from:

https://raw.githubusercontent.com/OpenVoiceOS/ovos-releases/refs/heads/main/constraints-stable.txt

A custom URL can be set in config under skills.installer.constraints.

Configuration

{
  "skills": {
    "installer": {
      "constraints": "https://...",
      "sounds": {
        "pip_error": "snd/error.mp3",
        "pip_success": "snd/acknowledge.mp3"
      }
    }
  }
}

Pip installs can be disabled entirely by not enabling the installer subsystem (default in --disable-installer mode).

Bus Events

Install a skill

ovos.skills.install
  data: {
    "packages": ["ovos-skill-foo"],   # pip package names or URLs
    "constraints": "https://..."      # optional override
  }
  → ovos.skills.install.complete  (success)
  → ovos.skills.install.failed    {"error": "...", "detail": "..."}

Uninstall a skill

ovos.skills.uninstall
  data: {"packages": ["ovos-skill-foo"]}
  → ovos.skills.uninstall.complete
  → ovos.skills.uninstall.failed  {"error": "...", "detail": "..."}

Install arbitrary Python packages

ovos.pip.install
  data: {"packages": ["some-lib>=1.0"]}
  → ovos.pip.install.complete
  → ovos.pip.install.failed  {"error": "...", "detail": "..."}

Uninstall arbitrary Python packages

ovos.pip.uninstall
  data: {"packages": ["some-lib"]}
  → ovos.pip.uninstall.complete
  → ovos.pip.uninstall.failed  {"error": "...", "detail": "..."}

Failure replies

Every .failed reply carries two fields. error is the InstallError value naming the failure (see below); detail is the last FAILURE_DETAIL_CHARS (2000) characters of what pip or uv printed, so a caller can tell "this version is not published yet" from "this dependency conflicts" without reading the service log. detail is an empty string when pip never ran (disabled installer, bad URL, empty package list, protected package).

pip's stdout and stderr are always captured as one stream, whichever backend runs; with print_logs (the default) each line is also echoed through the service log as it arrives, prefixed (pip). A non-zero exit raises RuntimeError carrying the full captured output.

After a successful install, ovos-plugin-manager's entry point cache is reloaded before the .complete message is sent, and SkillManager runs a discovery pass on that message, loading the new skill once it passes the same readiness and connectivity gating the periodic scan applies. The periodic scan (every 30 s) remains the backstop. After a successful uninstall the same reload happens before the .complete message. On that message, SkillManager unloads the skills that are neither discoverable nor declared in installed entry-point metadata: an import failure leaves a still-installed package undiscoverable, and the metadata is what keeps that from unloading it.

Error Types

InstallError	Meaning
DISABLED	pip disabled in config
PIP_ERROR	subprocess returned non-zero
BAD_URL	URL validation failed
NO_PKGS	empty package list

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Cross-References

Constraints file source

Default constraints are served from ovos-releases — the workspace repo that manages stable/testing/alpha constraint channels. See ovos-releases for the constraints file format. Custom constraints can point to any HTTP URL or local path (skills.installer.constraints in mycroft.conf).

Entry point cache reload

After a successful install, ovos_plugin_manager is reloaded via importlib.reload(ovos_plugin_manager) to pick up new entry points. SkillManager runs a discovery pass on ovos.skills.install.complete / ovos.pip.install.complete (or on request via skillmanager.rescan), and its scan loop (every 30 s) is the backstop. See skill-manager.md. See ovos-plugin-manager/docs/index.md.

uv acceleration

uv is a fast pip-compatible installer. It is the default in raspOVOS. If uv is on $PATH, SkillsStore.UV is set and uv pip install is used instead of pip. See the uv documentation for setup.

Configuration

Config is read from mycroft.conf via ovos_config.config.Configuration → ovos-config/docs/configuration.md.

Security note

validate_skill() currently only checks for the https://github.com/ prefix. See SUGGESTIONS.md entry S-003 for the proposed full validation (class compatibility, legacy Mycroft checks).

Full bus events list

See bus-events.md for the complete SkillsStore event reference.

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