sharpit

An embedded, local-only developer console for FastAPI apps. One call mounts a web console at /sharpit and a JSON API at /sharpit/api inside your own app, so a running service becomes understandable in minutes: its configuration and where each value came from, every route, the dependency providers, loggers you can retune live, and a vulnerability scan of the installed packages.

sharpit is a Python/FastAPI port of BootUI by Julien Dubois (Apache-2.0), the Spring Boot developer console. It ports BootUI's design goals, JSON contract and test cases; the UI is new.

Status: alpha (0.1.0, FastAPI only). Django and Flask are not supported. See CHANGELOG.md.

Install

sharpit is not on PyPI yet. Until 0.1.0 is published, install it from git:

pip install "sharpit @ git+https://github.com/ffroliva/sharpit.git"
# or
uv add "sharpit @ git+https://github.com/ffroliva/sharpit.git"

Once published, it is pip install sharpit or uv add sharpit.

Python 3.12+. Runtime dependencies are only starlette>=0.44 and packaging>=23. Optional extras:

Quickstart

from fastapi import FastAPI
import sharpit

app = FastAPI()
sharpit.install(app)  # mounts /sharpit and /sharpit/api

Run it with a dev signal and open http://127.0.0.1:8000/sharpit/:

fastapi dev app.py          # or: uvicorn app:app --reload

To show where your own settings values come from, pass the pydantic-settings instance (or a list of them): sharpit.install(app, settings=Settings()). Other options are keyword arguments, see the table below.

Why does a plain uvicorn app:app give 404?

sharpit is a development tool, so it fails closed. With no reason to be on, every path under /sharpit answers a plain 404 rendered by the host app's own 404 handler. The mount stays in place while inactive, as BootUI's does, so sharpit still owns the paths under it: a host route such as /{user}/... cannot answer for /sharpit/..., and a host with a catch-all or authenticate-first route answers /sharpit/* differently from its other paths (a 404 where it would otherwise send 401), which shows that sharpit is installed. It switches on when the first of these applies:

1. SHARPIT_ENABLED=ON (always on; OFF always off).
2. An active profile is in SHARPIT_ENABLED_PROFILES (default dev,local,development). Profiles are read from the variables in SHARPIT_PROFILE_VARS (default SHARPIT_PROFILES,APP_ENV,ENVIRONMENT), so APP_ENV=dev works.
3. A reloading dev server is detected from the command line: uvicorn ... --reload or fastapi dev.

A profile in SHARPIT_DISABLED_PROFILES (default prod,production) wins over 2 and 3 and switches it off. uvicorn.run(..., reload=True) from a script is not detected: set APP_ENV=dev or SHARPIT_ENABLED=ON.

When sharpit was asked for but ended up off, it logs the reason at WARNING; an explicit OFF or nothing asking for it logs at INFO. When on, it prints a banner on stderr and GET /sharpit/api/overview reports the reason under activation.

Panels

GET /sharpit/api/panels lists what this build offers and why a panel is unavailable or read-only.

MCP for AI agents

The MCP endpoint is off by default. Enable it with SHARPIT_MCP_ENABLED=ON (or install(app, mcp_enabled="ON"), or the switch in the MCP Server panel), then point a streamable-HTTP MCP client at http://127.0.0.1:8000/sharpit/api/mcp (POST only). It exposes read-only tools: get_overview, get_config, get_mappings, get_loggers, get_beans, get_vulnerabilities_report. There is no action tool, so an agent cannot change a logger or start a scan through MCP. The same guard chain and masking apply to it as to the UI.

An agent skill that teaches an AI assistant to install and use sharpit is in skills/sharpit. The sharpit command-line client is planned and not shipped; the /sharpit/api/cli HTTP endpoint is.

Settings

Every setting is an environment variable and an install() keyword. The environment variable wins over the keyword, so a deployment can always force SHARPIT_ENABLED=OFF. An empty value counts as unset. The name rule is SHARPIT_ + the keyword in upper case. An invalid value never raises: that setting takes its fail-safe value (disabled, read-only, masked) and a warning is recorded and shown on the Overview panel. Only an unusable path or api_path raises ValueError, and an unknown keyword raises TypeError with a suggestion. Booleans accept true/false/yes/no/on/off/1/0; durations accept 10s, 500ms or a bare number of seconds.

The first Config load scans your package's source for os.getenv keys and caches the result. On a large application that one-time scan can take several seconds. Set SHARPIT_CONFIG_SCAN=false to skip it, or narrow it to the smaller top-level packages that read settings (SHARPIT_CONFIG_SCAN=billing_config,accounts; a dotted name scans its whole top-level package).

Safety model

• Local only. Requests must come from a loopback address with a loopback or allow-listed Host. If Forwarded, X-Forwarded-For or X-Real-IP is present and no trusted proxy is configured, the caller counts as remote.
• Cross-site requests are refused on every method (Sec-Fetch-Site: cross-site, or, on API paths, an Origin that differs from the request's full origin: scheme, host and port; other paths compare the host), even when your app has CORSMiddleware(allow_origins=["*"]).
• Remote access needs a token. Only loopback, or the container gateway under SHARPIT_TRUST_CONTAINER_GATEWAY=AUTO, with no forwarded header skips the token. Callers admitted by SHARPIT_ALLOW_NON_LOCALHOST=true or by a SHARPIT_TRUSTED_PROXIES address (whose requests may carry a rewritten peer) must present the token as Authorization: Bearer <token>. Set SHARPIT_AUTHENTICATION_TOKEN; otherwise a token is generated per process and printed once to stderr. A browser trades it for an HttpOnly; SameSite=Strict cookie through POST /sharpit/api/auth/session.
• Secrets are masked (******) in values, defaults and suggestions, in API, MCP and CLI output, including pydantic SecretStr. sharpit masks any URL that carries userinfo, including a user name with no password (https://<key>@o1.ingest.sentry.io/1, redis://admin@cache:6379), because DSN-style keys sit in that slot. A harmless user name in a URL is shown as ****** too. That is intentional: sharpit errs towards hiding.
• GET has no side effects. No network call, no file write, no logger change. The vulnerability scan (OSV and EPSS) runs only on an explicit POST.
• Fails closed. When off, or in a prod/production profile (unless SHARPIT_ENABLED=ON forces it on, with a warning), the whole mount answers a plain 404 (see Why does a plain uvicorn app:app give 404? for what that does and does not hide).

Behind a TLS-terminating proxy

The Origin check compares scheme, host and port. If a proxy terminates TLS and forwards plain HTTP, uvicorn must see the original scheme or browser POSTs from the UI are rejected. Start uvicorn with --proxy-headers and --forwarded-allow-ips (or set FORWARDED_ALLOW_IPS) to the proxy's address, and add that address to SHARPIT_TRUSTED_PROXIES. Requests through the proxy still need the token.

Multiple workers and --reload

sharpit keeps its state in the process that serves the request. With uvicorn --workers N, gunicorn or --reload:

• Token. When SHARPIT_ALLOW_NON_LOCALHOST=true and no token is configured, each process generates its own token, so a token printed by one worker is rejected by the others and a reload invalidates the browser session. Set SHARPIT_AUTHENTICATION_TOKEN to a fixed value in these setups.
• MCP switch, logger levels, scan cache. The MCP on/off switch, the last scan result and logger levels changed in the panel live in memory per process, so each worker has its own. Dismissed vulnerability rules are shared because they live in sharpit.yml.

For a dev tool, the simplest setup is one worker.

Deviations from BootUI

sharpit follows BootUI's JSON contract and keeps its guard and masking rules, with deliberate differences (a stricter cross-site check, Python-specific activation, a new UI, deferred features). The log is section 14 of the design spec.

License

Apache License 2.0. See LICENSE and NOTICE. sharpit is derived from BootUI, Copyright Julien Dubois.