Static Files - StaticFiles

You can use the StaticFiles class to serve static files, like JavaScript, CSS, images, etc.

Read more about it in the FastAPI docs for Static Files.

You can import it directly from fastapi.staticfiles:

from fastapi.staticfiles import StaticFiles

fastapi.staticfiles.StaticFiles

StaticFiles(
    *,
    directory=None,
    packages=None,
    html=False,
    check_dir=True,
    follow_symlink=False
)

PARAMETER	DESCRIPTION
directory	TYPE: PathLike | None DEFAULT: None
packages	TYPE: list[str | tuple[str, str]] | None DEFAULT: None
html	TYPE: bool DEFAULT: False
check_dir	TYPE: bool DEFAULT: True
follow_symlink	TYPE: bool DEFAULT: False

Source code in starlette/staticfiles.py

def __init__(
    self,
    *,
    directory: PathLike | None = None,
    packages: list[str | tuple[str, str]] | None = None,
    html: bool = False,
    check_dir: bool = True,
    follow_symlink: bool = False,
) -> None:
    self.directory = directory
    self.packages = packages
    self.all_directories = self.get_directories(directory, packages)
    self.html = html
    self.config_checked = False
    self.follow_symlink = follow_symlink
    if check_dir and directory is not None and not os.path.isdir(directory):
        raise RuntimeError(f"Directory '{directory}' does not exist")

directory instance-attribute

directory = directory

packages instance-attribute

packages = packages

all_directories instance-attribute

all_directories = get_directories(directory, packages)

html instance-attribute

html = html

config_checked instance-attribute

config_checked = False

follow_symlink instance-attribute

follow_symlink = follow_symlink

get_directories

get_directories(directory=None, packages=None)

Given directory and packages arguments, return a list of all the directories that should be used for serving static files from.

PARAMETER	DESCRIPTION
directory	TYPE: PathLike | None DEFAULT: None
packages	TYPE: list[str | tuple[str, str]] | None DEFAULT: None

Source code in starlette/staticfiles.py

def get_directories(
    self,
    directory: PathLike | None = None,
    packages: list[str | tuple[str, str]] | None = None,
) -> list[PathLike]:
    """
    Given `directory` and `packages` arguments, return a list of all the
    directories that should be used for serving static files from.
    """
    directories = []
    if directory is not None:
        directories.append(directory)

    for package in packages or []:
        if isinstance(package, tuple):
            package, statics_dir = package
        else:
            statics_dir = "statics"
        spec = importlib.util.find_spec(package)
        assert spec is not None, f"Package {package!r} could not be found."
        assert spec.origin is not None, f"Package {package!r} could not be found."
        package_directory = os.path.normpath(os.path.join(spec.origin, "..", statics_dir))
        assert os.path.isdir(
            package_directory
        ), f"Directory '{statics_dir!r}' in package {package!r} could not be found."
        directories.append(package_directory)

    return directories

get_path

get_path(scope)

Given the ASGI scope, return the path string to serve up, with OS specific path separators, and any '..', '.' components removed.

PARAMETER	DESCRIPTION
scope	TYPE: Scope

Source code in starlette/staticfiles.py

def get_path(self, scope: Scope) -> str:
    """
    Given the ASGI scope, return the `path` string to serve up,
    with OS specific path separators, and any '..', '.' components removed.
    """
    route_path = get_route_path(scope)
    return os.path.normpath(os.path.join(*route_path.split("/")))

get_response async

get_response(path, scope)

Returns an HTTP response, given the incoming path, method and request headers.

PARAMETER	DESCRIPTION
path	TYPE: str
scope	TYPE: Scope

Source code in starlette/staticfiles.py

async def get_response(self, path: str, scope: Scope) -> Response:
    """
    Returns an HTTP response, given the incoming path, method and request headers.
    """
    if scope["method"] not in ("GET", "HEAD"):
        raise HTTPException(status_code=405)

    try:
        full_path, stat_result = await anyio.to_thread.run_sync(self.lookup_path, path)
    except PermissionError:
        raise HTTPException(status_code=401)
    except OSError as exc:
        # Filename is too long, so it can't be a valid static file.
        if exc.errno == errno.ENAMETOOLONG:
            raise HTTPException(status_code=404)

        raise exc

    if stat_result and stat.S_ISREG(stat_result.st_mode):
        # We have a static file to serve.
        return self.file_response(full_path, stat_result, scope)

    elif stat_result and stat.S_ISDIR(stat_result.st_mode) and self.html:
        # We're in HTML mode, and have got a directory URL.
        # Check if we have 'index.html' file to serve.
        index_path = os.path.join(path, "index.html")
        full_path, stat_result = await anyio.to_thread.run_sync(self.lookup_path, index_path)
        if stat_result is not None and stat.S_ISREG(stat_result.st_mode):
            if not scope["path"].endswith("/"):
                # Directory URLs should redirect to always end in "/".
                url = URL(scope=scope)
                url = url.replace(path=url.path + "/")
                return RedirectResponse(url=url)
            return self.file_response(full_path, stat_result, scope)

    if self.html:
        # Check for '404.html' if we're in HTML mode.
        full_path, stat_result = await anyio.to_thread.run_sync(self.lookup_path, "404.html")
        if stat_result and stat.S_ISREG(stat_result.st_mode):
            return FileResponse(full_path, stat_result=stat_result, status_code=404)
    raise HTTPException(status_code=404)

lookup_path

lookup_path(path)

PARAMETER	DESCRIPTION
path	TYPE: str

Source code in starlette/staticfiles.py

def lookup_path(self, path: str) -> tuple[str, os.stat_result | None]:
    for directory in self.all_directories:
        joined_path = os.path.join(directory, path)
        if self.follow_symlink:
            full_path = os.path.abspath(joined_path)
        else:
            full_path = os.path.realpath(joined_path)
        directory = os.path.realpath(directory)
        if os.path.commonpath([full_path, directory]) != directory:
            # Don't allow misbehaving clients to break out of the static files
            # directory.
            continue
        try:
            return full_path, os.stat(full_path)
        except (FileNotFoundError, NotADirectoryError):
            continue
    return "", None

file_response

file_response(
    full_path, stat_result, scope, status_code=200
)

PARAMETER	DESCRIPTION
full_path	TYPE: PathLike
stat_result	TYPE: stat_result
scope	TYPE: Scope
status_code	TYPE: int DEFAULT: 200

Source code in starlette/staticfiles.py

def file_response(
    self,
    full_path: PathLike,
    stat_result: os.stat_result,
    scope: Scope,
    status_code: int = 200,
) -> Response:
    request_headers = Headers(scope=scope)

    response = FileResponse(full_path, status_code=status_code, stat_result=stat_result)
    if self.is_not_modified(response.headers, request_headers):
        return NotModifiedResponse(response.headers)
    return response

check_config async

check_config()

Perform a one-off configuration check that StaticFiles is actually pointed at a directory, so that we can raise loud errors rather than just returning 404 responses.

Source code in starlette/staticfiles.py

async def check_config(self) -> None:
    """
    Perform a one-off configuration check that StaticFiles is actually
    pointed at a directory, so that we can raise loud errors rather than
    just returning 404 responses.
    """
    if self.directory is None:
        return

    try:
        stat_result = await anyio.to_thread.run_sync(os.stat, self.directory)
    except FileNotFoundError:
        raise RuntimeError(f"StaticFiles directory '{self.directory}' does not exist.")
    if not (stat.S_ISDIR(stat_result.st_mode) or stat.S_ISLNK(stat_result.st_mode)):
        raise RuntimeError(f"StaticFiles path '{self.directory}' is not a directory.")

is_not_modified

is_not_modified(response_headers, request_headers)

Given the request and response headers, return True if an HTTP "Not Modified" response could be returned instead.

PARAMETER	DESCRIPTION
response_headers	TYPE: Headers
request_headers	TYPE: Headers

Source code in starlette/staticfiles.py

def is_not_modified(self, response_headers: Headers, request_headers: Headers) -> bool:
    """
    Given the request and response headers, return `True` if an HTTP
    "Not Modified" response could be returned instead.
    """
    try:
        if_none_match = request_headers["if-none-match"]
        etag = response_headers["etag"]
        if etag in [tag.strip(" W/") for tag in if_none_match.split(",")]:
            return True
    except KeyError:
        pass

    try:
        if_modified_since = parsedate(request_headers["if-modified-since"])
        last_modified = parsedate(response_headers["last-modified"])
        if if_modified_since is not None and last_modified is not None and if_modified_since >= last_modified:
            return True
    except KeyError:
        pass

    return False