So this is embarrassing. I've put together an app in Flask and currently it just serves a static HTML page with some links to CSS and JS. I can't find a place in the documentation for Flask that describes returning static files. Yes, I can use render_template but I know the data is not templated. I think send_file or url_for are correct, but I can't get them to work. In the meantime, I open the file, read the contents, and set the Response using the appropriate mimetype:
import os.path from flask import Flask, Response app = Flask(__name__) app.config.from_object(__name__) def root_dir(): # pragma: no cover return os.path.abspath(os.path.dirname(__file__)) def get_file(filename): # pragma: no cover try: src = os.path.join(root_dir(), filename) # Figure out how flask returns static files #Tried: # - render_template # - send_file # This should not be so non-obvious return open(src).read() except IOError as exc: return str(exc) @app.route('/', methods=['GET']) def metrics(): # pragma: no cover content = get_file('jenkins_analytics.html') return Response(content, mimetype="text/html") @app.route('/', defaults={'path': ''}) @app.route('/') def get_resource(path): # pragma: no cover mimetypes = { ".css": "text/css", ".html": "text/html", ".js": "application/javascript", } complete_path = os.path.join(root_dir(), path) ext = os.path.splitext(path)[1] mimetype = mimetypes.get(ext, "text/html") content = get_file(complete_path) return Response(content, mimetype=mimetype) if __name__ == '__main__': # pragma: no cover app.run(port=80) Does anyone want to provide a code sample or URL for this? I knew it would be very simple.
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If you just want to move the location of the static files, the easiest way is to declare the path in the constructor. In the example below, I've moved the templates and static files into a subfolder called
web.static_url_path=''Remove all preceding paths from the URL.static_folder='web/static'Serves any files found in the folderweb/staticAs a static file.template_folder='web/templates'Similarly, this changes Template folder.Using this method, the following URL will return the CSS file:
Finally, here is a snapshot of the folder structure, where
flask_server.pyis the Flask instance:In production, configure an HTTP server (Nginx, Apache, etc.) in front of the application to handle
/staticrequests from the static folder. Dedicated web servers are very good at serving static files efficiently, although at low volumes you may not notice the difference compared to Flask.Flask will automatically create a
/static/route that will serve anyfilenameunder thestaticfolder next to Python Modules that define Flask applications. Useurl_forto link to static files:url_for('static', filename='js/analytics.js')You can also use
send_from_directoryto serve files from a directory in your own route. This takes a base directory and a path, and ensures that the path is contained within that directory so that user-supplied paths can be safely accepted. This can be useful if you want to check something before serving the file, such as whether the logged in user has permissions.from flask import send_from_directory @app.route('/reports/') def send_report(path): return send_from_directory('reports', path) Do notuse
send_fileorsend_static_filewith a user-supplied path. This will expose you to adirectory traversal attack.send_from_directoryDesigned to safely handle user-supplied paths to known directories, raising an error if the path attempts to escape the directory.If you are generating the file in memory without writing it to the file system, you can provide it as a file by passing a
BytesIOobject tosend_file. In this case you need to pass additional parameters tosend_fileas it cannot infer things like filename or content type.