base_url configuration setting

I’ve identified a couple of use-cases for running Datasette in a way that over-rides the default way that internal URLs are generated.

1. Running behind a reverse proxy. I tried running Datasette behind a proxy and found that some of the generated internal links incorrectly referenced http://127.0.0.1:8001/fixtures/... - when they should have been referencing http://my-host.my-domain.com/fixtures/... - this is a problem both for links within the HTML interface but also for the toggle_url keys returned in the JSON as part of the facets datastructure.
2. I would like it to be possible to host a Datasette instance at e.g. https://www.mynewspaper.com/interactives/2018/election-results/ - either through careful HTTP proxying or, once Datasette has been ported to ASGI, by mounting a Datasette ASGI instance deep within an existing set of URL routes.

I’m going to add a url_prefix configuration option. This will default to "", which means Datasette will behave as it does at the moment - it will use / for most URL prefixes in the HTML version, and an absolute URL derived from the incoming Host header for URLs that are returned as part of the JSON output.

If url_prefix is set to another value (either a full URL or a path) then this path will be appended to all generated URLs.

[LVerneyPEReN]

Hi @wragge,

This looks great, thanks for the share! I refactored it into a self-contained function, binding on a random available TCP port (multi-user context). I am using subprocess API directly since the %run magic was leaving defunct process behind 😕

import socket

from signal import SIGINT
from subprocess import Popen, PIPE

from IPython.display import display, HTML
from notebook.notebookapp import list_running_servers


def get_free_tcp_port():
    """
    Get a free TCP port.
    """
    tcp = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    tcp.bind(('', 0))
    _, port = tcp.getsockname()
    tcp.close()
    return port


def datasette(database):
    """
    Run datasette on an SQLite database.
    """
    # Get current running servers
    servers = list_running_servers()

    # Get the current base url
    base_url = next(servers)['base_url']

    # Get a free port
    port = get_free_tcp_port()

    # Create a base url for Datasette suing the proxy path
    proxy_url = f'{base_url}proxy/absolute/{port}/'

    # Display a link to Datasette
    display(HTML(f'<p><a href="{proxy_url}">View Datasette</a> (Click on the stop button to close the Datasette server)</p>'))

    # Launch Datasette
    with Popen(
        [
            'python', '-m', 'datasette', '--',
            database,
            '--port', str(port),
            '--config', f'base_url:{proxy_url}'
        ],
        stdout=PIPE,
        stderr=PIPE,
        bufsize=1,
        universal_newlines=True
    ) as p:
        print(p.stdout.readline(), end='')
        while True:
            try:
                line = p.stderr.readline()
                if not line:
                    break
                print(line, end='')
                exit_code = p.poll()
            except KeyboardInterrupt:
                p.send_signal(SIGINT)

Ideally, I’d like some extra magic to notify users when they are leaving the closing the notebook tab and make them terminate the running datasette processes. I’ll be looking for it.

[simonw]

Shipped in 0.39: https://datasette.readthedocs.io/en/latest/changelog.html#v0-39