--static option for datasette serve

You can now tell Datasette to serve static files from a specific location at a
specific mountpoint.

For example:

	datasette serve mydb.db --static extra-css:/tmp/static/css

Now if you visit this URL:

	http://localhost:8001/extra-css/blah.css

The following file will be served:

	/tmp/static/css/blah.css

Refs #160

datasette/app.py

@@ -773,7 +773,8 @@ class Datasette:
     def __init__(
             self, files, num_threads=3, cache_headers=True, page_size=100,
             max_returned_rows=1000, sql_time_limit_ms=1000, cors=False,
-            inspect_data=None, metadata=None, sqlite_extensions=None, template_dir=None):
+            inspect_data=None, metadata=None, sqlite_extensions=None,
+            template_dir=None, static_mounts=None):
         self.files = files
         self.num_threads = num_threads
         self.executor = futures.ThreadPoolExecutor(
@@ -789,6 +790,7 @@ def __init__(
         self.sqlite_functions = []
         self.sqlite_extensions = sqlite_extensions or []
         self.template_dir = template_dir
+        self.static_mounts = static_mounts or []
 
     def asset_urls(self, key):
         for url_or_dict in (self.metadata.get(key) or []):
@@ -918,6 +920,8 @@ def app(self):
         # TODO: /favicon.ico and /-/static/ deserve far-future cache expires
         app.add_route(favicon, '/favicon.ico')
         app.static('/-/static/', str(app_root / 'datasette' / 'static'))
+        for path, dirname in self.static_mounts:
+            app.static(path, dirname)
         app.add_route(
             DatabaseView.as_view(self),
             '/<db_name:[^/\.]+?><as_json:(.jsono?)?$>'

datasette/cli.py

@@ -1,6 +1,7 @@
 import click
 from click_default_group import DefaultGroup
 import json
+import os
 import shutil
 from subprocess import call, check_output
 import sys
@@ -140,6 +141,18 @@ def package(files, tag, metadata, extra_options, branch, **extra_metadata):
         call(args)
 
 
+class StaticMount(click.ParamType):
+    name = 'static mount'
+
+    def convert(self, value, param, ctx):
+        if ':' not in value:
+            self.fail('"%s" should be of format mountpoint:directory' % value, param, ctx)
+        path, dirpath = value.split(':')
+        if not os.path.exists(dirpath) or not os.path.isdir(dirpath):
+            self.fail('%s is not a valid directory path' % value, param, ctx)
+        return path, dirpath
+
+
 @cli.command()
 @click.argument('files', type=click.Path(exists=True), nargs=-1)
 @click.option('-h', '--host', default='127.0.0.1', help='host for server, defaults to 127.0.0.1')
@@ -157,7 +170,8 @@ def package(files, tag, metadata, extra_options, branch, **extra_metadata):
 @click.option('--inspect-file', help='Path to JSON file created using "datasette build"')
 @click.option('-m', '--metadata', type=click.File(mode='r'), help='Path to JSON file containing license/source metadata')
 @click.option('-t', '--template-dir', type=click.Path(exists=True, file_okay=False, dir_okay=True), help='Path to directory containing custom templates')
-def serve(files, host, port, debug, reload, cors, page_size, max_returned_rows, sql_time_limit_ms, sqlite_extensions, inspect_file, metadata, template_dir):
+@click.option('-s', '--static', type=StaticMount(), help='mountpoint:path-to-directory for serving static files', multiple=True)
+def serve(files, host, port, debug, reload, cors, page_size, max_returned_rows, sql_time_limit_ms, sqlite_extensions, inspect_file, metadata, template_dir, static):
     """Serve up specified SQLite database files with a web UI"""
     if reload:
         import hupper
@@ -183,6 +197,7 @@ def serve(files, host, port, debug, reload, cors, page_size, max_returned_rows,
         metadata=metadata_data,
         sqlite_extensions=sqlite_extensions,
         template_dir=template_dir,
+        static_mounts=static,
     )
     # Force initial hashing/table counting
     ds.inspect()