New 'datasette plugins' command to list installed plugins

datasette/app.py

@@ -369,7 +369,10 @@ class Datasette:
             },
         }
 
-    def plugins(self):
+    def plugins(self, show_all=False):
+        ps = list(get_plugins(pm))
+        if not show_all:
+            ps = [p for p in ps if p["name"] not in DEFAULT_PLUGINS]
         return [
             {
                 "name": p["name"],
@@ -377,7 +380,7 @@ class Datasette:
                 "templates": p["templates_path"] is not None,
                 "version": p.get("version"),
             }
-            for p in get_plugins(pm) if p["name"] not in DEFAULT_PLUGINS
+            for p in ps
         ]
 
     async def execute(

datasette/cli.py

@@ -159,6 +159,19 @@ def skeleton(files, metadata, sqlite_extensions):
     click.echo("Wrote skeleton to {}".format(metadata))
 
 
+@cli.command()
+@click.option("--all", help="Include built-in default plugins", is_flag=True)
+@click.option(
+    "--plugins-dir",
+    type=click.Path(exists=True, file_okay=False, dir_okay=True),
+    help="Path to directory containing custom plugins",
+)
+def plugins(all, plugins_dir):
+    "List currently available plugins"
+    app = Datasette([], plugins_dir=plugins_dir)
+    click.echo(json.dumps(app.plugins(all), indent=4))
+
+
 @cli.command()
 @click.argument("files", type=click.Path(exists=True), nargs=-1, required=True)
 @click.option(