Cannot deploy the Django example in the docs

The app I deployed is just the simplest django example in docs. The error message is:

Blockquote
(django_env) PS E:\OneDrive - zju.edu.cn\Python Projects\Django Projects\demo> fly deploy
==> Verifying app config
→ Verified app config
==> Building image
Remote builder fly-builder-holy-flower-7997 ready
==> Creating build context
→ Creating build context done
==> Building image with Docker
→ docker host: 20.10.12 linux x86_64
Sending build context to Docker daemon 5.409kB
[+] Building 1.5s (10/10) FINISHED
=> CACHED [internal] load remote build context 0.0s
=> CACHED copy /context / 0.0s
=> [internal] load metadata for Docker 0.5s
=> [1/7] FROM Docker 0.0s
=> CACHED [2/7] RUN mkdir -p /code 0.0s
=> CACHED [3/7] WORKDIR /code 0.0s
=> CACHED [4/7] COPY requirements.txt /tmp/requirements.txt 0.0s
=> CACHED [5/7] RUN set -ex && pip install --upgrade pip && pip install -r /tmp/requirements.txt && rm -rf /root/.cache/ 0.0s
=> CACHED [6/7] COPY . /code/ 0.0s
=> ERROR [7/7] RUN python manage.py collectstatic --noinput 1.0s


[7/7] RUN python manage.py collectstatic --noinput:
#10 0.950 Traceback (most recent call last):
#10 0.950 File “/code/manage.py”, line 22, in
#10 0.950 main()
#10 0.950 File “/code/manage.py”, line 18, in main
#10 0.950 execute_from_command_line(sys.argv)
#10 0.950 File “/usr/local/lib/python3.10/site-packages/django/core/management/init.py”, line 446, in execute_from_command_line
#10 0.950 utility.execute()
#10 0.950 File “/usr/local/lib/python3.10/site-packages/django/core/management/init.py”, line 440, in execute
#10 0.950 self.fetch_command(subcommand).run_from_argv(self.argv)
#10 0.950 File “/usr/local/lib/python3.10/site-packages/django/core/management/base.py”, line 402, in run_from_argv
#10 0.950 self.execute(*args, **cmd_options)
#10 0.950 File “/usr/local/lib/python3.10/site-packages/django/core/management/base.py”, line 448, in execute
#10 0.951 output = self.handle(*args, **options)
#10 0.951 File “/usr/local/lib/python3.10/site-packages/django/contrib/staticfiles/management/commands/collectstatic.py”, line 209, in handle
#10 0.951 collected = self.collect()
#10 0.951 File “/usr/local/lib/python3.10/site-packages/django/contrib/staticfiles/management/commands/collectstatic.py”, line 135, in collect
#10 0.951 handler(path, prefixed_path, storage)
#10 0.951 File “/usr/local/lib/python3.10/site-packages/django/contrib/staticfiles/management/commands/collectstatic.py”, line 368, in copy_file
#10 0.951 if not self.delete_file(path, prefixed_path, source_storage):
#10 0.951 File “/usr/local/lib/python3.10/site-packages/django/contrib/staticfiles/management/commands/collectstatic.py”, line 278, in delete_file
#10 0.951 if self.storage.exists(prefixed_path):
#10 0.951 File “/usr/local/lib/python3.10/site-packages/django/core/files/storage.py”, line 373, in exists
#10 0.951 return os.path.lexists(self.path(name))
#10 0.951 File “/usr/local/lib/python3.10/site-packages/django/contrib/staticfiles/storage.py”, line 39, in path
#10 0.951 raise ImproperlyConfigured(
#10 0.951 django.core.exceptions.ImproperlyConfigured: You’re using the staticfiles app without having set the STATIC_ROOT setting to a filesystem path.

Error failed to fetch an image or build from source: error building: executor failed running [/bin/sh -c python manage.py collectstatic --noinput]: exit code: 1

The error in the last line was suspicious.

Did you set STATIC_ROOT?