Scrapy script does not start spiders

I have created a new scrapy projects with a spider (multiple to be added). The spider works without any issues if started with

scrapy crawl myspider

However, when I try to run the scraper from a custom script, it does not start. I have broken down the script to a bare minimum that does not work:

from scrapy.spiderloader import SpiderLoader
from scrapy.crawler import CrawlerRunner
from scrapy.utils.project import get_project_settings
from scrapy.utils.log import configure_logging
from twisted.internet import reactor

settings = get_project_settings()
configure_logging(settings)
runner = CrawlerRunner(settings)
spider_loader = SpiderLoader.from_settings(settings)
for spider in spider_loader.list():
    print(f"Adding Spider: {spider}")
    runner.crawl(spider_loader.load(spider))

d = runner.join()
d.addBoth(lambda _: reactor.stop())
reactor.run()

The output of the script is:

$ python3 minimal.py
Adding Spider: myspider
2024-12-06 14:52:02 [scrapy.addons] INFO: Enabled addons:
[]

The script than hangs, and no additional messages from the spider are printed. I confirmed that no network traffic related to crawling is observed. The code is very close to the documentation, so I am little bit clueless on what the problem could be and where to look.

Edit:

This is a minimal crawler that does not run:

import scrapy


class GoogleSpider(scrapy.Spider):
    name = "google"
    allowed_domains = ["google.com"]
    start_urls = ["https://www.google.com"]

    def parse(self, response):
        pass

# Scrapy settings for fwscraper project
#
# For simplicity, this file contains only settings considered important or
# commonly used. You can find more settings consulting the documentation:
#
#     https://docs.scrapy.org/en/latest/topics/settings.html
#     https://docs.scrapy.org/en/latest/topics/downloader-middleware.html
#     https://docs.scrapy.org/en/latest/topics/spider-middleware.html

BOT_NAME = "fwscraper"

SPIDER_MODULES = ["fwscraper.spiders"]
NEWSPIDER_MODULE = "fwscraper.spiders"


# Crawl responsibly by identifying yourself (and your website) on the user-agent
#USER_AGENT = "fwscraper (+http://www.yourdomain.com)"

# Obey robots.txt rules
ROBOTSTXT_OBEY = True

# Configure maximum concurrent requests performed by Scrapy (default: 16)
#CONCURRENT_REQUESTS = 32

# Configure a delay for requests for the same website (default: 0)
# See https://docs.scrapy.org/en/latest/topics/settings.html#download-delay
# See also autothrottle settings and docs
#DOWNLOAD_DELAY = 3
# The download delay setting will honor only one of:
#CONCURRENT_REQUESTS_PER_DOMAIN = 16
#CONCURRENT_REQUESTS_PER_IP = 16

# Disable cookies (enabled by default)
#COOKIES_ENABLED = False

# Disable Telnet Console (enabled by default)
#TELNETCONSOLE_ENABLED = False

# Override the default request headers:
#DEFAULT_REQUEST_HEADERS = {
#    "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
#    "Accept-Language": "en",
#}

# Enable or disable spider middlewares
# See https://docs.scrapy.org/en/latest/topics/spider-middleware.html
#SPIDER_MIDDLEWARES = {
#    "fwscraper.middlewares.FwscraperSpiderMiddleware": 543,
#}

# Enable or disable downloader middlewares
# See https://docs.scrapy.org/en/latest/topics/downloader-middleware.html
#DOWNLOADER_MIDDLEWARES = {
#    "fwscraper.middlewares.FwscraperDownloaderMiddleware": 543,
#}

# Enable or disable extensions
# See https://docs.scrapy.org/en/latest/topics/extensions.html
#EXTENSIONS = {
#    "scrapy.extensions.telnet.TelnetConsole": None,
#}

# Configure item pipelines
# See https://docs.scrapy.org/en/latest/topics/item-pipeline.html
#ITEM_PIPELINES = {
#    "fwscraper.pipelines.FwscraperPipeline": 300,
#}

# Enable and configure the AutoThrottle extension (disabled by default)
# See https://docs.scrapy.org/en/latest/topics/autothrottle.html
#AUTOTHROTTLE_ENABLED = True
# The initial download delay
#AUTOTHROTTLE_START_DELAY = 5
# The maximum download delay to be set in case of high latencies
#AUTOTHROTTLE_MAX_DELAY = 60
# The average number of requests Scrapy should be sending in parallel to
# each remote server
#AUTOTHROTTLE_TARGET_CONCURRENCY = 1.0
# Enable showing throttling stats for every response received:
#AUTOTHROTTLE_DEBUG = False

# Enable and configure HTTP caching (disabled by default)
# See https://docs.scrapy.org/en/latest/topics/downloader-middleware.html#httpcache-middleware-settings
#HTTPCACHE_ENABLED = True
#HTTPCACHE_EXPIRATION_SECS = 0
#HTTPCACHE_DIR = "httpcache"
#HTTPCACHE_IGNORE_HTTP_CODES = []
#HTTPCACHE_STORAGE = "scrapy.extensions.httpcache.FilesystemCacheStorage"

# Set settings whose default value is deprecated to a future-proof value
TWISTED_REACTOR = "twisted.internet.asyncioreactor.AsyncioSelectorReactor"
FEED_EXPORT_ENCODING = "utf-8"

Solution

You requested a non-default reactor in your settings so you need to install it explicitly when using CrawlerRunner (this is mentioned in https://docs.scrapy.org/en/latest/topics/asyncio.html#installing-the-asyncio-reactor). You also need to do it before importing twisted.internet.reactor as that installs the default reactor (this is mentioned in https://docs.scrapy.org/en/latest/topics/asyncio.html#handling-a-pre-installed-reactor). A correct code example is shown in https://docs.scrapy.org/en/latest/topics/practices.html#run-scrapy-from-a-script:

import scrapy
from scrapy.crawler import CrawlerRunner
from scrapy.utils.reactor import install_reactor

install_reactor("twisted.internet.asyncioreactor.AsyncioSelectorReactor")
runner = CrawlerRunner()
d = runner.crawl(MySpider)

from twisted.internet import reactor

d.addBoth(lambda _: reactor.stop())
reactor.run()