How to Make a Web Crawler: Build it from Scratch Tutorial

First, why toss a web crawler?

Engage in data collection is like going to the market to buy food, you can not rely on manual copy and paste it? Especially now that websites haveAccess Frequency MonitoringIf you have too many requests in a row, you will be blocked in a minute.ipipgoSuch a proxy IP service is equivalent to preparing dozens of invisibility cloaks for you, so that you can change your vest without being detected every time you visit.

II. Don't be sloppy in your preparations

First installed Python environment (recommended version 3.8 +), with these libraries is enough to make:

pip install requests
pip install beautifulsoup4
pip install random-user-agent

Focus on the proxy settings, with ipipgo's API to get dynamic IP, remember to register on the official website to get theProprietary Key. Their interface return format is exceptionally simple and understandable by a white person:

{
  "proxy": "123.123.123:8888",
  "expire_time": "2024-03-20 12:00:00"
}

Third, hand-writing core code

Start with a random request header trick to make the site think you're a normal browser:

from fake_useragent import UserAgent
headers = {'User-Agent': UserAgent().random}

Then comes the kicker - proxy settings. Use ipipgo's API to get the latest IP, it's recommended that you get a new IP for each request to be safer:

import requests
def get_proxy(): api_url =
    api_url = "https://api.ipipgo.com/getproxy?key=你的密钥"
    return requests.get(api_url).json()['proxy']

proxies = {
    'http': 'http://'+get_proxy(),
    'https': 'https://'+get_proxy()
}
response = requests.get(target_url, headers=headers, proxies=proxies)

Fourth, to avoid the anti-crawler's tawdry operation

Webmasters are not vegetarians, common anti-climbing means to prevent:

Tested with ipipgo'sAutomatic mode switchingIf you set up a batch of IPs to change every 5 minutes, you can escape 90%'s wind detection.

V. Practical guide to avoiding pitfalls

Three common mistakes newbies make:

1. Not setting the timeout parameter causes the program to crash
2. Forgetting to handle SSL certificate validation
3. IPs are not changed frequently enough to be recognized

It is recommended that requests be made with atimeout=10The parameters, encounter timeout automatically retry. ipipgo IP validity period is recommended to set than the official document said and then shorter 20%, such as the official said that the validity of 5 minutes, we will be 4 minutes to change once.

VI. Quick questions and answers to frequently asked questions

Q: What should I do if my proxy IP suddenly fails?
A: Use ipipgo'sReal-time interface replacementIf you want to use a new IP address, add an exception retry mechanism in the code to automatically change to a new IP address when a connection failure is detected.

Q: What should I do if the collection speed is too slow?
A: Try multithreading with ipipgo'smultichannel IP poolIf you want to use different proxies for different threads, be careful to control the number of concurrencies so that you don't crash the site.

Q: Will I be held legally responsible?
A: Follow robots.txt rules and don't touch sensitive data. Use ipipgo'sCompliance agency servicesThe IPs in their house are all regular server room resources, much more reliable than those wildcards.

VII. Tips for upgrading and fighting monsters

Once you can collect data consistently, try these advanced operations:

• With ipipgo.Location FilteringFunction to specify IP access for specific regions
• Set up an automatic alarm mechanism to send an email reminder when 3 consecutive requests fail
• Collected data automatically stored in the database, recommended MongoDB to deal with unstructured data

Remember that collectors aren't a one and done deal, and site revisions have to be adjusted along with them. Use ipipgo'sIntelligent Routing FunctionBeing able to automatically select the fastest line is much less of a hassle than manual maintenance.