Day: November 18, 2021

Replace Contents in NGINX

Posted on by Bian Xi Leave a Comment on Replace Contents in NGINX

Replace Contents in NGINX

The content of a webpage contains URL or other information need to be replaced, especially when domain name changed in URL.

sub_filter

Use sub_filter module in NGINX to replace content.

For example,

server {
    ```
    location / {
        sub_filter 'www.example.com' 'www.xx.example.com';
        sub_filter_once on;

        proxy_pass  http://www.example.com;
        proxy_next_upstream error timeout invalid_header http_500 http_502 http_503 http_504;
        proxy_redirect off;
        proxy_buffering off;
        proxy_set_header        Host            $host;
        proxy_set_header        X-Real-IP       $remote_addr;
        proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
   }
}

Note: Place sub_filter at beginning of the location session

If required, also need to change host to allow server decide which page requested if it is also a NGINX server and displays page depending on the host as well.

proxy_set_header        Host            www.example.com;

References

Module ngx_http_sub_module
http_sub_module / sub_filter of nginx and reverse proxy not working

Add a website to Google

Posted on by Bian Xi Leave a Comment on Add a website to Google

Add a website to Google

To allow Google search a website.

Allow search engine

In WordPress, to allow search engine indexing

  • Settings => Reading
  • Uncheck Discourage search engines from indexing this site

Allow Google discovery

Verify

  • Visit site:your_website in google.com

If indexed, then will return result.

References

WordPress Help
How to add a website to Google: All you need to know

Using wildcard DNS record

Posted on by Bian Xi Leave a Comment on Using wildcard DNS record

Using wildcard DNS record

Using wildcard in DNS A or CNAME can reduce maintenance work, but this also has some drawback.

Pros

Updating DNS will take time, not only needs time to edit DNS entries, but also the DNS broadcast time, which can take more than 30 minutes to update an existing entry in other DNS server, and some DNS server can take even longer.

If use widecard, there is no editing requirement.

Cons

Search suffix

If /etc/resolv.conf has entry as below

search example.com

When searching for google.com, It might hit google.com.example.com if wildcard used, because google.com.example.com will return IP address as same as example.com.

Caching

Without editing entry, the some DNS servers might still caching old data. For example, if you have both wildcard *.example.com and a specific entry ftp.example.com, and you decided to remove ftp.example.com, the wildcard might not take effect.

Accessing non-exist domain

If using browser access undefined domain name, and hit the web server, using NGINX can perform redirect to change URL. This can fix the issues which web coding based on current URL.

server {
    listen 80;
    server_name *.mywebsite.tld;
    return 301 $scheme://mywebsite.tld$request_uri;
    }

server {
    listen  80;
    server_name mywebsite.tld;
    [...]
    }

References

Is a wildcard DNS record bad practice?