How to resolve the issue of proxy_pass not working in nginx?

If the proxy_pass directive in Nginx isn’t working, it could be due to several reasons and there are possible solutions for each.

1. Check the upstream configuration: First, make sure the upstream configuration in the proxy_pass directive is correct. You can verify the upstream configuration by checking the configuration of the parent location or server block in the Nginx configuration file that contains the proxy_pass directive.
2. Check DNS resolution: If the proxy_pass points to a domain name instead of an IP address, there may be a DNS resolution issue. You can try using the IP address instead of the domain name for testing to ensure that proxy_pass can correctly access the target service.
3. Check if the proxy service is available: Make sure that the target service pointed to by the proxy_pass is running and able to respond to requests properly. You can test if the target service can be accessed correctly by directly accessing its IP address and port.
4. Check firewall settings: If the target service that proxy_pass points to is restricted by a firewall or other network devices, it may result in being unable to access it. Verify the firewall rules of the target service to ensure that the Nginx server can access it.
5. Check for syntax errors in the Nginx configuration file: Make sure there are no syntax errors in the Nginx configuration file. You can use the command nginx -t to check if the syntax of the configuration file is correct. If there are syntax errors, you will need to correct them and reload the Nginx configuration.
6. Check for other Nginx configuration directives: Occasionally, other Nginx configuration directives may affect the effectiveness of proxy_pass. You can systematically examine other related configuration directives to ensure they do not override or interfere with the functionality of the proxy_pass directive.

If the above methods fail to solve the problem, you can provide more details and error logs based on the actual situation in order to more accurately pinpoint the problem.