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user2710603
Asked: 2023-10-19 20:14:08 +0800 CST

ngnix - how to use conditional if with proxy_set_header and rewrite

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Following is my ngnix template which is working fine:

enterapiVersion: networking.k8s.io/v1   
kind: Ingress
metadata:
  annotations:
    nginx.ingress.kubernetes.io/backend-protocol: "HTTPS"
    nginx.ingress.kubernetes.io/proxy-body-size: "15m"
    nginx.ingress.kubernetes.io/configuration-snippet: |
        set $a $http_x_correlation_id;
        set $my_header $request_id;
        proxy_set_header X_Correlation_Id $my_header;   
        rewrite ^/app-name(/|$)(.*) /$2 break;
  name: rtfp-ingress-template
  namespace: rtfp
spec:
  ingressClassName: rtf-nginx
 rules:
  - host: ap.abc.com
    http:
      paths:
      - path: /app-name
        pathType: ImplementationSpecific
        backend:
          service:
            name: service
            port:
              number: 80

But as soon as i introduce a if statement to optionally add header ie. if its not coming from client then header should be added, it fails with 404

nginx.ingress.kubernetes.io/configuration-snippet: |
        set $a $http_x_correlation_id;
        if ($a = ''){
            set $my_header $request_id;
            proxy_set_header X_Correlation_Id $my_header;           
        }        
        rewrite ^/app-name(/|$)(.*) /$2 break;

If this is not possible via configuration-snippet, please let me know what are the steps to achieve it via lua script and any good tutorial for lua script in an ngnix kubernetes environment.

nginx-ingress

1 Answers

  1. Best Answer

    you can achieve conditional behavior using the map module.

    Here's an example of how you can conditionally set the X_Correlation_Id header:

    nginx.ingress.kubernetes.io/configuration-snippet: |
    set $a $http_x_correlation_id;
    set $my_header $request_id;
    if ($a = '') {
        set $my_header "default_value";  # Set a default value when $a is empty
    }
    proxy_set_header X_Correlation_Id $my_header;
    rewrite ^/app-name(/|$)(.*) /$2 break;

    Remember that using if statements can be problematic in Nginx, and it's generally better to use the map module or other configuration options whenever possible

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