In NGINX, the if directive is a powerful yet somewhat limited tool. One of its key limitations is the inability to evaluate multiple conditions directly within a single if statement. This is because the if directive in NGINX is not a full-fledged programming construct but rather a directive designed for simple conditional logic. As a result, NGINX does not support logical operators like AND or OR to combine multiple conditions in a single if. This limitation often leads to challenges when configuring complex logic, requiring creative workarounds or alternative approaches to achieve the desired functionality.
I was recently tasked with implementing a redirect in NGINX based on two conditions: the request had to come from a specific domain and match a specific URL path. Initially, I tried to solve this by combining the two conditions in a single if statement, like this:
if ($host = "target.domain.com" && $request_uri = "/") {
return 301 https://target.domain.com/sub/url;
}
However, this approach failed because NGINX doesn’t support combining multiple conditions directly within a single if block using logical operators like &&.
The solution was surprisingly simple. Instead of comparing multiple conditions directly, I created a new variable by concatenating the $host and $request_uri values using the set directive. Then, I used a single if block to compare this new variable against the desired value:
nginx.ingress.kubernetes.io/server-snippet: |
set $host_uri "${host}${request_uri}";
if ($host_uri = "target.domain.com/") {
return 301 https://target.domain.com/sub/url;
}
This workaround leverages NGINX’s flexibility with variables and avoids the limitations of its if directive, resulting in a clean and functional solution.