I have the following in my config as a reverse proxy for images:
location ~ ^/image/(.+) {
proxy_pass http://example.com/$1;
}
The problem is that not all images will be example.com images and so we need to pass in the full url. If I try:
location ~ ^/image/(.+) {
proxy_pass $1;
}
I get an error:
invalid URL prefix in "https:/somethingelse.com/someimage.png"
The question is quite vague, but, based on the error message, what you're trying to do is perform a proxy_pass entirely based on the user input, by using the complete URL specified after the /image/ prefix of the URI.
Basically, this is a very bad idea, as you're opening yourself to become an open proxy. However, the reason it doesn't work as in the conf you supplied is due to URL normalisation, which, in your case, compacts http://example into http:/example (double slash becomes single), which is different in the context of proxy_pass.
If you don't care about security, you can just change merge_slashes from the default of on to off:
merge_slashes off;
location …
Another possibility is to somewhat related to nginx proxy_pass and URL decoding
location ~ ^/image/.+ {
rewrite ^ $request_uri;
rewrite ^/image/(.*) $1 break;
return 400;
proxy_pass $uri; # will result in an open-proxy, don't try at home
}
The proper solution would be to implement a whitelist, possibly with the help of map or even prefix-based location directives:
location ~ ^/image/(http):/(upload.example.org)/(.*) {
proxy_pass $1://$2/$3;
}
Do note that, as per the explanation in the begginning, the location above is subject to the merge_slash setting, so, it'll never have the double // by default, hence the need to add the double // manually at the proxy_pass stage.
I would use a map in this case
map $request_uri $proxied_url {
# if you don't care about domain and file extension
~*/image/(https?)://?(.*) $1://$2;
# if you want to limit file extension
~*/image/(https?)://?(.*\.(png|jpg|jpeg|ico))$ $1://$2;
# if you want to limit file extension and domain
~*/image/(https?)://?(abc\.xyz\.com/)(.*\.(png|jpg|jpeg|ico))$ $1://$2$3;
default "/404";
}
Then in your proxy pass part you would use something like below
location /image/ {
proxy_pass $proxied_url;
}
I have given three different example depending how you want to handle it
Related
So usually when creating a nginx location it would look something like this:
location /foo/ {
proxy_pass http://example.com/;
}
With this setup, requests to /foo/bar are forwarded to http://example.com/bar which is the intended behavior.
However when trying to prevent caching of the domain name example.com or when trying to prevent nginx from crashing if the upstream host is unavailable at startup the only solution seems to be to not use the target directly in the proxy_pass directive, but to instead create a variable containing the target like this:
location /foo/ {
set $targetUri http://example.com/;
proxy_pass $targetUri;
}
But this totally changes the setup. As soon as proxy_pass contains a variable, it no longer appends anything to the target uri, as the nginx docs describe:
When variables are used in proxy_pass [...]. In this case, if URI is specified in the directive, it is passed to the server as is, replacing the original request URI.
So requests to /foo/bar are simply forwarded to http://example.com/.
When bringing $request_uri into the mix, more than what we want is appended:
location /foo/ {
set $targetUri http://example.com$request_uri;
proxy_pass $targetUri;
}
Requests to /foo/bar are now forwarded to http://example.com/foo/bar.
The only workaround I have found is to resort to regex patterns for the location:
location ~ ^/foo/(.*)$ {
set $targetUri http://example.com/$1$is_args$args;
proxy_pass $targetUri;
}
Is there any way to replicate the behavior of proxy_pass when using variables without having to regex-match the location? The reason I want to avoid regex is because the location path is based on a user input from which the location block is generated.
Remove the trailing / from your $targetUri variable so that proxy_pass does not have the "optional URI" part in its value. Then use rewrite...break to duplicate the original behaviour.
For example:
location /foo/ {
set $targetUri http://example.com;
rewrite ^/foo(.*)$ $1 break;
proxy_pass $targetUri;
}
I am working with Nginx on Docker and I want to assign each user to a different port.
First, without adding anything, my code works fine:
location /viewer/ {
proxy_pass http://xx.xxx.xxx.xxx:18080/Road/;
}
Going to "/viewer/" in URL will proxy to the port 18080, just as expected.
But if I add any variable to the proxy_pass like:
set $test 1;
proxy_pass http://xx.xxx.xxx.xxx:18080/Road/?$test;
then, first of all, the static files do not load anymore and I have to add lines like these:
location ~ \.css {
add_header Content-Type text/css;
}
location ~ \.js {
add_header Content-Type application/x-javascript;
}
After this, the static files work again but the page starts to reload infinitely.
Before I was thinking it was because I replaced the port by a variable in proxy_pass, but as I showed you it happens when I add any variable there.
What do you think I could do wrong?
Thank you for your help!
Adding a variable to proxy_pass changes it's behaviour. You will need to construct the entire URI.
In your original configuration, the URI /viewer/foo is translated to /Road/foo before passing upstream.
In your new configuration, the URI /viewer/foo is translated to /Road/?1 and the tail of the original URI is lost.
You may have more success using rewrite...break to modify the URI.
For example:
location /viewer/ {
rewrite ^/viewer(.*)$ /road$1?something break;
proxy_pass http://xx.xxx.xxx.xxx:18080;
}
See this document for details.
According to your comment, you wish to change the destination port.
For example:
location /viewer/ {
rewrite ^/viewer(.*)$ /road$1 break;
proxy_pass http://xx.xxx.xxx.xxx:$myport;
}
If you specify the upstream server by IP address, a resolver statement will not be required. But if you specify the upstream by name, you will need to define a resolver. See this document for details.
I'm having trouble making nginx proxy an url with variable to a service within kubernetes.
Url looks like this:
http://localhost/user?username=Dave
I expect this url to take me to a subpage /user, which will read ?username=Dave and then fetch data from a database. However this takes me to the home page of the application(/ instead of /user) and does not read the variable even though url includes /user?username=Dave.
My current nginx config file looks like this:
server {
listen 0.0.0.0:80;
server_name localhost;
location / {
proxy_pass http://${FLASK_APP}:8080/;
}
location /user {
proxy_pass http://${GO_APP}:8000/;
}
}
I have read that location /user will match the url I'm passing. What is wrong with it? Or do I need to add something to proxy_pass http://${GO_APP}:8000/; or location /user?
As noted in the comments, the issue arises because you are using a variable in the proxy_pass target. As also noted in the comments, this question is related. As the answer referencing the docs states:
A special case is using variables in the proxy_pass statement: The
requested URL is not used and you are fully responsible to construct
the target URL yourself.
This means that you either need to use a static proxy_pass target, such as
// note that I added the forward slash
location /user/ {
proxy_pass http://destination:8000/;
}
Or as an alternative, I believe you can do it this way also
location /user/ {
proxy_pass http://${GO_APP}:8000/user$is_args$args;
}
I have nginx server with two locations:
location /service1 {
rewrite ^/service1/?(.*)$ /$1 break;
proxy_pass http://localhost:xxxx;
}
location ~* /service2(?<stuff>.*)$ {
rewrite ^ /service2$stuff break;
proxy_pass http://192.168.0.X;
}
Let's say I have a request http://hostname/service1/service2. I notice service2 always handle the request. But I want service 1 to handle it. How to set it?
It is important to understand how Nginx chooses which location block to handle requests. Please read https://www.digitalocean.com/community/tutorials/understanding-nginx-server-and-location-block-selection-algorithms, very helpful article.
Relevant excerpt from the article
It is important to understand that, by default, Nginx will serve regular expression matches in preference to prefix matches. However, it evaluates prefix locations first, allowing for the administer to override this tendency by specifying locations using the = and ^~ modifiers.
In your case you could use ‘location ^~ /service1’
Nginx location matcher - https://nginx.viraptor.info/
I have nginx location directive which purpose is to "remove" localization prefix from the URI for the proxy_pass directive.
For example, to make URI http://example.com/en/lalala use proxy_pass http://example.com/lalala
location ~ '^/(?<locale>[\w]{2})(/(?<rest>.*))?$' {
...
proxy_pass http://example/$rest;
...
}
This way the rest variable will be decoded when passed to proxy_pass directeve. It seems to be an expected behavior.
The problem is when my URI contains encoded space %20 passed from client
http://example.com/lala%20lala
nginx decodes URI to
http://example.com/lala lala
I can see it in my error.log.
The question is - is it possible do use encoded rest variable somehow as it is passed from client?
If I am doing something completely wrong, please, suggest the right way.
Thank you.
Yes, this behaviour is expected although docs also say:
If proxy_pass is specified without a URI, the request URI is passed to the server in the same form as sent by a client when the original request is processed, or the full normalized request URI is passed when processing the changed URI:
location /some/path/ {
proxy_pass http://127.0.0.1;
}
Nginx engineers say the same: https://serverfault.com/questions/459369/disabling-url-decoding-in-nginx-proxy
However if you append $request_uri to proxy_pass (and strip locale beforehand it may work as said by Nginx engineer):
set $modified_uri $request_uri;
if ($modified_uri ~ "^/([\w]{2})(/.*)") {
set $modified_uri $1;
}
proxy_pass http://example$modified_uri;
I have had some success using the following with Confluence and other Atlassian applications behind nginx where special characters such as ( ) < > [ ] were causing issues.
location /path {
# [... other proxy options ...]
# set proxy path with regex
if ($request_uri ~* "/path(/.*)") {
proxy_pass http://server:port/path$1;
break;
}
# fallback (probably not needed)
proxy_pass http://server:port/path;
}
The set directive can do the trick. It keeps the encoding intact or rather encodes decoded string.
location ~ '^/(?<locale>[\w]{2})(/(?<rest>.*))?$' {
...
set $encoded_rest $rest
proxy_pass http://example/$encoded_rest;
...
}