NGINX location directives for the same location - nginx

Question

I have a Nexus Repository Manager OSS 3.0 running behind NGINX as a private docker registry. My Docker client (not the official docker client) is expecting a 200 OK and an empty JSON string {} to be returned from /v2/. The problem i'm running into is that Nexus returns the 200 OK but an empty string.
My work-around is to have NGINX return a file containing an empty JSON string for /v2/ requests and proxy /v2/* requests to Nexus.
server {
listen 443 ssl;
server_name nexus.example.com;
ssl_certificate ssl/server.crt;
ssl_certificate_key ssl/server.key;
location = /v2/ {
root /home/ubuntu/www;
index empty.json;
}
location /v2/ {
proxy_pass http://localhost:5000;
proxy_set_header Host $http_host; # required for docker client's sake
proxy_set_header X-Real-IP $remote_addr; # pass on real client's IP
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_read_timeout 900;
}
}
I would expect this to work, but it directs all traffic (/v2/, /v2/_catalog, /v2/myimage/manifests/latest, etc) to the proxy_pass. How can I make /v2/ requests go to the location to sever the empty.json file?

Answer 1

So you have placed a file at /home/ubuntu/www/v2/empty.json?
The problem is that the index directive will rewrite the URI to /v2/empty.json which is then processed by the location /v2/ block.
One solution would be to create another location to match the rewritten URI and serve it as a static file:
root /home/ubuntu/www;
location = /v2/ {
index empty.json;
}
location = /v2/empty.json {
}
Another solution is to use the error_page directive. But you will still need to specify a location and root to handle the static file(s):
location = /v2/ {
return 405;
error_page 405 =200 /static/empty.json;
}
location / {
root /home/ubuntu/www;
}