upstream sent too big header while reading response header from upstream

Question 1

I am getting these kind of errors:

2014/05/24 11:49:06 [error] 8376#0: *54031 upstream sent too big header while reading response header from upstream, client: 107.21.193.210, server: aamjanata.com, request: "GET /the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https://aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20https:/aamjanata.com/the-brainwash-chronicles-sponsored-by-gujarat-government/,%20ht

Always it is the same. A url repeated over and over with comma separating. Can't figure out what is causing this. Anyone have an idea?

Update: Another error:

http request count is zero while sending response to client

Here is the config. There are other irrelevant things, but this part was added/edited

fastcgi_cache_path /var/nginx-cache levels=1:2 keys_zone=WORDPRESS:100m inactive=60m;
fastcgi_cache_key "$scheme$request_method$host$request_uri";
fastcgi_cache_use_stale error timeout invalid_header http_500;
fastcgi_ignore_headers Cache-Control Expires Set-Cookie;
proxy_buffer_size   128k;
proxy_buffers   4 256k;
proxy_busy_buffers_size   256k;
    # Upstream to abstract backend connection(s) for PHP.
    upstream php {
            #this should match value of "listen" directive in php-fpm pool
            server unix:/var/run/php5-fpm.sock;
    }

And then in the server block: set $skip_cache 0;

    # POST requests and urls with a query string should always go to PHP
    if ($request_method = POST) {
            set $skip_cache 1;
    }
    if ($query_string != "") {
            set $skip_cache 1;
    }

    # Don't cache uris containing the following segments
    if ($request_uri ~* "/wp-admin/|/xmlrpc.php|wp-.*.php|/feed/|index.php|sitemap(_index)?.xml") {
            set $skip_cache 1;
    }

    # Don't use the cache for logged in users or recent commenters
    if ($http_cookie ~* "comment_author|wordpress_[a-f0-9]+|wp-postpass|wordpress_no_cache|wordpress_logged_in") {
            set $skip_cache 1;
    }

    location / {
            # This is cool because no php is touched for static content.
            # include the "?$args" part so non-default permalinks doesn't break when using query string
            try_files $uri $uri/ /index.php?$args;
    }


    location ~ .php$ {
            try_files $uri /index.php;
            include fastcgi_params;
            fastcgi_pass php;
            fastcgi_read_timeout 3000;

            fastcgi_cache_bypass $skip_cache;
            fastcgi_no_cache $skip_cache;

            fastcgi_cache WORDPRESS;
            fastcgi_cache_valid  60m;
    }

    location ~ /purge(/.*) {
        fastcgi_cache_purge WORDPRESS "$scheme$request_method$host$1";
    }`

Question 2

Add the following to your conf file

fastcgi_buffers 16 16k; 
fastcgi_buffer_size 32k;

Question 3

You can invoke a named location as the default action of your try_files statement.

For example:

location / {
    try_files $uri $uri/ @proxy;
}
location @proxy {
    proxy_pass http://backend;
}

See this document for details.

Question 4

To answer your question:

in php-fpm.d/www.conf file:

set the access.log entry:

access.log = /var/log/$pool.access.log

restart php-fpm service.
try to access your page
cat /var/log/www.access.log, you will see access logs like:

- - 10/Nov/2016:19:02:11 +0000 "GET /app.php" 404 - - 10/Nov/2016:19:02:37 +0000 "GET /app.php" 404

To resolve "Primary script unknown" problem:

if you see "GET /" without a correct php file name, then it's your nginx conf problem.
if you see "GET /app.php" with 404, it means nginx is correctly passing the script file name but php-fpm failed to access this file (user "php-fpm:php-fpm" don't have access to your file, which trapped me for 3 hours)

Hope my answer helps.

Question 5

I think that error from Nginx is indicating that the connection was closed by your nodejs server (i.e., "upstream"). How is nodejs configured?

Question 6

Your server is listening to port 80:

listen 80 default_server; 
listen [::]:80 default_server;

So, you should make your request to that port:

GET http://127.0.0.1/api/     => http://127.0.0.1:1323/
GET http://127.0.0.1:80/api/  => http://127.0.0.1:1323/
GET http://127.0.0.1/         => http://127.0.0.1:4100/
GET http://127.0.0.1:80/      => http://127.0.0.1:4100/

Then nginx should correctly proxy your requests.

Update

To be more clear about nginx config.

server { 

listen 80 default_server;  // The port nginx is listening to ipv4
listen [::]:80 default_server; // The port nginx is listening to ipv6

server_name _; 

location / { // When you call this location...

proxy_pass http://127.0.0.1:4100; // You'll be redirected to this location

} 

location /api { // When you call this location...

proxy_pass http://127.0.0.1:1323/; // You'll be redirected to this location

 } 
}

Your configuration is okay according to nginx docs.

You said your client is trying to reach http://127.0.0.1:1323/api/ but It should be requesting http://127.0.0.1/api/ (whitout the port) to be redirected to http://127.0.0.1:1323/.

Here's another example:

server { 

    listen 80; 

    server_name localhost anywebsite.com; 

    location ~* ^/MyApp {
        proxy_pass http://localhost:5130;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection keep-alive;
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_send_timeout 2m;
        proxy_read_timeout 2m;
    }
}

In this case, everytime my url ends with /MyApp ex.: http://anywebsite.com/api/MyApp I'm being proxyed to http://localhost:5130. But if I try to access http://localhost:5130 or http://anywebsite.com:5130/api/MyApp I won't be able because nginx is listening to port 80 only. If you want to access another port you need to specify like this:

server {
    listen 80; 
    listen 5130; 

[...]

upstream sent too big header while reading response header from upstream

Answers

To answer your question:

To resolve "Primary script unknown" problem:

Update

php,wordpress,nginx,fastcgi,nginx-reverse-proxy