Nginx essential cheatsheet

Nginx saves it’s logs, configs, binaries in different folder in different operating system. Every time I struggle to find them in different locations.
Also, the commands are different. I have curated these in this document based on Ubuntu, Macbook and CentOS(coming soon).
Moreover, there are some frequently encountered issues and solution.

Root config file location

Mac: /usr/local/etc/nginx/nginx.conf

Ubuntu: /etc/nginx/nginx.conf

Log file location

You may need to uncomment a line in the config file to actually get error dump in the file. You may wish to keep it clean periodically.

Mac: /usr/local/Cellar/nginx/1.23.2/logs/error.log

Ubuntu: access_log /var/log/nginx/access.log
error_log /var/log/nginx/error.log

Commands

Test config files

Mac: sudo nginx -t

Reload config files

Mac: sudo nginx -s reload

Linux: sudo systemctl reload nginx

sudo service nginx reload

Stop nginx

Mac: sudo nginx -s stop
Ubuntu: sudo systemctl start nginx

Start nginx

Mac: sudo nginx

Linux: sudo systemctl start nginx

Restart nginx

Linux: sudo systemctl restart nginx

sudo /etc/init.d/nginx restart

Troubleshooting

upstream sent too big header while reading response header from upstream

It occurs in a reverse proxy block. To fix this issue, find the reverse proxy block and add the following statements.

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location / {
    proxy_pass http://127.0.0.1:8080;
    proxy_busy_buffers_size 512k;
    proxy_buffers 4 512k;
    proxy_buffer_size 256k;
}

Rewrite based on a part of URL

I actually don’t try to use the rewrite statement until it’s really necessary. Here are some examples, that can be achieved using rewrite and regex based location block both.

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location ~ /server1/(.*)$ {
    proxy_pass http://127.0.0.1:3050/$1;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
    proxy_read_timeout 86400s;
}

location ~ /server2/(.*)$ {
    proxy_pass http://127.0.0.1:3052/$1;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
    proxy_read_timeout 86400s;
}

Rewrite

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rewrite regex URL [flag];

Using rewrite URL(not tested),

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location /server1/ {
    rewrite ^/server1/(.*)$ /$1 last;
    proxy_pass http://127.0.0.1:3050/;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
    proxy_read_timeout 86400s;
}

location /server2/ {
    rewrite ^/server2/(.*)$ /$1 last;
    proxy_pass http://127.0.0.1:3052/;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection "upgrade";
    proxy_read_timeout 86400s;
}

Above blocks can be merged, will update it later.

Above config sends http://example.com/server1/robin request to a service running in the 3050 port, like LOCALHOST:3050/robin.
Also, sends http://example.com/server2/robin request to a service running in the 3052 port, like LOCALHOST:3052/robin.
Note: It’s not redirection.