Nginx rewrite and proxy_pass explanation - nginx

Question

I can see a following locations in nginx/okd configuration:
location /STFlow/ {
rewrite ^/STFlow(.*)$ $1 last;
#
# Are four lines below executed if rewrite has last option ???
# What's the point of them?
#
proxy_pass http://zuul-proxy:8080;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $http_x_forwarded_for;
proxy_set_header X-Forwarded-For $http_x_forwarded_for;
}
location / {
add_header debug-header dbg5;
set $realip $remote_addr;
if ($http_x_forwarded_for ~ "^(\d+\.\d+\.\d+\.\d+)") {
set $realip $1;
}
proxy_pass http://zuul-proxy:8080;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $http_x_forwarded_for;
proxy_set_header X-Forwarded-For $http_x_forwarded_for;
client_max_body_size 50M;
}
In location /STFlow/ are four lines below rewrite ^/STFlow(.*)$ $1 last; ever executed?
If so when?
What's the point of them?

Answer 1

If that rewrite rule had a break flag instead of last, it would remove the /STFlow prefix from /STFlow/some/path URI before passing it to the upstream, i. e. do the same as the second location block except of setting debug-header and $realip variable. But as far as I understand using the last flag makes that four lines never executed, further URI processing would be done inside the second location block.