Docker Angular Nginx can't connect to other service (netcore 8)

Angular 17. When running services with docker-compose can't connect from nginx to other service (actually gateway with port 5000). After main page loads it starts to fetch data from gateway and I get an error for all requests. Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at http://localhost:5000/api/settings/background. (Reason: CORS request did not succeed). Status code: (null)

Now I set Netcore8 services AllowAnyOrigins to true. Use Docker default network - bridge - all services run inside that network - checked. In NetCore containers use servers names setup in docker (not ip's) Swagger for NetCore runs. Dockerfile for Front is as follows:

#STAGE 1
FROM node:18-alpine AS build
EXPOSE 4200
WORKDIR /usr/src/app
COPY package*.json ./
RUN npm install
RUN npm ci
COPY . .
RUN npm run ng -- build --configuration production
#STAGE 2
FROM nginx:alpine
EXPOSE 80
COPY nginx.conf /etc/nginx/nginx.conf
COPY --from=build /usr/src/app/dist/EZui /usr/share/nginx/html
CMD ["nginx", "-g", "daemon off;"]


nginx.conf is

user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log notice;
pid /run/nginx.pid;
events {
worker_connections 1024;
}
http {
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"';
access_log /var/log/nginx/access.log main;
include /etc/nginx/mime.types;
server {
listen 80;
server_name localhost;
root /usr/share/nginx/html;
default_type application/octet-stream;
gzip on;
gzip_comp_level 9;
gzip_vary on;
gzip_min_length 256;
gzip_proxied expired no-cache no-store private auth;
gzip_types text/plain text/css application/json application/javascript application/x-javascript text/xml application/xml application/xml+rss text/javascript;
gzip_buffers 16 8k;
gunzip on;
client_max_body_size 256M;
location /api {
proxy_pass http://localhost:5000/;
#proxy_next_upstream error timeout invalid_header http_500 http_502 http_503 http_504;
#proxy_buffering off;
#proxy_set_header Accept-Encoding "";
}
location / {
root /usr/share/nginx/html;
try_files $uri $uri/ /index.html;
}
}
sendfile on;
#tcp_nopush on;
keepalive_timeout 65;
include /etc/nginx/conf.d/*.conf;
}


In angular I use environment.production

api = 'http://localhost:5000/api';


I tried to change localhost to names that are set for docker on front and back (for instance to gateway- that's the name of gateway Netcore service.

Tried to play with nginx.conf - added even location / settings:

if ($request_method = 'OPTIONS') {
add_header 'Access-Control-Allow-Origin' '*';
add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
#
# Custom headers and headers various browsers *should* be OK with but aren't
#
add_header 'Access-Control-Allow-Headers' 'DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range';
#
# Tell client that this pre-flight info is valid for 20 days
#
#add_header 'Access-Control-Max-Age' 1728000;
add_header 'Content-Type' 'text/plain; charset=utf-8';
add_header 'Content-Length' 0;
return 204;
}
if ($request_method = 'POST') {
add_header 'Access-Control-Allow-Origin' '*' always;
add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS' always;
add_header 'Access-Control-Allow-Headers' 'DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range' always;
add_header 'Access-Control-Expose-Headers' 'Content-Length,Content-Range' always;
}
if ($request_method = 'GET') {
add_header 'Access-Control-Allow-Origin' '*' always;
add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS' always;
add_header 'Access-Control-Allow-Headers' 'DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range' always;
add_header 'Access-Control-Expose-Headers' 'Content-Length,Content-Range' always;
}


also tried to add reverse_proxy to nginx.conf.

Still get the same error. Read a lot of issues and tried different fixes (many of them failed to run nginx) most of them in nginx.conf - nothing helped.

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