Not able to check the health of the flask application which inside the dockerised NGINX

Question

I have the python flask application which i am using inside the NGINX and i have dockerised this image. By default flask application runs in 5000 port and NGINX in 80 port. If I run image in the container all the services are working fine. I am able to access the services from NGINX port 80 which internally mapped to flask 5000 port. Now I want to add the health check for this image. So i am using the py-healthcheck module in the flask application like this.

health = HealthCheck()
def redis_available():
    return True, "UP"

health.add_check(redis_available)

app.add_url_rule("/health", "healthcheck", view_func=lambda: health.run())

Now If i run only the flask application(without NGINX in my local system) using the URL

http://localhost:5000/health

I am getting the proper response saying the applicarion is up. In order to add the healthcheck for image i have adde this command in Dockerfile

HEALTHCHECK --interval=30s --timeout=120s --retries=3  CMD wget --no-check-certificate --quiet --tries=1 --spider https://localhost:80/health || exit 1

Here i am assuming that i am trying to access the healthcheck endpoint from NGINX thats why i am using localhost:80. But if i run the conainer the container is always unhealthy but all the end points are working fine. Whether i have to do some configuration in NGINX conf file in order access the healthcheck endpoint of flask from NGINX?

Here is the nginx config:

# based on default config of nginx 1.12.1
# Define the user that will own and run the Nginx server
user nginx;
# Define the number of worker processes; recommended value is the number of
# cores that are being used by your server
# auto will default to number of vcpus/cores
worker_processes auto;

# altering default pid file location
pid /tmp/nginx.pid;

# turn off daemon mode to be watched by supervisord
daemon off;

# Enables the use of JIT for regular expressions to speed-up their processing.
pcre_jit on;

# events block defines the parameters that affect connection processing.
events {
    # Define the maximum number of simultaneous connections that can be opened by a worker process
    worker_connections  1024;
}


# http block defines the parameters for how NGINX should handle HTTP web traffic
http {
    # Include the file defining the list of file types that are supported by NGINX
    include /opt/conda/envs/analytics_service/etc/nginx/mime.types;
    # Define the default file type that is returned to the user
    default_type text/html;

    # Don't tell nginx version to clients.
    server_tokens off;

    # Specifies the maximum accepted body size of a client request, as
    # indicated by the request header Content-Length. If the stated content
    # length is greater than this size, then the client receives the HTTP
    # error code 413. Set to 0 to disable.
    client_max_body_size 0;

    # Define the format of log messages.
    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                        '$status $body_bytes_sent "$http_referer" '
                        '"$http_user_agent" "$http_x_forwarded_for"';

    # Define the location of the log of access attempts to NGINX
    access_log /opt/conda/envs/analytics_service/etc/nginx/access.log  main;

    # Define the location on the file system of the error log, plus the minimum
    # severity to log messages for
    error_log /opt/conda/envs/analytics_service/etc/nginx/error.log warn;

    # Define the parameters to optimize the delivery of static content
    sendfile       on;
    tcp_nopush     on;
    tcp_nodelay    on;

    # Define the timeout value for keep-alive connections with the client
    keepalive_timeout  65;

    # Define the usage of the gzip compression algorithm to reduce the amount of data to transmit
    #gzip  on;

    # Include additional parameters for virtual host(s)/server(s)
    include /opt/conda/envs/analytics_service/etc/nginx/conf.d/*.conf;
}