nginx.conf

user  nginx;
worker_processes  auto;

# error log config comes from external file created by entrypoint, to toggle debug on/off.
include /etc/nginx/error.log.debug.warn;

pid        /var/run/nginx.pid;

events {
    worker_connections  1024;
}

http {
    map_hash_bucket_size 128;
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    # Include nginx timeout configs
    include       /etc/nginx/nginx.timeouts.config.conf;

    # Use a debug-oriented logging format.
    log_format debugging escape=json
      '{'
        '"access_time":"$time_local",'
        '"remote_addr":"$remote_addr",'
        '"remote_user":"$remote_user",'
        '"request":"$request",'
        '"status":"$status",'
        '"bytes_sent":"$body_bytes_sent",'
        '"host":"$host",'
        '"proxy_host":"$proxy_host",'
        '"upstream":"$upstream_addr"'
        '"upstream_status":"$upstream_status",'
        '"ssl_protocol":"$ssl_protocol",'
        '"connect_host":"$connect_host",'
        '"connect_port":"$connect_port",'
        '"connect_addr":"$connect_addr",'
        '"upstream_http_location":"$upstream_http_location",'
        '"upstream_cache_status":"$upstream_cache_status",'
        '"http_authorization":"$http_authorization",'
      '}';

    log_format debug_proxy escape=json
      '{'
        '"access_time":"$time_local",'
        '"remote_addr":"$remote_addr",'
        '"remote_user":"$remote_user",'
        '"request":"$request",'
        '"status":"$status",'
        '"bytes_sent":"$body_bytes_sent",'
        '"host":"$host",'
        '"proxy_host":"$proxy_host",'
        '"upstream":"$upstream_addr"'
        '"upstream_status":"$upstream_status",'
        '"ssl_protocol":"$ssl_protocol",'
        '"connect_host":"$connect_host",'
        '"connect_port":"$connect_port",'
        '"connect_addr":"$connect_addr",'
        '"upstream_http_location":"$upstream_http_location",'
        '"upstream_cache_status":"$upstream_cache_status",'
        '"http_authorization":"$http_authorization",'
      '}';

    log_format tweaked escape=json
      '{'
        '"access_time":"$time_local",'
        '"upstream_cache_status":"$upstream_cache_status",'
        '"method":"$request_method",'
        '"uri":"$uri",'
        '"request_type":"$docker_proxy_request_type",'
        '"status":"$status",'
        '"bytes_sent":"$body_bytes_sent",'
        '"upstream_response_time":"$upstream_response_time",'
        '"host":"$host",'
        '"proxy_host":"$proxy_host",'
        '"upstream":"$upstream_addr"'
      '}';

    gzip  off;

    # Entrypoint generates the proxy_cache_path here, so it is configurable externally.
    include /etc/nginx/conf.d/cache_max_size.conf;

    # Just in case you want to rewrite some hosts. Default maps directly.
    map $host $targetHost {
        hostnames;
        include /etc/nginx/docker.targetHost.map;
        default $host;
    }

    # A map to enable authentication to some specific docker registries.
    # This is auto-generated by the entrypoint.sh based on environment variables
    map $host $dockerAuth {
        hostnames;
        include /etc/nginx/docker.auth.map;
        default "";
    }

    # @TODO: actually for auth.docker.io, if we want to support multiple authentications, we'll need to decide
    # @TODO: based not only on the hostname, but also URI (/token) and query string (?scope)
    # @TODO: I wonder if this would help gcr.io and quay.io with authentication also....

    map $dockerAuth $finalAuth {
        "" "$http_authorization";    # if empty, keep the original passed-in from the docker client.
        default "Basic $dockerAuth"; # if not empty, add the Basic preamble to the auth
    }


    # Map to decide which hosts get directed to the caching portion.
    # This is automatically generated from the list of cached registries, plus a few fixed hosts
    # By default, we don't intercept, allowing free flow of non-registry traffic
    map $connect_host $interceptedHost {
        hostnames;
        include /etc/nginx/docker.intercept.map;
        default "$connect_addr"; # $connect_addr is 'IP address and port of the remote host, e.g. "192.168.1.5:12345". IP address is resolved from host name of CONNECT request line.'
    }


    # These maps parse the original Host and URI from a /forcecache redirect.
    map $request_uri $realHost {
        ~/forcecacheinsecure/([^:/]+)/originalwas(/.+) $1;
        ~/forcecachesecure/([^:/]+)/originalwas(/.+) $1;
        default "DID_NOT_MATCH_HOST";
    }

    map $request_uri $realPath {
        ~/forcecacheinsecure/([^:/]+)/originalwas(/.+) $2;
        ~/forcecachesecure/([^:/]+)/originalwas(/.+) $2;
        default "DID_NOT_MATCH_PATH";
    }


    # The proxy director layer, listens on 3128
    server {
        listen 3128;
        listen [::]:3128;
        server_name proxy_director_;

        # dont log the CONNECT proxy.
        #access_log /var/log/nginx/access.log debug_proxy;
        access_log off;
        set $docker_proxy_request_type "unknown-connect";

        proxy_connect;
        proxy_connect_address $interceptedHost;
        proxy_max_temp_file_size 0;

        # We need to resolve the real names of our proxied servers.
        #resolver 8.8.8.8 4.2.2.2 ipv6=off; # Avoid ipv6 addresses for now
        include /etc/nginx/resolvers.conf;

        # forward proxy for non-CONNECT request
        location / {
            add_header "Content-type" "text/plain" always;
            return 200 "docker-registry-proxy: The docker caching proxy is working!";
        }

        location /ca.crt {
             alias /ca/ca.crt;
        }

        location /setup/systemd {
            add_header "Content-type" "text/plain" always;
            return 200 '
set -e

if [ ! -d /etc/systemd ]; then
   echo "Not a systemd system"
   exit 1
fi

mkdir -p /etc/systemd/system/docker.service.d
cat << EOD > /etc/systemd/system/docker.service.d/http-proxy.conf
[Service]
Environment="HTTPS_PROXY=$scheme://$http_host/"
EOD

# Get the CA certificate from the proxy and make it a trusted root.
curl $scheme://$http_host/ca.crt > /usr/share/ca-certificates/docker_registry_proxy.crt
if fgrep -q "docker_registry_proxy.crt" /etc/ca-certificates.conf ; then
   echo "certificate refreshed"
else
   echo "docker_registry_proxy.crt" >> /etc/ca-certificates.conf
fi

update-ca-certificates --fresh

# Reload systemd
systemctl daemon-reload

# Restart dockerd
systemctl restart docker.service
echo "Docker configured with HTTPS_PROXY=$scheme://$http_host/"
';
        } # end location /setup/systemd
    } # end server


    # The caching layer
    server {
        # Listen on both 80 and 443, for all hostnames.
        # actually could be 443 or 444, depending on debug. this is now generated by the entrypoint.
        listen 80 default_server;
        include /etc/nginx/caching.layer.listen;
        server_name proxy_caching_;

        # Do some tweaked logging.
        access_log  /var/log/nginx/access.log  tweaked;
        set $docker_proxy_request_type "unknown";

        # Send upstream status as header
        add_header X-Docker-Registry-Proxy-Cache-Upstream-Status "$upstream_cache_status";

        # Use the generated certificates, they contain names for all the proxied registries.
        ssl_certificate /certs/fullchain.pem;
        ssl_certificate_key /certs/web.key;

        # We need to resolve the real names of our proxied servers.
        #resolver 8.8.8.8 4.2.2.2 ipv6=off; # Avoid ipv6 addresses for now
        include /etc/nginx/resolvers.conf;

        # Docker needs this. Don't ask.
        chunked_transfer_encoding on;

        # configuration of the different allowed methods
        include "/etc/nginx/conf.d/allowed.methods.conf";

        proxy_read_timeout 900;

        # Use cache locking, with a huge timeout, so that multiple Docker clients asking for the same blob at the same time
        # will wait for the first to finish instead of doing multiple upstream requests.
        proxy_cache_lock on;
        proxy_cache_lock_timeout 880s;

        # Cache all 200, 206 for 60 days.
        proxy_cache_valid 200 206 60d;

        # Some extra settings to maximize cache hits and efficiency
        proxy_force_ranges on;
        proxy_ignore_client_abort on;
        proxy_cache_revalidate on;

        # Hide/ignore headers from caching. S3 especially likes to send Expires headers in the past in some situations.
        proxy_hide_header      Set-Cookie;
        proxy_ignore_headers   X-Accel-Expires Expires Cache-Control Set-Cookie;

        # Add the authentication info, if the map matched the target domain.
        proxy_set_header Authorization $finalAuth;

        # Use SNI during the TLS handshake with the upstream.
        proxy_ssl_server_name on;

        # This comes from a include file generated by the entrypoint.
        include /etc/nginx/docker.verify.ssl.conf;

        # Block API v1. We dont know how to handle these.
        # Docker-client should start with v2 and fallback to v1 if something fails, for example, if authentication failed to a protected v2 resource.
        location /v1 {
            return 405 "docker-registry-proxy: docker is trying to use v1 API. Either the image does not exist upstream, or you need to configure docker-registry-proxy to authenticate against $host";
        }

        # For blob requests by digest, do cache, and treat redirects.
        location ~ ^/v2/(.*)/blobs/sha256:(.*) {
            set $docker_proxy_request_type "blob-by-digest";
            include "/etc/nginx/nginx.manifest.common.conf";
        }

        # For manifest requests by digest, do cache, and treat redirects.
        # These are some of the requests that DockerHub will throttle.
        location ~ ^/v2/(.*)/manifests/sha256:(.*) {
            set $docker_proxy_request_type "manifest-by-digest";
            include "/etc/nginx/nginx.manifest.common.conf";
        }

        # Config for manifest URL caching is generated by the entrypoint based on ENVs.
        # Go check it out, entrypoint.sh
        include "/etc/nginx/nginx.manifest.caching.config.conf";


        # Cache blobs requests that are not by digest
        # Since these are mutable, we invalidate them immediately and keep them only in case the backend is down
        location ~ ^/v2/(.*)/blobs/ {
            set $docker_proxy_request_type "blob-mutable";
            proxy_cache_valid 0s;
            include "/etc/nginx/nginx.manifest.stale.conf";
        }

        location @handle_redirects {
            #store the current state of the world so we can reuse it in a minute
            # We need to capture these values now, because as soon as we invoke
            # the proxy_* directives, these will disappear
            set $original_uri $uri;
            set $orig_loc $upstream_http_location;

            # during this process, nginx will preserve the headers intended for the original destination.
            # in most cases thats okay, but for some (eg: google storage), passing an Authorization
            # header can cause problems. Also, that would leak the credentials for the registry
            # into the storage system (unrelated).
            proxy_set_header      Authorization "";

            # nginx goes to fetch the value from the upstream Location header
            proxy_pass $orig_loc;
            proxy_cache cache;
            # But we store the result with the cache key of the original request URI
            # so that future clients don't need to follow the redirect too
            proxy_cache_key $original_uri;
        }

        # by default, dont cache anything.
        location / {
            proxy_pass https://$targetHost;
            proxy_cache off;
        }
    }
}