0

I am attempting to send a request to endpoint /v1/resource, and I am getting the following error:

2021/06/02 23:17:17 [crit] 30#0: *2963 connect() failed (101: Network unreachable), context: ngx.timer, client: 172.13.0.21, server: 0.0.0.0:8443
2021/06/02 23:17:18 [crit] 30#0: *2969 connect() failed (101: Network unreachable), context: ngx.timer, client: 172.13.0.21, server: 0.0.0.0:8443
2021/06/02 23:17:19 [crit] 30#0: *2988 connect() failed (101: Network unreachable), context: ngx.timer, client: 172.13.0.21, server: 0.0.0.0:8443
2021/06/02 23:17:20 [crit] 30#0: *3007 connect() failed (101: Network unreachable), context: ngx.timer, client: 172.13.0.21, server: 0.0.0.0:8443
2021/06/02 23:17:21 [crit] 30#0: *3039 connect() failed (101: Network unreachable), context: ngx.timer, client: 172.13.0.21, server: 0.0.0.0:8443
2021/06/02 23:17:21 [crit] 30#0: *3053 connect() failed (101: Network unreachable), context: ngx.timer, client: 172.13.0.21, server: 0.0.0.0:8443
2021/06/02 22:16:27 [error] 30#0: *29609 [lua] balancer.lua:1064: execute(): DNS resolution failed: dns lookup pool exceeded retries (1): failed to create a resolver: failed to set peer name: network unreachable. Tried: ["(short)my.hostname.com:(na) - cache-miss","my.hostname.com:33 - cache-miss/scheduled/try 1 error: failed to create a resolver: failed to set peer name: network unreachable/scheduled/try 2 error: failed to create a resolver: failed to set peer name: network unreachable/dns lookup pool exceeded retries (1): failed to create a resolver: failed to set peer name: network unreachable","my.hostname.com:1 - cache-miss/scheduled/try 1 error: failed to create a resolver: failed to set peer name: network unreachable/scheduled/try 2 error: failed to create a resolver: failed to set peer name: network unreachable/dns lookup pool exceeded retries (1): failed to create a resolver: failed to set peer name: network unreachable","my.hostname.com:5 - cache-miss/scheduled/try 1 error: failed to create a resolver: failed to set peer name: network unreachable/scheduled/try 2 error: failed to create a resolver: failed to set peer name: network unreachable/dns lookup pool exceeded retries (1): failed to create a resolver: failed to set peer name: network unreachable"], client: 172.13.0.21, server: kong, request: "GET /v1/resource HTTP/1.1", host: "my.hostname.com"
172.18.0.11 - - [02/Jun/2021:23:17:22 +0000] "GET /v1/resource HTTP/1.1" 500 42 "-" "curl/7.29.0"

It complains that i cannot resolve my.hostname.com, however, when I exec into the Kong docker, I am able to successfully get a response, and able to ping my.hostname.com successfully.

bash-5.0# nslookup my.hostname.com
Server:     172.13.0.1
Address:    172.13.0.1:5

Non-authoritative answer: Name: my.hostname.com Address: 172.13.0.21

Non-authoritative answer:

And ping:

bash-5.0# ping my.hostname.com
PING my.hostname.com (172.13.0.21): 56 data bytes
64 bytes from 172.13.0.21: seq=0 ttl=64 time=0.065 ms
64 bytes from 172.13.0.21: seq=1 ttl=64 time=0.055 ms
64 bytes from 172.13.0.21: seq=2 ttl=64 time=0.063 ms

The issue can be fixed if a default route is added, however, on our setup this is not possible and this should work because all services are localhost.

bash-5.0$ kong version
2.4.1

nginx.conf:

charset UTF-8;
server_tokens off;

error_log /dev/stderr debug;

lua_package_path './?.lua;./?/init.lua;;;;'; lua_package_cpath ';;;'; lua_socket_pool_size 30; lua_socket_log_errors off; lua_max_running_timers 4096; lua_max_pending_timers 16384; lua_ssl_verify_depth 1;

lua_shared_dict kong 5m; lua_shared_dict kong_locks 8m; lua_shared_dict kong_healthchecks 5m; lua_shared_dict kong_process_events 5m; lua_shared_dict kong_cluster_events 5m; lua_shared_dict kong_rate_limiting_counters 12m; lua_shared_dict kong_core_db_cache 128m; lua_shared_dict kong_core_db_cache_miss 12m; lua_shared_dict kong_db_cache 128m; lua_shared_dict kong_db_cache_miss 12m;

underscores_in_headers on; ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384;

injected nginx_http_* directives

client_body_buffer_size 8k; client_max_body_size 0; lua_shared_dict prometheus_metrics 5m; lua_ssl_protocols TLSv1.1 TLSv1.2 TLSv1.3; ssl_dhparam /usr/local/kong/ssl/ffdhe2048.pem; ssl_prefer_server_ciphers off; ssl_protocols TLSv1.2 TLSv1.3; ssl_session_tickets on; ssl_session_timeout 1d;

init_by_lua_block { Kong = require 'kong' Kong.init() }

init_worker_by_lua_block { Kong.init_worker() }

upstream kong_upstream { server 0.0.0.1;

# injected nginx_upstream_* directives

balancer_by_lua_block {
    Kong.balancer()
}

}

server { server_name kong; listen 0.0.0.0:8000 reuseport backlog=16384; listen 0.0.0.0:8443 ssl http2 reuseport backlog=16384;

error_page 400 404 405 408 411 412 413 414 417 494 /kong_error_handler;
error_page 500 502 503 504                     /kong_error_handler;

access_log /dev/stdout;
error_log  /dev/stderr debug;

ssl_certificate     /usr/local/kong/ssl/kong-default.crt;
ssl_certificate_key /usr/local/kong/ssl/kong-default.key;
ssl_certificate     /usr/local/kong/ssl/kong-default-ecdsa.crt;
ssl_certificate_key /usr/local/kong/ssl/kong-default-ecdsa.key;
ssl_session_cache   shared:SSL:10m;
ssl_certificate_by_lua_block {
    Kong.ssl_certificate()
}

# injected nginx_proxy_* directives
real_ip_header X-Real-IP;
real_ip_recursive off;

rewrite_by_lua_block {
    Kong.rewrite()
}

access_by_lua_block {
    Kong.access()
}

header_filter_by_lua_block {
    Kong.header_filter()
}

body_filter_by_lua_block {
    Kong.body_filter()
}

log_by_lua_block {
    Kong.log()
}

location / {
    default_type                     '';

    set $ctx_ref                     '';
    set $upstream_te                 '';
    set $upstream_host               '';
    set $upstream_upgrade            '';
    set $upstream_connection         '';
    set $upstream_scheme             '';
    set $upstream_uri                '';
    set $upstream_x_forwarded_for    '';
    set $upstream_x_forwarded_proto  '';
    set $upstream_x_forwarded_host   '';
    set $upstream_x_forwarded_port   '';
    set $upstream_x_forwarded_path   '';
    set $upstream_x_forwarded_prefix '';
    set $kong_proxy_mode             'http';

    proxy_http_version      1.1;
    proxy_buffering          on;
    proxy_request_buffering  on;

    proxy_set_header      TE                 $upstream_te;
    proxy_set_header      Host               $upstream_host;
    proxy_set_header      Upgrade            $upstream_upgrade;
    proxy_set_header      Connection         $upstream_connection;
    proxy_set_header      X-Forwarded-For    $upstream_x_forwarded_for;
    proxy_set_header      X-Forwarded-Proto  $upstream_x_forwarded_proto;
    proxy_set_header      X-Forwarded-Host   $upstream_x_forwarded_host;
    proxy_set_header      X-Forwarded-Port   $upstream_x_forwarded_port;
    proxy_set_header      X-Forwarded-Path   $upstream_x_forwarded_path;
    proxy_set_header      X-Forwarded-Prefix $upstream_x_forwarded_prefix;
    proxy_set_header      X-Real-IP          $remote_addr;
    proxy_pass_header     Server;
    proxy_pass_header     Date;
    proxy_ssl_name        $upstream_host;
    proxy_ssl_server_name on;
    proxy_pass            $upstream_scheme://kong_upstream$upstream_uri;
}

location @unbuffered {
    internal;
    default_type         '';
    set $kong_proxy_mode 'unbuffered';

    proxy_http_version      1.1;
    proxy_buffering         off;
    proxy_request_buffering off;

    proxy_set_header      TE                 $upstream_te;
    proxy_set_header      Host               $upstream_host;
    proxy_set_header      Upgrade            $upstream_upgrade;
    proxy_set_header      Connection         $upstream_connection;
    proxy_set_header      X-Forwarded-For    $upstream_x_forwarded_for;
    proxy_set_header      X-Forwarded-Proto  $upstream_x_forwarded_proto;
    proxy_set_header      X-Forwarded-Host   $upstream_x_forwarded_host;
    proxy_set_header      X-Forwarded-Port   $upstream_x_forwarded_port;
    proxy_set_header      X-Forwarded-Path   $upstream_x_forwarded_path;
    proxy_set_header      X-Forwarded-Prefix $upstream_x_forwarded_prefix;
    proxy_set_header      X-Real-IP          $remote_addr;
    proxy_pass_header     Server;
    proxy_pass_header     Date;
    proxy_ssl_name        $upstream_host;
    proxy_ssl_server_name on;
    proxy_pass            $upstream_scheme://kong_upstream$upstream_uri;
}

location @unbuffered_request {
    internal;
    default_type         '';
    set $kong_proxy_mode 'unbuffered';

    proxy_http_version      1.1;
    proxy_buffering          on;
    proxy_request_buffering off;

    proxy_set_header      TE                 $upstream_te;
    proxy_set_header      Host               $upstream_host;
    proxy_set_header      Upgrade            $upstream_upgrade;
    proxy_set_header      Connection         $upstream_connection;
    proxy_set_header      X-Forwarded-For    $upstream_x_forwarded_for;
    proxy_set_header      X-Forwarded-Proto  $upstream_x_forwarded_proto;
    proxy_set_header      X-Forwarded-Host   $upstream_x_forwarded_host;
    proxy_set_header      X-Forwarded-Port   $upstream_x_forwarded_port;
    proxy_set_header      X-Forwarded-Path   $upstream_x_forwarded_path;
    proxy_set_header      X-Forwarded-Prefix $upstream_x_forwarded_prefix;
    proxy_set_header      X-Real-IP          $remote_addr;
    proxy_pass_header     Server;
    proxy_pass_header     Date;
    proxy_ssl_name        $upstream_host;
    proxy_ssl_server_name on;
    proxy_pass            $upstream_scheme://kong_upstream$upstream_uri;
}

location @unbuffered_response {
    internal;
    default_type         '';
    set $kong_proxy_mode 'unbuffered';

    proxy_http_version      1.1;
    proxy_buffering         off;
    proxy_request_buffering  on;

    proxy_set_header      TE                 $upstream_te;
    proxy_set_header      Host               $upstream_host;
    proxy_set_header      Upgrade            $upstream_upgrade;
    proxy_set_header      Connection         $upstream_connection;
    proxy_set_header      X-Forwarded-For    $upstream_x_forwarded_for;
    proxy_set_header      X-Forwarded-Proto  $upstream_x_forwarded_proto;
    proxy_set_header      X-Forwarded-Host   $upstream_x_forwarded_host;
    proxy_set_header      X-Forwarded-Port   $upstream_x_forwarded_port;
    proxy_set_header      X-Forwarded-Path   $upstream_x_forwarded_path;
    proxy_set_header      X-Forwarded-Prefix $upstream_x_forwarded_prefix;
    proxy_set_header      X-Real-IP          $remote_addr;
    proxy_pass_header     Server;
    proxy_pass_header     Date;
    proxy_ssl_name        $upstream_host;
    proxy_ssl_server_name on;
    proxy_pass            $upstream_scheme://kong_upstream$upstream_uri;
}

location @grpc {
    internal;
    default_type         '';
    set $kong_proxy_mode 'grpc';

    grpc_set_header      TE                 $upstream_te;
    grpc_set_header      X-Forwarded-For    $upstream_x_forwarded_for;
    grpc_set_header      X-Forwarded-Proto  $upstream_x_forwarded_proto;
    grpc_set_header      X-Forwarded-Host   $upstream_x_forwarded_host;
    grpc_set_header      X-Forwarded-Port   $upstream_x_forwarded_port;
    grpc_set_header      X-Forwarded-Path   $upstream_x_forwarded_path;
    grpc_set_header      X-Forwarded-Prefix $upstream_x_forwarded_prefix;
    grpc_set_header      X-Real-IP          $remote_addr;
    grpc_pass_header     Server;
    grpc_pass_header     Date;
    grpc_ssl_name        $upstream_host;
    grpc_ssl_server_name on;
    grpc_pass            $upstream_scheme://kong_upstream;
}

location = /kong_buffered_http {
    internal;
    default_type         '';
    set $kong_proxy_mode 'http';

    rewrite_by_lua_block       {;}
    access_by_lua_block        {;}
    header_filter_by_lua_block {;}
    body_filter_by_lua_block   {;}
    log_by_lua_block           {;}

    proxy_http_version 1.1;
    proxy_set_header      TE                 $upstream_te;
    proxy_set_header      Host               $upstream_host;
    proxy_set_header      Upgrade            $upstream_upgrade;
    proxy_set_header      Connection         $upstream_connection;
    proxy_set_header      X-Forwarded-For    $upstream_x_forwarded_for;
    proxy_set_header      X-Forwarded-Proto  $upstream_x_forwarded_proto;
    proxy_set_header      X-Forwarded-Host   $upstream_x_forwarded_host;
    proxy_set_header      X-Forwarded-Port   $upstream_x_forwarded_port;
    proxy_set_header      X-Forwarded-Path   $upstream_x_forwarded_path;
    proxy_set_header      X-Forwarded-Prefix $upstream_x_forwarded_prefix;
    proxy_set_header      X-Real-IP          $remote_addr;
    proxy_pass_header     Server;
    proxy_pass_header     Date;
    proxy_ssl_name        $upstream_host;
    proxy_ssl_server_name on;
    proxy_pass            $upstream_scheme://kong_upstream$upstream_uri;
}

location = /kong_error_handler {
    internal;
    default_type                 '';

    uninitialized_variable_warn  off;

    rewrite_by_lua_block {;}
    access_by_lua_block  {;}

    content_by_lua_block {
        Kong.handle_error()
    }
}

}

server { server_name kong_admin; listen 0.0.0.0:8001;

access_log /dev/stdout;
error_log  /dev/stderr debug;


# injected nginx_admin_* directives
client_body_buffer_size 10m;
client_max_body_size 10m;

location / {
    default_type application/json;
    content_by_lua_block {
        Kong.admin_content()
    }
    header_filter_by_lua_block {
        Kong.admin_header_filter()
    }
}

location /nginx_status {
    internal;
    access_log off;
    stub_status;
}

location /robots.txt {
    return 200 'User-agent: *\nDisallow: /';
}

}

Does anyone know what may cause this issue, can kong operate without network? or if there is a setting that is needed to get around this issue?

lion_bash
  • 113

1 Answers1

1

DNS resolving is done by using UDP request/response actions or TCP connections. Both require that the system can send packets to the IP address of the DNS resolver.

In order to do that, one needs to have a route defined at least to the name server.

In your case, you would need to have a route to 172.13.0.21.

Tero Kilkanen
  • 38,887