ingress-nginx-helm/controllers/nginx

Nginx Ingress Controller

This is a nginx Ingress controller that uses ConfigMap to store the nginx configuration. See Ingress controller documentation for details on how it works.

What it provides?

• Ingress controller
• nginx 1.9.x with
• SSL support
• custom ssl_dhparam (optional). Just mount a secret with a file named dhparam.pem.
• support for TCP services (flag --tcp-services-configmap)
• custom nginx configuration using ConfigMap

Requirements

• default backend 404-server

Dry running the Ingress controller

Before deploying the controller to production you might want to run it outside the cluster and observe it.

$ make controller
$ mkdir /etc/nginx-ssl
$ ./nginx-ingress-controller --running-in-cluster=false --default-backend-service=kube-system/default-http-backend

Deploy the Ingress controller

First create a default backend:

$ kubectl create -f examples/default-backend.yaml
$ kubectl expose rc default-http-backend --port=80 --target-port=8080 --name=default-http-backend

Loadbalancers are created via a ReplicationController or Daemonset:

$ kubectl create -f examples/default/rc-default.yaml

HTTP

First we need to deploy some application to publish. To keep this simple we will use the echoheaders app that just returns information about the http request as output

kubectl run echoheaders --image=gcr.io/google_containers/echoserver:1.4 --replicas=1 --port=8080

Now we expose the same application in two different services (so we can create different Ingress rules)

kubectl expose deployment echoheaders --port=80 --target-port=8080 --name=echoheaders-x
kubectl expose deployment echoheaders --port=80 --target-port=8080 --name=echoheaders-y

Next we create a couple of Ingress rules

kubectl create -f examples/ingress.yaml

we check that ingress rules are defined:

$ kubectl get ing
NAME      RULE          BACKEND   ADDRESS
echomap   -
          foo.bar.com
          /foo          echoheaders-x:80
          bar.baz.com
          /bar          echoheaders-y:80
          /foo          echoheaders-x:80

Before the deploy of the Ingress controller we need a default backend 404-server

kubectl create -f examples/default-backend.yaml
kubectl expose rc default-http-backend --port=80 --target-port=8080 --name=default-http-backend

Check NGINX it is running with the defined Ingress rules:

$ LBIP=$(kubectl get node `kubectl get po -l name=nginx-ingress-lb --template '{{range .items}}{{.spec.nodeName}}{{end}}'` --template '{{range $i, $n := .status.addresses}}{{if eq $n.type "ExternalIP"}}{{$n.address}}{{end}}{{end}}')
$ curl $LBIP/foo -H 'Host: foo.bar.com'

TLS

You can secure an Ingress by specifying a secret that contains a TLS private key and certificate. Currently the Ingress only supports a single TLS port, 443, and assumes TLS termination. This controller supports SNI. The TLS secret must contain keys named tls.crt and tls.key that contain the certificate and private key to use for TLS, eg:

apiVersion: v1
data:
  tls.crt: base64 encoded cert
  tls.key: base64 encoded key
kind: Secret
metadata:
  name: testsecret
  namespace: default
type: Opaque

Referencing this secret in an Ingress will tell the Ingress controller to secure the channel from the client to the loadbalancer using TLS:

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: no-rules-map
spec:
  tls:
    secretName: testsecret
  backend:
    serviceName: s1
    servicePort: 80

Please follow test.sh as a guide on how to generate secrets containing SSL certificates. The name of the secret can be different than the name of the certificate.

Check the example

HTTP Strict Transport Security

HTTP Strict Transport Security (HSTS) is an opt-in security enhancement specified through the use of a special response header. Once a supported browser receives this header that browser will prevent any communications from being sent over HTTP to the specified domain and will instead send all communications over HTTPS.

By default the controller redirects (301) to HTTPS if there is a TLS Ingress rule.

To disable this behavior use hsts=false in the NGINX ConfigMap.

Optimizing TLS Time To First Byte (TTTFB)

NGINX provides the configuration option ssl_buffer_size to allow the optimization of the TLS record size. This improves the Time To First Byte (TTTFB). The default value in the Ingress controller is 4k (nginx default is 16k);

Proxy Protocol

If you are using a L4 proxy to forward the traffic to the NGINX pods and terminate HTTP/HTTPS there, you will lose the remote endpoint's IP addresses. To prevent this you could use the Proxy Protocol for forwarding traffic, this will send the connection details before forwarding the acutal TCP connection itself.

Amongst others ELBs in AWS and HAProxy support Proxy Protocol.

Please check the proxy-protocol example

Exposing TCP services

Ingress does not support TCP services (yet). For this reason this Ingress controller uses a ConfigMap where the key is the external port to use and the value is <namespace/service name>:<service port> It is possible to use a number or the name of the port.

The next example shows how to expose the service example-go running in the namespace default in the port 8080 using the port 9000

apiVersion: v1
kind: ConfigMap
metadata:
  name: tcp-configmap-example
data:
  9000: "default/example-go:8080"

Please check the tcp services example

Exposing UDP services

Since 1.9.13 NGINX provides UDP Load Balancing.

Ingress does not support UDP services (yet). For this reason this Ingress controller uses a ConfigMap where the key is the external port to use and the value is <namespace/service name>:<service port> It is possible to use a number or the name of the port.

The next example shows how to expose the service kube-dns running in the namespace kube-system in the port 53 using the port 53

apiVersion: v1
kind: ConfigMap
metadata:
  name: udp-configmap-example
data:
  53: "kube-system/kube-dns:53"

Please check the udp services example

Custom NGINX configuration

Using a ConfigMap it is possible to customize the defaults in nginx.

Please check the tcp services example

Custom NGINX template

The NGINX template is located in the file /etc/nginx/template/nginx.tmpl. Mounting a volume is possible to use a custom version. Use the custom-template example as a guide

Please note the template is tied to the go code. Be sure to no change names in the variable $cfg

Custom NGINX upstream checks

NGINX exposes some flags in the upstream configuration that enables the configuration of each server in the upstream. The ingress controller allows custom max_fails and fail_timeout parameters in a global context using upstream-max-fails or upstream-fail-timeout in the NGINX Configmap or in a particular Ingress rule. By default this values are 0. This means NGINX will respect the readinessProbe, if is defined. If there is no probe, NGINX will not mark a server inside an upstream down.

With the default values NGINX will not health check your backends, and whenever the endpoints controller notices a readiness probe failure that pod's ip will be removed from the list of endpoints, causing nginx to also remove it from the upstreams.

To use custom values in an Ingress rule define this annotations:

ingress-nginx.kubernetes.io/upstream-max-fails: number of unsuccessful attempts to communicate with the server that should happen in the duration set by the fail_timeout parameter to consider the server unavailable

ingress-nginx.kubernetes.io/upstream-fail-timeout: time in seconds during which the specified number of unsuccessful attempts to communicate with the server should happen to consider the server unavailable. Also the period of time the server will be considered unavailable.

Important: The upstreams are shared. i.e. Ingress rule using the same service will use the same upstream. This means only one of the rules should define annotations to configure the upstream servers

Please check the auth example

Authentication

Is possible to add authentication adding additional annotations in the Ingress rule. The source of the authentication is a secret that contains usernames and passwords inside the the key auth

The annotations are:

ingress-nginx.kubernetes.io/auth-type:[basic|digest]

Indicates the HTTP Authentication Type: Basic or Digest Access Authentication.

ingress-nginx.kubernetes.io/auth-secret:secretName

Name of the secret that contains the usernames and passwords with access to the path/s defined in the Ingress Rule. The secret must be created in the same namespace than the Ingress rule

ingress-nginx.kubernetes.io/auth-realm:"realm string"

NGINX status page

The ngx_http_stub_status_module module provides access to basic status information. This is the default module active in the url /nginx_status. This controller provides an alternitive to this module using nginx-module-vts third party module. To use this module just provide a ConfigMap with the key enable-vts-status=true. The URL is exposed in the port 8080. Please check the example example/rc-default.yaml

To extract the information in JSON format the module provides a custom URL: /nginx_status/format/json

Custom errors

In case of an error in a request the body of the response is obtained from the default backend. Each request to the default backend includes two headers:

• X-Code indicates the HTTP code
• X-Format the value of the Accept header

Using this two headers is possible to use a custom backend service like this one that inspect each request and returns a custom error page with the format expected by the client. Please check the example custom-errors

Annotations

Annotation	Values	Description
ingress.kubernetes.io/rewrite-target	URI
ingress.kubernetes.io/add-base-url	true|false
ingress.kubernetes.io/limit-connections
ingress.kubernetes.io/limit-rps
ingress.kubernetes.io/auth-type	basic or digest	Indicates the HTTP Authentication Type: Basic or Digest Access Authentication
ingress.kubernetes.io/auth-secret	string	Name of the secret that contains the usernames and passwords.
		The secret must be created in the same namespace than the Ingress rule
ingress.kubernetes.io/auth-realm	string
ingress.kubernetes.io/upstream-max-fails
ingress.kubernetes.io/upstream-max-fails
ingress.kubernetes.io/upstream-fail-timeout

Custom configuration options

Running /nginx-ingress-controller --dump-nginx-configuration is possible to get the value of the options that can be changed. The next table shows the options, the default value and a description

name	default
body-size	1m
custom-http-errors	" "
enable-sticky-sessions	"false"
enable-vts-status	"false"
error-log-level	notice
gzip-types
hsts	"true"
hsts-include-subdomains	"true"
hsts-max-age	"15724800"
keep-alive	"75"
max-worker-connections	"16384"
proxy-connect-timeout	"5"
proxy-read-timeout	"60"
proxy-real-ip-cidr	0.0.0.0/0
proxy-send-timeout	"60"
retry-non-idempotent	"false"
server-name-hash-bucket-size	"64"
server-name-hash-max-size	"512"
ssl-buffer-size	4k
ssl-ciphers
ssl-protocols	TLSv1 TLSv1.1 TLSv1.2
ssl-session-cache	"true"
ssl-session-cache-size	10m
ssl-session-tickets	"true"
ssl-session-timeout	10m
use-gzip	"true"
use-http2	"true"
vts-status-zone-size	10m
worker-processes

Description:

body-size:

Sets the maximum allowed size of the client request body. See NGINX client_max_body_size

custom-http-errors:

Enables which HTTP codes should be passed for processing with the error_page directive Setting at least one code this also enables proxy_intercept_errors (required to process error_page)

enable-sticky-sessions:

Enables sticky sessions using cookies. This is provided by nginx-sticky-module-ng module

enable-vts-status:

Allows the replacement of the default status page with a third party module named nginx-module-vts

error-log-level:

Configures the logging level of errors. Log levels above are listed in the order of increasing severity http://nginx.org/en/docs/ngx_core_module.html#error_log

retry-non-idempotent:

Since 1.9.13 NGINX will not retry non-idempotent requests (POST, LOCK, PATCH) in case of an error in the upstream server. The previous behavior can be restored using the value "true"

hsts:

Enables or disables the header HSTS in servers running SSL. HTTP Strict Transport Security (often abbreviated as HSTS) is a security feature (HTTP header) that tell browsers that it should only be communicated with using HTTPS, instead of using HTTP. https://developer.mozilla.org/en-US/docs/Web/Security/HTTP_strict_transport_security Why HSTS is important?

hsts-include-subdomains:

Enables or disables the use of HSTS in all the subdomains of the servername

hsts-max-age:

Sets the time, in seconds, that the browser should remember that this site is only to be accessed using HTTPS.

keep-alive:

Sets the time during which a keep-alive client connection will stay open on the server side. The zero value disables keep-alive client connections http://nginx.org/en/docs/http/ngx_http_core_module.html#keepalive_timeout

max-worker-connections:

Sets the maximum number of simultaneous connections that can be opened by each worker process

proxy-connect-timeout:

Sets the timeout for establishing a connection with a proxied server. It should be noted that this timeout cannot usually exceed 75 seconds.

proxy-read-timeout:

Sets the timeout in seconds for reading a response from the proxied server. The timeout is set only between two successive read operations, not for the transmission of the whole response

proxy-send-timeout:

Sets the timeout in seconds for transmitting a request to the proxied server. The timeout is set only between two successive write operations, not for the transmission of the whole request.

resolver:

Configures name servers used to resolve names of upstream servers into addresses

server-name-hash-max-size:

Sets the maximum size of the server names hash tables used in server names, map directive’s values, MIME types, names of request header strings, etc. http://nginx.org/en/docs/hash.html

server-name-hash-bucket-size:

Sets the size of the bucker for the server names hash tables http://nginx.org/en/docs/hash.html http://nginx.org/en/docs/http/ngx_http_core_module.html#server_names_hash_bucket_size

ssl-buffer-size:

Sets the size of the SSL buffer used for sending data. 4k helps NGINX to improve TLS Time To First Byte (TTTFB) https://www.igvita.com/2013/12/16/optimizing-nginx-tls-time-to-first-byte/

ssl-ciphers:

Sets the ciphers list to enable. The ciphers are specified in the format understood by the OpenSSL library

ssl-dh-param:

Base64 string that contains Diffie-Hellman key to help with "Perfect Forward Secrecy" https://www.openssl.org/docs/manmaster/apps/dhparam.html https://wiki.mozilla.org/Security/Server_Side_TLS#DHE_handshake_and_dhparam http://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_dhparam

ssl-protocols:

Sets the SSL protocols to use

ssl-session-cache:

Enables or disables the use of shared SSL cache among worker processes.

ssl-session-cache-size:

Sets the size of the SSL shared session cache between all worker processes.

ssl-session-tickets:

Enables or disables session resumption through TLS session tickets

ssl-session-timeout:

Sets the time during which a client may reuse the session parameters stored in a cache.

upstream-max-fails:

Sets the number of unsuccessful attempts to communicate with the server that should happen in the duration set by the fail_timeout parameter to consider the server unavailable

upstream-fail-timeout:

Sets the time during which the specified number of unsuccessful attempts to communicate with the server should happen to consider the server unavailable

use-proxy-protocol:

Enables or disables the use of the PROXY protocol to receive client connection (real IP address) information passed through proxy servers and load balancers such as HAproxy and Amazon Elastic Load Balancer (ELB).

use-gzip:

Enables or disables the use of the nginx module that compresses responses using the "gzip" module

use-http2:

Enables or disables the HTTP/2 support in secure connections

gzip-types:

MIME types in addition to "text/html" to compress. The special value "*"" matches any MIME type. Responses with the "text/html" type are always compressed if use-gzip is enabled

worker-processes:

Sets the number of worker processes. By default "auto" means number of available CPU cores

Troubleshooting

Problems encountered during 1.2.0-alpha7 deployment:

• make setup-files.sh file in hypercube does not provide 10.0.0.1 IP to make-ca-certs, resulting in CA certs that are issued to the external cluster IP address rather then 10.0.0.1 -> this results in nginx-third-party-lb appearing to get stuck at "Utils.go:177 - Waiting for default/default-http-backend" in the docker logs. Kubernetes will eventually kill the container before nginx-third-party-lb times out with a message indicating that the CA certificate issuer is invalid (wrong ip), to verify this add zeros to the end of initialDelaySeconds and timeoutSeconds and reload the RC, and docker will log this error before kubernetes kills the container.
  • To fix the above, setup-files.sh must be patched before the cluster is inited (refer to https://github.com/kubernetes/kubernetes/pull/21504)

Debug

Using the flag --v=XX it is possible to increase the level of logging. In particular:

• --v=2 shows details using diff about the changes in the configuration in nginx

I0316 12:24:37.581267       1 utils.go:148] NGINX configuration diff a//etc/nginx/nginx.conf b//etc/nginx/nginx.conf
I0316 12:24:37.581356       1 utils.go:149] --- /tmp/922554809  2016-03-16 12:24:37.000000000 +0000
+++ /tmp/079811012  2016-03-16 12:24:37.000000000 +0000
@@ -235,7 +235,6 @@

     upstream default-echoheadersx {
         least_conn;
-        server 10.2.112.124:5000;
         server 10.2.208.50:5000;

     }
I0316 12:24:37.610073       1 command.go:69] change in configuration detected. Reloading...

• --v=3 shows details about the service, Ingress rule, endpoint changes and it dumps the nginx configuration in JSON format
• --v=5 configures NGINX in debug mode

Retries in no idempotent methods

Since 1.9.13 NGINX will not retry non-idempotent requests (POST, LOCK, PATCH) in case of an error. The previous behavior can be restored using retry-non-idempotent=true in the configuration ConfigMap

Limitations

• Ingress rules for TLS require the definition of the field host