sozu/doc/configure.md

Configure Sōzu

Before a deep dive in the configuration part of the proxy, you should take a look at the getting started documentation if you haven't yet.

Configuration file

The configuration file uses the .toml format.

Sōzu configuration process involves 3 major sources of parameters:

• The global section, which sets process-wide parameters.
• The definition of the protocols like https, http, tcp.
• The clusters sections under: [clusters].

Global parameters

Parameters in the global section allow you to define the global settings shared by the main process and workers (like the log level):

parameter	description	possible values
saved_state	path from which sozu tries to load its state at startup
log_level	possible values are	debug, trace, error, warn, info
log_target	possible values are	stdout, tcp or udp address
access_logs_target	possible values are (if activated, sends access logs to a separate target)	stdout, tcp or udp address
command_socket	path to the unix socket command
command_buffer_size	size, in bytes, of the buffer used by the main process to handle commands.
max_command_buffer_size	maximum size of the buffer used by the main process to handle commands.
worker_count	number of workers
worker_automatic_restart	if activated, workers that panicked or crashed are restarted (activated by default)
handle_process_affinity	bind workers to cpu cores.
max_connections	maximum number of simultaneous / opened connections
max_buffers	maximum number of buffers use to proxying
min_buffers	minimum number of buffers preallocated for proxying
buffer_size	size, in bytes, of requests buffer use by the workers
ctl_command_timeout	maximum time the command line will wait for a command to complete
pid_file_path	stores the pid in a specific file location
front_timeout	maximum time of inactivity for a front socket
connect_timeout	maximum time of inactivity for a request to connect
request_timeout	maximum time of inactivity for a request
zombie_check_interval	duration between checks for zombie sessions
activate_listeners	automatically start listeners

Example:

command_socket = "./command_folder/sock"
saved_state = "./state.json"
log_level = "info"
log_target = "stdout"
command_buffer_size = 16384
worker_count = 2
handle_process_affinity = false
max_connections = 500
max_buffers = 500
buffer_size = 16384
activate_listeners = true

Listeners

The listener section describes a set of listening sockets accepting client connections. You can define as many listeners as you want. They follow the format:

General parameters:

[[listeners]]
# possible values are http, https or tcp
protocol = "http"
# listening address
address = "0.0.0.0:8080"
# address = "[::]:8080"

# specify a different IP than the one the socket sees, for logs and forwarded headers
# public_address = "1.2.3.4:80

# Configures the client socket to receive a PROXY protocol header
# expect_proxy = false

Options specific to HTTP and HTTPS listeners

Since version 1.0.0, Sōzu allows custom HTTP answers defined for HTTP and HTTPS listeners.

These answers are customizable:

• 301 Moved Permanently
• 400 Bad Request
• 401 Unauthorized
• 404 Not Found
• 408 Request Timeout
• 413 Payload Too Large
• 502 Bad Gateway
• 503 Service Unavailable
• 504 Gateway Timeout
• 507 Insufficient Storage

These answers are to be provided in plain text files of whichever extension (we recommend .http for clarity) and may look like this:

HTTP/1.1 404 Not Found
Cache-Control: no-cache
Connection: close
Sozu-Id: %REQUEST_ID

<style>pre{background:#EEE;padding:10px;border:1px solid #AAA;border-radius: 5px;}</style>
<h1>404 Not Found</h1>

<p>insert your custom text here, in fact, all HTML is changeable, including the CSS.</p>

<pre>
{
    \"route\": \"%ROUTE\",
    \"request_id\": \"%REQUEST_ID\",
}
</pre>
<footer>This is an automatic answer by Sozu.</footer>",

There are a number of available template variables, like REQUEST_ID or CLUSTER_ID, that will be replaced by the proxying logic when producing the error.

To create your own custom HTTP answers, we highly suggest you first copy the default answers present in lib/src/protocol/kawa_h1/answers.rs, and then change them to your liking. Feel free to remove the \r newlines of the default strings for clarity. Sōzu will parse your file and replace whatever newline symbol(s) you use.

Then, for each listener, provide the absolute paths of each custom answer.

# a 404 response is sent when sozu does not know about the requested domain or path
answer_404 = "/path/to/my-404-answer.http"
# a 503 response is sent if there are no backend servers available
answer_503 = "/path/to/my-503-answer.http"
# answer_507 = ...

If a frontend has a sticky_session, the sticky name is defined at the listener level.

# defines the sticky session cookie's name, if `sticky_session` is activated format
# a cluster. Defaults to "SOZUBALANCEID"
sticky_name = "SOZUBALANCEID"

Options specific to HTTPS listeners

# supported TLS versions. Possible values are "SSL_V2", "SSL_V3",
# "TLS_V12", "TLS_V13". Defaults to "TLS_V12" and "TLS_V13"
tls_versions = ["TLS_V12", "TLS_V13"]

Options specific to Rustls based HTTPS listeners

# option specific to rustls based HTTPS listeners
cipher_list = [
    # TLS 1.3 cipher suites
    "TLS13_AES_256_GCM_SHA384",
    "TLS13_AES_128_GCM_SHA256",
    "TLS13_CHACHA20_POLY1305_SHA256",
    # TLS 1.2 cipher suites
    "TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384",
    "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256",
    "TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256",
    "TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384",
    "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256",
    "TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256",
]

Clusters

You can declare the list of your clusters under the [clusters] section. They follow the format:

Mandatories parameters:

[clusters]

[clusters.NameOfYourCluster]
# possible values are http or tcp
# https proxies will use http here
protocol = "http"

# per cluster load balancing algorithm. The possible values are
# "roundrobin" and "random". Defaults to "roundrobin"
# load_balancing_policy="roundrobin"

# force cluster to redirect http traffic to https
# https_redirect = true

frontends = [
  { address = "0.0.0.0:8080", hostname = "lolcatho.st" },
  { address = "0.0.0.0:8443", hostname = "lolcatho.st", certificate = "../lib/assets/certificate.pem", key = "../lib/assets/key.pem", certificate_chain = "../lib/assets/certificate_chain.pem" }
]
# additional options for frontends: sticky_session (boolean)

backends  = [
  { address = "127.0.0.1:1026" }
]

Metrics

Sōzu reports its own state to another network component through a UDP socket. The main process and the workers are responsible to send their states. We implement the statsd protocol to send statistics. Any service that understands the statsd protocol can then gather metrics from Sōzu.

Configure metrics

In your config.toml, you can define the address and port of your external service by adding:

[metrics]
address = "127.0.0.1:8125"
# use InfluxDB's statsd protocol flavor to add tags
# tagged_metrics = false
# metrics key prefix
# prefix = "sozu"

Currently, we can't change the frequency of sending messages.

Example of externals services

• statsd
• grad

PROXY Protocol

When a network stream goes through a proxy, the backend server will only see the IP address and port used by the proxy as client address. The real source IP address and port will only be seen by the proxy. Since this information is useful for logging, security, etc, the PROXY protocol was developed to transmit it to backend servers. With this protocol, after connecting to the backend server, the proxy will first send a small header indicating the client IP address and port, and the proxy's receiving IP address and port, and will then send the stream from the client.

Sōzu support the version 2 of the PROXY protocol in three configurations:

• "send" protocol: Sōzu, in TCP proxy mode, will send the header to the backend server
• "expect" protocol: Sōzu receives the header from a proxy, interprets it for its own logging and metrics, and uses it in HTTP forwarding headers
• "relay" protocol: Sōzu, in TCP proxy mode, can receive the header, and transmit it to a backend server

More information here: proxy-protocol spec

Configuring Sōzu to expect a PROXY Protocol header

Configures the client-facing connection to receive a PROXY protocol header before any byte sent by the client is read from the socket.

                           send PROXY                    expect PROXY
                           protocol header               protocol header
    +--------+
    | client |             +---------+                   +------------+      +-----------+
    |        |             | proxy   |                   | Sozu       |      | upstream  |
    +--------+  ---------> | server  |  ---------------> |            |------| server    |
   /        /              |         |                   |            |      |           |
  /________/               +---------+                   +------------+      +-----------+

It is supported by HTTP, HTTPS and TCP proxies.

Configuration:

[[listeners]]
address = "0.0.0.0:80"
expect_proxy = true

Configuring Sōzu to send a PROXY Protocol header to an upstream backend

Send a PROXY protocol header over any connection established to the backends declared in the cluster.

                           send PROXY
    +--------+             protocol header
    | client |             +---------+                +-----------------+
    |        |             | Sozu    |                | proxy/upstream  |
    +--------+  ---------> |         |  ------------> | server          |
   /        /              |         |                |                 |
  /________/               +---------+                +-----------------+

Configuration:

[[listeners]]
address = "0.0.0.0:81"

[clusters]
[clusters.NameOfYourTcpCluster]
send_proxy = true
frontends = [
  { address = "0.0.0.0:81" }
]

NOTE: Only for TCP clusters (HTTP and HTTPS proxies will use the forwarding headers).

Configuring Sōzu to relay a PROXY Protocol header to an upstream

Sōzu will receive a PROXY protocol header from the client connection, check its validity and then forward it to an upstream backend. This allows for chains of reverse-proxies without losing the client connection information.

                           send PROXY                       expect PROXY               send PROXY
                           protocol header                  protocol header            protocol header
    +--------+
    | client |             +---------+                      +------------+             +-------------------+
    |        |             | proxy   |                      | Sozu       |             | proxy/upstream    |
    +--------+  +--------> | server  |  +-----------------> |            | +---------> | server            |
   /        /              |         |                      |            |             |                   |
  /________/               +---------+                      +------------+             +-------------------+

Configuration:

This only concerns TCP clusters (HTTP and HTTPS proxies can work directly in expect mode, and will use the forwarding headers).

[[listeners]]
address = "0.0.0.0:80"
expect_proxy = true

[clusters]

[clusters.NameOfYourCluster]
send_proxy = true
frontends = [
  { address = "0.0.0.0:80" }
]