caddy-website/src/docs/markdown/caddyfile/options.md

title
Global options (Caddyfile)

Global options

The Caddyfile has a way for you to specify options that apply globally. Some options act as default values; others customize HTTP servers and don't apply to just one particular site; while yet others customize the behavior of the Caddyfile adapter.

The very top of your Caddyfile can be a global options block. This is a block that has no keys:

{
	...
}

There can only be one at most, and it must be the first block of the Caddyfile.

Possible options are:

{
	# General Options
	debug
	http_port    <port>
	https_port   <port>
	default_bind <hosts...>
	order <dir1> first|last|[before|after <dir2>]
	storage <module_name> {
		<options...>
	}
	storage_clean_interval <duration>
	renew_interval <duration>
	ocsp_interval  <duration>
	admin   off|<addr> {
		origins <origins...>
		enforce_origin
	}
	log [name] {
		output  <writer_module> ...
		format  <encoder_module> ...
		level   <level>
		include <namespaces...>
		exclude <namespaces...>
	}
	grace_period   <duration>
	shutdown_delay <duration>

	# TLS Options
	auto_https off|disable_redirects|ignore_loaded_certs|disable_certs
	email <yours>
	default_sni <name>
	local_certs
	skip_install_trust
	acme_ca <directory_url>
	acme_ca_root <pem_file>
	acme_eab <key_id> <mac_key>
	acme_dns <provider> ...
	on_demand_tls {
		ask      <endpoint>
		interval <duration>
		burst    <n>
	}
	key_type ed25519|p256|p384|rsa2048|rsa4096
	cert_issuer <name> ...
	ocsp_stapling off
	preferred_chains [smallest] {
		root_common_name <common_names...>
		any_common_name  <common_names...>
	}

	# Server Options
	servers [<listener_address>] {
		listener_wrappers {
			<listener_wrappers...>
		}
		timeouts {
			read_body   <duration>
			read_header <duration>
			write       <duration>
			idle        <duration>
		}
		metrics
		max_header_size <size>
		log_credentials
		protocols [h1|h2|h2c|h3]
		strict_sni_host [on|insecure_off]
	}

	# PKI Options
	pki {
		ca [<id>] {
			name                  <name>
			root_cn               <name>
			intermediate_cn       <name>
			intermediate_lifetime <duration>
			root {
				format <format>
				cert   <path>
				key    <path>
			}
			intermediate {
				format <format>
				cert   <path>
				key    <path>
			}
		}
	}

	# Event options
	events {
		on <event> <handler...>
	}
}

General Options

debug

Enables debug mode, which sets the log level to DEBUG for the default logger. This reveals more details that can be useful when troubleshooting (and is very verbose in production). We ask that you enable this before asking for help on the community forums. For example, at the top of your Caddyfile, if you have no other global options:

{
	debug
}

http_port

The port for the server to use for HTTP. For internal use only; does not change the HTTP port for clients. Default: 80

https_port

The port for the server to use for HTTPS. For internal use only; does not change the HTTPS port for clients. Default: 443

default_bind

The default bind address(es) to be used for all sites, if the bind directive is not used in the site. Default: empty, which binds to all interfaces.

order

Assigns an order to HTTP handler directive(s). As HTTP handlers execute in a sequential chain, it is necessary for the handlers to be executed in the right order. Standard directives have a pre-defined order, but if using third-party HTTP handler modules, you'll need to define the order explicitly by either using this option or placing the directive in a route block. Ordering can be described absolutely (first or last), or relatively (before or after) to another directive.

For example, to use the replace-response plugin, you'd want to make sure its directive is ordered after encode so that it can perform replacements before the response is encoded (because responses flow up the handler chain, not down):

order replace after encode

storage

Configures Caddy's storage mechanism. The default is file_system. There are many other available storage modules provided as plugins.

For example, to change the file system's storage location:

storage file_system /path/to/custom/location

Customizing the storage module is typically needed when syncing Caddy's storage across multiple instances of Caddy to make sure they all use the same certificates and keys. See the Automatic HTTPS section on storage for more details.

storage_clean_interval

How often to scan storage units for old or expired assets and remove them. These scans exert lots of reads (and list operations) on the storage module, so choose a longer interval for large deployments. The value is a duration value. Default: 24h.

Storage will always be cleaned when the process first starts. Then, a new cleaning will be started this duration after the previous cleaning started if the previous cleaning finished in less than half the time of this interval (otherwise next start will be skipped).

renew_interval

How often to scan all loaded, managed certificates for expiration, and trigger renewal if expired. Default: 10m.

ocsp_interval

How often to check if OCSP staples need updating. Default: 1h.

admin

Customizes the admin API endpoint. Accepts placeholders. If off, then the admin endpoint will be disabled. If disabled, config changes will be impossible without stopping and starting the server.

• origins configures the list of remotes/origins that are allowed to connect to the endpoint.

• enforce_origin enables enforcement of the Origin header. (This is different from enforcing origins generally, which is always done.)

log

Configures named loggers. The name can be passed to indicate a specific logger for which to customize the behavior. If no name is specified, the behavior of the default logger is modified. Multiple loggers with different names can be configured by using the log multiple times. You can read more about the default logger and an explanation of how logging works in Caddy.

The differs from the log directive, which only configures HTTP request logging (also known as access logs). The log global option shares its configuration structure with the directive (except for include and exclude), and complete documentation can be found on the directive's page.

• output configures where to write the logs. See the log directive for complete documentation.
• format describes how to encode, or format, the logs. See the log directive for complete documentation.
• level is the minimum entry level to log. Default: INFO.
• include specifies the log names to be included in this logger. For example, to include only logs emitted by the admin API, you would include admin.api. By default, this list is empty (i.e. all logs are included).
• exclude specifies the log names to be excluded from this logger. For example, to exclude only HTTP access logs, you would exclude http.log.access. By default, this list is empty (i.e. no logs are excluded).

The logger names that include and exclude accept depend on the modules used, and easiest way to discover them is from prior logs.

Here is an example logging as json all http access logs and admin logs to stdout:

log default {
	output stdout
	format json
	include http.log.access admin.api
}

grace_period

Defines the grace period for shutting down HTTP servers during config changes. During the grace period, no new connections are accepted, idle connections are closed, and active connections are impatiently waited upon to finish their requests. If clients do not finish their requests within the grace period, the server will be forcefully terminated to allow the reload to complete and free up resources. By default, no grace period is set.

shutdown_delay

Defines a duration before the grace period during which a server that is going to be stopped continues to operate normally, except the {http.shutting_down} placeholder evaluates to true and {http.time_until_shutdown} gives the time until the grace period begins. This causes a delay if any server is being shut down as part of a config change and effectively schedules the change for a later time. It is useful for announcing to health checkers of this server's impending doom and to give time for a load balancer to move it out of the rotation; for example:

handle /health-check {
	@goingDown vars {http.shutting_down} true
	respond @goingDown "Bye-bye in {http.time_until_shutdown}" 503
	respond 200
}

TLS Options

auto_https

Configure automatic HTTPS. There are a few modes to choose from:

• off: Disabled entirely. No certificate management or redirects.
• disable_redirects: Disable only HTTP-to-HTTPS redirects.
• disable_certs: Disable only certificate automation.
• ignore_loaded_certs: Automate certificates even for names which appear on manually-loaded certificates

See the Automatic HTTPS page for more details.

email

Your email address. Mainly used when creating an ACME account with your CA, and is highly recommended in case there are problems with your certificates.

default_sni

Sets a default TLS ServerName for when clients do not use SNI in their ClientHello.

local_certs

Causes all certificates to be issued internally by default, rather than through a (public) ACME CA such as Let's Encrypt. This is useful in development environments.

skip_install_trust

Skips the attempts to install the local CA's root into the system trust store, as well as into Java and Mozilla Firefox trust stores.

acme_ca

Specifies the URL to the ACME CA's directory. It is strongly recommended to set this to Let's Encrypt's staging endpoint for testing or development. Default: ZeroSSL and Let's Encrypt's production endpoints.

acme_ca_root

Specifies a PEM file that contains a trusted root certificate for ACME CA endpoints, if not in the system trust store.

acme_eab

Specifies an External Account Binding to use for all ACME transactions.

acme_dns

Configures the ACME DNS challenge provider to use for all ACME transactions. The tokens following the name of the provider set up the provider the same as if specified in the tls directive's acme issuer.

on_demand_tls

Configures On-Demand TLS where it is enabled, but does not enable it (to enable it, use the on_demand tls subdirective). Highly recommended if using in production environments, to prevent abuse.

• ask will cause Caddy to make an HTTP request to the given URL with a query string of ?domain= containing the value of the domain name. If the endpoint returns a 2xx status code, Caddy will be authorized to obtain a certificate for that name. Any other status code will result in cancelling issuance of the certificate.

• interval and burst allows <n> certificate operations within <duration> interval.

key_type

Specifies the type of key to generate for TLS certificates; only change this if you have a specific need to customize it. The possible values are: ed25519, p256, p384, rsa2048, rsa4096.

cert_issuer

Defines the issuer (or source) of TLS certificates. The tokens following the name of the issuer set up the issuer the same as if specified in the tls directive. May be repeated if you wish to configure more than one issuer to try. They will be tried in the order they are defined.

ocsp_stapling

Can be set to off to disable OCSP stapling. Useful in environments where responders are not reachable due to firewalls.

preferred_chains

If your CA provides multiple certificate chains, you can use this option to specify which chain Caddy should prefer. Set one of the following options:

• smallest will tell Caddy to prefer chains with the fewest amount of bytes.
• root_common_name is a list of one or more common names; Caddy will choose the first chain that has a root that matches with at least one of the specified common names.
• any_common_name is a list of one or more common names; Caddy will choose the first chain that has an issuer that matches with at least one of the specified common names.

Note that specifying preferred_chains as a global option will affect all issuers if there isn't any overriding issuer level config.

Server Options

Customizes HTTP servers with settings that potentially span multiple sites and thus can't be rightly configured in site blocks. These options affect the listener/socket or other facilities beneath the HTTP layer.

Can be specified more than once with different listener_address values to configure different options per server. For example, servers :443 will only apply to the server that is bound to the listener address :443. Omitting the listener address will apply the options to any remaining server.

Use the caddy adapt command to find the listen address for the servers in your Caddyfile.

For example, to configure different options for the servers on ports :80 and :443, you would specify two servers blocks:

{
	servers :443 {
		listener_wrappers {
			http_redirect
			tls
		}
	}

	servers :80 {
		protocols h1 h2c
	}
}

listener_wrappers

Allows configuring listener wrappers, which can modify the behaviour of the socket listener. They are applied in the given order.

There is a special no-op tls listener wrapper provided as a standard module which marks where TLS should be handled in the chain of listener wrappers. It should only be used if another listener wrapper must be placed in front of the TLS handshake.

The standard distribution of Caddy includes the http_redirect listener wrapper, which can look at the first few bytes of an incoming request to determine if it's likely HTTP (instead of TLS), and trigger an HTTP->HTTPS redirect on the same port but using the https:// scheme. It must be placed before the tls listener wrapper. For example:

listener_wrappers {
	http_redirect
	tls
}

Another example, assuming you have the proxy_protocol plugin installed, which must be used before the tls listener wrapper:

listener_wrappers {
	proxy_protocol {
		timeout 2s
		allow 192.168.86.1/24 192.168.86.1/24
	}
	tls
}

timeouts

• read_body is a duration value that sets how long to allow a read from a client's upload. Setting this to a short, non-zero value can mitigate slowloris attacks, but may also affect legitimately slow clients. Defaults to no timeout.

• read_header is a duration value that sets how long to allow a read from a client's request headers. Defaults to no timeout.

• write is a duration value that sets how long to allow a write to a client. Note that setting this to a small value when serving large files may negatively affect legitimately slow clients. Defaults to no timeout.

• idle is a duration value that sets the maximum time to wait for the next request when keep-alives are enabled. Defaults to 5 minutes to help avoid resource exhaustion.

metrics

Enables Prometheus metrics collection; necessary before scraping metrics. Note that metrics reduce performance on really busy servers. (Our community is working on improving this. Please get involved!)

max_header_size

The maximum size to parse from a client's HTTP request headers. It accepts all formats supported by go-humanize.

log_credentials

Since Caddy v2.5, by default, headers with potentially sensitive information (Cookie, Set-Cookie, Authorization and Proxy-Authorization) will be logged with empty values in access logs (see the log directive).

If you wish to not have these headers redacted, you may enable the log_credentials option.

protocols

The space-separated list of HTTP protocols to support. Default: h1 h2 h3. Accepted values are:

• h1 for HTTP/1.1
• h2 For HTTP/2
• h2c for HTTP/2 over cleartext
• h3 for HTTP/3

Currently, enabling HTTP/2 (including H2C) necessarily implies enabling HTTP/1.1 because the Go standard library does not let us disable HTTP/1.1 when using its HTTP server. However, either HTTP/1.1 or HTTP/3 can be enabled independently.

Note that H2C ("Cleartext HTTP/2" or "H2 over TCP") and HTTP/3 are not implemented by the Go standard library, so some functionality or features may be limited. We recommend against enabling H2C unless it is absolutely necessary for your application.

strict_sni_host

Enabling this requires that a request's Host header matches the value of the ServerName sent by the client's TLS ClientHello, a necessary safeguard when using TLS client authentication. If there's a mismatch, HTTP status 421 Misdirected Request response is written to the client.

This option will automatically be turned on if client authentication is configured. This disallows TLS client auth bypass (domain fronting) which could otherwise be exploited by sending an unprotected SNI value during a TLS handshake, then putting a protected domain in the Host header after establishing connection. This behavior is a safe default, but you may explicitly turn it off with insecure_off; for example in the case of running a proxy where domain fronting is desired and access is not restricted based on hostname.

PKI Options

The PKI (Public Key Infrastructure) app is the foundation for Caddy's Local HTTPS and ACME server features. The app defines certificate authorities (CAs) which are capable of signing certificates.

The default CA ID is local. If the ID is omitted when configuring the ca, then local is assumed.

name

The user-facing name of the certificate authority. Default: Caddy Local Authority

root_cn

The name to put in the CommonName field of the root certificate. Default: {pki.ca.name} - {time.now.year} ECC Root

intermediate_cn

The name to put in the CommonName field of the intermediate certificates. Default: {pki.ca.name} - ECC Intermediate

intermediate_lifetime

The duration for which intermediate certificates are valid. This value must be less than the lifetime of the root cert (3600d). Default: 7d. It is recommended not to change this unless absolutely necessary.

root

A key pair (certificate and private key) to use as the root for the CA. If not specified, one will be generated and managed automatically.

• format is the format in which the certificate and private key are provided. Currently, only pem_file is supported, which is the default, so this field is optional.
• cert is the certificate. This should be the path to a PEM file, when using pem_file format.
• key is the private key. This should be the path to a PEM file, when using pem_file format.

intermediate

A key pair (certificate and private key) to use as the intermediate for the CA. If not specified, one will be generated and managed automatically.

• format is the format in which the certificate and private key are provided. Currently, only pem_file is supported, which is the default, so this field is optional.
• cert is the certificate. This should be the path to a PEM file, when using pem_file format.
• key is the private key. This should be the path to a PEM file, when using pem_file format.

Event Options

Caddy modules emit events when interesting things happen (or are about to happen).

on

Binds an event handler to the named event. Specify the name of the event handler module, followed by its configuration.

For example, to run a command after a certificate is obtained (third-party plugin required):

on cert_obtained exec systemctl reload mydaemon