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](/docs/config-adapters).
Enables debug mode, which sets the log level to `DEBUG` for the [default logger](#log). 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](https://caddy.community). For example, at the top of your Caddyfile, if you have no other global options:
The default bind address(es) to be used for all sites, if the [`bind` directive](/docs/caddyfile/directives/bind) is not used in the site. Default: empty, which binds to all interfaces.
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](/docs/caddyfile/directives#directive-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](/docs/caddyfile/directives/route). Ordering can be described absolutely (`first` or `last`), or relatively (`before` or `after`) to another directive.
For example, to use the [`replace-response` plugin](https://github.com/caddyserver/replace-response), 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):
Configures Caddy's storage mechanism. The default is [`file_system`](/docs/json/storage/file_system/). There are many other available [storage modules](/docs/json/storage/) provided as plugins.
For example, to change the file system's storage location:
```caddy-d
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](/docs/automatic-https#storage) for more details.
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](/docs/conventions#durations). 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).
Customizes the [admin API endpoint](/docs/api). Accepts placeholders. If `off`, then the admin endpoint will be disabled. If disabled, config changes will be impossible without stopping and starting the server.
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](/docs/logging).
The differs from the [`log` directive](/docs/caddyfile/directives/log), 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](/docs/caddyfile/directives/log#output-modules) for complete documentation.
- **format** describes how to encode, or format, the logs. See the [`log` directive](/docs/caddyfile/directives/log#format-modules) 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).
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.
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:
```caddy-d
handle /health-check {
@goingDown vars {http.shutting_down} true
respond @goingDown "Bye-bye in {http.time_until_shutdown}" 503
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.
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.
Specifies the URL to the ACME CA's directory. It is strongly recommended to set this to Let's Encrypt's [staging endpoint](https://letsencrypt.org/docs/staging-environment/) for testing or development. Default: ZeroSSL and Let's Encrypt's production endpoints.
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](/docs/caddyfile/directives/tls#acme).
Configures [On-Demand TLS](/docs/automatic-https#on-demand-tls) where it is enabled, but does not enable it (to enable it, use the [on_demand `tls` subdirective](/docs/caddyfile/directives/tls#syntax)). 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.
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`.
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](/docs/caddyfile/directives/tls#issuer). May be repeated if you wish to configure more than one issuer to try. They will be tried in the order they are defined.
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](/docs/caddyfile/directives/tls#acme).
Customizes [HTTP servers](/docs/json/apps/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.
Allows configuring [listener wrappers](/docs/json/apps/http/servers/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`](/docs/json/apps/http/servers/listener_wrappers/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`](/docs/json/apps/http/servers/listener_wrappers/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:
Another example, assuming you have the [`proxy_protocol`](/docs/json/apps/http/servers/listener_wrappers/proxy_protocol/) plugin installed, which must be used _before_ the `tls` listener wrapper:
- **read_body** is a [duration value](/docs/conventions#durations) 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](/docs/conventions#durations) that sets how long to allow a read from a client's request headers. Defaults to no timeout.
- **write** is a [duration value](/docs/conventions#durations) 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](/docs/conventions#durations) 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.
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!)
The maximum size to parse from a client's HTTP request headers. It accepts all formats supported by [go-humanize](https://github.com/dustin/go-humanize/blob/master/bytes.go).
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](/docs/caddyfile/directives/log)).
If you wish to _not_ have these headers redacted, you may enable the `log_credentials` option.
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.
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](/docs/caddyfile/directives/tls#client_auth) 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.
The PKI (Public Key Infrastructure) app is the foundation for Caddy's [Local HTTPS](/docs/automatic-https#local-https) and [ACME server](/docs/caddyfile/directives/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`
The [duration](/docs/conventions#durations) 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.
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.
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 <img src="/resources/images/external-link.svg" class="external-link">](https://github.com/mholt/caddy-events-exec) required):
