adapt: validation: loading app modules: module name 'tls': provision tls: loading certificates: open cert_notexist.pem: no such file or directory
</code></pre>
Even though that Caddyfile can be adapted to JSON without errors, the actual certificate and/or key files do not exist, so validation fails because that error arises during the provisioning phase. Thus, validation is a stronger error check than adaptation is.
#### Example
To adapt a Caddyfile to JSON that you can easily read and tweak manually:
`--domain` will only serve files through that hostname, and Caddy will attempt to serve it over HTTPS, so make sure any public DNS is configured properly first if it's a public domain name. The default port will be changed to 443.
NOTE: Due to [a bug in Go](https://github.com/golang/go/issues/29228), version information is only available if Caddy is built as a dependency and not as the main module. TODO: Link to docs that explain how to build Caddy with version info
Gives the running Caddy instance a new configuration. This has the same effect as POSTing a document to the [/load endpoint](/docs/api#post-load), but this command is convenient for simple workflows revolving around config files. Compared to the `stop`, `start`, and `run` commands, this single command is the correct, semantic way to change/reload the running configuration.
`--config` is the config file to apply. If not specified, it will try a file called `Caddyfile` in the current working directory and, if it exists, it will adapt it using the `caddyfile` config adapter; otherwise, it is an error if there is no config file to load.
`--adapter` specifies a config adapter to use, if any.
`--address` needs to be used if the admin endpoint is not listening on the default address and if it is different from the address in the provided config file.
`--change-host-header` will cause Caddy to change the Host header from the incoming value to the address of the upstream.
Both `--from` and `--to` parameters can be URLs, as scheme, domain name, and URI rewrite information will be inferred from the provided URL (paths and query strings ignored). Or they can be a simple network address and not a complete URL.
To change the active configuration while running in production, do not stop the server! That will result in downtime. (This should be obvious but you'd be surprised how many complaints we get about it.) Use the <ahref="#caddy-reload">caddy reload</a> command instead.
Runs Caddy and blocks indefinitely; i.e. "daemon" mode.
`--config` specifies an initial config file to immediately load and use. If no config is specified, Caddy will run with a blank configuration and use default settings for the [admin API endpoints](/docs/api), which can be used to feed it new configuration. As a special case, if the current working directory has a file called "Caddyfile" and the `caddyfile` config adapter is plugged in (default), then that file will be loaded and used to configure Caddy, even without any command line flags.
`--adapter` is the name of the config adapter to use when loading the initial config, if any. This flag is not necessary if the `--config` filename starts with "Caddyfile" which assumes the `caddyfile` adapter. Otherwise, this flag is required if the provided config file is not in Caddy's native JSON format. Any warnings will be printed to the log, but beware that any adaptation without errors will immediately be used, even if there are warnings. If you want to review the results of the adaptation first, use the [`caddy adapt`](#caddy-adapt) subcommand.
`--environ` prints out the environment before starting. This is the same as the `caddy environ` command, but does not exit after printing.
`--resume` uses the last loaded configuration. This flag is useful primarily in [API](/docs/api)-heavy deployments, and overrides `--config` if a saved config exists.
`--watch` will watch the config file and automatically reload it after it changes. ⚠️ This feature is dangerous in production! Only use it in a local development environment.
Same as [`caddy run`](#caddy-run), but in the background. This command only blocks until the background process is running successfully (or fails to run), then returns.
Use of this command is discouraged with system services or on Windows. On Windows, the child process will remain attached to the terminal, so closing the window will forcefully stop Caddy, which is not obvious.
Once started, you can use [`caddy stop`](#caddy-stop) or [the /stop API endpoint](/docs/api#post-stop) to exit the background process.
Stopping (and restarting) the server is orthogonal to config changes. Do not use the stop command to change configuration in production, unless you want downtime. Use the <ahref="#caddy-reload">caddy reload</a> command instead.
Gracefully stops the running Caddy process (other than the process of the stop command) and causes it to exit. It uses the [/stop endpoint](/docs/api#post-stop) of the admin API to perform a graceful shutdown.
`--address` can be used if the running instance's admin API is not on the default port; an alternate address can be specified here.
If you want to stop the current configuration but do not want to exit the process, use [`caddy reload`](#caddy-reload) with a blank config, or the [`DELETE /config/`](/docs/api#delete-configpath) endpoint.
Untrusts a root certificate from the local trust store(s). Intended for development environments only. Specify either the `--ca` or `--cert` flags, but not both. If neither are specified, Caddy's default CA (`local`).
`--ca` specifies the ID of the Caddy CA to untrust. The default CA's ID is `local`.
`--cert` specifies the path to the PEM-encoded certificate file to uninstall.
Validates a configuration file, then exits. This command deserializes the config, then loads and provisions all of its modules as if to start the config, but the config is not actually started. This exposes errors in a configuration that arise during loading or provisioning phases and is a stronger error check than merely serializing a config as JSON.
`--adapter` is the name of the config adapter to use, if the config file is not in Caddy's native JSON format. If the config file starts with `Caddyfile`, the `caddyfile` adapter is used by default.
