> ## Documentation Index > Fetch the complete documentation index at: https://mintlify.com/caddyserver/caddy/llms.txt > Use this file to discover all available pages before exploring further. # Templates > Execute response bodies as Go templates with rich template functions The templates module is a middleware which executes response bodies as Go templates. The syntax is documented in the [Go standard library's text/template package](https://golang.org/pkg/text/template/). **Module ID:** `http.handlers.templates` Template functions/actions are still experimental and subject to change. ## Configuration The root path from which to load files. Required if template functions accessing the file system are used (such as `include`). Default is `{http.vars.root}` if set, or current working directory otherwise. The MIME types for which to render templates. Important to use this if the route matchers do not exclude images or other binary files. The template action delimiters. Must be precisely two elements: the opening and closing delimiters. ```json theme={null} "delimiters": ["[[", "]]"] ``` Custom template functions registered as modules. These often act as components on web pages. Module namespace: `http.handlers.templates.functions` ## Template Context The following data and functions are available to templates: ### Request Data Arguments passed to this page/context, for example as the result of an `include`. ``` {{index .Args 0}} {{/* first argument */}} ``` The current HTTP request object with fields: * `.Method` - The HTTP method * `.URL` - The URL with component fields (Scheme, Host, Path, etc.) * `.Header` - The header fields * `.Host` - The Host or :authority header ``` {{.Req.Header.Get "User-Agent"}} {{.Req.Method}} {{.Req.URL.Path}} ``` Like `.Req`, except it accesses the original HTTP request before rewrites or other internal modifications. Returns the hostname portion (no port) of the Host header. ``` {{.Host}} ``` Returns the connection's IP address. ``` {{.RemoteIP}} ``` Returns the real client's IP address if `trusted_proxies` was configured, otherwise returns the connection's IP address. ``` {{.ClientIP}} ``` ### Response Manipulation Adds a header field to the HTTP response. ``` {{.RespHeader.Add "Field-Name" "val"}} ``` Sets a header field on the HTTP response, replacing any existing value. ``` {{.RespHeader.Set "Field-Name" "val"}} ``` Deletes a header field on the HTTP response. ``` {{.RespHeader.Del "Field-Name"}} ``` ## Template Functions All [Sprig functions](https://masterminds.github.io/sprig/) are supported, plus Caddy-specific functions: ### Placeholders and Environment Gets an environment variable. ``` {{env "PATH"}} {{env "DATABASE_URL"}} ``` Gets a placeholder variable. The braces (`{}`) must be omitted. ``` {{placeholder "http.request.uri.path"}} {{placeholder "http.error.status_code"}} ``` Short alias: `ph` ``` {{ph "http.request.method"}} ``` ### Cookies Gets the value of a cookie by name. ``` {{.Cookie "session_id"}} ``` ### File Operations Includes the contents of another file, rendering it in-place. Optionally pass key-value pairs as arguments to be accessed by the included file using `.Args`. The contents are NOT escaped, so only include trusted template files. ``` {{include "path/to/file.html"}} {{/* no arguments */}} {{include "path/to/file.html" "arg0" 1 "value 2"}} {{/* with arguments */}} ``` Reads and returns the contents of another file, parsing it as a template and adding any template definitions to the template stack. If there are no definitions, the filepath will be the definition name. Any `{{ define }}` blocks will be accessible by `{{ template }}` or `{{ block }}`. Imports must happen before the template or block action is called. The contents are NOT escaped. ``` {{import "/path/to/filename.html"}} {{template "main"}} ``` Reads and returns the contents of another file, as-is. The contents are NOT escaped, so only read trusted files. ``` {{readFile "path/to/file.html"}} ``` Returns a list of files in the given directory, which is relative to the template context's file root. ``` {{range listFiles "/mydir"}} {{.Name}} - {{.Size}} bytes {{end}} ``` Returns true if the file exists. ``` {{if fileExists "/path/to/file.txt"}} File exists! {{end}} ``` ### HTTP Includes Includes the contents of another file by making a virtual HTTP request (sub-request). The URI path must exist on the same virtual server. The request is crafted in memory and the handler is invoked directly for increased efficiency. ``` {{httpInclude "/api/data?format=html"}} ``` ### Content Processing Renders the given Markdown text as HTML using the [Goldmark](https://github.com/yuin/goldmark) library (CommonMark compliant). Extensions enabled: * GitHub Flavored Markdown * Footnote * Syntax highlighting (via [Chroma](https://github.com/alecthomas/chroma)) ``` {{markdown "My _markdown_ **text**"}} ``` Splits front matter from the body. Front matter is metadata at the beginning of a file. Supported formats: * **YAML**: Surrounded by `---` * **TOML**: Surrounded by `+++` * **JSON**: Surrounded by `{` and `}` Returns object with: * `.Meta` - Metadata fields * `.Body` - Body after front matter ``` {{$parsed := splitFrontMatter (readFile "post.md")}}

{{$parsed.Meta.title}}

{{markdown $parsed.Body}} ``` Removes HTML from a string. ``` {{stripHTML "Shows only text content"}} {{/* Output: Shows only text content */}} ``` ### Formatting Transforms size and time inputs to human readable format using [go-humanize](https://github.com/dustin/go-humanize). Format types: * `size` - Turns bytes into "2.3 MB" * `time` - Turns time string into "2 weeks ago" For `time` format, append `:layout` to specify custom time layout (default: RFC1123Z). ``` {{humanize "size" "2048000"}} {{/* Output: 2.0 MB */}} {{placeholder "http.response.header.Content-Length" | humanize "size"}} {{humanize "time" "Mon, 02 Jan 2006 15:04:05 -0700"}} {{/* Output: 2 weeks ago */}} {{humanize "time:2006-Jan-02" "2022-May-05"}} ``` Passes a string through `url.PathEscape`, replacing characters that have special meaning in URL path parameters. Useful for including filenames containing `?`, `&`, `%` in URL paths or as `img` src attributes. ``` {{pathEscape "50%_valid_filename?.jpg"}} {{/* Output: 50%25_valid_filename%3F.jpg */}} ``` ### Error Handling Returns an error with the given status code to the HTTP handler chain. ``` {{if not (fileExists $includedFile)}} {{httpError 404}} {{end}} ``` ### Experimental Functions Invokes a custom template function only if it is registered (plugged-in) in the `http.handlers.templates.functions.*` namespace. If the named function is not available, the invocation is ignored and a log message is emitted. EXPERIMENTAL: Subject to change or removal. ``` {{maybe "myOptionalFunc" "arg1" 2}} ``` ## Configuration Examples ### Basic Templates ```json JSON theme={null} { "handler": "templates" } ``` ```caddyfile Caddyfile theme={null} templates ``` ### Custom File Root ```json JSON theme={null} { "handler": "templates", "file_root": "/var/www/templates" } ``` ```caddyfile Caddyfile theme={null} templates { root /var/www/templates } ``` ### Custom Delimiters ```json theme={null} { "handler": "templates", "delimiters": ["[[", "]]"], "mime_types": ["text/html"] } ``` ### Full Stack Example ```caddyfile theme={null} example.com { templates file_server } ``` ## Template Examples ### Dynamic Navigation ```html theme={null} ``` ### Markdown Blog Post ```html theme={null} {{$post := readFile "/posts/my-post.md"}} {{$parsed := splitFrontMatter $post}}

{{$parsed.Meta.title}}

{{markdown $parsed.Body}}
``` ### Conditional Content ```html theme={null} {{if eq .Req.Method "POST"}}

Thanks for submitting!

{{else}}
{{end}} ``` ### Include Header/Footer ```html theme={null} {{include "header.html" .Req.URL.Path}}

Welcome to {{.Host}}

Your IP: {{.ClientIP}}

{{include "footer.html"}} ``` Templates are executed after other response transformers in the handler chain. Place the `templates` handler **after** `encode` so that templates execute on uncompressed content.