folder

folder serves files from a directory. It can also provide directory browsing, SPA fallback, path rewrites, and cache headers.

server:
  http:
    middlewares:
      docs:
        folder:
          path: ./dist
          index: true
          spa: true
          browse: false
          cache_regex:
            - regex: .*
              cache_control: no-cache

Fields

Field	Default	Description
base_path	/	Base path used by the browse UI.
path		Filesystem path to serve.
index	false	Serve index_name for directory requests when it exists.
strip_index_name	false	Redirect /index.html to /.
index_name	index.html	Index file name.
spa	false	Serve the SPA index for missing non-file paths.
spa_enable_file	false	Also serve the SPA index for missing paths that look like files.
spa_index	index_name	SPA fallback file.
spa_index_regex		Regex replacements that choose the SPA index from the URL path.
browse	false	Enable directory listing.
utc	false	Render browse timestamps in UTC.
prefix_path		Prefix stripped before filesystem lookup.
file_path_regex		Regex replacements applied to the cleaned filesystem path.
cache_regex		Regex-based Cache-Control rules.
browse_cache	no-cache	Cache-Control value for browse pages.
disable_folder_slash_redirect	false	Disable automatic slash redirect for directories.
etag		ETag generation for files: weak or strong. Empty disables it.

ETag

When etag is set, served files get an ETag header and conditional requests (If-None-Match, If-Match, If-Range) are answered with 304 Not Modified / 412 as appropriate.

Mode	Value	Notes
weak	W/"<modtime>-<size>"	Cheap, no file read. Skipped for filesystems without a modification time.
strong	"<sha256 of content>"	Content hash, cached per file path, modification time and size. Works for embedded filesystems.

folder:
  path: ./dist
  etag: strong
  cache_regex:
    - regex: index\.html$
      cache_control: no-cache

Last-Modified / If-Modified-Since keep working independently of this setting.

Versioned Docs Example

folder:
  path: ./site
  spa: true
  index: true
  spa_index_regex:
    - regex: ^/docs/([^/]*)/.*$
      replacement: /$1/index.html
  file_path_regex:
    - regex: ^/docs/([^/]*)/?(.*)$
      replacement: /$1/latest/$2