NAME

mccs - Fully-featured static file server.

SYNOPSIS

$ mccs [OPTS] [DIR]

# serve current working directory over HTTP, port 5000
$ mccs

# serve a directory on port 80 using Starman
$ mccs -s Starman --listen :80 /some/directory

DESCRIPTION

mccs is an HTTP static file server that can be used as a standalone application, or as a Plack component.

FEATURES

• Automatic, durable compression of files based on client support.
• Automatic minification of CSS and JavaScript files.
• Content negotiation including proper setting and handling of cache-related headers.
• Optional virtual-hosts mode for serving multiple websites.
• Flexible deployment with support for various HTTP servers, FastCGI servers, UNIX domain sockets, and more.

mccs aims for reducing CPU load by retaining minified and compressed representations of files until they are no longer valid. It does not recompress on every request.

For information on how to use mccs as a library or embedded in Plack applications, see Plack::App::MCCS and Plack::Middleware::MCCS.

ARGUMENTS

DIR

The directory to serve files from. Defaults to the current working
directory.

OPTIONS

• --minify/--nominify

  Whether to minify CSS/JS files automatically. By default, --minify is on.

• --compress/--nocompress

  Whether to compress files automatically. By default, --compress is on.

• --etag/--noetag

  Whether to calculate ETag values for files and support If-None-Match headers. By default, --etag is on.

• --vhost-mode

  Enables virtual hosts mode, which allows serving multiple websites based on the HTTP Host header (HTTP/1.0 requests will not be supported in this mode). When enabled, the directory being served must contain subdirectories named after each host/domain to be served.

• --ignore-file

  Accepts a path to a file in the Gitignore format. Any request that matches a rule in this file will result in a 404 Not Found response. Defaults to .mccsignore in the root directory. In vhost mode, every host can have its own ignore file, and there can also one global file for all hosts. Both the host-specific file and the global file will be used if they exist.

• -s, --server, the PLACK_SERVER environment variable

  Selects a specific server implementation to run on. When provided, the -s or --server flag will be preferred over the environment variable.

  If no option is given, mccs will try to detect the best server implementation based on the environment variables as well as modules loaded by your application in %INC. See Plack::Loader for details.

• -S, --socket

  Listens on a UNIX domain socket path. Defaults to undef. This option is only valid for servers which support UNIX sockets.

• -l, --listen

  Listens on one or more addresses, whether "HOST:PORT", ":PORT", or "PATH" (without colons). You may use this option multiple times to listen on multiple addresses, but the server will decide whether it supports multiple interfaces.

• -D, --daemonize

  Makes the process run in the background. It's up to the backend server/handler implementation whether this option is respected or not.

• --access-log

  Specifies the pathname of a file where the access log should be written. By default, in the development environment access logs will go to STDERR.

Note that mccs is an extension of plackup, and accepts all the flags and options supported by it, but not all make sense in the context of mccs usage. It is recommended to use an HTTP server such as Twiggy or Starman in a production setting. Other options that starts with "--" are passed through to the backend server. See each Plack::Handler backend's documentation for more details on their available options.

HOW DOES IT WORK?

When a request is accepted by the server, the following process is initiated:

• 1. Discovery:

  mccs attempts to find the requested path in the root directory. If the path is not found, 404 Not Found is returned. If the path exists but is a directory, 403 Forbidden is returned (directory listings are currently not supported).

• 1. Examination:

  mccs will try to find the content type of the file, either by its extension (relying on Plack::MIME for that), or by a specific setting provided to the app by the user (will take precedence). If not found (or file has no extension), text/plain is assumed (which means you should give your files proper extensions if possible).

  mccs will also determine for how long to allow clients (whether browsers, proxy caches, etc.) to cache the file. By default, it will set a representation as valid for 86400 seconds (i.e. one day). However, this can be changed either by setting a different global validity interval, or by setting a specific value for certain file types.

  By default, mccs also sets the public option for the Cache-Control header, meaning caches are allowed to save responses even when authentication is performed. You can change that the same way.

• 1. Minification

  If the content type is text/css or application/javascript, mccs will try to find a pre-minified version of it on disk. If found, and the version is younger than the original file, then it will be marked for serving. Otherwise, if CSS::Minifier::XS or JavaScript::Minifier:XS are installed, mccs will minify the file, save the minified version to disk, and mark it as the version to serve. Future requests to the same file will see the minified version and not minify again.

  mccs searches for files that end with .min.css and .min.js, and that's how it creates them too. If a request comes to style.css, for example, then mccs will look for style.min.css, possibly creating it if not found or stale. The request path remains the same (style.css) though, even internally. If a request comes to style.min.css (which you don't really want when using mccs), the app will not attempt to minify it again (so you won't get things like style.min.min.css).

  If min_cache_dir is specified, it will do all its searching and storing of generated minified files within $root/$min_cache_dir and ignore minified files outside that directory.

• 1. Compression

  If the client supports compressed responses (via the gzip, deflate or zstd algorithms), as noted by the Accept-Encoding header, mccs will try to find a precompressed version of the file on disk. If found, and is not stale, this version is marked for serving. Otherwise, if the appropriate compression module is installed, mccs will compress the file, save the compressed version to disk, and mark it as the version to serve. Future requests to the same file will see the compressed version and not compress again.

  mccs searches for files that end with the appropriate extension for the algorithm (i.e. .gz, .zip, .zstd), and that's how it creates them too. If a request comes to style.css from a client that prefers gzip responses, for example, and the file was minified in the previous step, mccs will look for style.min.css.gz, possibly creating it if not found. The request path remains the same (style.css) though, even internally.

  mccs honors weight values supplied in the Accept-Encoding header, and will serve using the highest-weighted algorithm it supports.

• 1. Cache Validation

  If the client provided the If-Modified-Since header, mccs will determine if the file we're serving has been modified after the supplied date, and return 304 Not Modified immediately if not.

  If file doesn't have the 'no-store' cache control option, and the client provided the If-None-Match header, mccs will look for a file that has the the same name as the file we're going to serve, plus an .etag suffix, such as style.min.css.gz.etag, for example. If found, and not stale, the content of this file is read and compared with the provided ETag. If the two values are equal, mccs will immediately return 304 Not Modified.

• 1. ETagging

  If an .etag file wasn't found in the previous step, and the file we're serving doesn't have the 'no-store' cache control option, mccs will create one from the file's inode, last modification date and size. Future requests to the same file will see this ETag file, so it is not created again.

• 1. Headers and Cache-Control

  mccs now sets headers, especially cache control headers, as appropriate:

  • Content-Encoding is set to the compression algorithm used, if any.
  • Content-Length is set with the size of the file in bytes.
  • Content-Type is set with the MIME type of the file (if a text file, the character string is appended, e.g. text/css; charset=UTF-8).
  • Last-Modified is set with the last modification date of the file in HTTP date format.
  • Expires is set with the date on which cached versions should expire, as determined in stage 2, in HTTP date format.
  • Cache-Control is set with the number of seconds the representation is valid for (unless caching of the file is not allowed) and other options, as determined in stage 2.
  • Etag is set with the ETag value (if exists).
  • Vary is set with Accept-Encoding.
• 1. Serving

  The selected file is served to the client.

CAVEATS AND THINGS TO CONSIDER

• You can't tell mccs not to minify/compress a specific file type, but only disable minification/compression altogether.
• Directory listings are not supported.
• Caching middlewares such as Plack::Middleware::Cache and Plack::Middleware::Cached don't rely on Cache-Control headers (or so I understand) for their expiration values, which makes them less useful for applications that rely on Plack::App::MCCS or Plack::Middleware::MCCS. You'll probably be better off with an external cache like Varnish if you want a cache on your application server. Even without a server cache, your application should still appear faster for users due to browser caching (and also CPU load should be decreased).
• Range requests are not supported. See Plack::App::File::Range if you need that.
• The app is mounted on a directory and can't be set to only serve requests that match a certain regular expression. Use the middleware for that.

DIAGNOSTICS

mccs doesn't directly throw any exceptions, instead returning HTTP errors to the client and possibly issuing some warns. The following list should help you to determine some potential problems with MCCS:

• "Failed compressing %s with %s: %s"

  This warning is issued when mccs fails to compress a file with a certain algorithm. When it happens, a compressed representation will not be returned.

• "Can't open ETag file %s.etag for reading"

  This warning is issued when mccs can't read an ETag file, probably because it does not have enough permissions. The request will still be fulfilled, but it won't have the ETag header.

• "Can't open ETag file %s.etag for writing"

  Same as before, but when mccs can't write an ETag file.

• 403 Forbidden is returned for files that exist

  If a request for a certain file results in a 403 Forbidden error, it probably means mccs has no read permissions for that file.

CONFIGURATION AND ENVIRONMENT

mccs requires no configuration files or environment variables.

REQUIREMENTS

mccs requires the following dependencies:

• Perl 5.36+
• HTTP::Date
• Plack

mccs will use the following CPAN modules if they exist:

• CSS::Minifier::XS
• JavaScript::Minifier::XS
• IO::Compress::Zstd

The following CPAN modules are also recommended:

• Twiggy for an event-loop based HTTP server.
• Starman for a preforking HTTP server.

INCOMPATIBILITIES WITH OTHER MODULES

None reported.

BUGS AND LIMITATIONS

Please report any bugs or feature requests to bug-Plack-App-MCCS@rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Plack-App-MCCS.

SEE ALSO

Plack::App::MCCS, Plack::Middleware::MCCS, Plack::Runner, plackup.

AUTHOR

Ido Perlmuter ido@ido50.net

ACKNOWLEDGMENTS

Some of this application's code is based on Plack::App::File by Tatsuhiko Miyagawa and Plack::Middleware::ETag by Franck Cuny.

Christian Walde contributed new features and fixes for the 1.0.0 release.

LICENSE AND COPYRIGHT

Copyright (c) 2011-2023, Ido Perlmuter ido@ido50.net.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.