Using Phar Archives: Introduction
Phar archives are similar in concept to Java JAR archives, but are
tailored to the needs and to the flexibility of PHP applications. A
Phar archive is used to distribute a complete PHP application
or library in a single file. Unlike Java's implementation of JAR archives,
no external tool is required to process or run a PHP Phar archive. A
Phar archive application is used exactly like any other PHP application:
Using a Phar archive library is identical to using any other PHP library:
The phar stream wrapper provides the core of the phar extension, and
is explained in detail here.
The phar stream wrapper allows accessing the files within a phar archive using
PHP's standard file functions fopen(), opendir(), and
others that work on regular files. The phar stream wrapper supports all
read/write operations on both files and directories.
The Phar class implements advanced functionality for accessing
files and for creating phar archives. The Phar class is explained in detail
here.
In addition, verification of phar file contents can be done using any of the
supported symmetric hash algorithms (MD5, SHA1, SHA256 and SHA512 if ext/hash is enabled)
and using asymmetric public/private key signing using OpenSSL (new in Phar 2.0.0). To
take advantage of OpenSSL signing, you need to generate a public/private key pair, and
use the private key to set the signature using
Phar::setSignatureAlgorithm(). In addition, the public key
as extracted using this code:
$public = openssl_get_publickey(file_get_contents('private.pem'));
$pkey = '';
openssl_pkey_export($public, $pkey);
must be saved adjacent to the phar archive it verifies. If the phar archive
is saved as
/path/to/my.phar, the public key must be saved
as
/path/to/my.phar.pubkey, or phar will be unable to verify
the OpenSSL signature.
As of version 2.0.0, The Phar class also provides 3 static methods, Phar::webPhar(),
Phar::mungServer() and Phar::interceptFileFuncs() that are crucial
to packaging up PHP applications designed for usage on regular filesystems and for web-based applications.
Phar::webPhar() implements a front controller that routes HTTP calls to the correct
location within the phar archive. Phar::mungServer() is used to modify the values of
the $_SERVER array to trick applications that process these values.
Phar::interceptFileFuncs() instructs Phar to intercept calls to
fopen(), file_get_contents(), opendir(), and
all of the stat-based functions (file_exists(), is_readable() and so on) and
route all relative paths to locations within the phar archive.
As an example, packaging up a release of the popular phpMyAdmin application for use as a phar archive requires
only this simple script and then phpMyAdmin.phar.tar.php can be accessed as a regular file
from your web server after modifying the user/password: