template($file [, %params])

Parse a template and return the content.

By default, it uses Rex::Template. If any of the template_ng or 1.3 (or newer) feature flag is enabled, then Rex::Template::NG is used instead of this module (recommended).

For more advanced functionality, you may use your favorite template engine via the set_template_function configuration option.

Template variables may be passed either as hash or a hash reference. The following calls are equivalent:

 template( $template, variable => value );
 
 template( $template, { variable => value } );

List of exposed template variables

The following template variables are passed to the underlying templating engine, in order of precedence from low to high (variables of the same name are overridden by the next level aka "last one wins"):

task parameters

All task parameters coming from the command line via "rex taskname --param=value", or from calling a task as a function, like "taskname( { param => value } )".

resource parameters

All resource parameters as returned by "Rex::Resource->get_current_resource()->get_all_parameters", when called inside a resource.

explicit template variables

All manually specified, explicit template variables passed to "template()".

system information

The results from all available Rex::Hardware modules as returned by "Rex::Hardware->get('All')".

Pass "__no_sys_info__ => TRUE" as a template variable to disable including system information:

 my $content = template( $template, __no_sys_info__ => TRUE );
    

Embedded templates

Use "__DATA__" to embed templates at the end of the file. Prefix embedded template names with "@". If embedding multiple templates, mark their end with @end.

Single template

 my $content = template( '@hello', name => 'world' ); # Hello, world!
 __DATA__
 @hello
 Hello, <%= $name -%>!

Multiple templates

Use @end to separate multiple templates inside "__DATA__".

 my $content     = template( '@hello', name => 'world' ); # Hello, world!
 my $alternative = template( '@hi',    name => 'world' ); # Hi, world!
 __DATA__
 @hello
 Hello, <%= $name -%>!
 @end
 @hi
 Hi, <%= $name -%>!
 @end

File templates

 my $content = template("/files/templates/vhosts.tpl",
               name      => "test.lan",
               webmaster => 'webmaster@test.lan');

The file name specified is subject to "path_map" processing as documented under the file() function to resolve to a physical file name.

In addition to the "path_map" processing, if the -E command line switch is used to specify an environment name, existence of a file ending with '.<env>' is checked and has precedence over the file without one, if it exists. E.g. if rex is started as:

 $ rex -E prod task1

then in task1 defined as:

 task "task1", sub {
    say template("files/etc/ntpd.conf");
 };

will print the content of 'files/etc/ntpd.conf.prod' if it exists.

Note: the appended environment mechanism is always applied, after the 'path_map' mechanism, if that is configured.

file($file_name [, %options])

This function is the successor of install file. Please use this function to upload files to your server.

 task "prepare", "server1", "server2", sub {
   file "/file/on/remote/machine",
     source => "/file/on/local/machine";
 
   file "/etc/hosts",
     content => template("templates/etc/hosts.tpl"),
     owner  => "user",
     group  => "group",
     mode   => 700,
     on_change => sub { say "Something was changed." },
     on_no_change => sub { say "Nothing has changed." };
 
   file "/etc/motd",
     content => `fortune`;
 
   file "/etc/named.conf",
     content    => template("templates/etc/named.conf.tpl"),
     no_overwrite => TRUE;  # this file will not be overwritten if already exists.
 
   file "/etc/httpd/conf/httpd.conf",
     source => "/files/etc/httpd/conf/httpd.conf",
     on_change => sub { service httpd => "restart"; };
 
   file "/etc/named.d",
     ensure => "directory",  # this will create a directory
     owner  => "root",
     group  => "root";
 
   file "/etc/motd",
     ensure => "absent";   # this will remove the file or directory
 
 };

The first parameter is either a string or an array reference. In the latter case the function is called for all strings in the array. Therefore, the following constructs are equivalent:

  file '/tmp/test1', ensure => 'directory';
  file '/tmp/test2', ensure => 'directory';
  file [ qw( /tmp/test1 /tmp/test2 ) ], ensure => 'directory'; # use array ref
  file [ glob('/tmp/test{1,2}') ], ensure => 'directory'; # explicit glob call for array contents

Use the glob carefully as it can leak local filesystem information (e.g. when using wildcards).

The source is subject to a path resolution algorithm. This algorithm can be configured using the set function to set the value of the path_map variable to a hash containing path prefixes as its keys. The associated values are arrays listing the prefix replacements in order of (decreasing) priority.

  set "path_map", {
    "files/" => [ "files/{environment}/{hostname}/_root_/",
                  "files/{environment}/_root_/" ]
  };

With this configuration, the file "files/etc/ntpd.conf" will be probed for in the following locations:

 - files/{environment}/{hostname}/_root_/etc/ntpd.conf
 - files/{environment}/_root_/etc/ntpd.conf
 - files/etc/ntpd.conf

Furthermore, if a path prefix matches multiple prefix entries in 'path_map', e.g. "files/etc/ntpd.conf" matching both "files/" and "files/etc/", the longer matching prefix(es) have precedence over shorter ones. Note that keys without a trailing slash (i.e. "files/etc") will be treated as having a trailing slash when matching the prefix ("files/etc/").

If no file is found using the above procedure and source is relative, it will search from the location of your Rexfile or the .pm file if you use Perl packages.

All the possible variables ('{environment}', '{hostname}', ...) are documented in the CMDB YAML documentation.

Hooks

This function supports the following hooks:

before

This gets executed before anything is done. All original parameters are passed to it, including the applied defaults ("ensure => 'present'", resolved path for "source").

The return value of this hook overwrites the original parameters of the function call.

before_change

This gets executed right before the new file is written. All original parameters are passed to it, including the applied defaults ("ensure => 'present'", resolved path for "source").

after_change

This gets executed right after the file is written. All original parameters, including the applied defaults ("ensure => 'present'", resolved path for "source"), and any returned results are passed to it.

after

This gets executed right before the "file()" function returns. All original parameters, including the applied defaults ("ensure => 'present'", resolved path for "source"), and any returned results are passed to it.

file_write($file_name)

This function opens a file for writing (it will truncate the file if it already exists). It returns a Rex::FS::File object on success.

On failure it will die.

 my $fh;
 eval {
   $fh = file_write("/etc/groups");
 };
 
 # catch an error
 if($@) {
   print "An error occurred. $@.\n";
 }
 
 # work with the filehandle
 $fh->write("...");
 $fh->close;

file_append($file_name)

file_read($file_name)

This function opens a file for reading. It returns a Rex::FS::File object on success.

On failure it will die.

 my $fh;
 eval {
   $fh = file_read("/etc/groups");
 };
 
 # catch an error
 if($@) {
   print "An error occurred. $@.\n";
 }
 
 # work with the filehandle
 my $content = $fh->read_all;
 $fh->close;

cat($file_name)

This function returns the complete content of $file_name as a string.

 print cat "/etc/passwd";

delete_lines_matching($file, $regexp)

Delete lines that match $regexp in $file.

 task "clean-logs", sub {
    delete_lines_matching "/var/log/auth.log" => "root";
 };

delete_lines_according_to($search, $file [, @options])

This is the successor of the delete_lines_matching() function. This function also allows the usage of on_change and on_no_change hooks.

It will search for $search in $file and remove the found lines. If on_change hook is present it will execute this if the file was changed.

 task "cleanup", "server1", sub {
   delete_lines_according_to qr{^foo:}, "/etc/passwd",
    on_change => sub {
      say "removed user foo.";
    };
 };

append_if_no_such_line($file, $new_line [, @regexp])

Append $new_line to $file if none in @regexp is found. If no regexp is supplied, the line is appended unless there is already an identical line in $file.

 task "add-group", sub {
   append_if_no_such_line "/etc/groups", "mygroup:*:100:myuser1,myuser2", on_change => sub { service sshd => "restart"; };
 };

Since 0.42 you can use named parameters as well

 task "add-group", sub {
   append_if_no_such_line "/etc/groups",
     line  => "mygroup:*:100:myuser1,myuser2",
     regexp => qr{^mygroup},
     on_change => sub {
                say "file was changed, do something.";
              };
 
   append_if_no_such_line "/etc/groups",
     line  => "mygroup:*:100:myuser1,myuser2",
     regexp => [qr{^mygroup:}, qr{^ourgroup:}]; # this is an OR
 };

append_or_amend_line($file, $line [, @regexp])

Similar to append_if_no_such_line, but if the line in the regexp is found, it will be updated. Otherwise, it will be appended.

 task "update-group", sub {
   append_or_amend_line "/etc/groups",
     line  => "mygroup:*:100:myuser3,myuser4",
     regexp => qr{^mygroup},
     on_change => sub {
       say "file was changed, do something.";
     },
     on_no_change => sub {
       say "file was not changed, do something.";
     };
 };

extract($file [, %options])

This function extracts a file. The target directory optionally specified with the `to` option will be created automatically.

Supported formats are .box, .tar, .tar.gz, .tgz, .tar.Z, .tar.bz2, .tbz2, .zip, .gz, .bz2, .war, .jar.

 task prepare => sub {
   extract "/tmp/myfile.tar.gz",
    owner => "root",
    group => "root",
    to   => "/etc";
 
   extract "/tmp/foo.tgz",
    type => "tgz",
    mode => "g+rwX";
 };

Can use the type=> option if the file suffix has been changed. (types are tar, tgz, tbz, zip, gz, bz2)

sed($search, $replace, $file [, %options])

Search some string in a file and replace it.

 task sar => sub {
   # this will work line by line
   sed qr{search}, "replace", "/var/log/auth.log";
 
   # to use it in a multiline way
   sed qr{search}, "replace", "/var/log/auth.log",
    multiline => TRUE;
 };

Like similar file management commands, it also supports "on_change" and "on_no_change" hooks.