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.\" ========================================================================
.\"
.IX Title "Rex::CMDB::YAML 3pm"
.TH Rex::CMDB::YAML 3pm "2023-08-09" "perl v5.36.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.SH "NAME"
Rex::CMDB::YAML \- YAML\-based CMDB provider for Rex
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This module collects and merges data from a set of \s-1YAML\s0 files to provide configuration management database for Rex.
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& use Rex::CMDB;
\&
\& set cmdb => {
\&   type           => \*(AqYAML\*(Aq,
\&   path           => [ \*(Aqcmdb/{hostname}.yml\*(Aq, \*(Aqcmdb/default.yml\*(Aq, ],
\&   merge_behavior => \*(AqLEFT_PRECEDENT\*(Aq,
\& };
\&
\& task \*(Aqprepare\*(Aq, \*(Aqserver1\*(Aq, sub {
\&   my %all_information          = get cmdb;
\&   my $specific_item            = get cmdb(\*(Aqitem\*(Aq);
\&   my $specific_item_for_server = get cmdb( \*(Aqitem\*(Aq, \*(Aqserver\*(Aq );
\& };
.Ve
.SH "CONFIGURATION AND ENVIRONMENT"
.IX Header "CONFIGURATION AND ENVIRONMENT"
.SS "path"
.IX Subsection "path"
The path used to look for \s-1CMDB\s0 files. It supports various use cases depending on the type of data passed to it.
.IP "\(bu" 4
Scalar
.Sp
.Vb 4
\& set cmdb => {
\&   type => \*(AqYAML\*(Aq,
\&   path => \*(Aqpath/to/cmdb\*(Aq,
\& };
.Ve
.Sp
If a scalar is used, it tries to look up a few files under the given path:
.Sp
.Vb 4
\& path/to/cmdb/{environment}/{hostname}.yml
\& path/to/cmdb/{environment}/default.yml
\& path/to/cmdb/{hostname}.yml
\& path/to/cmdb/default.yml
.Ve
.IP "\(bu" 4
Array reference
.Sp
.Vb 4
\& set cmdb => {
\&   type => \*(AqYAML\*(Aq,
\&   path => [ \*(Aqcmdb/{hostname}.yml\*(Aq, \*(Aqcmdb/default.yml\*(Aq, ],
\& };
.Ve
.Sp
If an array reference is used, it tries to look up the mentioned files in the given order.
.IP "\(bu" 4
Code reference
.Sp
.Vb 8
\& set cmdb => {
\&   type => \*(AqYAML\*(Aq,
\&   path => sub {
\&     my ( $provider, $item, $server ) = @_;
\&     my @files = ( "$server.yml", "$item.yml" );
\&     return @files;
\&   },
\& };
.Ve
.Sp
If a code reference is passed, it should return a list of files that would be looked up in the same order. The code reference gets the \s-1CMDB\s0 provider instance, the item, and the server as parameters.
.PP
When the 0.51 feature flag or later is used, the default value of the \f(CW\*(C`path\*(C'\fR option is:
.PP
.Vb 8
\& [qw(
\&   cmdb/{operatingsystem}/{hostname}.yml
\&   cmdb/{operatingsystem}/default.yml
\&   cmdb/{environment}/{hostname}.yml
\&   cmdb/{environment}/default.yml
\&   cmdb/{hostname}.yml
\&   cmdb/default.yml
\& )]
.Ve
.PP
The path specification supports macros enclosed within curly braces, which are dynamically expanded during runtime. By default, the valid macros are Rex::Hardware variables, \f(CW\*(C`{server}\*(C'\fR for the server name of the current connection, and \f(CW\*(C`{environment}\*(C'\fR for the current environment.
.PP
Please note that the default environment is, well, \f(CW\*(C`default\*(C'\fR.
.PP
You can define additional \s-1CMDB\s0 paths via the \f(CW\*(C`\-O\*(C'\fR command line option by using a semicolon-separated list of \f(CW\*(C`cmdb_path=$path\*(C'\fR key-value pairs:
.PP
.Vb 1
\& rex \-O \*(Aqcmdb_path=cmdb/{domain}.yml;cmdb_path=cmdb/{domain}/{hostname}.yml;\*(Aq taskname
.Ve
.PP
Those additional paths will be prepended to the current list of \s-1CMDB\s0 paths (so the last one specified will get on top, and thus checked first).
.SS "merge_behavior"
.IX Subsection "merge_behavior"
This \s-1CMDB\s0 provider looks up the specified files in order, and returns the requested data. If multiple files specify the same data for a given item, then the first instance of the data will be returned by default.
.PP
Rex uses Hash::Merge internally to merge the data found on different levels of the \s-1CMDB\s0 hierarchy. Any merge strategy supported by that module can be specified to override the default one. For example one of the built-in strategies:
.PP
.Vb 5
\& set cmdb => {
\&   type           => \*(AqYAML\*(Aq,
\&   path           => \*(Aqcmdb\*(Aq,
\&   merge_behavior => \*(AqLEFT_PRECEDENT\*(Aq,
\& };
.Ve
.PP
Or even custom ones:
.PP
.Vb 8
\& set cmdb => {
\&   type           => \*(AqYAML\*(Aq,
\&   path           => \*(Aqcmdb\*(Aq,
\&   merge_behavior => {
\&     SCALAR => sub {},
\&     ARRAY  => sub {},
\&     HASH   => sub {},
\& };
.Ve
.PP
For the full list of options, please see the documentation of Hash::Merge.