CPack External Generator¶
CPack provides many generators to create packages for a variety of platforms and packaging systems. The intention is for CMake/CPack to be a complete end-to-end solution for building and packaging a software project. However, it may not always be possible to use CPack for the entire packaging process, due to either technical limitations or policies that require the use of certain tools. For this reason, CPack provides the “External” generator, which allows external packaging software to take advantage of some of the functionality provided by CPack, such as component installation and the dependency graph.
Integration with External Packaging Tools¶
The CPack External generator generates a .json
file containing the
CPack internal metadata, which gives external software information
on how to package the software. External packaging software may itself
invoke CPack, consume the generated metadata,
install and package files as required.
Alternatively CPack can invoke an external packaging software
through an optional custom CMake script in
CPACK_EXTERNAL_PACKAGE_SCRIPT
instead.
Staging of installation files may also optionally be
taken care of by the generator when enabled through the
CPACK_EXTERNAL_ENABLE_STAGING
variable.
JSON Format¶
The JSON metadata file contains a list of CPack components and component groups,
the various options passed to cpack_add_component()
and
cpack_add_component_group()
, the dependencies between the components
and component groups, and various other options passed to CPack.
The JSON’s root object will always provide two fields:
formatVersionMajor
and formatVersionMinor
, which are always integers
that describe the output format of the generator. Backwards-compatible changes
to the output format (for example, adding a new field that didn’t exist before)
cause the minor version to be incremented, and backwards-incompatible changes
(for example, deleting a field or changing its meaning) cause the major version
to be incremented and the minor version reset to 0. The format version is
always of the format major.minor
. In other words, it always has exactly two
parts, separated by a period.
You can request one or more specific versions of the output format as described
below with CPACK_EXTERNAL_REQUESTED_VERSIONS
. The output format will
have a major version that exactly matches the requested major version, and a
minor version that is greater than or equal to the requested minor version. If
no version is requested with CPACK_EXTERNAL_REQUESTED_VERSIONS
, the
latest known major version is used by default. Currently, the only supported
format is 1.0, which is described below.
Version 1.0¶
In addition to the standard format fields, format version 1.0 provides the following fields in the root:
components
The
components
field is an object with component names as the keys and objects describing the components as the values. The component objects have the following fields:name
The name of the component. This is always the same as the key in the
components
object.displayName
The value of the
DISPLAY_NAME
field passed tocpack_add_component()
.description
The value of the
DESCRIPTION
field passed tocpack_add_component()
.isHidden
True if
HIDDEN
was passed tocpack_add_component()
, false if it was not.isRequired
True if
REQUIRED
was passed tocpack_add_component()
, false if it was not.isDisabledByDefault
True if
DISABLED
was passed tocpack_add_component()
, false if it was not.group
Only present if
GROUP
was passed tocpack_add_component()
. If so, this field is a string value containing the component’s group.dependencies
An array of components the component depends on. This contains the values in the
DEPENDS
argument passed tocpack_add_component()
. If noDEPENDS
argument was passed, this is an empty list.installationTypes
An array of installation types the component is part of. This contains the values in the
INSTALL_TYPES
argument passed tocpack_add_component()
. If noINSTALL_TYPES
argument was passed, this is an empty list.isDownloaded
True if
DOWNLOADED
was passed tocpack_add_component()
, false if it was not.archiveFile
The name of the archive file passed with the
ARCHIVE_FILE
argument tocpack_add_component()
. If noARCHIVE_FILE
argument was passed, this is an empty string.
componentGroups
The
componentGroups
field is an object with component group names as the keys and objects describing the component groups as the values. The component group objects have the following fields:name
The name of the component group. This is always the same as the key in the
componentGroups
object.displayName
The value of the
DISPLAY_NAME
field passed tocpack_add_component_group()
.description
The value of the
DESCRIPTION
field passed tocpack_add_component_group()
.parentGroup
Only present if
PARENT_GROUP
was passed tocpack_add_component_group()
. If so, this field is a string value containing the component group’s parent group.isExpandedByDefault
True if
EXPANDED
was passed tocpack_add_component_group()
, false if it was not.isBold
True if
BOLD_TITLE
was passed tocpack_add_component_group()
, false if it was not.components
An array of names of components that are direct members of the group (components that have this group as their
GROUP
). Components of subgroups are not included.subgroups
An array of names of component groups that are subgroups of the group (groups that have this group as their
PARENT_GROUP
).
installationTypes
The
installationTypes
field is an object with installation type names as the keys and objects describing the installation types as the values. The installation type objects have the following fields:name
The name of the installation type. This is always the same as the key in the
installationTypes
object.displayName
The value of the
DISPLAY_NAME
field passed tocpack_add_install_type()
.index
The integer index of the installation type in the list.
projects
The
projects
field is an array of objects describing CMake projects which comprise the CPack project. The values in this field are derived fromCPACK_INSTALL_CMAKE_PROJECTS
. In most cases, this will be only a single project. The project objects have the following fields:projectName
The project name passed to
CPACK_INSTALL_CMAKE_PROJECTS
.component
The name of the component or component set which comprises the project.
directory
The build directory of the CMake project. This is the directory which contains the
cmake_install.cmake
script.subDirectory
The subdirectory to install the project into inside the CPack package.
packageName
The package name given in
CPACK_PACKAGE_NAME
. Only present if this option is set.packageVersion
The package version given in
CPACK_PACKAGE_VERSION
. Only present if this option is set.packageDescriptionFile
The package description file given in
CPACK_PACKAGE_DESCRIPTION_FILE
. Only present if this option is set.packageDescriptionSummary
The package description summary given in
CPACK_PACKAGE_DESCRIPTION_SUMMARY
. Only present if this option is set.buildConfig
The build configuration given to CPack with the
-C
option. Only present if this option is set.defaultDirectoryPermissions
The default directory permissions given in
CPACK_INSTALL_DEFAULT_DIRECTORY_PERMISSIONS
. Only present if this option is set.setDestdir
True if
CPACK_SET_DESTDIR
is true, false if it is not.packagingInstallPrefix
The install prefix given in
CPACK_PACKAGING_INSTALL_PREFIX
. Only present ifCPACK_SET_DESTDIR
is true.stripFiles
True if
CPACK_STRIP_FILES
is true, false if it is not.warnOnAbsoluteInstallDestination
True if
CPACK_WARN_ON_ABSOLUTE_INSTALL_DESTINATION
is true, false if it is not.errorOnAbsoluteInstallDestination
True if
CPACK_ERROR_ON_ABSOLUTE_INSTALL_DESTINATION
is true, false if it is not.
Variables specific to CPack External generator¶
-
CPACK_EXTERNAL_REQUESTED_VERSIONS
¶ This variable is used to request a specific version of the CPack External generator. It is a list of
major.minor
values, separated by semicolons.If this variable is set to a non-empty value, the CPack External generator will iterate through each item in the list to search for a version that it knows how to generate. Requested versions should be listed in order of descending preference by the client software, as the first matching version in the list will be generated.
The generator knows how to generate the version if it has a versioned generator whose major version exactly matches the requested major version, and whose minor version is greater than or equal to the requested minor version. For example, if
CPACK_EXTERNAL_REQUESTED_VERSIONS
contains 1.0, and the CPack External generator knows how to generate 1.1, it will generate 1.1. If the generator doesn’t know how to generate a version in the list, it skips the version and looks at the next one. If it doesn’t know how to generate any of the requested versions, an error is thrown.If this variable is not set, or is empty, the CPack External generator will generate the highest major and minor version that it knows how to generate.
If an invalid version is encountered in
CPACK_EXTERNAL_REQUESTED_VERSIONS
(one that doesn’t matchmajor.minor
, wheremajor
andminor
are integers), it is ignored.
-
CPACK_EXTERNAL_ENABLE_STAGING
¶ This variable can be set to true to enable optional installation into a temporary staging area which can then be picked up and packaged by an external packaging tool. The top level directory used by CPack for the current packaging task is contained in
CPACK_TOPLEVEL_DIRECTORY
. It is automatically cleaned up on each run before packaging is initiated and can be used for custom temporary files required by the external packaging tool. It also contains the staging areaCPACK_TEMPORARY_DIRECTORY
into which CPack performs the installation when staging is enabled.
-
CPACK_EXTERNAL_PACKAGE_SCRIPT
¶ This variable can optionally specify the full path to a CMake script file to be run as part of the CPack invocation. It is invoked after (optional) staging took place and may run an external packaging tool. The script has access to the variables defined by the CPack config file.