28 Working with Packages

This section describes a few tasks that involve packages:

Excluding Packages from an Image
Incrementing a Package Version
Handling Optional Module Packaging
Using Runtime Package Management
Generating and Using Signed Packages
Setting up and running package test (ptest)
Creating Node Package Manager (NPM) Packages
Adding custom metadata to packages

28.1 Excluding Packages from an Image

You might find it necessary to prevent specific packages from being installed into an image. If so, you can use several variables to direct the build system to essentially ignore installing recommended packages or to not install a package at all.

The following list introduces variables you can use to prevent packages from being installed into your image. Each of these variables only works with IPK and RPM package types, not for Debian packages. Also, you can use these variables from your local.conf file or attach them to a specific image recipe by using a recipe name override. For more detail on the variables, see the descriptions in the Yocto Project Reference Manual’s glossary chapter.

BAD_RECOMMENDATIONS: Use this variable to specify “recommended-only” packages that you do not want installed.
NO_RECOMMENDATIONS: Use this variable to prevent all “recommended-only” packages from being installed.
PACKAGE_EXCLUDE: Use this variable to prevent specific packages from being installed regardless of whether they are “recommended-only” or not. You need to realize that the build process could fail with an error when you prevent the installation of a package whose presence is required by an installed package.

28.2 Incrementing a Package Version

This section provides some background on how binary package versioning is accomplished and presents some of the services, variables, and terminology involved.

In order to understand binary package versioning, you need to consider the following:

Binary Package: The binary package that is eventually built and installed into an image.
Binary Package Version: The binary package version is composed of two components — a version and a revision.

Note

Technically, a third component, the “epoch” (i.e. PE) is involved but this discussion for the most part ignores PE.

The version and revision are taken from the PV and PR variables, respectively.
PV: The recipe version. PV represents the version of the software being packaged. Do not confuse PV with the binary package version.
PR: The recipe revision.
SRCPV: The OpenEmbedded build system uses this string to help define the value of PV when the source code revision needs to be included in it.
PR Service: A network-based service that helps automate keeping package feeds compatible with existing package manager applications such as RPM, APT, and OPKG.

Whenever the binary package content changes, the binary package version must change. Changing the binary package version is accomplished by changing or “bumping” the PR and/or PV values. Increasing these values occurs one of two ways:

Automatically using a Package Revision Service (PR Service).
Manually incrementing the PR and/or PV variables.

Given a primary challenge of any build system and its users is how to maintain a package feed that is compatible with existing package manager applications such as RPM, APT, and OPKG, using an automated system is much preferred over a manual system. In either system, the main requirement is that binary package version numbering increases in a linear fashion and that there is a number of version components that support that linear progression. For information on how to ensure package revisioning remains linear, see the “Automatically Incrementing a Package Version Number” section.

The following three sections provide related information on the PR Service, the manual method for “bumping” PR and/or PV, and on how to ensure binary package revisioning remains linear.

28.2.1 Working With a PR Service

As mentioned, attempting to maintain revision numbers in the Metadata is error prone, inaccurate, and causes problems for people submitting recipes. Conversely, the PR Service automatically generates increasing numbers, particularly the revision field, which removes the human element.

Note

For additional information on using a PR Service, you can see the PR Service wiki page.

The Yocto Project uses variables in order of decreasing priority to facilitate revision numbering (i.e. PE, PV, and PR for epoch, version, and revision, respectively). The values are highly dependent on the policies and procedures of a given distribution and package feed.

Because the OpenEmbedded build system uses “signatures”, which are unique to a given build, the build system knows when to rebuild packages. All the inputs into a given task are represented by a signature, which can trigger a rebuild when different. Thus, the build system itself does not rely on the PR, PV, and PE numbers to trigger a rebuild. The signatures, however, can be used to generate these values.

The PR Service works with both OEBasic and OEBasicHash generators. The value of PR bumps when the checksum changes and the different generator mechanisms change signatures under different circumstances.

As implemented, the build system includes values from the PR Service into the PR field as an addition using the form “.x” so r0 becomes r0.1, r0.2 and so forth. This scheme allows existing PR values to be used for whatever reasons, which include manual PR bumps, should it be necessary.

By default, the PR Service is not enabled or running. Thus, the packages generated are just “self consistent”. The build system adds and removes packages and there are no guarantees about upgrade paths but images will be consistent and correct with the latest changes.

The simplest form for a PR Service is for a single host development system that builds the package feed (building system). For this scenario, you can enable a local PR Service by setting PRSERV_HOST in your local.conf file in the Build Directory:

PRSERV_HOST = "localhost:0"

Once the service is started, packages will automatically get increasing PR values and BitBake takes care of starting and stopping the server.

If you have a more complex setup where multiple host development systems work against a common, shared package feed, you have a single PR Service running and it is connected to each building system. For this scenario, you need to start the PR Service using the bitbake-prserv command:

bitbake-prserv --host ip --port port --start

In addition to hand-starting the service, you need to update the local.conf file of each building system as described earlier so each system points to the server and port.

It is also recommended you use build history, which adds some sanity checks to binary package versions, in conjunction with the server that is running the PR Service. To enable build history, add the following to each building system’s local.conf file:

# It is recommended to activate "buildhistory" for testing the PR service
INHERIT += "buildhistory"
BUILDHISTORY_COMMIT = "1"

For information on build history, see the “Maintaining Build Output Quality” section.

Note

The OpenEmbedded build system does not maintain PR information as part of the shared state (sstate) packages. If you maintain an sstate feed, it’s expected that either all your building systems that contribute to the sstate feed use a shared PR Service, or you do not run a PR Service on any of your building systems. Having some systems use a PR Service while others do not leads to obvious problems.

For more information on shared state, see the “Shared State Cache” section in the Yocto Project Overview and Concepts Manual.

28.2.2 Manually Bumping PR

The alternative to setting up a PR Service is to manually “bump” the PR variable.

If a committed change results in changing the package output, then the value of the PR variable needs to be increased (or “bumped”) as part of that commit. For new recipes you should add the PR variable and set its initial value equal to “r0”, which is the default. Even though the default value is “r0”, the practice of adding it to a new recipe makes it harder to forget to bump the variable when you make changes to the recipe in future.

Usually, version increases occur only to binary packages. However, if for some reason PV changes but does not increase, you can increase the PE variable (Package Epoch). The PE variable defaults to “0”.

Binary package version numbering strives to follow the Debian Version Field Policy Guidelines. These guidelines define how versions are compared and what “increasing” a version means.

28.2.3 Automatically Incrementing a Package Version Number

When fetching a repository, BitBake uses the SRCREV variable to determine the specific source code revision from which to build. You set the SRCREV variable to AUTOREV to cause the OpenEmbedded build system to automatically use the latest revision of the software:

SRCREV = "${AUTOREV}"

Furthermore, you need to reference SRCPV in PV in order to automatically update the version whenever the revision of the source code changes. Here is an example:

PV = "1.0+git${SRCPV}"

The OpenEmbedded build system substitutes SRCPV with the following:

AUTOINC+source_code_revision

The build system replaces the AUTOINC with a number. The number used depends on the state of the PR Service:

If PR Service is enabled, the build system increments the number, which is similar to the behavior of PR. This behavior results in linearly increasing package versions, which is desirable. Here is an example:
```
hello-world-git_0.0+git0+b6558dd387-r0.0_armv7a-neon.ipk
hello-world-git_0.0+git1+dd2f5c3565-r0.0_armv7a-neon.ipk
```
If PR Service is not enabled, the build system replaces the AUTOINC placeholder with zero (i.e. “0”). This results in changing the package version since the source revision is included. However, package versions are not increased linearly. Here is an example:
```
hello-world-git_0.0+git0+b6558dd387-r0.0_armv7a-neon.ipk
hello-world-git_0.0+git0+dd2f5c3565-r0.0_armv7a-neon.ipk
```

In summary, the OpenEmbedded build system does not track the history of binary package versions for this purpose. AUTOINC, in this case, is comparable to PR. If PR server is not enabled, AUTOINC in the package version is simply replaced by “0”. If PR server is enabled, the build system keeps track of the package versions and bumps the number when the package revision changes.

28.3 Handling Optional Module Packaging

Many pieces of software split functionality into optional modules (or plugins) and the plugins that are built might depend on configuration options. To avoid having to duplicate the logic that determines what modules are available in your recipe or to avoid having to package each module by hand, the OpenEmbedded build system provides functionality to handle module packaging dynamically.

To handle optional module packaging, you need to do two things:

Ensure the module packaging is actually done.
Ensure that any dependencies on optional modules from other recipes are satisfied by your recipe.

28.3.1 Making Sure the Packaging is Done

To ensure the module packaging actually gets done, you use the do_split_packages function within the populate_packages Python function in your recipe. The do_split_packages function searches for a pattern of files or directories under a specified path and creates a package for each one it finds by appending to the PACKAGES variable and setting the appropriate values for FILES:packagename, RDEPENDS:packagename, DESCRIPTION:packagename, and so forth. Here is an example from the lighttpd recipe:

python populate_packages:prepend () {
    lighttpd_libdir = d.expand('${libdir}')
    do_split_packages(d, lighttpd_libdir, '^mod_(.*).so$',
                     'lighttpd-module-%s', 'Lighttpd module for %s',
                      extra_depends='')
}

The previous example specifies a number of things in the call to do_split_packages.

A directory within the files installed by your recipe through do_install in which to search.
A regular expression used to match module files in that directory. In the example, note the parentheses () that mark the part of the expression from which the module name should be derived.
A pattern to use for the package names.
A description for each package.
An empty string for extra_depends, which disables the default dependency on the main lighttpd package. Thus, if a file in ${libdir} called mod_alias.so is found, a package called lighttpd-module-alias is created for it and the DESCRIPTION is set to “Lighttpd module for alias”.

Often, packaging modules is as simple as the previous example. However, there are more advanced options that you can use within do_split_packages to modify its behavior. And, if you need to, you can add more logic by specifying a hook function that is called for each package. It is also perfectly acceptable to call do_split_packages multiple times if you have more than one set of modules to package.

For more examples that show how to use do_split_packages, see the connman.inc file in the meta/recipes-connectivity/connman/ directory of the poky source repository. You can also find examples in meta/classes-recipe/kernel.bbclass.

Following is a reference that shows do_split_packages mandatory and optional arguments:

Mandatory arguments

root
   The path in which to search
file_regex
   Regular expression to match searched files.
   Use parentheses () to mark the part of this
   expression that should be used to derive the
   module name (to be substituted where %s is
   used in other function arguments as noted below)
output_pattern
   Pattern to use for the package names. Must
   include %s.
description
   Description to set for each package. Must
   include %s.

Optional arguments

postinst
   Postinstall script to use for all packages
   (as a string)
recursive
   True to perform a recursive search --- default
   False
hook
   A hook function to be called for every match.
   The function will be called with the following
   arguments (in the order listed):

   f
      Full path to the file/directory match
   pkg
      The package name
   file_regex
      As above
   output_pattern
      As above
   modulename
      The module name derived using file_regex
extra_depends
   Extra runtime dependencies (RDEPENDS) to be
   set for all packages. The default value of None
   causes a dependency on the main package
   (${PN}) --- if you do not want this, pass empty
   string '' for this parameter.
aux_files_pattern
   Extra item(s) to be added to FILES for each
   package. Can be a single string item or a list
   of strings for multiple items. Must include %s.
postrm
   postrm script to use for all packages (as a
   string)
allow_dirs
   True to allow directories to be matched -
   default False
prepend
   If True, prepend created packages to PACKAGES
   instead of the default False which appends them
match_path
   match file_regex on the whole relative path to
   the root rather than just the filename
aux_files_pattern_verbatim
   Extra item(s) to be added to FILES for each
   package, using the actual derived module name
   rather than converting it to something legal
   for a package name. Can be a single string item
   or a list of strings for multiple items. Must
   include %s.
allow_links
   True to allow symlinks to be matched --- default
   False
summary
   Summary to set for each package. Must include %s;
   defaults to description if not set.

28.3.2 Satisfying Dependencies

The second part for handling optional module packaging is to ensure that any dependencies on optional modules from other recipes are satisfied by your recipe. You can be sure these dependencies are satisfied by using the PACKAGES_DYNAMIC variable. Here is an example that continues with the lighttpd recipe shown earlier:

PACKAGES_DYNAMIC = "lighttpd-module-.*"

The name specified in the regular expression can of course be anything. In this example, it is lighttpd-module- and is specified as the prefix to ensure that any RDEPENDS and RRECOMMENDS on a package name starting with the prefix are satisfied during build time. If you are using do_split_packages as described in the previous section, the value you put in PACKAGES_DYNAMIC should correspond to the name pattern specified in the call to do_split_packages.

28.4 Using Runtime Package Management

During a build, BitBake always transforms a recipe into one or more packages. For example, BitBake takes the bash recipe and produces a number of packages (e.g. bash, bash-bashbug, bash-completion, bash-completion-dbg, bash-completion-dev, bash-completion-extra, bash-dbg, and so forth). Not all generated packages are included in an image.

In several situations, you might need to update, add, remove, or query the packages on a target device at runtime (i.e. without having to generate a new image). Examples of such situations include:

You want to provide in-the-field updates to deployed devices (e.g. security updates).
You want to have a fast turn-around development cycle for one or more applications that run on your device.
You want to temporarily install the “debug” packages of various applications on your device so that debugging can be greatly improved by allowing access to symbols and source debugging.
You want to deploy a more minimal package selection of your device but allow in-the-field updates to add a larger selection for customization.

In all these situations, you have something similar to a more traditional Linux distribution in that in-field devices are able to receive pre-compiled packages from a server for installation or update. Being able to install these packages on a running, in-field device is what is termed “runtime package management”.

In order to use runtime package management, you need a host or server machine that serves up the pre-compiled packages plus the required metadata. You also need package manipulation tools on the target. The build machine is a likely candidate to act as the server. However, that machine does not necessarily have to be the package server. The build machine could push its artifacts to another machine that acts as the server (e.g. Internet-facing). In fact, doing so is advantageous for a production environment as getting the packages away from the development system’s Build Directory prevents accidental overwrites.

A simple build that targets just one device produces more than one package database. In other words, the packages produced by a build are separated out into a couple of different package groupings based on criteria such as the target’s CPU architecture, the target board, or the C library used on the target. For example, a build targeting the qemux86 device produces the following three package databases: noarch, i586, and qemux86. If you wanted your qemux86 device to be aware of all the packages that were available to it, you would need to point it to each of these databases individually. In a similar way, a traditional Linux distribution usually is configured to be aware of a number of software repositories from which it retrieves packages.

Using runtime package management is completely optional and not required for a successful build or deployment in any way. But if you want to make use of runtime package management, you need to do a couple things above and beyond the basics. The remainder of this section describes what you need to do.

28.4.1 Build Considerations

This section describes build considerations of which you need to be aware in order to provide support for runtime package management.

When BitBake generates packages, it needs to know what format or formats to use. In your configuration, you use the PACKAGE_CLASSES variable to specify the format:

Open the local.conf file inside your Build Directory (e.g. poky/build/conf/local.conf).
Select the desired package format as follows:
```
PACKAGE_CLASSES ?= "package_packageformat"
```
where packageformat can be “ipk”, “rpm”, “deb”, or “tar” which are the supported package formats.

Note

Because the Yocto Project supports four different package formats, you can set the variable with more than one argument. However, the OpenEmbedded build system only uses the first argument when creating an image or Software Development Kit (SDK).

If you would like your image to start off with a basic package database containing the packages in your current build as well as to have the relevant tools available on the target for runtime package management, you can include “package-management” in the IMAGE_FEATURES variable. Including “package-management” in this configuration variable ensures that when the image is assembled for your target, the image includes the currently-known package databases as well as the target-specific tools required for runtime package management to be performed on the target. However, this is not strictly necessary. You could start your image off without any databases but only include the required on-target package tool(s). As an example, you could include “opkg” in your IMAGE_INSTALL variable if you are using the IPK package format. You can then initialize your target’s package database(s) later once your image is up and running.

Whenever you perform any sort of build step that can potentially generate a package or modify existing package, it is always a good idea to re-generate the package index after the build by using the following command:

$ bitbake package-index

It might be tempting to build the package and the package index at the same time with a command such as the following:

$ bitbake some-package package-index

Do not do this as BitBake does not schedule the package index for after the completion of the package you are building. Consequently, you cannot be sure of the package index including information for the package you just built. Thus, be sure to run the package update step separately after building any packages.

You can use the PACKAGE_FEED_ARCHS, PACKAGE_FEED_BASE_PATHS, and PACKAGE_FEED_URIS variables to pre-configure target images to use a package feed. If you do not define these variables, then manual steps as described in the subsequent sections are necessary to configure the target. You should set these variables before building the image in order to produce a correctly configured image.

When your build is complete, your packages reside in the ${TMPDIR}/deploy/packageformat directory. For example, if ${TMPDIR} is tmp and your selected package type is RPM, then your RPM packages are available in tmp/deploy/rpm.

28.4.2 Host or Server Machine Setup

Although other protocols are possible, a server using HTTP typically serves packages. If you want to use HTTP, then set up and configure a web server such as Apache 2, lighttpd, or Python web server on the machine serving the packages.

To keep things simple, this section describes how to set up a Python web server to share package feeds from the developer’s machine. Although this server might not be the best for a production environment, the setup is simple and straight forward. Should you want to use a different server more suited for production (e.g. Apache 2, Lighttpd, or Nginx), take the appropriate steps to do so.

From within the Build Directory where you have built an image based on your packaging choice (i.e. the PACKAGE_CLASSES setting), simply start the server. The following example assumes a Build Directory of poky/build and a PACKAGE_CLASSES setting of “package_rpm.bbclass”:

$ cd poky/build/tmp/deploy/rpm
$ python3 -m http.server

28.4.3 Target Setup

Setting up the target differs depending on the package management system. This section provides information for RPM, IPK, and DEB.

28.4.3.1 Using RPM

The Dandified Packaging (DNF) performs runtime package management of RPM packages. In order to use DNF for runtime package management, you must perform an initial setup on the target machine for cases where the PACKAGE_FEED_* variables were not set as part of the image that is running on the target. This means if you built your image and did not use these variables as part of the build and your image is now running on the target, you need to perform the steps in this section if you want to use runtime package management.

Note

For information on the PACKAGE_FEED_* variables, see PACKAGE_FEED_ARCHS, PACKAGE_FEED_BASE_PATHS, and PACKAGE_FEED_URIS in the Yocto Project Reference Manual variables glossary.

On the target, you must inform DNF that package databases are available. You do this by creating a file named /etc/yum.repos.d/oe-packages.repo and defining the oe-packages.

As an example, assume the target is able to use the following package databases: all, i586, and qemux86 from a server named my.server. The specifics for setting up the web server are up to you. The critical requirement is that the URIs in the target repository configuration point to the correct remote location for the feeds.

Note

For development purposes, you can point the web server to the build system’s deploy directory. However, for production use, it is better to copy the package directories to a location outside of the build area and use that location. Doing so avoids situations where the build system overwrites or changes the deploy directory.

When telling DNF where to look for the package databases, you must declare individual locations per architecture or a single location used for all architectures. You cannot do both:

Create an Explicit List of Architectures: Define individual base URLs to identify where each package database is located:
```
[oe-packages]
baseurl=http://my.server/rpm/i586  http://my.server/rpm/qemux86 http://my.server/rpm/all
```
This example informs DNF about individual package databases for all three architectures.
Create a Single (Full) Package Index: Define a single base URL that identifies where a full package database is located:
```
[oe-packages]
baseurl=http://my.server/rpm
```
This example informs DNF about a single package database that contains all the package index information for all supported architectures.

Once you have informed DNF where to find the package databases, you need to fetch them:

# dnf makecache

DNF is now able to find, install, and upgrade packages from the specified repository or repositories.

Note

See the DNF documentation for additional information.

28.4.3.2 Using IPK

The opkg application performs runtime package management of IPK packages. You must perform an initial setup for opkg on the target machine if the PACKAGE_FEED_ARCHS, PACKAGE_FEED_BASE_PATHS, and PACKAGE_FEED_URIS variables have not been set or the target image was built before the variables were set.

The opkg application uses configuration files to find available package databases. Thus, you need to create a configuration file inside the /etc/opkg/ directory, which informs opkg of any repository you want to use.

As an example, suppose you are serving packages from a ipk/ directory containing the i586, all, and qemux86 databases through an HTTP server named my.server. On the target, create a configuration file (e.g. my_repo.conf) inside the /etc/opkg/ directory containing the following:

src/gz all http://my.server/ipk/all
src/gz i586 http://my.server/ipk/i586
src/gz qemux86 http://my.server/ipk/qemux86

Next, instruct opkg to fetch the repository information:

# opkg update

The opkg application is now able to find, install, and upgrade packages from the specified repository.

28.4.3.3 Using DEB

The apt application performs runtime package management of DEB packages. This application uses a source list file to find available package databases. You must perform an initial setup for apt on the target machine if the PACKAGE_FEED_ARCHS, PACKAGE_FEED_BASE_PATHS, and PACKAGE_FEED_URIS variables have not been set or the target image was built before the variables were set.

To inform apt of the repository you want to use, you might create a list file (e.g. my_repo.list) inside the /etc/apt/sources.list.d/ directory. As an example, suppose you are serving packages from a deb/ directory containing the i586, all, and qemux86 databases through an HTTP server named my.server. The list file should contain:

deb http://my.server/deb/all ./
deb http://my.server/deb/i586 ./
deb http://my.server/deb/qemux86 ./

Next, instruct the apt application to fetch the repository information:

$ sudo apt update

After this step, apt is able to find, install, and upgrade packages from the specified repository.

28.5 Generating and Using Signed Packages

In order to add security to RPM packages used during a build, you can take steps to securely sign them. Once a signature is verified, the OpenEmbedded build system can use the package in the build. If security fails for a signed package, the build system stops the build.

This section describes how to sign RPM packages during a build and how to use signed package feeds (repositories) when doing a build.

28.5.1 Signing RPM Packages

To enable signing RPM packages, you must set up the following configurations in either your local.config or distro.config file:

# Inherit sign_rpm.bbclass to enable signing functionality
INHERIT += " sign_rpm"
# Define the GPG key that will be used for signing.
RPM_GPG_NAME = "key_name"
# Provide passphrase for the key
RPM_GPG_PASSPHRASE = "passphrase"

Note

Be sure to supply appropriate values for both key_name and passphrase.

Aside from the RPM_GPG_NAME and RPM_GPG_PASSPHRASE variables in the previous example, two optional variables related to signing are available:

GPG_BIN: Specifies a gpg binary/wrapper that is executed when the package is signed.
GPG_PATH: Specifies the gpg home directory used when the package is signed.

28.5.2 Processing Package Feeds

In addition to being able to sign RPM packages, you can also enable signed package feeds for IPK and RPM packages.

The steps you need to take to enable signed package feed use are similar to the steps used to sign RPM packages. You must define the following in your local.config or distro.config file:

INHERIT += "sign_package_feed"
PACKAGE_FEED_GPG_NAME = "key_name"
PACKAGE_FEED_GPG_PASSPHRASE_FILE = "path_to_file_containing_passphrase"

For signed package feeds, the passphrase must be specified in a separate file, which is pointed to by the PACKAGE_FEED_GPG_PASSPHRASE_FILE variable. Regarding security, keeping a plain text passphrase out of the configuration is more secure.

Aside from the PACKAGE_FEED_GPG_NAME and PACKAGE_FEED_GPG_PASSPHRASE_FILE variables, three optional variables related to signed package feeds are available:

GPG_BIN Specifies a gpg binary/wrapper that is executed when the package is signed.
GPG_PATH: Specifies the gpg home directory used when the package is signed.
PACKAGE_FEED_GPG_SIGNATURE_TYPE: Specifies the type of gpg signature. This variable applies only to RPM and IPK package feeds. Allowable values for the PACKAGE_FEED_GPG_SIGNATURE_TYPE are “ASC”, which is the default and specifies ascii armored, and “BIN”, which specifies binary.

28.6 Testing Packages With ptest

A Package Test (ptest) runs tests against packages built by the OpenEmbedded build system on the target machine. A ptest contains at least two items: the actual test, and a shell script (run-ptest) that starts the test. The shell script that starts the test must not contain the actual test — the script only starts the test. On the other hand, the test can be anything from a simple shell script that runs a binary and checks the output to an elaborate system of test binaries and data files.

The test generates output in the format used by Automake:

result: testname

where the result can be PASS, FAIL, or SKIP, and the testname can be any identifying string.

For a list of Yocto Project recipes that are already enabled with ptest, see the Ptest wiki page.

Note

A recipe is “ptest-enabled” if it inherits the ptest.bbclass class.

28.6.1 Adding ptest to Your Build

To add package testing to your build, add the DISTRO_FEATURES and EXTRA_IMAGE_FEATURES variables to your local.conf file, which is found in the Build Directory:

DISTRO_FEATURES:append = " ptest"
EXTRA_IMAGE_FEATURES += "ptest-pkgs"

Once your build is complete, the ptest files are installed into the /usr/lib/package/ptest directory within the image, where package is the name of the package.

28.6.2 Running ptest

The ptest-runner package installs a shell script that loops through all installed ptest test suites and runs them in sequence. Consequently, you might want to add this package to your image.

28.6.3 Getting Your Package Ready

In order to enable a recipe to run installed ptests on target hardware, you need to prepare the recipes that build the packages you want to test. Here is what you have to do for each recipe:

Be sure the recipe inherits the ptest.bbclass class: Include the following line in each recipe:
```
inherit ptest
```
Create run-ptest: This script starts your test. Locate the script where you will refer to it using SRC_URI. Here is an example that starts a test for dbus:
```
#!/bin/sh
cd test
make -k runtest-TESTS
```
Ensure dependencies are met: If the test adds build or runtime dependencies that normally do not exist for the package (such as requiring “make” to run the test suite), use the DEPENDS and RDEPENDS variables in your recipe in order for the package to meet the dependencies. Here is an example where the package has a runtime dependency on “make”:
```
RDEPENDS:${PN}-ptest += "make"
```
Add a function to build the test suite: Not many packages support cross-compilation of their test suites. Consequently, you usually need to add a cross-compilation function to the package.

Many packages based on Automake compile and run the test suite by using a single command such as make check. However, the host make check builds and runs on the same computer, while cross-compiling requires that the package is built on the host but executed for the target architecture (though often, as in the case for ptest, the execution occurs on the host). The built version of Automake that ships with the Yocto Project includes a patch that separates building and execution. Consequently, packages that use the unaltered, patched version of make check automatically cross-compiles.

Regardless, you still must add a do_compile_ptest function to build the test suite. Add a function similar to the following to your recipe:
```
do_compile_ptest() {
    oe_runmake buildtest-TESTS
}
```
Ensure special configurations are set: If the package requires special configurations prior to compiling the test code, you must insert a do_configure_ptest function into the recipe.
Install the test suite: The ptest.bbclass class automatically copies the file run-ptest to the target and then runs make install-ptest to run the tests. If this is not enough, you need to create a do_install_ptest function and make sure it gets called after the “make install-ptest” completes.

28.7 Creating Node Package Manager (NPM) Packages

NPM is a package manager for the JavaScript programming language. The Yocto Project supports the NPM fetcher. You can use this fetcher in combination with devtool to create recipes that produce NPM packages.

There are two workflows that allow you to create NPM packages using devtool: the NPM registry modules method and the NPM project code method.

Note

While it is possible to create NPM recipes manually, using devtool is far simpler.

Additionally, some requirements and caveats exist.

28.7.1 Requirements and Caveats

You need to be aware of the following before using devtool to create NPM packages:

Of the two methods that you can use devtool to create NPM packages, the registry approach is slightly simpler. However, you might consider the project approach because you do not have to publish your module in the NPM registry, which is NPM’s public registry.
Be familiar with devtool.
The NPM host tools need the native nodejs-npm package, which is part of the OpenEmbedded environment. You need to get the package by cloning the meta-openembedded repository. Be sure to add the path to your local copy to your bblayers.conf file.
devtool cannot detect native libraries in module dependencies. Consequently, you must manually add packages to your recipe.
While deploying NPM packages, devtool cannot determine which dependent packages are missing on the target (e.g. the node runtime nodejs). Consequently, you need to find out what files are missing and be sure they are on the target.
Although you might not need NPM to run your node package, it is useful to have NPM on your target. The NPM package name is nodejs-npm.

28.7.2 Using the Registry Modules Method

This section presents an example that uses the cute-files module, which is a file browser web application.

Note

You must know the cute-files module version.

The first thing you need to do is use devtool and the NPM fetcher to create the recipe:

$ devtool add "npm://registry.npmjs.org;package=cute-files;version=1.0.2"

The devtool add command runs recipetool create and uses the same fetch URI to download each dependency and capture license details where possible. The result is a generated recipe.

After running for quite a long time, in particular building the nodejs-native package, the command should end as follows:

INFO: Recipe /home/.../build/workspace/recipes/cute-files/cute-files_1.0.2.bb has been automatically created; further editing may be required to make it fully functional

The recipe file is fairly simple and contains every license that recipetool finds and includes the licenses in the recipe’s LIC_FILES_CHKSUM variables. You need to examine the variables and look for those with “unknown” in the LICENSE field. You need to track down the license information for “unknown” modules and manually add the information to the recipe.

recipetool creates a “shrinkwrap” file for your recipe. Shrinkwrap files capture the version of all dependent modules. Many packages do not provide shrinkwrap files but recipetool will create a shrinkwrap file as it runs.

Note

A package is created for each sub-module. This policy is the only practical way to have the licenses for all of the dependencies represented in the license manifest of the image.

The devtool edit-recipe command lets you take a look at the recipe:

$ devtool edit-recipe cute-files
# Recipe created by recipetool
# This is the basis of a recipe and may need further editing in order to be fully functional.
# (Feel free to remove these comments when editing.)

SUMMARY = "Turn any folder on your computer into a cute file browser, available on the local network."
# WARNING: the following LICENSE and LIC_FILES_CHKSUM values are best guesses - it is
# your responsibility to verify that the values are complete and correct.
#
# NOTE: multiple licenses have been detected; they have been separated with &
# in the LICENSE value for now since it is a reasonable assumption that all
# of the licenses apply. If instead there is a choice between the multiple
# licenses then you should change the value to separate the licenses with |
# instead of &. If there is any doubt, check the accompanying documentation
# to determine which situation is applicable.

SUMMARY = "Turn any folder on your computer into a cute file browser, available on the local network."
LICENSE = "BSD-3-Clause & ISC & MIT"
LIC_FILES_CHKSUM = "file://LICENSE;md5=71d98c0a1db42956787b1909c74a86ca \
                    file://node_modules/accepts/LICENSE;md5=bf1f9ad1e2e1d507aef4883fff7103de \
                    file://node_modules/array-flatten/LICENSE;md5=44088ba57cb871a58add36ce51b8de08 \
...
                    file://node_modules/cookie-signature/Readme.md;md5=57ae8b42de3dd0c1f22d5f4cf191e15a"

SRC_URI = " \
    npm://registry.npmjs.org/;package=cute-files;version=${PV} \
    npmsw://${THISDIR}/${BPN}/npm-shrinkwrap.json \
    "

S = "${WORKDIR}/npm"

inherit npm

LICENSE:${PN} = "MIT"
LICENSE:${PN}-accepts = "MIT"
LICENSE:${PN}-array-flatten = "MIT"
...
LICENSE:${PN}-vary = "MIT"

Here are three key points in the previous example:

SRC_URI uses the NPM scheme so that the NPM fetcher is used.
recipetool collects all the license information. If a sub-module’s license is unavailable, the sub-module’s name appears in the comments.
The inherit npm statement causes the npm.bbclass class to package up all the modules.

You can run the following command to build the cute-files package:

$ devtool build cute-files

Remember that nodejs must be installed on the target before your package.

Assuming 192.168.7.2 for the target’s IP address, use the following command to deploy your package:

$ devtool deploy-target -s cute-files root@192.168.7.2

Once the package is installed on the target, you can test the application to show the contents of any directory:

$ cd /usr/lib/node_modules/cute-files
$ cute-files

On a browser, go to http://192.168.7.2:3000 and you see the following:

You can find the recipe in workspace/recipes/cute-files. You can use the recipe in any layer you choose.

28.7.3 Using the NPM Projects Code Method

Although it is useful to package modules already in the NPM registry, adding node.js projects under development is a more common developer use case.

This section covers the NPM projects code method, which is very similar to the “registry” approach described in the previous section. In the NPM projects method, you provide devtool with an URL that points to the source files.

Replicating the same example, (i.e. cute-files) use the following command:

$ devtool add https://github.com/martinaglv/cute-files.git

The recipe this command generates is very similar to the recipe created in the previous section. However, the SRC_URI looks like the following:

SRC_URI = " \
    git://github.com/martinaglv/cute-files.git;protocol=https;branch=master \
    npmsw://${THISDIR}/${BPN}/npm-shrinkwrap.json \
    "

In this example, the main module is taken from the Git repository and dependencies are taken from the NPM registry. Other than those differences, the recipe is basically the same between the two methods. You can build and deploy the package exactly as described in the previous section that uses the registry modules method.

28.8 Adding custom metadata to packages

The variable PACKAGE_ADD_METADATA can be used to add additional metadata to packages. This is reflected in the package control/spec file. To take the ipk format for example, the CONTROL file stored inside would contain the additional metadata as additional lines.

The variable can be used in multiple ways, including using suffixes to set it for a specific package type and/or package. Note that the order of precedence is the same as this list:

PACKAGE_ADD_METADATA_<PKGTYPE>:<PN>
PACKAGE_ADD_METADATA_<PKGTYPE>
PACKAGE_ADD_METADATA:<PN>
PACKAGE_ADD_METADATA

<PKGTYPE> is a parameter and expected to be a distinct name of specific package type:

IPK for .ipk packages
DEB for .deb packages
RPM for .rpm packages

<PN> is a parameter and expected to be a package name.

The variable can contain multiple [one-line] metadata fields separated by the literal sequence ‘\n’. The separator can be redefined using the variable flag separator.

Here is an example that adds two custom fields for ipk packages:

PACKAGE_ADD_METADATA_IPK = "Vendor: CustomIpk\nGroup:Applications/Spreadsheets"