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Scope

Background

Dobby uses the crun runtime underneath to actually run the containerized processes. This is a Red Hat maintained OCI runtime written in C. It is equivalent to the runc tool, which was originally developed by Docker and written in Go. crun was chosen for RDK platforms due to its significantly reduced footprint compared to runc, and easier integration with build systems. 

In brief, Dobby is a container management tool, to make it easy for other applications to start/stop/monitor containers. It can be thought of as a "Docker for the embedded world".  

This page demonstrates building a sample Java application in RDK framework and running in a container using Dobby in a RDK-B reference board ( Rpi ).

Key Links

• Dobby source code: https://github.com/rdkcentral/Dobby

• DAC Working Group: DAC - Advanced Support Program - RDK Central Wiki

Major Dobby

Components in RDK-B

• DobbyDaemon

  • This is the main Dobby process, which is launched at bootup by systemd. When started, DobbyDaemon registers itself on dbus. It then idles and waits for commands over dbus to start, stop or inspect containers.

Some daemon settings are configurable in the /etc/dobby.json file. Note that many settings here (such as vpu/gpu device nodes) are only applicable to containers started from Dobby specs, not directly from OCI bundles.

DobbyTool

• CLI to interact with Dobby for developers, and issue commands such as start, stop or info

• This is really only meant as a development tool and is normally removed from production builds (building Dobby in RELEASE mode does not include DobbyTool by default)

RDK-B build for Dobby

1.

2.

• DobbyTool

  • CLI to interact with Dobby for developers, and issue commands such as start, stop or info

Build Dobby in RDK-B

• Getting the RDK-B dunfell Code 

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  mkdir < workspace_dir> cd  <workspace_dir> repo init -u https://code.rdkcentral.com/r/manifests -b dunfell -m rdkb-extsrc.xml repo sync -j4 --no-clone-bundle

• Add dobby,readline, and crun packages to the package recipe file to consider it during the build

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  Path: ./meta-cmf-raspberrypi/recipes-core/packagegroups/packagegroup-rdk-ccsp-broadband.bbappend

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  :~/DAC_RDKB/meta-cmf-raspberrypi$ git diff recipes-core/packagegroups/packagegroup-rdk-ccsp-broadband.bbappend diff --git a/recipes-core/packagegroups/packagegroup-rdk-ccsp-broadband.bbappend b/recipes-core/packagegroups/packagegroup-rdk-ccsp-broadband.bbappend index 87a66a2..43d0f8f 100644 --- a/recipes-core/packagegroups/packagegroup-rdk-ccsp-broadband.bbappend +++ b/recipes-core/packagegroups/packagegroup-rdk-ccsp-broadband.bbappend @@ -6,6 +6,9 @@ RDEPENDS_packagegroup-rdk-ccsp-broadband_append = "\ libseshat \ notify-comp \ start-parodus \ + dobby \ + crun \ + readline \ \ " :~/DAC_RDKB/meta-cmf-raspberrypi$

• Add readline dependencies in the dobby recipe file

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  Path: ./meta-rdk/recipes-containers/dobby/dobby-thunderplugin.bb

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  :~/DAC_RDKB/meta-rdk$ git diff recipes-containers/dobby/dobby-thunderplugin.bb diff --git a/recipes-containers/dobby/dobby-thunderplugin.bb b/recipes-containers/dobby/dobby-thunderplugin.bb index 877b7fc..592b2db 100644 --- a/recipes-containers/dobby/dobby-thunderplugin.bb +++ b/recipes-containers/dobby/dobby-thunderplugin.bb @@ -5,7 +5,8 @@ LIC_FILES_CHKSUM = "file://${WORKDIR}/git/LICENSE;md5=c466d4ab8a68655eb1edf0bf8c include dobby.inc -DEPENDS = "dobby wpeframework-clientlibraries" +DEPENDS = "dobby" +DEPENDS += "readline" S = "${WORKDIR}/git/rdkPlugins/Thunder" :~/DAC_RDKB/meta-rdk$

• Add the below kernel options to support containerization

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  Path: ./meta-raspberrypi/recipes-kernel/linux/linux-raspberrypi.inc

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  :~/DAC_RDKB/meta-raspberrypi$ git diff recipes-kernel/linux/linux-raspberrypi.inc diff --git a/recipes-kernel/linux/linux-raspberrypi.inc b/recipes-kernel/linux/linux-raspberrypi.inc index 3219a23..9262374 100644 --- a/recipes-kernel/linux/linux-raspberrypi.inc +++ b/recipes-kernel/linux/linux-raspberrypi.inc @@ -35,6 +35,8 @@ CMDLINE_append = ' ${@oe.utils.conditional("ENABLE_KGDB", "1", "kgdboc=serial0,1 # Disable rpi logo on boot CMDLINE_append += ' ${@oe.utils.conditional("DISABLE_RPI_BOOT_LOGO", "1", "logo.nologo", "", d)}' +CMDLINE_append += "cgroup_enable=cpuset cgroup_enable=memory cgroup_memory=1" + # You can define CMDLINE_DEBUG as "debug" in your local.conf or distro.conf # to enable kernel debugging. CMDLINE_DEBUG ?= "" :~/DAC_RDKB/meta-raspberrypi$

Build Java Application in RDK-B

• Download the meta-java layer for Java support in RDKB image for Raspberry Pi

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  cd  <workspace_dir> git clone git://git.yoctoproject.org/meta-java cd meta-java git checkout remotes/origin/dunfell

• Add a new java application

           1. Create a new recipe under meta-rdk-ext/

           2. New recipe should have the java application, corresponding .bb and license files

                Example: sample application (HelloWorld.java) under meta-rdk-ext/recipes-java/

           3. Add the new recipe to the package group to consider it during the build

               Example : java-helloworld added in meta-cmf-raspberrypi/recipes-core/packagegroups/packagegroup-rdk-ccsp-broadband.bbappend

:~/DAC_RDKB/meta-cmf-raspberrypi$ git diff recipes-core/packagegroups/packagegroup-rdk-ccsp-broadband.bbappend
diff --git a/recipes-core/packagegroups/packagegroup-rdk-ccsp-broadband.bbappend b/recipes-core/packagegroups/packagegroup-rdk-ccsp-broadband.bbappend
index 87a66a2..87f70b8 100644
--- a/recipes-core/packagegroups/packagegroup-rdk-ccsp-broadband.bbappend
+++ b/recipes-core/packagegroups/packagegroup-rdk-ccsp-broadband.bbappend
@@ -6,6 +6,11 @@ RDEPENDS_packagegroup-rdk-ccsp-broadband_append = "\
     libseshat \
     notify-comp \
     start-parodus \
+    dobby \
+    crun \
+    readline \
+    openjdk-8 \
+    java-helloworld \
     \
 "

:~/DAC_RDKB/meta-cmf-raspberrypi$

•  Creating Runtime spec to Containerize the java application

           1.  Create a configuration file that is config.json for the java application and place it under meta-rdk-ext/recipes-java/<application_folder>

:~/DAC_RDKB$ cd meta-rdk-ext/recipes-java/
:~/DAC_RDKB/meta-rdk-ext/recipes-java$ ls
java-helloworld
:~/DAC_RDKB/meta-rdk-ext/recipes-java$ cd java-helloworld/
:~/DAC_RDKB/meta-rdk-ext/recipes-java/java-helloworld$ ls
java-helloworld-1.0  java-helloworld_1.0.bb
:~/DAC_RDKB/meta-rdk-ext/recipes-java/java-helloworld$ cd java-helloworld-1.0
:~/DAC_RDKB/meta-rdk-ext/recipes-java/java-helloworld/java-helloworld-1.0$ ls
config.json  HelloWorld.java  LICENSE
:~/DAC_RDKB/meta-rdk-ext/recipes-java/java-helloworld/java-helloworld-1.0$

          2.  Install the config.json through the Application recipe file  

SRC_URI += "file://config.json"

:~/DAC_RDKB/meta-rdk-ext/recipes-java/java-helloworld$ cat java-helloworld_1.0.bb
DESCRIPTION = "Simple Java hello world application"

LICENSE = "Apache-2.0"
LIC_FILES_CHKSUM = "file://LICENSE;md5=e3fc50a88d0a364313df4b21ef20c29e"

RDEPENDS_${PN} = "openjdk-8"

SRC_URI = "file://HelloWorld.java"
SRC_URI += "file://LICENSE"
SRC_URI += "file://config.json"

S = "${WORKDIR}"

inherit java-library

do_compile() {
    mkdir -p build
    javac -d build `find . -name "*.java"`
    fastjar cf ${JARFILENAME} -C build .
}

do_install() {
    install -d ${D}/usr/bin
    install ${S}/build/* ${D}/usr/bin/
    install ${S}/build/HelloWorld.class ${D}/usr/bin/HelloWorld
}

do_install_append() {
    install -d ${D}${sysconfdir}/java_container
    install -d ${D}${sysconfdir}/java_container/rootfs
    install -m 0777 ${WORKDIR}/config.json ${D}${sysconfdir}/java_container
    install -m 0777 ${WORKDIR}/config.json ${D}${sysconfdir}/java_container/rootfs
}


BBCLASSEXTEND = "native"
FILES_${PN} += "/usr/bin/*"
FILES_${PN} += "${sysconfdir}/java_container"
FILES_${PN} += "${sysconfdir}/java_container/rootfs"
FILES_${PN} += "${sysconfdir}/java_container/config.json"

Running Dobby Container in Rpi

Build Java application

Sample Code

Attaching the config,json and Helloworld Java Application recipe file.

recipes-java.zip2.