Overview#
I spent the last months playing around Docker. Even if I have some doubts about using it in production environment and the way you need to use it on Windows and OSx (with a Linux VirtualBox VM), it’s really impressive what you can do and how it can simplify your workflow.
But I don’t want to talk about all the pros and cons of Docker, I just want to show you how I fixed a recent problem I had using it!
The Problem#
My production server runs EL7 (CentOS7) and I need the latest git package installed. There was no existing RPM to install and I don’t have any other ready server to use to build the RPM.
Solution (quick and dirty): Download the sources of git directly on the production server; install all required packages to build it; make && make install. In case of problem… you know… it’s the production server!
Docker Solution#
Configure a CentOS7 docker container and use it to build the RPM (and it’s the thing I did ;) docker-gitrpm-centos7).
After this, I tried to create a sort of dynamic docker container I can reuse to build any sort of RPMs for any sort of RedHat based platform. The result of this work is the docker-mock-rpmbuilder.
You just need sources+spec file or directly the SourceRPM package, run the docker selecting your target platform, and wait for the RPM.
The build process is based on Mock and my current implementation allows to build packages for which all dependencies are available on the online repositories (official + EPEL)… I’ll try something more complex in the future ;)
Here you are a little doc to use my project (you can find it on the github Readme file too).
Building the Container#
First of all you need to build the docker container:
git clone https://github.com/mmornati/docker-mock-rpmbuilder.git
cd docker-mock-rpmbuilder
docker build -t mmornati/mockrpmbuilder .Creating a Working Directory#
To allow the import/export of created RPMs you need to create a docker volume and allow the read/write rights (or add owner) to the user builder (uid: 1000).
mkdir /tmp/rpmbuild
chown -R 1000:1000 /tmp/rpmbuildIn this folder you can place the source RPMs to rebuild.
Building RPMs#
To execute the docker container and rebuild RPMs from SRPMs you can run it in this way:
docker run -d -e MOCK_CONFIG=epel-6-i386 -e SOURCE_RPM=git-2.3.0-1.el7.centos.src.rpm -v /tmp/rpmbuild:/rpmbuild --privileged=true mmornati/mockrpmbuilderIf you don’t have the source RPMs yet, but you have a spec file + sources, to build RPMs you need to start the docker container in this way:
docker run -d -e MOCK_CONFIG=epel-6-i386 -e SOURCES=SOURCES/git-2.3.0.tar.gz -e SPEC_FILE=SPECS/git.spec -v /tmp/rpmbuild:/rpmbuild --privileged=true mmornati/mockrpmbuilderIt is important to know:
- With spec file the build process could be longer. The reason is mock it is invoked 2 times: the first to build SRPM the second to build all other RPMs.
- The folders specified for SPEC_FILE, SOURCES and SOURCE_RPM env variables are relative to your mount point. This means if files are at the root of mount point you need to specify only the file name, otherwise the subfolder should be added too. (SOURCES in my example)
NB: It’s important to run the container with privileged rights because mock needs the “unshare” system call to create a new mountpoint inside the process. Without this you will get this error:
ERROR: Namespace unshare failed.
A different solution (which didn’t work for me currently) should be to change the lxc-configuration to allow docker the right admin just for this operation. With this command: setcap cap_sys_admin+ep but I haven’t found the right way to do it (any hint is welcome) :)
Allowed configurations#
default epel-7-x86_64 fedora-19-x86_64 fedora-20-x86_64 fedora-21-s390x fedora-rawhide-s390
epel-5-i386 fedora-19-armhfp fedora-20-armhfp fedora-21-aarch64 fedora-21-x86_64 fedora-rawhide-s390x
epel-5-ppc fedora-19-i386 fedora-20-i386 fedora-21-armhfp fedora-rawhide-aarch64 fedora-rawhide-sparc
epel-5-x86_64 fedora-19-ppc64 fedora-20-ppc64 fedora-21-i386 fedora-rawhide-armhfp fedora-rawhide-x86_64
epel-6-i386 fedora-19-ppc fedora-20-ppc fedora-21-ppc64 fedora-rawhide-i386
epel-6-ppc64 fedora-19-s390 fedora-20-s390 fedora-21-ppc64le fedora-rawhide-ppc64
epel-6-x86_64 fedora-19-s390x fedora-20-s390x fedora-21-s390 fedora-rawhide-ppc64leChecking Progress#
To check the rpmbuild progress (and/or errors) you can simply check docker logs.
docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f8d161e72832 mmornati/mockrpmbuilder:latest "/build-rpm.sh" 2 seconds ago Up 1 seconds modest_bardeen
docker logs -f f8d161e72832
=> Building parameters:
MOCK_CONFIG: epel-6-i386
SOURCE_RPM: git-2.3.0-1.el7.centos.src.rpm
INFO: mock.py version 1.2.6 starting (python version = 2.7.5)...
Start: init plugins
INFO: selinux disabled
Finish: init plugins
Start: run
INFO: Start(/rpmbuild/git-2.3.0-1.el7.centos.src.rpm) Config(epel-6-i386)
Start: clean chroot
Finish: clean chroot
Start: chroot init
INFO: calling preinit hooks
INFO: enabled root cache
INFO: enabled yum cache
Start: cleaning yum metadata
Finish: cleaning yum metadata
INFO: enabled ccache
Mock Version: 1.2.6
INFO: Mock Version: 1.2.6
Start: yum install
[....]And use Mock log files, that are created in the output dir:
ll /tmp/rpmbuild/output/
totale 188
-rw-rw-r--. 1 1000 1000 40795 21 feb 10:37 build.log
-rw-rw-r--. 1 1000 1000 144994 21 feb 10:34 root.log
-rw-rw-r--. 1 1000 1000 962 21 feb 10:34 state.logOutput#
If all worked well, you should have all the RPMs (source + binaries) available in the configured output folder:
ll /tmp/rpmbuild/output/
totale 28076
-rw-rw-r--. 1 1000 1000 117010 21 feb 10:40 build.log
-rw-rw-r--. 1 1000 mock 7941092 21 feb 10:39 git-2.3.0-1.el6.i686.rpm
-rw-rw-r--. 1 1000 mock 5193722 21 feb 10:33 git-2.3.0-1.el6.src.rpm
-rw-rw-r--. 1 1000 mock 5472 21 feb 10:39 git-all-2.3.0-1.el6.i686.rpm
-rw-rw-r--. 1 1000 mock 24540 21 feb 10:39 git-arch-2.3.0-1.el6.i686.rpm
-rw-rw-r--. 1 1000 mock 90668 21 feb 10:39 git-cvs-2.3.0-1.el6.i686.rpm
-rw-rw-r--. 1 1000 mock 14123468 21 feb 10:40 git-debuginfo-2.3.0-1.el6.i686.rpm
-rw-rw-r--. 1 1000 mock 37600 21 feb 10:39 git-email-2.3.0-1.el6.i686.rpm
-rw-rw-r--. 1 1000 mock 240400 21 feb 10:39 git-gui-2.3.0-1.el6.i686.rpm
-rw-rw-r--. 1 1000 mock 148940 21 feb 10:39 gitk-2.3.0-1.el6.i686.rpm
-rw-rw-r--. 1 1000 mock 437148 21 feb 10:39 git-svn-2.3.0-1.el6.i686.rpm
-rw-rw-r--. 1 1000 mock 145996 21 feb 10:39 gitweb-2.3.0-1.el6.i686.rpm
-rw-rw-r--. 1 1000 mock 67256 21 feb 10:39 perl-Git-2.3.0-1.el6.i686.rpm
-rw-rw-r--. 1 1000 1000 147267 21 feb 10:40 root.log
-rw-rw-r--. 1 1000 1000 1248 21 feb 10:40 state.log