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Revision as of 09:30, 14 February 2017 by Phracek (talk | contribs) (Building the module locally using a local module-build-service instance)

Adding and building a module for Fedora

This document describes the process of adding a new module to the Fedora Modularity project, how to build it locally and how to build it in Fedora infrastructure

Process and policy for how to add a module to Fedora

Adding a module repository is a manual process. At the moment the preferred way is to create a ticket at to add the new repository and give you write access. Make sure to mention that you need a 'module' repository and that it needs to be on, that's the staging environment. One example path for a module git repository is

Later on this will be automated by MBS, the module build server, but this is still being worked on.

Writing a new modulemd file

A modulemd file is a yaml file that contains the module metadata like description, license and dependencies. The sample file in the upstream git repository of modulemd contains a complete documentation of the required and optional yaml tags.

The Modularity team uses a shorter modulemd file to test builds, but it can also be used as a base for new modules. Another good example is base-runtime.yml

Lets use the vim modulemd as an example for this document. It is in the /home/karsten/Modularity/modules/vim/ directory on my system.

document: modulemd
version: 1
    summary: The best text editor and IDE
    description: The classic, extensible text editor, the legend.
        module: [ MIT ]
            base_runtime: master
            base_runtime: master
                - vim-enhanced
                - vim-common
                - vim-filesystem
                - vim-minimal
            - vim-common
                rationale: Provides API for this module
                ref: f25                                                        
                buildorder: 10                                                  
                rationale: build dependency
                ref: f25
                rationale: build dependency
                ref: f25
                rationale: build dependency
                ref: f25
                rationale: build dependency
                ref: f25

All dependencies of vim need to be listed under components/rpms, except those that are already included in Base Runtime. Here's how you can get the list of vim dependencies that are not in Base Runtime:

for i in `repoquery --requires --recursive --resolve --qf "%{SOURCERPM}\n" \
  vim-enhanced vim-minimal vim-common vim-filesystem \
  | sed -e "s/-[^-]*-[^-]*$//" | sort -n | uniq` ; do
  grep -wq $i gen-core-binary-pkgs.txt || echo $i

verifying the syntax of the new modulemd file and bug fixing

Once the modulemd file is finished, it is a good idea to check if there any errors in the yaml syntax. The check_modulemd program checks modulemd files for errors. You need to install some packages to use this:

  • python2-aexpect - dependency for python-avocado
  • python2-avocado - avocado testing framework
  • python2-modulemd - Module metadata manipulation library
  • python-enchant - spell checker library (needed only for
  • hunspell-en-US - English dictionary (needed only for

Then run

./ /home/karsten/Modularity/modules/vim/vim.yaml

and check the output for errors:

Running: avocado run ./ --mux-inject 'run:modulemd:/home/karsten/Modularity/modules/vim/vim.yaml'
JOB ID     : 51581372fec0086a50d9be947ea06873b33dd0e5
JOB LOG    : /home/karsten/avocado/job-results/job-2017-01-19T11.28-5158137/job.log                                                                                                                                                          
TESTS      : 11                                                                                                                                                                                                                              
 (01/11) ./ PASS (0.16 s)                                                                                                                                                                      
 (02/11) ./ PASS (0.15 s)                                                                                                                                                                            
 (03/11) ./ PASS (0.16 s)                                                                                                                                                                     
 (04/11) ./ WARN (0.02 s)                                                                                                                                                                   
 (05/11) ./ PASS (0.16 s)                                                                                                                                                                    
 (06/11) ./ PASS (0.16 s)                                                                                                                                                           
 (07/11) ./ PASS (0.16 s)                                                                                                                                                                        
 (08/11) ./ WARN (0.02 s)                                                                                                                                                               
 (09/11) ./ ERROR (0.04 s)                                                                                                                                                                    
 (10/11) ./ PASS (0.16 s)                                                                                                                                                            
 (11/11) ./ WARN (0.02 s)                                                                                                                                                         
RESULTS    : PASS 7 | ERROR 1 | FAIL 0 | SKIP 0 | WARN 3 | INTERRUPT 0                                                                                                                                                                       
TESTS TIME : 1.20 s

So this isn't quite right yet, lets have a look at the logfile mentioned in the output.

grep -i error /home/karsten/avocado/job-results/job-2017-01-19T11.28-5158137
TestError: Rationale for component RPM generic-release should end with a period: build dependency

It seems that rationales need to end with a period. Change all those lines so that they look like this:

                rationale: Provides API for this module.
                ref: f25
                buildorder: 10
                rationale: build dependency.
                ref: f25
                rationale: build dependency.
                ref: f25
                rationale: build dependency.
                ref: f25
                rationale: build dependency.
                ref: f25
                rationale: build dependency.
                ref: f25

Another run of completes without errors.

Building the module locally

The build_module script from the build-module repository on github makes local module builds really easy. It sets up the environment and then builds a module and its components locally with mock. One requirement is to have docker installed and running on your system. It is also required that the name of the new modulemd file, the repository name of that module and the name of the module itself match in order to use the build_module script. As build_module builds the latest commit in the master branch of the module git repository, changes need to be checked into git, a push to upstream (dist-git) is not required at this stage.

The basic usage of build_module is

./build_module /home/karsten/Modularity/modules/vim/ /tmp/results

This will download a container with the Module build service and rebuild the dependencies that are listed in the modulemd file. This step can take quite some time, depending on the module and how many components need to be built.

When build_module is done there will be a couple of rebuilt rpms in /tmp/results/module-vim-master-*/results/:

cd /tmp/results/module-vim-master-*/results/
find . -name "*.rpm"

These will now be put into a container.

Putting the packages into a container

For this step you'll need to create a rpm repository of the new packages.

cd /tmp/results/module-vim-master-20170119120233/
mkdir vim-module-repo
cp results/*.rpm vim-module-repo
cd vim-module-repo
createrepo .

The /tmp/results/module-vim-master-20170119120233/vim-module-repo need to uploaded somewhere public so that docker can access it. A good place for that is the webspace that each Fedora developer has.

scp -r /tmp/results/module-vim-master-20170119120233/vim-module-repo

You'll also need a dnf/yum configfile (/home/karsten/Modularity/modules/vim/vimmodule.repo) that points at this new repo:

cat /home/karsten/Modularity/modules/vim/vimmodule.repo
name=VIM module

Now put everything into a Dockerfile. We're using Adam Samalik's fake-gen-core-module as there is no usable base-runtime module yet:

cat /home/karsten/Modularity/modules/vim/Dockerfile
FROM asamalik/fake-gen-core-module
ADD vimmodule.repo /etc/yum.repos.d/vimmodule.repo
RUN dnf -y update vim-minimal
RUN dnf -y install vim-enhanced

Building the module in Fedora infrastructure using a local module-build-service instance

Filip Valder recorded a video that covers this part.

This step uses a local module-build-service and other components in containers and passes results on to the Fedora staging infrastructure. A checkout of the module-build-service and an installation of the docker-compose package are required. Change into your local copy of this repository and run

docker-compose down
docker-compose up --build

This will start the module-build-service frontend and scheduler as well as fedmsg and you'll see when messages about module builds are coming in over the Federated Message Bus. The local module-build-service will connect to product-definition-center (PDC) on the modularity developer server At the moment an account on is required for this step as remote port forwarding needs to be established via ssh:

cat ~/.ssh/config
  user fedora
  RemoteForward 3007

Some changes need to be made to the local module-build-service (aka fm-orchestrator) git repository so that it allows to build from a git repositoy on github:

diff --git a/conf/ b/conf/
index 97eed6e..2ddb61b 100644
--- a/conf/
+++ b/conf/
@@ -35,7 +35,7 @@ class BaseConfiguration(object):
     PDC_URL = ''
     PDC_INSECURE = True
     PDC_DEVELOP = True
-    SCMURLS = ["git://"]
+    SCMURLS = ["git://",""]

     # How often should we resort to polling, in seconds
     # Set to zero to disable polling
diff --git a/contrib/submit-build.json b/contrib/submit-build.json
index 0e312a5..e46bf8a 100644
--- a/contrib/submit-build.json
+++ b/contrib/submit-build.json
@@ -1,3 +1,3 @@
-    "scmurl": "git://"
+    "scmurl": "git://"

Now you need to get a kerberos ticket for the Fedora staging environment. If you haven't already done so, add

  kdc =

to the realms section of your /etc/krb5.conf file. Then point your web browser at and log in with your Fedora credentials so that the account will get synced from the Fedora production environment. Run


(replace 'karsten' with your FAS account) and get a kerberos ticket. In another window, ssh into to establish required port forwarding.

Now you can run 'python' from within the module-build-service git repo. You might need to login again at, just follow the instructions. Now the module build will be submitted to the Fedora build servers. Log messages will show the progress on your screen.

Building the module locally using a local module-build-service instance

Prerequisites for building the module locally are:

  • fedmsg-relay
  • python-flask-script
  • python2-flask-migrate
  • python2-flask-sqlalchemy
  • module-build-service from asamalik/mbs copr repo
  • mock

copy /etc/rpkg/fedpkg.conf file to ~/stg.conf

cp /etc/rpkg/fedpkg.conf ~/stg.conf

in the file ~/stg.conf replace all with

Clone your module via command:

fedpkg -C ~/stg.conf clone modules/<your_module_name>

Next step is to clone module build orchestrator and enter to fm_orchestrator directory:

git clone
cd fm_orchestrator

The last step is to run build service by command:

python module_build_service/ build_module_locally file://<full_path_to_you_module_directory>?#<hash_commit>

The last command builds the module and results (including RPMs) are stored in directory like /tmp/module-<module_name>-master-<timestamp>/results

Building the module

When your module is ready to get added to Fedora, you need to have write access to the module dist-git on and you need to have pushed all your changes to this module git repository. You can build your module using two different methods:

  • A special version of rpkg with module-build support is required for this step. Change the working directory to your local copy of your module repo and simply run
 fedpkg module-build
  • The other method requires that you add the git URL of your latest module commit to the submit-build.json file in the module-build-server git repository and then run

Building a container image

There are two ways to build a Docker container image in Fedora infrastructure:

  1. In production environment -- the process starts by initiating a review request, as specified in Container:Review_Process.
  2. In staging environment -- this is where we can bypass the review process and iterate more quickly; In order to use staging environment, we should request creation of dist-git repo and pkgdb entry via Fedora Infra tracker.

If you want to clone your dist-git repository using fedpkg, you need to select correct namespace:

$ fedpkg clone docker/$COMPONENT


$ fedpkg clone modules/memcached

Once you are ready to submit a build, you need to push changes to a remote and initiate a build

$ fedpkg container-build

Inspecting registry

At the time of writing this (Feb 2017), Fedora docker image registry doesn't have any frontend. You can access API of registry to get a list of available images:

$ curl -s | python -m json.tool
    "repositories": [

Thank you to Adam Miller for providing info about using Docker Layered Image Build System.