Trying to Understand Koji Tags (i need a picture...)

Nov 12, 2014 | categories: releng, graphviz, fedora, koji View Comments

Over the past few days I've been trying to replicate our release-engineering infrastructure in our staging environment so we can try out changes with less worry, move faster in the future, etc. There been some progress but there are a lot of pieces -- this won't be done for a while.

The latest subject of my efforts has been koji. I had some authentication problems off the bat but I got it to the point now so that it is pulling it's CRL correctly from FAS. You can edit /etc/koji.conf and actually point your builds at it. It only has one builder (all we need) but they'll run and complete!:

;server = http://koji.fedoraproject.org/kojihub
;weburl = http://koji.fedoraproject.org/koji
;topurl = https://kojipkgs.fedoraproject.org/
server = http://koji.stg.fedoraproject.org/kojihub
weburl = http://koji.stg.fedoraproject.org/koji
topurl = https://kojipkgs.stg.fedoraproject.org/

I even have the kojira service running now (it is a background service responsible for rebuilding and maintaining the repos that hang off of https://koji.fedoraproject.org/repos/ -- notably the rawhide/ one that I'm interested in for performing fake staging 'composes'. It is notoriously absent from the staging repos.)

This led me into the dark nest that is koji tags and targets. I've been using them for years to build my packages, but I never really understood how they all fit together and what was even the difference between a tag and a target. I wrote the following graph-generating script the try and make sense:

#!/usr/bin/env python
""" koji2graphviz.py - Visualize Koji Tags and their relationships.

Author:     Ralph Bean <rbean@redhat.com>
License:    LGPLv2+

import multiprocessing.pool
import sys

from operator import itemgetter as getter

import koji

# https://pypi.python.org/pypi/graphviz
from graphviz import Digraph

N = 40

graph_options = {'format': 'png'}
tags_parent_child = Digraph(
    name='tags_parent_child', comment='Koji Tags, Parent/Child relationships',
tags_groups = Digraph(
    name='tags_groups', comment='Koji Tags and what Groups they are in',
tags_and_targets = Digraph(
    name='tags_and_targets', comment='Koji Tags and Targets',

client = koji.ClientSession('https://koji.fedoraproject.org/kojihub')
tags = client.listTags()
for tag in tags:
    tags_parent_child.node(tag['name'], tag['name'])

def get_relations(tag):
    idx = tag['id']
    return (tag, {
        'parents': client.getInheritanceData(tag['name']),
        'group_list': sorted(map(getter('name'), client.getTagGroups(idx))),
        'dest_targets': client.getBuildTargets(destTagID=idx),
        'build_targets': client.getBuildTargets(buildTagID=idx),
        'external_repos': client.getTagExternalRepos(tag_info=idx),

print "getting parent/child relationships with %i threads" % N
pool = multiprocessing.pool.ThreadPool(N)
relationships = pool.map(get_relations, tags)
print "got relationships for all %i tags" % len(relationships)

print "collating known groups"
known_groups = list(set(sum([
    data['group_list'] for tag, data in relationships
], [])))
for group in known_groups:
    tags_groups.node('group-' + group, 'Group: ' + group)

print "collating known targets"
known_targets = list(set(sum([
    [target['name'] for target in data['build_targets']] +
    [target['name'] for target in data['dest_targets']]
    for tag, data in relationships
], [])))
for target in known_targets:
    tags_and_targets.node('target-' + target, 'Target: ' + target)

print "building graph"
for tag, data in relationships:
    for parent in data['parents']:
        tags_parent_child.edge(parent['name'], tag['name'])
    for group in data['group_list']:
        tags_groups.edge(tag['name'], 'group-' + group)
    for target in data['build_targets']:
        tags_and_targets.edge('target-' + target['name'], tag['name'], 'build')
    for target in data['dest_targets']:
        tags_and_targets.edge(tag['name'], 'target-' + target['name'], 'dest')

print "writing"
print "done"

Check out this first beast of a graph that it generates. It is a mapping of the parent/child inheritance relationship between tags (you can get at similar information with the $ koji list-tag-inheritance SOME_TAG command.

Koji tag inheritance relationships

This next one shows koji tags and what 'targets' they have relationships with. There are two kind of relationships here. A target can be a "destination target" for a tag or it can be a "build target" for a tag.

Dennis Gilmore tells me that:

Targets are glue for builds. Targets define the tag used for the buildroot
and the tag that the resulting build is tagged to.

Trying to unpack that -- take the rawhide target in this graph. It gets its buildroot definition from the f22-build tag, and builds that succeed there are sent to the f22 tag.

Koji tags and what and_targets they belong to

Anyways, the next step for my compose-in-staging project is to get that rawhide-repo-holder target setup. I think kojira will notice that and start building the appropriate rawhide/ repo for the next bits down the pipeline. Feel free to reuse and modify the graph-generating script above, it was fun to write, and I hope it's useful to you some day. Happy Hacking!

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