Add tag2distrepo plugin to hub

Fixes: https://pagure.io/koji/issue/2820

docs/source/plugins.rst

@@ -282,9 +282,8 @@ option. Similarly to other image tasks, alternative architecture failures can be
 ignored for successful build by ``--can-fail`` option. ``--arch`` can be used to
 limit build tag architectures.
 
-
 Driver Update Disks building
-===========================
+============================
 
 **This is just a tech-preview. API/usage can drastically change in upcoming
 releases**
@@ -329,3 +328,91 @@ inside the produced ISO.
 Similarly to other image tasks, alternative architecture failures can be
 ignored for successful build by ``--can-fail`` option. ``--arch`` can be used
 to limit build tag architectures.
+
+tag2distrepo
+============
+
+Koji plugin to automatically regenerate distrepos on tag operations
+
+It uses the following options on a tag to control behaviour:
+
+- ``tag2distrepo.enabled``: set to "true" to enable automatic distrepos
+- ``tag2distrepo.keys``: set to a space-separated list of keys to use for distrepos
+
+The tag must have at least one arch configured on it.
+
+Installing plugin on Koji Hub
+-----------------------------
+
+1. Edit the following settings in ``/etc/koji-hub/hub.conf`` to enable the plugin:
+
+.. code-block:: ini
+
+         PluginPath = /usr/lib/koji-hub-plugins
+         Plugins = tag2distrepo
+
+2. Reload Apache
+
+.. code-block:: shell
+
+        $ systemctl reload httpd
+
+Example usage
+-------------
+
+Here is an example of enabling the plugin on an "f33-infra" tag. Create the tag and ensure it has
+at least one arch and a package list (direct or inherited) so we can tag packages into it.
+
+.. code-block:: shell
+
+    $ koji add-tag f33-infra --arches=x86_64
+    $ koji add-pkg --owner kdreyer f33-infra bash
+
+Set the extra options on the tag so the plugin will generate the repository:
+
+.. code-block:: shell
+
+    $ koji edit-tag -x tag2distrepo.enabled=True -x tag2distrepo.keys=47dd8ef9 f33-infra
+
+Tag a new build to trigger the plugin:
+
+.. code-block:: shell
+
+    $ koji tag f33-infra bash-5.0.17-2.fc33
+
+The hub will immediately queue a new distRepo task, using the tagBuild task host as the distRepo
+task owner. When the distRepo task completes, you can find the new repository under the ``topurl``
+for your Koji instance.
+
+To confirm that the tag has the correct options set, use the `koji taginfo` command:
+
+.. code-block:: shell
+
+    $ koji taginfo f33-infra
+    Tag: f33-infra [18680]
+    Arches: x86_64
+    Tag options:
+      tag2distrepo.enabled : 'true'
+      tag2distrepo.keys : '47dd8ef9'
+
+To disable the plugin for the same tag:
+
+.. code-block:: shell
+
+    $ koji edit-tag -r tag2distrepo.enabled -r tag2distrepo.keys f33-infra
+
+Using Multiple Keys
+-------------------
+
+If you want to create a repository that contains builds signed by more than one key, list your
+desired key IDs ordered by preference.
+
+For example:
+
+.. code-block:: shell
+
+    $ koji edit-tag coreos-pool -x tag2distrepo.keys="45719a39 9867c58f 38ab71f4 5323552a"
+
+For each RPM in the tag, Koji will use the first signed copy that it finds. In other words,
+Koji will try the first key (`45719a39`), and if Koji does not have the first key's signature
+for that RPM, then it will try the second key (`9867c58f`), third key (`38ab71f4`), and so on.

plugins/hub/tag2distrepo.py

@@ -0,0 +1,61 @@
+# Koji tag2distrepo hub plugin
+# Copyright (c) 2019 Red Hat, Inc.
+# This callback automatically schedules distrepo tasks based on a tags config
+#
+# Authors:
+#   Patrick Uiterwijk <puiterwijk@redhat.com>
+
+from __future__ import absolute_import
+from koji.plugin import callback
+from kojihub import dist_repo_init, make_task, readTaggedRPMS, write_signed_rpm
+import logging
+
+
+@callback('postTag', 'postUntag')
+def tag2distrepo(cbtype, tag, build, user, force=False, strict=True):
+    logger = logging.getLogger('koji.plugin.tag2distrepo')
+
+    if not tag['extra'].get("tag2distrepo.enabled"):
+        logger.debug("No tag2distrepo enabled for tag %s" % tag['name'])
+        return
+    if not tag['arches']:
+        raise ValueError(
+            "Tag %s has no arches configured but tag2distrepo is enabled" % tag['name'])
+
+    keys = tag['extra'].get("tag2distrepo.keys", '').split()
+
+    if keys:
+        logger.debug("Ensuring signed RPMs are written out")
+        [rpms, _] = readTaggedRPMS(tag['id'], rpmsigs=True)
+        for rpm in rpms:
+            for key in keys:
+                if rpm['sigkey'] == key:
+                    write_signed_rpm(rpm['id'], key, False)
+
+    task_opts = {
+        'arch': tag['arches'].split(),
+        'comp': None,
+        'delta': [],
+        'event': None,
+        'inherit': False,
+        'latest': False,
+        'multilib': False,
+        'split_debuginfo': False,
+        'skip_missing_signatures': False,
+        'allow_missing_signatures': not keys,
+    }
+    logger.debug(
+        "Scheduling distRepo for tag %s, keys %s",
+        tag['name'],
+        keys,
+    )
+
+    repo_id, event_id = dist_repo_init(tag['name'], keys, task_opts)
+    task_opts['event'] = event_id
+    task_id = make_task(
+        'distRepo',
+        [tag['name'], repo_id, keys, task_opts],
+        priority=15,
+        channel='createrepo',
+    )
+    logger.info("distRepo task %d scheduled for tag %s" % (task_id, tag['name']))