Post a comment per dist-git PR about transition (#3012)

Post a comment per dist-git PR about transition

Fixes #3008
Should look like:

Reviewed-by: gemini-code-assist[bot]
Reviewed-by: Maja Massarini
Reviewed-by: Nikola Forró
Reviewed-by: František Lachman <flachman@redhat.com>

Author: centosinfra-prod-github-app[bot]

packit_service/constants.py

@@ -341,3 +341,23 @@ def from_number(number: int):
 
 # Default URL of the logdetective-packit interface server for sending the Log Detective requests.
 LOGDETECTIVE_PACKIT_SERVER_URL = "https://logdetective01.fedorainfracloud.org"
+
+# CI Transition comment for Fedora dist-git PRs
+# TODO: Remove this after March 2026
+# https://github.com/packit/packit-service/issues/3008
+FEDORA_CI_TRANSITION_COMMENT = (
+    "**:information_source: Fedora CI Transition Notice**\n\n"
+    "Packit is now the default CI system for Fedora dist-git. "
+    "For more information, see:\n"
+    "- [Fedora Discussion: Packit as Fedora dist-git CI - Final Phase]"
+    "(https://discussion.fedoraproject.org/t/packit-as-fedora-dist-git-ci-final-phase/180160)\n"
+    "- [Packit Fedora CI Documentation](https://packit.dev/fedora-ci)\n\n"
+    "**Retriggering jobs:**\n"
+    "- Scratch build: `/packit-ci scratch-build`\n"
+    "- Tests: `/packit-ci test`\n\n"
+    "- See more in the "
+    "[retriggering documentation](https://packit.dev/fedora-ci/retriggering).\n\n"
+    "Questions? Reach us at [#packit:fedora.im](https://matrix.to/#/#packit:fedora.im)\n\n"
+    "---\n"
+    "*This notice is posted during the introduction period (until the end of March 2026).*"
+)

packit_service/worker/jobs.py

@@ -14,12 +14,20 @@
 
 import celery
 from ogr.exceptions import GithubAppNotInstalledError
-from packit.config import JobConfig, JobConfigTriggerType, JobConfigView, JobType, PackageConfig
+from packit.config import (
+    Deployment,
+    JobConfig,
+    JobConfigTriggerType,
+    JobConfigView,
+    JobType,
+    PackageConfig,
+)
 from packit.utils import nested_get
 
 from packit_service.config import ServiceConfig
 from packit_service.constants import (
     COMMENT_REACTION,
+    FEDORA_CI_TRANSITION_COMMENT,
     HELP_COMMENT_DESCRIPTION,
     HELP_COMMENT_EPILOG,
     HELP_COMMENT_PROG,
@@ -88,6 +96,8 @@
 from packit_service.worker.monitoring import Pushgateway
 from packit_service.worker.parser import Parser
 from packit_service.worker.reporting import BaseCommitStatus
+from packit_service.worker.reporting.enums import DuplicateCheckMode
+from packit_service.worker.reporting.utils import has_identical_comment_in_comments
 from packit_service.worker.result import TaskResults
 
 logger = logging.getLogger(__name__)
@@ -484,6 +494,44 @@ def report_task_accepted(
 
         self.push_copr_metrics(handler_kls, number_of_build_targets)
 
+    def _post_fedora_ci_transition_comment(self) -> None:
+        """
+        Post a one-time CI introduction comment on the dist-git PR.
+
+        Only posts if the comment doesn't already exist.
+
+        TODO: Remove this method after March 2026 (end of introduction period).
+        https://github.com/packit/packit-service/issues/3008
+        """
+        # Check if event is a PR-related event (has pr_id and pull_request_object)
+        if not (
+            isinstance(self.event, (pagure.pr.Action, pagure.pr.Comment))
+            and (pr := self.event.pull_request_object)
+        ):
+            return
+
+        try:
+            comments = pr.get_comments()
+
+            # Check if we already posted this comment
+            packit_user = (
+                "packit" if self.service_config.deployment == Deployment.prod else "packit-stg"
+            )
+            if has_identical_comment_in_comments(
+                body=FEDORA_CI_TRANSITION_COMMENT,
+                comments=comments,
+                packit_user=packit_user,
+                mode=DuplicateCheckMode.check_all_comments,
+            ):
+                logger.debug("CI transition comment already exists on PR.")
+                return
+
+            pr.comment(FEDORA_CI_TRANSITION_COMMENT)
+            logger.info(f"Posted CI transition comment on dist-git PR #{self.event.pr_id}")
+        except Exception as ex:
+            # Don't fail the job if we can't post the comment
+            logger.warning(f"Failed to post CI transition comment: {ex}")
+
     def report_task_accepted_for_fedora_ci(self, handler_kls: type[FedoraCIJobHandler]):
         """
         For CI-related dist-git PR comment events report the initial status
@@ -639,6 +687,8 @@ def process_fedora_ci_jobs(self) -> list[TaskResults]:
 
         # TODO: add allowlist checks here
 
+        self._post_fedora_ci_transition_comment()
+
         processing_results: list[TaskResults] = []
 
         for handler_kls in matching_handlers:

tests/integration/test_dg_pr.py

@@ -73,6 +73,15 @@ def test_downstream_koji_scratch_build(distgit_pr_event, target_branch, uid, che
         .should_receive("set_flag")
         .with_args(username=check_name, comment=str, url=str, status=CommitStatus, uid=uid)
         .mock()
+        # Mock for CI transition comment
+        .should_receive("get_comments")
+        .and_return([])
+        .once()
+        .mock()
+        .should_receive("comment")
+        .with_args(str)
+        .once()
+        .mock()
     )
     if eln:
         check_name = "Packit - scratch build - rawhide [889f07a]"

tests/integration/test_pr_comment.py

@@ -2500,6 +2500,15 @@ def test_downstream_koji_scratch_build_retrigger_via_dist_git_pr_comment(
         )
         .once()
         .mock()
+        # Mock for CI transition comment
+        .should_receive("get_comments")
+        .and_return([])
+        .once()
+        .mock()
+        .should_receive("comment")
+        .with_args(str)
+        .once()
+        .mock()
     )
     dg_project = (
         flexmock(
@@ -3328,6 +3337,9 @@ def _test_downstream_tf_retrigger_common(
             status=CommitStatus,
             uid=uid,
         )
+    # Mock for CI transition comment
+    pr_object.should_receive("get_comments").and_return([]).once()
+    pr_object.should_receive("comment").with_args(str).once()
 
     dg_project = (
         flexmock(