= DNF Counting

We use DNF Counting to get statistics about the number of Fedora
installations.

== Contact Information

Owner::
  Fedora Infrastructure Team
Contact::
  #fedora-admin, #fedora-noc,
  admin@fedoraproject.org
Servers::
  log01, proxy0*
Purpose::
  Give interested parties information about the number of Fedora
  installations.
Repositories::
  * https://github.com/fedora-infra/mirrors-countme
  * https://pagure.io/fedora-infra/ansible/blob/main/f/roles/web-data-analysis

== What it is

DNF Counting is a way for us to gather statistics about the number of Fedora
installations, differentiated by version, spin, etc. On the infrastructure
side this is implemented by a bunch of scripts and a Python package
(`mirrors-countme`).

== Scope

This SOP concerns itself with the infrastructure side of the equation. For any
issues with the various frontends logging in to be counted (DNF, PackageKit,
…), contact their respective maintainers or upstreams.

== How it works

Clients (DNF, PackageKit, …) have been modified so they add a `countme`
variable in their requests to `mirrors.fedoraproject.org` once a week. This
ends up in our webserver log data which lets us generate usage statistics.

Cron jobs are set up on `log01` which collect http log files from the various
web proxies, combine them (accesses to different backend services including
`mirrors.fedoraproject.org` are scattered across the proxy logs), and produce
statistics from them. The various pieces live in a) the `mirrors-countme`
project (Python package and related scripts to generate statistics from the
log data) and b) shell scripts in the `web-data-analysis` role in Ansible:

* `sync-http-logs.py` (Ansible) syncs individual log files from various hosts
  including proxies to `log01`.
* `combineHttpLogs.sh` (Ansible) combines the logs for the different web sites
  which are scattered across the proxy hosts.
* `condense-mirrorlogs.sh` & `mirrorlist.py` (Ansible) extracts hosts from the
  combined log data.
* `countme-update.sh` (Ansible) drives `countme-update-rawdb.sh` &
  `countme-update-totals.sh` (`mirrors-countme`) which generates statistics.
* `countme-trim-raw` (`mirrors-countme`) to trim the intermediary database file
  (``raw.db``).

== Changes implemented in the Q2/2023 DNF mirrors-countme initiative

* The “traditional“ statistics which were done before DNF
  learned about the `countme` variable were reimplemented: Count any
  individual IP sighted, no matter if with or without `countme`. This is
  necessary to count systems which don’t have that feature in their DNF or
  YUM, and – while giving different numbers – gives us an idea how things
  develop when compared to the same numbers for more modern OSes.
* The ``countme-trim-raw`` tool was implemented, to trim the intermediary
  database ``raw.db`` which contains necessary information gleamed from
  parsing the merged log files. This database grows steadily and – with the
  brought back counting of any individual IP sighted – quickly, so once these
  data have been safely turned into the final statistics, we wanted a way to
  remove them so that the local volume were it is stored doesn’t fill up
  completely.
* The project repository was cleaned up, i.e. large data files used in
  integration tests were removed because they made cloning the repository
  unnecessarily slow, for a couple hundred KB of code, the repo was more than
  300 MB in size. In the context, the repository was moved from Pagure to
  GitHub.
* Unused code was removed, the remaining code was refactored and condensed
  to remove redundancies and comprehensive unit tests were added so that the
  barrier to contributing is lower and changes are less risky.

== Changes implemented in the Q3/2021 DNF Counting Initiative

During the Q3/2021 DNF Counting Initiative, a number of changes were
implemented which improved the DNF Counting backend in the areas of monitoring
& debugging, performance & robustness.

* The involved scripts send messages about state changes and errors to the
fedora-messaging bus. State changes are e.g. start and finish of a complete
script or of its individual steps.
* The shell script which syncs log files from various hosts to `log01`
(`syncHttpLogs.sh`) was reimplemented in Python (as `sync-http-logs.py`), with
several improvements which reduced the time it takes for syncing from 6-7
hours to little more than 30 minutes per day:
** All log files for one date of one host are synced in one call to `rsync`.
This greatly reduces overhead.
+
The reason to sync these files one-by-one previously was because `rsync` only
allows differing file names when syncing single files, which we have: the log
files on the hosts contain their date in the name, on `log01` they don't but
are stored in directories for each date.
+
To overcome this limitation, `sync-http-logs.py` maintains a shadow structure
of hard links with dates in their names, and `rsync` operates on this
structure instead, which are linked back to "date-less" file names afterwards
for further processing.
** Because syncing log files from some hosts is pretty slow, several hosts are
synced in parallel.
* Previously, `syncHttpLogs.sh` and `combineHttpLogs.sh` were run from
  individual cron jobs which were set to run a couple of hours apart.
  Sometimes, this caused problems because the former wasn't finished when the
  latter started to run (i.e. a race condition). Now, `sync-http-logs.py` and
  `combineHttpLogs.sh` are run from one cron job to avoid this.
* Previously, the scripts where scattered across the `web-data-analysis`,
  `awstats` and `base` roles. All of the deployment has been consolidated into
  the `web-data-analysis` role, `awstats` has been removed.
* The `mirrors-countme` Python package and scripts are packaged as RPM
  packages in Fedora, previously they were deployed from a local clone of the
  upstream git repository.

== Reboot me

Yes, just reboot. Or don't. There are no continuously running services,
everything is regularly run as cronjobs.

== Logs

The `sync-http-logs.py` script sends relatively verbose output to syslog.
Other than that, the closest anything comes to logs are mails sent if cronjobs
produce (error) output and messages sent to the bus.

== First steps to debug

The scripts send messages with a topic prefix of `logging.stats` to the bus,
in various stages of their operation. If anything doesn't work as it should,
review if every step started is also finished, compare run times between days.

If anything crashes, cron should have sent mails to the recipients configured
(at least `root@fedoraproject.org`), which could also contain valuable
information.

== Ephemeral data

Generated CSV reports and images are in `/var/www/html/csv-reports` which are
exposed on https://data-analysis.fedoraproject.org/ – but they get regenerated
with every cycle of the scripts that is run.

== Persistent data

All combined http log data is kept on the `/fedora_stats` NFS share.  Log
files from the proxy hosts are synced to `/var/log/hosts/<hostname>` locally,
but these are just copies of what exists elsewhere already.

== Other operational considerations

The scripts only process data from the previous three days (roughly). If they
don't run for a longer time, there might be gaps in the generated statistics
which can be plugged by temporarily adjusting the respective settings in the
scripts and re-running them.

== Where are the docs?

Here :) and at https://github.com/fedora-infra/mirrors-countme

== Is there data that needs to be backed up?

Yes, but it's on the `/fedora_stats` file share, so it's assumed to get backed
up regularly already.

== Upgrading

=== `mirrors-countme`

The `mirrors-countme` shell and Python scripts create statistics from the
already combined log data.

==== Making upstream changes available

Prerequisites: A change (bug fix or feature) is available in the `main`
branch of `mirrors-countme`.

. Publish an upstream release
+
From a clone of the upstream repository:
+
.. In `pyproject.toml`, bump `tool.poetry.version` (e.g. to `0.1.2`) and
commit the change, e.g.:
+
....
git commit -s -m "Version 0.1.2" -- pyproject.toml
....
.. Tag the previous change with a GPG-signed tag:
+
....
git tag -s 0.1.2
....
.. Push both the change and the tag:
+
....
git push origin main 0.1.2
....
.. Create a source tarball (this will be created as e.g.
`dist/mirrors_countme-0.1.2.tar.gz`):
+
....
poetry build
....
From the https://github.com/fedora-infra/mirrors-countme/tags[list of tags],
select “Create release” in the menu for the respective tag, and attach the
created tarball and wheel files to the created release.
. Update and Build the `python-mirrors-countme` Fedora Package
+
From a clone of the Fedora package repository, in the `rawhide` branch:
+
.. Bump the version in `python-mirrors-countme.spec`. No other changes
are necessary, the packages uses automatic release fields and changelog.
+
.. Download the source tarball, either manually or one of:
+
....
spectool -g python-mirrors-countme.spec
....
+
....
rpmspectool get python-mirrors-countme.spec
....
.. Upload the source tarball to the lookaside cache:
+
....
fedpkg new-sources mirrors_countme-0.1.2.tar.gz
....
.. Commit the changes to the repository, e.g.:
+
....
git commit -s -m "Version 0.1.2" -- python-mirrors-countme.spec
....
.. Push the changes and build:
+
....
git push && fedpkg build
....
.. For any other active Fedora and EPEL branch, fast forward them to the
state of the `rawhide` branch, push and build, e.g.:
+
....
git checkout epel8 \
&& git merge --ff-only rawhide \
&& git push \
&& fedpkg build
....
. Submit Fedora/EPEL Package Updates
+
Either submit the update via the
https://bodhi.fedoraproject.org/updates/new[Bodhi web interface], or
from the command line in the respective checked out Fedora or EPEL
branch, e.g.:
+
....
fedpkg update --type bugfix --notes 'Put in some notes!'
....
. Tag with Infra-Tags in Koji
.. Tag the build into the respective infra candidate tag in Koji, e.g.:
+
....
koji tag-build epel8-infra-candidate
....
.. Check that the build was picked up and signed (this should take no
more than a few minutes), e.g.:
+
....
koji buildinfo python-mirrors-countme-0.1.2-1.el8
....
+
The build must be tagged with the corresponding `*-infra-stg` tag.
.. Tag the build into the respective infra production tag in Koji, e.g.:
+
....
koji tag-build epel8-infra
....

When the respective infra tag repository is updated, the new version
should be ready to be installed/updated in our infrastructure.

=== Other scripts

Scripts other than what is contained in `mirrors-countme` live in the
`web-data-analysis` role in Ansible. Simply "upgrade" them in place.

=== Deployment of updates

To deploy updated scripts, etc. from the Ansible repository, simply run the
`groups/logging.yaml` playbook.

To update `mirrors-countme`, run the `manual/update-packages.yml` playbook
with `--extra-vars="package='*mirrors-countme*'"` set.

== Related applications

The scripts send out status messages over `fedora-messaging` with a topic
prefix of `logging.stats`.

== How is it deployed?

All of this runs on `log01.iad2.fedoraproject.org` and is deployed through the
`web-data-analysis` role and the `groups/logserver.yml` playbook,
respectively.

The `mirrors-countme` upstream project publishes source tarballs to their
corresponding releases in the repository on GitHub:

https://github.com/fedora-infra/mirrors-countme/releases

These are packaged in Fedora as the `python-mirrors-countme` (SRPM) and
`python3-mirrors-countme` (RPM) packages.

Other scripts are located directly in the Fedora Infrastructure Ansible
repository, in the `web-data-analysis` role.

== Does it have any special requirements?

No.

== Are there any security requirements?

The same as anything else that deals with log data.

== Bug reports

Report bugs with `mirrors-countme` at its upstream project:

https://github.com/fedora-infra/mirrors-countme/issues/new

Anything concerning the cron jobs or other scripts should probably go into our
Infrastructure tracker:

https://pagure.io/fedora-infrastructure/new_issue

== Are there any GDPR related concerns? Mechanisms to deal with PII?

The same as anything else that deals with log data.
