Arvados

Our Salt installer uses the package sources from the grafana-formula project, that is to say, it gets Grafana-related packages from Grafana itself.

Here's the list of sources depending on the distro, the Debian-specific one is:

name: deb https://apt.grafana.com stable main
file: /etc/apt/sources.list.d/grafana.list
key_url: https://apt.grafana.com/gpg.key

Given this, the new role needs to look more like arvados_docker: it should install package pins, install the repository, then install the package. You can start writing the tasks now (if you haven't already) and I'll work on putting good pins together.

We discussed at standup we are rarely affected by Loki changes, so pinning the major version seems fine. It should look like this (untested, feel free to fix typos):

Package: loki
Pin: version 3.*
Pin-Priority: 995

For the playbook, add a play for a new arvados_loki group that includes the role, following the same pattern as most of the plays in there now.

My understanding is that we typically delpoy such that all the Arvados servers run Alloy, and then send logs to a separate server running Loki+Grafana. But any of these could be shuffled around so I think it makes sense to have separate groups for all of them.

Changes at arvados|117c4811ee8acf89691aeb3c161c5fef705c9119 branch 23295-loki-ansible-role

• The role:
  • Adds the apt version pin following the example of arvados_docker
  • Adds the grafana repo, notifies apt-update and flushes handlers
  • Installs loki v3.*
  • Copies the provided config file
  • Enables and restarts (if config changed) or starts loki.service
• Added example arvados_loki group to full inventory with some descriptions and invoke the role on the group in the main playbook

A couple comments:

• I think that if we pin the loki package, it's better to not repeat the version information in the install package step, to avoid future issues.
• The arvados_loki role needs to depend on distro_apt so that it can notify 'apt update'. Check how it's declared in roles/arvados_docker/meta/main.yml

Changes at arvados|3724c52910058b9e5945cc5d907bfac648f89cca

• Added the distro_apt dependency
• Removed redundant version specifier from apt task

A couple more comments:

• I believe the task that checks/creates the /etc/loki/ directory and the one that writes the configuration file need to have become: yes.
• Also, I would make sure that ownership & permissions on /etc/loki/ are also correctly set.

With that, it LGTM. Thanks!