Migrate from Promtail to Alloy

[gsanchietti]

Current promtail installations will be EOL next year.

• Promtail EOL on March 2026
• Migration guide https://grafana.com/docs/alloy/latest/set-up/migrate/from-promtail/

Since we already switched to Loki 3 (#7273), we can also upgrade from Promtail to Alloy.

Discussion https://mattermost.nethesis.it/nethesis/pl/kde9kfndq3nizrhcsb49aoxwjc

Thanks to @Amygos

See also #7273

[gsanchietti]

Testing image: core-3.6.4-dev.2

Test case 1: clean install with Loki 2

• Install a clean machine:

  curl https://raw.githubusercontent.com/NethServer/ns8-core/main/core/install.sh > install.sh 
  bash install.sh ghcr.io/nethserver/loki:1.2.2 ghcr.io/nethserver/core:3.6.4-dev.2
  create-cluster rl1.leader.cluster0.gs.nethserver.net:55820 10.5.4.0/24 Nethesis,1234
  

• Access the cluster admin and go to the Log page
• Verify logs are presents and searchable

Test case 2: clean install with Loki 3

• Install a clean machine:

  curl https://raw.githubusercontent.com/NethServer/ns8-core/main/core/install.sh > install.sh 
  bash install.sh  ghcr.io/nethserver/loki:1.2.3-dev.2 ghcr.io/nethserver/core:3.6.4-dev.2
  create-cluster rl1.leader.cluster0.gs.nethserver.net:55820 10.5.4.0/24 Nethesis,1234
  

• Access the cluster admin and go to the Log page
• Verify logs are presents and searchable

Test case 3: upgrade

• Install a clean stable machine:

  curl https://raw.githubusercontent.com/NethServer/ns8-core/main/core/install.sh > install.sh 
  bash install.sh 
  create-cluster rl1.leader.cluster0.gs.nethserver.net:55820 10.5.4.0/24 Nethesis,1234
  

• Upgrade promtail:

  api-cli run update-core --data '{"core_url":"ghcr.io/nethserver/core:alloy","nodes":[1], "force": true}
  

• Access the cluster admin and go to the Log page
• Verify logs are presents and searchable
• Verify alloy is installed: podman ps should show a promtail container that runs alloy
• Verify promtail has been restarted and now runs the alloy image systemctl status promtail

[mrmarkuz]

Test case 1 - verified

Test case 2 - verified

Test case 3 - verified