François Scala

François Scala arcenik

Switzerland
https://francois.scala.name/

Organizations

Previous situation

Until now, Unifi was deployed using the included MongoDB server.

  unifi:
    image: goofball222/unifi:10.0.160-ubuntu
    hostname: unifi
    user: unifi
    restart: always
    ports:
      - 3478:3478/udp # STUN connection
      - 6789:6789 # throughput measurement from Android/iOS app
      - 8080:8080 # UAP/USW/USG to inform controller
      - 8443:8443 # controller GUI / API
      - 8880:8880 # HTTP portal redirect
      - 8843:8843 # HTTPS portal redirect
      - 10001:10001/udp # UBNT discovery broadcasts
    environment:
      - DB_MONGO_LOCAL=true
    volumes:
      - /srv/unifi/data:/usr/lib/unifi/data
      - /srv/unifi/log:/usr/lib/unifi/log
      - /srv/unifi/cert:/usr/lib/unifi/cert

Migration plan

Check Unifi backup
Stop the Unifi container
Copy/move the MongoDB folder to the new location
Start the MongoDB container, using the same version
Update Unifi Docker Compose to use the external MongoDB
Start the Unifi container

Check Unifi backup

# cd /srv
# ls -lh unifi/data/backup/

Stop the Unifi container

$ docker compose down unifi

Copy the data

# cd /srv
# cp -rp unifi/data/db mongounifi

New mongounifi service

Using the same version as in the Unifi container, to be upgraded later.

Write a Prometheus exporter in Go

How to expose Prometheus metrics from a json blob returned by a server.

Here is a walk through, based on json retreived from an EthSwarm node.

Retreive the json from EthSwarm status API

Here is a sample for the status json, from the API documentation,

{
  "overlay": "36b7efd913ca4cf880b8eeac5093fa27b0825906c600685b6abdd6566e6cfe8f",
  "proximity": 0,
  "beeMode": "light",
  "reserveSize": 0,
  "reserveSizeWithinRadius": 0,
  "pullsyncRate": 0,
  "storageRadius": 0,
  "connectedPeers": 0,
  "neighborhoodSize": 0,
  "requestFailed": true,
  "batchCommitment": 0,
  "isReachable": true,
  "lastSyncedBlock": 0,
  "committedDepth": 0
}

Prometheus exporter package

ethswarm/status.go start with the package declaration and imports

Observations and analysis about systemd-networkd-wait-online.service

Since a few time, I have to wait two minutes on each reboot, waiting for a faulty systemd service: systemd-networkd-wait-online.service

server# journalctl --boot -u systemd-networkd-wait-online.service
Jun 22 13:38:00 server systemd[1]: Starting systemd-networkd-wait-online.service - Wait for Network to be Configured...
Jun 22 13:40:00 server systemd-networkd-wait-online[472]: Timeout occurred while waiting for network connectivity.
Jun 22 13:40:00 server systemd[1]: systemd-networkd-wait-online.service: Main process exited, code=exited, status=1/FAILURE
Jun 22 13:40:00 server systemd[1]: systemd-networkd-wait-online.service: Failed with result 'exit-code'.
Jun 22 13:40:00 server systemd[1]: Failed to start systemd-networkd-wait-online.service - Wait for Network to be Configured.

The service is linked to the network-online systemd target.

server# ls -l /etc/systemd/system/network-online.target.wants/
total 4
lrwxrwxrwx 1 root root 42 Mar 23 12:02 networking.service -> /usr/lib/systemd/system/networking.service
lrwxrwxrwx 1 root root 60 Apr 26 18:26 systemd-networkd-wait-online.service -> /usr/lib/systemd/system/systemd-networkd-wait-online.service

Identify the problem

Reproduce the problem, running the command without any additional argument. Real time is 2 minutes and return 1.

server# time /usr/lib/systemd/systemd-networkd-wait-online ; echo $?
Timeout occurred while waiting for network connectivity.

real    2m0.236s
user    0m0.004s
sys     0m0.011s
1

Docker as Build Environment
You have a small/mid sized server and you want to install new software or custom kernel on it. But it take forever to build anything on it compared to your brand new 8 or 12 core modern laptop with fast NVMe SSD.
In addition, you don´t want to pollute your server with all the build dependencies.
Docker is here to save the day, allowing you to create fast and disposable build environments.
-rw-r--r-- 1 fs fs 8.6M 2024-12-22 17:33 linux-headers-6.12.6-test_6.12.6-1_amd64.deb -rw-r--r-- 1 fs fs 19M 2024-12-22 17:33 linux-image-6.12.6-test_6.12.6-1_amd64.deb -rw-r--r-- 1 fs fs 285M 2024-12-22 17:33 linux-image-6.12.6-test-dbg_6.12.6-1_amd64.deb -rw-r--r-- 1 fs fs 1.4M 2024-12-22 17:33 linux-libc-dev_6.12.6-1_amd64.deb
Here are two examples with linux kernel image and zfs-linux backport.

Shrink Debian Docker Image

1.8Gb docker image

As I encountered some ruby problem with Vagrant on my Archlinux laptop, I decided to use Docker as a workaround.

$ vagrant
/usr/lib/ruby/3.3.0/rubygems/specification.rb:2245:in `raise_if_conflicts': Unable to activate vagrant_cloud-3.1.1, because rexml-3.3.2 conflicts with rexml (~> 3.2.5) (Gem::ConflictError)
        from /usr/lib/ruby/3.3.0/rubygems/specification.rb:1383:in `activate'
        from /usr/lib/ruby/3.3.0/rubygems/core_ext/kernel_gem.rb:62:in `block in gem'
        from /usr/lib/ruby/3.3.0/rubygems/core_ext/kernel_gem.rb:62:in `synchronize'
        from /usr/lib/ruby/3.3.0/rubygems/core_ext/kernel_gem.rb:62:in `gem'
        from /opt/vagrant/embedded/gems/gems/vagrant-2.4.2/bin/vagrant:17:in `block in <main>'
        from /opt/vagrant/embedded/gems/gems/vagrant-2.4.2/bin/vagrant:16:in `each'
        from /opt/vagrant/embedded/gems/gems/vagrant-2.4.2/bin/vagrant:16:in `<main>'

So let’s create a Docker image, using a debian slim image and just install vagrant and some vagrant plugins.

First steps with Bosh on Virtualbox
Introduction
BOSH is an open source project from Cloud Foundry that allow release engineering, software deployment and application lifecycle management of large scale and distributed system.
I wanted to take a look at it and fortunately it is possible to play on a local playground environment on VirtualBox using the bosh-lite instruction.