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openhab2: check if alive

As mentioned in my previous openHAB blog post: it seems to be too much to ask to have a reliable and working display in the kitchen.

Another problem I found is that the weather data occasionally does not update. Everything seems to work, no errors in the log, just no updated data. Of course this results in outdated weather info in the kitchen, and the threat that "someone" will buy a regular weather station and render my 7" Raspberry display useless.

After fighting with logs and debugging and not finding any real clue, I decided to tackle this problem from another angle, and regularly check if the weather data is up to date.


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Ansible, delegate_to and set_fact

Another Ansible upgrade, another Playbook failing.

I have a number Playbooks which run on virtual machines. Some tasks are "outsourced" to the physical machine where the VM is running on, using "delegate_to". One of the tasks (which I haven't used in a while, because I rarely touch this machine) stopped working, and instead throws a "variable undefined" error. But from the beginning, here is the VM Playbook:

- block:
  - include: server-part.yml
  delegate_to: "{{ ansible_host }}"
  delegate_facts: True

That's the short form of it, and the $ansible_host variable holds the physical server address. That part is working. In "server-part.yml" I have the following:

# re-do the gather_facts task for the host
- action: setup

- name: Determine network interface name
    main_interface: "{{ item }}"
    "{{ hostvars[physicalhost]['ansible_interfaces'] }}"
  when: item is match("^e[tn]")
  changed_when: false

- name: Verify interface name is set
    msg: "Could not determine network interface name!"
  when: main_interface is not defined

The only physical network interface in this server is "eth0", that's still the case. There are a couple reasons why I still scan the list of interfaces, instead of just depending on "eth0". The main reason however is that this part also works with the enumeration systemd is doing with network interfaces (they have "en" names, instead of "eth"). But suddenly $main_interface in the next step is no longer defined.

Digging deeper (aka: -vvvv) it shows that Ansible is setting the correct interface name in the "set_fact" task, but then the variable is no longer defined immediately after that. What? I'm not sure I had to use this Playbook since my host was upgraded to Ansible 2.8.3, but I couldn't find any issues matching this problem either.


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Apache Karaf client in openHAB, and the "Session has been closed" error

Don't you love it when things suddenly stop working?

In my openHAB installation I have a check which verifies that the weather data is up to date. Otherwise it restarts the openhab2 service. And this check stopped working ... Leaving the kitchen display not updated for a longer time. The same display where I expect the entire installation to "just work", and don't create so many different problems. Seems to be a hard problem to have an openHAB installation without any trouble ...


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Related Projects

The PostgreSQL main website has a new page: "Related Projects".

This page lists the projects which help running and maintaining the PostgreSQL project, the infrastructure, and other things like the translations for press releases. For each project it lists links to the source, as well as information where to send updates, patches, or input.

If you want to get involved in one of the projects, that's your starting point. If a project is missing, please send a note or a patch to pgsql-www.

Many thanks to Jonathan S. Katz for polishing the patch, and making it look nice!

openHAB HABpanel configuration gets destroyed, HABpanel stays blank

openHAB is a stream of pure joy when it comes to debugging. Especially when all I want is a small display in the kitchen, working autonomous and without the need to restart it all the time or login to fix issues.

The latest installment of that endeavor was a black screen in the browser, with no way to even get to the usual HABpanel controls. After some debugging, it turns out that the file "habpanel.config" (/var/lib/openhab2/config/org/openhab/habpanel.config) on the openHAB server was destroyed, or more accurate: shortened to 4829 bytes. Lucky me I have this file in my Ansible playbooks, and whenever there is a change, a copy of this file is fetched to my Ansible host. From there it goes into my backups, and I can restore a couple dozen versions back, if needed. So not all is bad, but still something is not working as expected. First I installed a copy of this file from my backups - but turns out shortly later the file is shortened again. Later I figured that the file is always shortened when the openHAB service restarts. This particular instance was still running openHAB 2.4, and I used this opportunity to upgrade to 2.5, test my Playbooks (and exclude the one config file from everything) and see if the problem persists. It does. Except that after upgrading to 2.5 the file is no longer shortened to 4829 bytes, but to 4875 bytes.

Every time that happens, the file ends somewhere in the middle of the HABpanel panel configuration - and naturally the HABpanel service can no longer read that file and shows a blank screen. I would wish that it rather shows an error message, or does something useful here, but oh well.

For a while (and mostly because I was busy with other tasks) I helped myself by changing the owner of "habpanel.config" and the directory this files lives in to "root:root". This threw a couple other errors into the logfile, but helped somewhat because the config file got no longer destroyed when the service restarted.


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Internet access in Cuba

Cuba is still a developing country in terms of Internet access. For a few years tinternet was only available via satellite, and that was slow. There are now a few submarine cables, which has improved the speed, reliability and accessibility. Internet access in Cuba is basically offered by the state provider ETECSA. The internet available in hotels is just passed through to the provider as well.


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