Avoid constraint errors when running parallel pg_restore

To enhance the restore speed for PostgreSQL databases, the pg_restore command running the most time-consumping steps concurrently by providing the number of jobs with -j/--jobs.

Unfortunately the parallel restore can fail when restoring foreign keys due to not yet restored tables:

pg_restore: error: could not execute query: ERROR:  there is no unique constraint matching given keys for referenced table "page"
Command was: ALTER TABLE ONLY pagecontent
    ADD CONSTRAINT "$1" FOREIGN KEY (page_id) REFERENCES page(id);


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How to use SSH FIDO2 on a remote machine

Configuring and using a local Yubikey for SSH with FIDO2 is very straight forward using the Yubico manual Securing SSH with FIDO2

But in some cases I would like to use my Yubikey based SSH key on my office's workstation when I am at home using my notebook.

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Old Let’s Encrypt Root Certificate Expiration workaround

The expiring Let’s Encrypt DST Root CA X3 can cause problems on old servers:

root@server:/etc# wget https://www.example.com/monitoring
--2021-09-30 21:34:39--  https://www.example.com/monitoring
Resolving www.example.com (www.example.com)...
Connecting to www.example.com (www.example.com)||:443... connected.
ERROR: The certificate of `www.example.com' is not trusted.

Fortunately there is an easy workaround to ensure the expired chain is not checked.

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Configuring an Unify Dream Machine for Swisscom 6RD IPv6

The residential Swisscom Internet Box 2 does not allow to autoconfigure an Unify Dream Machine with IPv6.

After several hours of research I found a workaround to get IPv6 support.

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Workaround for missing DomainClassConverter in Spring Boot JUnit tests

In one of my projects I let Spring Boot automatically bind domain objects from the database.

This fails in the reduced unit test setup, because DomainClassConverter is not available. But it can be mocked!

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Avoid conversion warnings when using yedit ansible role

When I fist started to use yedit to modify YAML files I got the following warning:

[WARNING]: The value {...} (type dict) in a string field was converted to "{...}" (type string). If this does not look like what you expect, quote the entire value to ensure it does not change.


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Shrinking LVM physical volume running on software RAID

Due to a misconfiguration I had to shrink a LVM 2 volume group and its physical volume running on a software RAID.

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Formatting phone numbers using libphonenumber in Thymeleaf

The Google phone number parser & formatter is very helpful to ensure the same number format for user prodived data. To simplify the use in Spring Boot application with Thymeleaf I created a wrapping TagLib/ExpressionFactory.

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Samsung SSD as Linux Software RAID

Initially I thought adding a pair of Samsung 860 EVO as software RAID to my small home server cannot be too hard...

... but they seem to require special kernel settings to work.

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Setup Unifi Controller on Debian 10 / Buster

The requirements of the Unifi Controller do not allow a direct installation. But with a few manual steps a successful setup is possible!

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