Posts about Misc

Ignoring SSL Errors in Chrome

May 7, 2024 •
Very useful when you are developing anything WebAuthn related.
```
google-chrome --ignore-certificate-errors --user-data-dir=$HOME/tmp/chrome-dev
```
--ignore-certificate-errors will disable any SSL warnings like self-signed certs.

--user-data-dir will isolate this unsafe Chrome instance from your regular browsing.
Category: Misc • Tags: chrome, ssl

Generating UUIDv7 in PostgreSQL

Jan 20, 2024 •

But what about Postgres? We can do it too. Hopefully generators for new UUID versions will be added to uuid-ossp but it is not yet the case.

The easiest way for now is to use pgcrypto, so let's start with that:

create extension pgcrypto;

Now port the solution from the MySQL post:

select
    lpad(to_hex((extract(epoch from now()) * 1000)::bigint), '12', '0') ||
    '7' || -- version
    substr(encode(gen_random_bytes(2), 'hex'), 2) ||
    to_hex((floor(random() * 4) + 8)::int) || -- variant bits
    substr(encode(gen_random_bytes(8), 'hex'), 2)
    as uuid;

Like with MariaDB, Postgres doesn't care about dashes on insertion, so this value can be directly applied to a field with the uuid type.

And again, to make it a formatted value, use a type cast:

select
    (lpad(to_hex((extract(epoch from now()) * 1000)::bigint), '12', '0') ||
    '7' ||
    substr(encode(gen_random_bytes(2), 'hex'), 2) ||
    to_hex((floor(random() * 4) + 8)::int) ||
    substr(encode(gen_random_bytes(8), 'hex'), 2))::uuid
    as uuid;

And to have a bytea value, use decode:

select
    decode(
        lpad(to_hex((extract(epoch from now()) * 1000)::bigint), '12', '0') ||
        '7' ||
        substr(encode(gen_random_bytes(2), 'hex'), 2) ||
        to_hex((floor(random() * 4) + 8)::int) ||
        substr(encode(gen_random_bytes(8), 'hex'), 2),
        'hex'
    ) as uuid;

Category: Misc • Tags: postgres, sql, uuid, uuidv7

Generating UUIDv7 in MySQL and MariaDB

Jan 20, 2024 •

A quick way to generate UUIDv7 in MySQL 8 and MariaDB 11:

select
    concat(
        -- Use NOW(3) to get milliseconds
        lpad(hex(unix_timestamp(now(3)) * 1000), 12, '0'),
        '7', -- version
        substr(hex(random_bytes(2)), 2),
        hex(floor(rand() * 4 + 8)), -- variant bits
        substr(hex(random_bytes(8)), 2)
   ) as uuid;

This will generate a hex string that can be inserted into MariaDB's UUID type as is, dashes will be added automatically.

If you need it as a binary value, wrap with unhex:

select
    unhex(concat(
        lpad(hex(unix_timestamp(now(3)) * 1000), 12, '0'),
        '7',
        substr(hex(random_bytes(2)), 2),
        hex(floor(rand() * 4 + 8)),
        substr(hex(random_bytes(8)), 2)
    )) as uuid;

If you specifically need a valid RFC 4122 string representation, use a bin formatter function (MySQL) or a type cast (MariaDB):

-- MySQL
select
    bin_to_uuid(unhex(concat(
        lpad(hex(unix_timestamp(now(3)) * 1000), 12, '0'),
        '7',
        substr(hex(random_bytes(2)), 2),
        hex(floor(rand() * 4 + 8)),
        substr(hex(random_bytes(8)), 2)
    ))) as uuid;

-- MariaDB
select
    cast((concat(
        lpad(hex(unix_timestamp(now(3)) * 1000), 12, '0'),
        '7',
        substr(hex(random_bytes(2)), 2),
        hex(floor(rand() * 4 + 8)),
        substr(hex(random_bytes(8)), 2)
    )) as uuid) as uuid;

UPD: Postgres can do it too!

Category: Misc • Tags: mariadb, mysql, sql, uuid, uuidv7

Running 32-bit Images in GitLab CI

Sep 7, 2023 •

A thing that was not obvious to me and relatively hard to google was a way to run a 32-bit docker image in the GitLab CI. Docker itself has --platform param but it is not exposed to the .gitlab-ci.yml file.

Luckily it's easy for the official Docker registry. Apart from auto-selection images, it also contains per-architecture image repos with distinct package names. You only need to specify a desired architecture prefix: like amd64/php or i386/php.

Example:

.test:
  script:
    - composer update
    - vendor/bin/phpunit

test-64bit:
  extends: .test
  stage: test
  image: amd64/php:8

test-32bit:
  extends: .test
  stage: test
  image: i386/php:8

or using the matrix:

test:
  stage: test
  image: ${ARCH}/php:${PHP_VERSION}
  script:
    - composer update
    - vendor/bin/phpunit
  parallel:
    matrix:
      - PHP_VERSION:
          - '7'
          - '8'
        ARCH:
          - amd64
          - i386

Category: Misc • Tags: gitlab, gitlab ci, i386

Resizing small EFI partition

Apr 17, 2023 •
It started with the firmware failing to update because the EFI partition was low on free space. (Dell, why do you need 70 MB on the EFI while also making it as small as 150 MB at the same time?) Well, resizing the partition is the obvious solution except it ended in a wonderful error message:
GNU parted cannot resize this partition to this size. We're working on it!
(spoiler: they're not)

In my case the GPT partition was resized, just the filesystem was not grown, I only needed to reformat it.

Read more…
Category: Misc • Tags: efi, fat32, linux, parted, til, windows
GPL Incompatibility

Feb 22, 2023 •

"GPL incompatibility" of a FOSS license is not a problem of the incompatible license, it's the problem of the GPL. Most permissive licenses and file-based copyleft licenses can be used together in a project without any conflict and that's great. It's GPL that doesn't like any neighbors.

Category: Misc • Tags: copyleft, gnu gpl, opensource
LGPL is a bad practice

Jan 2, 2023 •

TL;DR: Don't use LGPL, avoid library-based copyleft in general.

The closest acceptable no-brainer replacement should be GNU GPL with Classpath Exception, but the concept of library-based copyleft itself is flawed. It's better to consider MPL (less copyleft) or full GPL (more copyleft).

Read more…

Category: Misc • Tags: copyleft, lgpl, licensing
Python Type Hints

Jun 22, 2022 •

Python type hints are garbage.

Category: Misc • Tags: python, short, types
No Discrimination

Mar 16, 2022 •
In these uneasy times I just want to remind to all these passionate activists around that there are other ethical points beyond any given "today thing" even when the today thing is truly horrible.

The Open Source Definition states that open-source software must comply with the following criteria:

5. No Discrimination Against Persons or Groups The license must not discriminate against any person or group of persons.

6. No Discrimination Against Fields of Endeavor The license must not restrict anyone from making use of the program in a specific field of endeavor. For example, it may not restrict the program from being used in a business, or from being used for genetic research.

So whether you are breaking these rules for fun or showing your political position, you should remember:
- It is not as fun as it seems.
- You are not hurting the people you hate, you are hurting the open-source community.
Category: Misc • Tags: open source, politics
sass-hsv

Aug 28, 2021 •

I haven't found a nice small helper for HSV/HSB color format like the one LESS has so I published my first npm package.

https://sandfox.dev/js/sass-hsv.html

Category: Misc • Tags: hsb, hsv, sass

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