Month: September 2023

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How I would Relearn Linux #4: Package Management

Good Morning from my Robotics Lab! This is Shadow_8472 with part four of How I Would Relearn Linux, where I answer the questions I had and offer the tips I wish I knew a few years ago when I started exploring Linux. Let’s get started!

Why Package Managers are Important

Linux software is often distributed in modular units known as packages be they applications, drivers, or kernel modules. If you’ve ever assembled a modpack for a game, there’s a chance you’ve had to chase down a dependencies or address conflicts before you could use it. Now imagine doing that for a full operating system, and you get the idea of what using Linux was like. A single packaged game might require tens or hundreds of prerequisite packages by the time you settle everything. This problem was quickly automated with package managers.

How to Use a Package Manager

Specific features of a package manager will vary, but their primary goal is to install, update, and remove packages. It will have a repository list telling it where to install software from. Android is Linux… kinda. Its default package manager is the Play Store. Its job is to install, update, and remove packages per user direction while making the process as invisible as possible. Unlike Android, a package manager in Linux is typically invoked using another program called Sudo (my preferred pneumonic is “Super User DO” even though I use the su-dough pronunciation).

When installing packages, a package manager has a list of repositories to contact. It will reach out to them with each package being installed and usually ask for clarification if multiple matches are found. It then does the same thing for all the listed prerequisites until it generates a full list of the missing packages needed to make your desired package run. On user confirmation, it begins download/installation.

Updating software is similar to initial installation. New versions may add features that rely on new or different library packages. A package manager will recalculate the missing packages and notify the user if any installed packages are either missing or no longer needed (This is true for the Debian/Ubuntu family’s package manager, apt. I’m not as familiar with pacman or dnf to speak for their specific behavior – as in they might just auto-remove them and I’d be none the wiser).

Uninstalling packages is similar to updating, only an explicitly installed package is being removed along with its unneeded dependencies. This may also be a necessary step if a conflict arises which the package manager cannot automatically resolve, though additional force may be required to bypass dependency checking.

Secondary Package Managers

Going back to Android for a moment, it is possible to “sideload” apps by downloading them from outside the Play Store. It’s even possible to download other app stores, such as F-Droid, which specializes in Free and Open Source Software and the Aurora Store, which uses the Play Store’s repositories, but with an emphasis on being privacy conscious. Similarly, there exist Linux package managers aimed at less-trusted community packages or packages that take care of more of their prerequisites. In this way, multiple versions of a program my be installed simultaneously, which may lead to confusion if a broken copy isn’t cleaned up in the hopes that an update will fix it.

Caution is often advised though when considering adding multiple primary package managers. I’ve not seen or looked for a solid explanation, but I can guess it’s so you don’t break your system by installing everything twice and having things call the wrong programs using twisted system links.

Takeaway

Whatever package manager your installed distro uses, you will get more out of your experience if you take the time to learn how to search for packages (a case where you don’t need sudo). When an exact version matters, you can usually extract that information from your package manager. If you cannot find a package, www.pkgs.org is also your friend. Your package may be in the repositories for the next or previous distribution, or in a repository you have to add special.

For example: in another project of mine, I found and looked up the version of Podman I had on Debian to learn it doesn’t support the Secrets feature I had been using on Rocky Linux: I had to adjust my approach accordingly.

Final Question

What package manager(s) came with your system(s)?

I look forward to hearing from you in the comments below or on my Socials!

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What are Relational Databases?

Good Morning from my Robotics Lab! This is Shadow_8472 and today I am targeting Nextcloud for major milestone completion. Let’s get started.

Previously on my Nextcloud saga, I finally managed to run a pod with both Nextcloud and MariaDB in their own containers and get them to talk. The words they exchanged were along the lines of “Access Denied.” I also have a script to add a temporary third container for database command line access.

My next immediate job is learning enough MySQL to diagnose Nextcloud’s refusal to create an admin account. I found a few commands to try and learned that the database I expected to be there on container creation didn’t appear to be. Container logs didn’t report any errors. I need some more background research, even if that’s the only thing I do this week.

Most important things first: what is the relationship between MariaDB and MySQL? I’ve been treating the former as if it were an implementation or distribution of the later – like the difference between Debian and Linux. But according to MariaDB’s site, they’re a fork that avoids “vendor-lock” while maintaining protocol compatibility with MySQL [1]. So MySQL help should still work for MariaDB on a “close enough” basis, sort of like how Debian solutions may still work for Ubuntu systems. When available: use a matching guide.

Contrary to what I said in my closing words last time I handled Nextcloud, commands being written in all caps is only convention – the software is usually a lot more forgiving. SELECT equals sELeCT which equals select and SelEct as well as the other 60 possible combinations.

MariaDB is what is called a “relational database.” Fancy phrase to me, but here goes an explanation. Data is information. Information can be organized into tables for later retrieval. Zoom out one level, and now tables with information themselves become data that interacts with information in other tables. MariaDB can track these “relations.”

Takeaway

Needless to say, relational databases gets messy fast. Considering how my database is meant to be locked up tight within a pod on a server that blocks direct access, a containerized webUI I can expose will do nicely. MariaDB’s website has a lengthy list of graphical clients, but only phpMyAdmin showed up as having this feature when I used “find on page” [2]. Importantly, it also shows up in Docker.io as a Docker Official Image, which I can run on Podman.

Final Question

As of posting, I’m planning on spending a week or few each for learning phpMyAdmin and refining my MariaDB understanding. Otherwise, if someone can answer what my problem is that Nextcloud isn’t finding the expected database. The following is a command from my pod creation script.

podman create \
        --pod NextcloudRedLaptop \
        --name MariaDBContainer \
        -v MariaDBVolume:/var/lib/mysql:Z \
        -e MARIADB_ROOT_PASSWORD="<gibberish1>" \
        -e MARIADB_DATABASE=NextcloudDB \
        -e MARIADB_USER=nextcloudDbUser \
        -e MARIADB_PASSWORD="Gibberish2" \
        --restart on-failure \
        docker.io/library/mariadb:latest

And here is what I think is the important output from MariaDB:

MariaDB [(none)]> SHOW DATABASES;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.010 sec)

If I understand what I need correctly, I should have had one show up titled “NextcloudDB” on container creation.

And so, my final question is this: Why doesn’t it work? Am I even looking in the right spot?

If I oversimplified or got something wrong about relational databases, be sure to tell me all about it in the comments!

Works Cited

[1] MariaDB, “MariaDB vs. MySQL The difference between choice and vendor lock-in,” MariaDB, [Online]. Available: https://mariadb.com/database-topics/mariadb-vs-mysql/. [Accessed Sept. 18, 2023].

[2] MariaDB, “Graphical and Enhanced Clients,” MariaDB, [Online]. Available: https://mariadb.com/kb/en/graphical-and-enhanced-clients/. [Accessed Sept. 18, 2023].

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Patriot Day, 2023

This morning of September 11 marks the 22 year anniversary of one of the greatest tragedies within living memory for the American people. In 2001, Islamic terrorists hijacked airplanes and crashed them into the Twin Towers in New York, leading to collapse of both and the loss of many lives. People around the world came out in solidarity with the US as fitting. Queen Elizabeth broke centuries-long tradition by playing the Star Spangled Banner at Buckingham palace not just on September 13, 2001, but again on the 20 year anniversary of the attacks.

I pitched the idea of a Stable Diffusion image and a short post, and my sister, Tzarina8472, suggested a firefighter saluting a US flag at half mast.

Producing this image required an update and a reboot (something I’ve put off for weeks). There were around a couple dozen “solid nope!” attempts before it as I was fighting with Automatic1111, the Stable Diffusion WebUI I am learning. The flag came out backwards and the firefighter has some metal socket where his backbone should be – not to mention his shoulders are all wrong, but I’m happy enough with how it turned out that I’m not upset my graphics card refused to customize it further without optimizations I don’t have time for because this piece invokes the emotional response I set out to invoke.

Thank you to firefighters and other first responders everywhere for your public service.

We never know what tomorrow may bring. We may wake up and it will be a whole new world.

Leo_8472 on the night of Sept. 10, 2001.
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My Nextcloud Sees its Database, but…

Good Morning from my Robotics Lab! This is Shadow_8472, and today is another Nextcloud shot. Let’s get started!

It almost needs not an introduction at this point. I’ve lost track of how long I’ve been after a Nextcloud instance – and even the number of times I’ve complained about the same. I’ve demoed it using an integrated database, and I’ve since gotten its container into a Podman pod. My task today is getting the paired MariaDB container to behave.

Let’s start with my first error. Nextcloud is starting for the first time and it’s time to make an admin account.

Failed to connect to the database: An exception occurred in the driver: SQLSTATE[HY000] [2002] No such file or directory

The container has been launched with flags providing environment variables pointing Nextcloud at the database and specifying the username/password to get in. I found someone having the exact same problem 4 years ago on Stack Overflow, and if I get user2880156’s explanation, “localhost” is not the same as spelling out a loopback IP address, like 127.0.0.1 [1]. While some networked applications don’t care how they interact as server and client when on the same computer [namespace?], Nextcloud and MariaDB are not such a pair. It has something to do with types of network sockets, but I don’t understand beyond that. What matters to me now is that replacing “localhost” with “127.0.0.1” got me to my next error.

MySQL username and/or password not valid You need to enter details of an existing account.

I’ve checked my environment variables more times than I can count. The required usernames and passwords were copy-pasted between the respective environment variables. The best lead I have is that the container may be bugged. People online have reported success with manually creating the full permissions/non-root account the database container is supposed to create on initial creation.

This insight led me to seek a manual fix from within the pod – specifically from a MariaDB command line as mentioned in the container’s documentation. After trying several different ways to modify a terminal command to run with Cockpit, I gave up, re-added a couple flags I was avoiding, and got the interface I was after rendered to both bash and Cockpit. I additionally split the command back into a separate script.

The MariaDB command line is unlike any I’ve used before. My first impressions are that commands are in all caps and variables are lower case. My final achievement before running out of time was to extract a list of user names (root, healthCheck, and databaseUser), where they’ve logged in from (variations on locations within the pod), and a partial hexadecimal output of their passwords.

Takeaway

Solving localhost vs 127.0.0.1 addresses has given me insight into Cockpit’s curious behavior when remoting into to itself with localhost. Command line access to the database from within the pod is also huge.

Final Question

I’m not taking bets, and I’m afraid to ask, but what additional roadblocks should I expect?

Work Cited

[1] akrea, et. all, “nextcloud and mariadb (both) on docker: SQLSTATE[HY000] [2002] No such file or directory,” stackoverflow.com Mar. 10, 2019-Mar. 22, 2023. [Online]. Available:https://stackoverflow.com/questions/55088828/nextcloud-and-mariadb-both-on-docker-sqlstatehy000-2002-no-such-file-or-d. [Accessed Sept. 4, 2023].

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