Tag: MySQL

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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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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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