From f9ab492c34259fd02579f2fa3c7e7f3aa4f2f0e3 Mon Sep 17 00:00:00 2001
From: cghague <53837824+cghague@users.noreply.github.com>
Date: Thu, 10 Aug 2023 00:58:31 +0100
Subject: [PATCH] Improve voltage warning lines in TinyPilot logs (#1544)
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Resolves #1495

Parses the output of `journalctl` into a simple “yes” or “no” result. If
the result is “yes”, the latest voltage warning is also included in the
output.

## Parsing the output of `journalctl`

I initially considered piping the output of `journalctl` into `grep` for
readability, but getting the correct exit code as well as just the
latest voltage warning was quite awkward with this approach. I therefore
settled on using just the filtering and output options that are built
into `journalctl`:

- The `-q` argument is used to suppress the unwanted `journalctl` header
text.
- The `-r` argument causes `journalctl` to output from newest to oldest.
- The `-n 1` argument causes `journalctl` to stop after outputting a
single line.
- The `-g "voltage"` argument limits output to only lines that contain
the word “voltage”.

The end result of this combination of arguments is that `journalctl`
will efficiently output only the most recent voltage warning. In
addition, the exit status of the command reflects whether or not any
matching lines were found, which allows for a simple `if <command>` test
to be used.

Short arguments were used for consistency with the majority of the rest
of the `collect-debug-logs` script.
<a data-ca-tag
href="https://codeapprove.com/pr/tiny-pilot/tinypilot/1544"><img
src="https://codeapprove.com/external/github-tag-allbg.png" alt="Review
on CodeApprove" /></a>
---
 .../tinypilot-privileged/scripts/collect-debug-logs    | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/debian-pkg/opt/tinypilot-privileged/scripts/collect-debug-logs b/debian-pkg/opt/tinypilot-privileged/scripts/collect-debug-logs
index b67666201..98b132778 100755
--- a/debian-pkg/opt/tinypilot-privileged/scripts/collect-debug-logs
+++ b/debian-pkg/opt/tinypilot-privileged/scripts/collect-debug-logs
@@ -148,9 +148,13 @@ print_info "Checking throttled state..."
 
 print_info "Checking for voltage issues..."
 {
-  echo "voltage logs"
-  journalctl --catalog --pager-end | grep --ignore-case "voltage"
-  printf "\n"
+  printf "Voltage issues: "
+  if LAST_VOLTAGE_LINE="$(journalctl --quiet --reverse --lines=1 --grep='voltage')" ; then
+    printf "yes - %s" "${LAST_VOLTAGE_LINE}"
+  else
+    printf "no"
+  fi
+  printf "\n\n"
 } >> "${LOG_FILE}"
 
 print_info "Checking TinyPilot settings..."