From 16108f0c2e7daeb006df0610ec189c58955d1bb8 Mon Sep 17 00:00:00 2001
From: Mike Gerwitz <mtg@gnu.org>
Date: Thu, 24 Jun 2021 21:52:32 -0400
Subject: [PATCH] printer/epson/et-2720/metrics: Add serial number

Distinguish between two printers of the same model without having to
rely on URL, which can change over time.
---
 printer/epson/et-2720/metrics | 36 ++++++++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/printer/epson/et-2720/metrics b/printer/epson/et-2720/metrics
index 58bf807..b9a96f6 100755
--- a/printer/epson/et-2720/metrics
+++ b/printer/epson/et-2720/metrics
@@ -38,14 +38,27 @@ et-usage-status()
 }
 
 
-# Add host and URL to metric.
-#
-# WARNING: This does _not_ sanitize the URL; do not include double quotes.
-add-host()
+# Printer serial number.
+et-serial()
 {
   local -r url="${1?Missing URL}"
 
-  sed 's|}|, url="'"$url"'", model="ET-2720"}|; s/{, /{/'
+  et-product-status "$url" \
+    | grep -oP 'Serial Number.*?</div>' \
+    | awk -F'[<>]' '{print $9}'
+}
+
+
+# Add URL and serial number to metric.
+#
+# WARNING: This does _not_ sanitize the URL; do not include double quotes.
+add-labels()
+{
+  local -r url="${1?Missing URL}"
+  local -r serial="${2?Missing serial number}"
+
+  sed 's|}|, url="'"$url"'", serial="'"$serial"'", model="ET-2720"}|;
+        s/{, /{/'
 }
 
 
@@ -56,11 +69,10 @@ main()
 
   local -ri start=$( date +%s%3N )
 
-  # printer_ink_level
-  et-product-status "$url" | awk -f ink.awk | add-host "$url"
+  local -r serial=$( et-serial "$url" )
 
-  # printer_pages_count
-  et-usage-status "$url" | awk -f usage.awk | add-host "$url"
+  et-product-status "$url" | awk -f ink.awk | add-labels "$url" "$serial"
+  et-usage-status "$url" | awk -f usage.awk | add-labels "$url" "$serial"
 
   local -ri end=$( date +%s%3N )
   local -ri duration_s=$(( ( end - start ) / 1000 ))
@@ -68,11 +80,13 @@ main()
 
   echo '# HELP printer_scrape_time_seconds Timestamp of last scrape.'
   echo '# TYPE printer_scrape_time_seconds counter'
-  echo "printer_scrape_time_seconds $(date +%s)"
+  echo "printer_scrape_time_seconds{} $(date +%s)" | add-labels "$url" "$serial"
 
   echo '# HELP printer_scrape_duration_seconds Number of seconds spent scraping data from web interface.'
   echo '# TYPE printer_scrape_duration_seconds gauge'
-  printf 'printer_scrape_duration_seconds %0.3f\n' "$duration_s.$duration_ms"
+  printf 'printer_scrape_duration_seconds{} %0.3f\n' \
+         "$duration_s.$duration_ms" \
+    | add-labels "$url" "$serial"
 }
 
 main "$@"