fix(workflow): schedule the check off the hour

.github/workflows/check-updates.yml

@@ -2,7 +2,9 @@ name: Check AUR Package Updates
 
 on:
   schedule:
-    - cron: "0 * * * *" # every hour
+    # Every hour at minute 17. GitHub delays scheduled runs at the start of
+    # every hour and drops some of them.
+    - cron: "17 * * * *"
   workflow_dispatch:
 
 permissions:

docs/WORKFLOW.md

@@ -650,7 +650,7 @@ A PKGBUILD is a bash script, and every step that reads it executes it: the audit
 
 ### 5.1 Trigger
 
-The workflow runs every hour (`cron: "0 * * * *"`) and by hand through `workflow_dispatch`. The `check-updates` concurrency group serializes runs: a new run waits for the running one.
+The workflow runs every hour at minute 17 (`cron: "17 * * * *"`) and by hand through `workflow_dispatch`. GitHub delays scheduled runs at the start of every hour and drops some of them when the load is high, so the schedule avoids minute 0. The `check-updates` concurrency group serializes runs: a new run waits for the running one.
 
 ### 5.2 Permissions and container
 

tests/workflows.bats

@@ -164,6 +164,13 @@ step_run() {
   yq ".jobs.$1.steps[] | select(.name == \"$2\") | .run" "$CHECK_UPDATES"
 }
 
+# GitHub delays scheduled runs at the start of every hour and drops some
+@test "check-updates: runs every hour, off the start of the hour" {
+  run yq '.on.schedule[].cron' "$CHECK_UPDATES"
+  [ "$status" -eq 0 ]
+  [[ "$output" =~ ^([1-9]|[1-5][0-9])\ \*\ \*\ \*\ \*$ ]]
+}
+
 @test "check-updates: the check job decides the run and executes no PKGBUILD" {
   run yq '.jobs.check.steps[] | select(has("run")) | .run' "$CHECK_UPDATES"
   [ "$status" -eq 0 ]