GHA: Migrate inline script to file

Inline scripts make github-action workflow YAML harder to read/maintain.
Relocate the e-mail formation script to a dedicated file.  This also
permits better input-validation and re-use of a common `err()` function.

Signed-off-by: Chris Evich <cevich@redhat.com>

.github/actions/check_cirrus_cron/cron_failures.sh

@@ -5,11 +5,7 @@ set -eo pipefail
 # Intended to be executed from a github action workflow step.
 # Outputs the Cirrus cron names and IDs of any failed builds
 
-err() {
+source $(dirname "${BASH_SOURCE[0]}")/lib.sh
-    # Ref: https://docs.github.com/en/free-pro-team@latest/actions/reference/workflow-commands-for-github-actions
-    echo "::error file=${BASH_SOURCE[0]},line=${BASH_LINENO[0]}::${1:-No error message given}"
-    exit 1
-}
 
 _errfmt="Expecting %s value to not be empty"
 if [[ -z "$GITHUB_REPOSITORY" ]]; then
@@ -118,5 +114,5 @@ cat "$NAME_ID_FILEPATH"
 records=$(wc --words "$NAME_ID_FILEPATH" | cut -d ' ' -f 1)
 # Always two words per record
 failures=$((records/2))
-echo "::set-output name=failures::$failures"
+echo "failures::$failures" >> $GITHUB_OUTPUT
 echo "Total failed Cirrus-CI cron builds: $failures"

.github/actions/check_cirrus_cron/lib.sh

@@ -0,0 +1,7 @@
+
+# Must be called from top-level of script, not another function.
+err() {
+    # Ref: https://docs.github.com/en/free-pro-team@latest/actions/reference/workflow-commands-for-github-actions
+    echo "::error file=${BASH_SOURCE[1]},line=${BASH_LINENO[1]}::${1:-No error message given}"
+    exit 1
+}

.github/actions/check_cirrus_cron/make_email_body.sh

@@ -0,0 +1,35 @@
+#!/bin/bash
+
+set -eo pipefail
+
+# Intended to be executed from a github action workflow step.
+# Input: File listing space separated failed cron build names and IDs
+# Output: $GITHUB_WORKSPACE/artifacts/email_body.txt file
+
+source $(dirname "${BASH_SOURCE[0]}")/lib.sh
+
+_errfmt="Expecting %s value to not be empty"
+if [[ -z "$GITHUB_REPOSITORY" ]]; then
+    err $(printf "$_errfmt" "\$GITHUB_REPOSITORY")
+elif [[ -z "$GITHUB_WORKFLOW" ]]; then
+    err $(printf "$_errfmt" "\$GITHUB_WORKFLOW")
+elif [[ ! -r "$NAME_ID_FILEPATH" ]]; then
+    _errfmt="Expecting %s value to be a readable file"
+    err $(printf "$_errfmt" "\$NAME_ID_FILEPATH")
+fi
+
+mkdir -p artifacts
+(
+    echo "Detected one or more Cirrus-CI cron-triggered jobs have failed recently:"
+    echo ""
+
+    while read -r NAME BID; do
+        echo "Cron build '$NAME' Failed: https://cirrus-ci.com/build/$BID"
+    done < "$NAME_ID_FILEPATH"
+
+    echo ""
+    echo "# Source: ${GITHUB_WORKFLOW} workflow on ${GITHUB_REPOSITORY}."
+    # Separate content from sendgrid.com automatic footer.
+    echo ""
+    echo ""
+) > ./artifacts/email_body.txt

.github/workflows/check_cirrus_cron.yml

@@ -42,24 +42,7 @@ jobs:
 
             - if: steps.cron.outputs.failures > 0
               shell: bash
-              # Must be inline, since context expressions are used.
+              run: './.github/actions/check_cirrus_cron/make_email_body'
-              # Ref: https://docs.github.com/en/free-pro-team@latest/actions/reference/context-and-expression-syntax-for-github-actions
-              run: |
-                set -eo pipefail
-                (
-                echo "Detected one or more Cirrus-CI cron-triggered jobs have failed recently:"
-                echo ""
-
-                while read -r NAME BID; do
-                    echo "Cron build '$NAME' Failed: https://cirrus-ci.com/build/$BID"
-                done < "$NAME_ID_FILEPATH"
-
-                echo ""
-                echo "# Source: ${{ github.workflow }} workflow on ${{ github.repository }}."
-                # Separate content from sendgrid.com automatic footer.
-                echo ""
-                echo ""
-                ) > ./artifacts/email_body.txt
 
             - if: steps.cron.outputs.failures > 0
               name: Send failure notification e-mail