ci-build: do not deploy when building PRs

If my reading of the GitHub Actions documentation is correct, then
organization secrets will be available to pull request builds from
a branch of the same repository (as opposed to from a project fork).

In that case, we still want the build script to skip deployment,
because we don't want to be deploying snapshots from from PRs,
only those from the mainline integration branch.

Author: ctrueden

ci-build.sh

@@ -93,7 +93,7 @@ EOL
 
 	# --== DEPLOYMENT CHECKS ==--
 
-	# Determine whether deploying will be possible.
+	# Determine whether deploying is both possible and warranted.
 	echo "Performing deployment checks"
 	deployOK=
 
@@ -139,7 +139,12 @@ EOL
 						fi
 						;;
 				esac
-				deployOK=1
+				if [ "$BUILD_BASE_REF" -o "$BUILD_HEAD_REF" ]
+				then
+					echo "No deploy -- proposed change: $BUILD_BASE_REF -> $BUILD_HEAD_REF"
+				else
+					deployOK=1
+				fi
 			fi
 		fi
 	fi

ci-setup-github-actions.sh

@@ -4,9 +4,14 @@
 # ci-setup-github-actions.sh - Set CI-related environment variables from GitHub Actions.
 #
 
-echo "BUILD_REPOSITORY=https://github.com/${GITHUB_REPOSITORY}"
-echo "BUILD_OS=${RUNNER_OS}"
-echo "BUILD_DEPLOY_FORBIDDEN=..." # CTR START HERE - use GITHUB-specific env vars set upon PR to decide this
+echo "BUILD_REPOSITORY=https://github.com/$GITHUB_REPOSITORY"
+echo "BUILD_REPOSITORY=https://github.com/$GITHUB_REPOSITORY" >> $GITHUB_ENV
 
-echo "BUILD_REPOSITORY=https://github.com/${GITHUB_REPOSITORY}" >> $GITHUB_ENV
-echo "BUILD_OS=${RUNNER_OS}" >> $GITHUB_ENV
+echo "BUILD_OS=$RUNNER_OS"
+echo "BUILD_OS=$RUNNER_OS" >> $GITHUB_ENV
+
+echo "BUILD_BASE_REF=$GITHUB_BASE_REF"
+echo "BUILD_BASE_REF=$GITHUB_BASE_REF" >> $GITHUB_ENV
+
+echo "BUILD_HEAD_REF=$GITHUB_HEAD_REF"
+echo "BUILD_HEAD_REF=$GITHUB_HEAD_REF" >> $GITHUB_ENV