Ignore buildkit-isms during build/history check

Author: tianon

.github/workflows/history.sh

@@ -13,6 +13,16 @@ docker image history --no-trunc --format '{{ .CreatedBy }}' "$@" \
 		# remove "org.label-schema.build-date" and "org.opencontainers.image.created" (https://github.com/elastic/dockerfiles/pull/101#pullrequestreview-879623350)
 		$1 == "LABEL" { gsub(/ (org[.]label-schema[.]build-date|org[.]opencontainers[.]image[.]created)=[^ ]+( [0-9:+-]+)?/, "") }
 
+		# remove several buildkit-isms
+		/# buildkit$/ {
+			sub(/^RUN[[:space:]]+/, "")
+			sub(/^\/bin\/sh[[:space:]]+-c[[:space:]]+/, "")
+			sub(/[[:space:]]*# buildkit$/, "")
+		}
+		$1 == "EXPOSE" { gsub(/map\[|\/tcp:\{\}|\]/, "") }
+		# buildkit makes COPY expressions hyper-simplified ("COPY --chown=1000:0 --from=foo /foo /bar" becomes just "COPY /foo /bar" vs "COPY --chown=1000:0 dir:xxxx in /bar")
+		$1 == "COPY" { $0 = gensub(/^[[:space:]]*(COPY)[[:space:]]+([^[:space:]]+[[:space:]]+)+([^[:space:]]+)[[:space:]]*$/, "\\1 ... \\3", 1) }
+
 		# in logstash, Elastic builds pull artifacts from "http://localhost:8000" instead of "https://artifacts.elastic.co/downloads/logstash"
 		/localhost:8000\/logstash/ { gsub(/http:\/\/localhost:8000\/logstash/, "https://artifacts.elastic.co/downloads/logstash/logstash") }