Add as much multiarch as Cassandra's repos can handle

.travis.yml

@@ -3,9 +3,13 @@ services: docker
 
 env:
   - VERSION=3.11
+  - VERSION=3.11 ARCH=i386
   - VERSION=3.0
+  - VERSION=3.0 ARCH=i386
   - VERSION=2.2
+  - VERSION=2.2 ARCH=i386
   - VERSION=2.1
+  - VERSION=2.1 ARCH=i386
 
 install:
   - git clone https://github.com/docker-library/official-images.git ~/official-images
@@ -14,6 +18,12 @@ before_script:
   - env | sort
   - cd "$VERSION"
   - image="cassandra:$VERSION"
+  - |
+    if [ -n "$ARCH" ]; then
+        from="$(awk '$1 == toupper("FROM") { print $2 }' Dockerfile)"
+        docker pull "$ARCH/$from"
+        docker tag "$ARCH/$from" "$from"
+    fi
 
 script:
   - travis_retry docker build -t "$image" .

generate-stackbrew-library.sh

@@ -60,9 +60,14 @@ for version in "${versions[@]}"; do
 	fi
 	versionAliases+=( ${aliases[$version]:-} )
 
+	# $ wget -qO- 'https://dl.bintray.com/apache/cassandra/dists/311x/Release' | grep '^Architectures:'
+	# Architectures: i386 amd64
+	arches='amd64 i386'
+
 	echo
 	cat <<-EOE
 		Tags: $(join ', ' "${versionAliases[@]}")
+		Architectures: $(join ', ' $arches)
 		GitCommit: $commit
 		Directory: $version
 	EOE

update.sh

@@ -21,6 +21,7 @@ for version in "${versions[@]}"; do
 		sed 's/%%CASSANDRA_DIST%%/'$dist'/g; s/%%CASSANDRA_VERSION%%/'$fullVersion'/g' Dockerfile.template > "$version/Dockerfile"
 	)
 
+	travisEnv='\n  - VERSION='"$version ARCH=i386$travisEnv"
 	travisEnv='\n  - VERSION='"$version$travisEnv"
 done