Update Alpine to 3.7 (for multiarch support)

This also adds an appropriate "Architectures" value to "generate-stackbrew-library.sh". Signed-off-by: Konstantin Pavlov <thresh@nginx.com>

Author: tianon

generate-stackbrew-library.sh

@@ -91,11 +91,10 @@ for version in "${versions[@]}"; do
 variantAliases=( "${versionAliases[@]/%/-$variant}" )
 variantAliases=( "${variantAliases[@]//latest-/}" )
 
-# TODO Architectures once https://github.com/gliderlabs/docker-alpine/issues/304 is resolved
-
 echo
 cat <<-EOE
 Tags: $(join ', ' "${variantAliases[@]}")
+Architectures: amd64, arm32v6, arm64v8, i386, ppc64le, s390x
 GitCommit: $commit
 Directory: $version/$variant
 EOE

mainline/alpine-perl/Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.5
+FROM alpine:3.7
 
 LABEL maintainer="NGINX Docker Maintainers <docker-maint@nginx.com>"
 

mainline/alpine/Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.5
+FROM alpine:3.7
 
 LABEL maintainer="NGINX Docker Maintainers <docker-maint@nginx.com>"
 

stable/alpine-perl/Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.5
+FROM alpine:3.7
 
 LABEL maintainer="NGINX Docker Maintainers <docker-maint@nginx.com>"
 

stable/alpine/Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.5
+FROM alpine:3.7
 
 LABEL maintainer="NGINX Docker Maintainers <docker-maint@nginx.com>"