Allow specifying version for docker build

Dockerfile

@@ -1,13 +1,15 @@
 FROM ruby:3.2-alpine
 MAINTAINER Samuel Cochran <[email protected]>
 
+# Use --build-arg VERSION=... to override
+# or `rake docker VERSION=...`
 ARG VERSION=0.9.0
 
 # sqlite3 aarch64 is broken on alpine, so use ruby:
 # https://github.com/sparklemotion/sqlite3-ruby/issues/372
 RUN apk add --no-cache build-base sqlite-libs sqlite-dev && \
     ( [ "$(uname -m)" != "aarch64" ] || gem install sqlite3 --version="~> 1.3" --platform=ruby ) && \
-    gem install mailcatcher -v $VERSION && \
+    gem install mailcatcher -v "$VERSION" && \
     apk del --rdepends --purge build-base sqlite-dev
 
 EXPOSE 1025 1080

Rakefile

@@ -43,18 +43,22 @@ task "release" => ["package"] do
   %x[gem push mailcatcher-#{MailCatcher::VERSION}.gem]
 end
 
-desc "Build and push Docker images"
+desc "Build and push Docker images (optional: VERSION=#{MailCatcher::VERSION})"
 task "docker" do
+  version = ENV.fetch("VERSION", MailCatcher::VERSION)
+
   Dir.chdir(__dir__) do
     system "docker", "buildx", "build",
       # Push straight to Docker Hub (only way to do multi-arch??)
       "--push",
       # Build for both intel and arm (apple, graviton, etc)
       "--platform", "linux/amd64",
       "--platform", "linux/arm64",
-      # Push latest and currrent version
+      # Version respected within Dockerfile
+      "--build-arg", "VERSION=#{version}",
+      # Push latest and version
       "-t", "sj26/mailcatcher:latest",
-      "-t", "sj26/mailcatcher:v#{MailCatcher::VERSION}",
+      "-t", "sj26/mailcatcher:v#{version}",
       # Use current dir as context
       "."
   end