Run on Ruby 2.5; test only on Ruby 2.5 (#4)

Run on Ruby 2.5; test only on Ruby 2.5 (#4)

mobystash must be deployed as a container. We have full control over which Ruby we target. Running tests over a slew of rubies does not serve much use.

Ruby 2.3 will be EOL soon. Removing some elements from the Travis build matrix avoids us burning time on CI environmental problems. (See #3.)

diff --git a/.travis.yml b/.travis.yml
index 718874a..8834663 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,9 +3,7 @@ sudo: false
 cache: bundler
 
 rvm:
-  - 2.5.1
-  - 2.4.4
-  - 2.3.7
+  - 2.5.3
 
 gemfile:
   - Gemfile
diff --git a/Dockerfile b/Dockerfile
index 30335c5..e377ce5 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM ruby:2.3-alpine
+FROM ruby:2.5-alpine
 
 MAINTAINER Matt Palmer "matt.palmer@discourse.org"
 
@@ -19,7 +19,7 @@ ARG GIT_REVISION=invalid-build
 ENV MOBYSTASH_GIT_REVISION=$GIT_REVISION
 
 COPY bin/* /usr/local/bin/
-COPY lib/ /usr/local/lib/ruby/2.3.0/
+COPY lib/ /usr/local/lib/ruby/2.5.0/
 
 EXPOSE 9367
 LABEL org.discourse.service._prom-exp.port=9367 org.discourse.service._prom-exp.instance=mobystash org.discourse.mobystash.disable=yes
diff --git a/Rakefile b/Rakefile
index 263c5be..d700a09 100644
--- a/Rakefile
+++ b/Rakefile
@@ -56,8 +56,7 @@ namespace :docker do
 
   desc "Build a new docker image"
   task :build do
-    sh "docker pull ruby:2.3-alpine"
-    sh "docker build -t discourse/mobystash --build-arg=http_proxy=#{ENV['http_proxy']} --build-arg=GIT_REVISION=$(git rev-parse HEAD) ."
+    sh "docker build --pull -t discourse/mobystash --build-arg=http_proxy=#{ENV['http_proxy']} --build-arg=GIT_REVISION=$(git rev-parse HEAD) ."
     sh "docker tag discourse/mobystash discourse/mobystash:#{tag}"
   end

GitHub sha: c8dec09b