use ruby image for deployment workflow

because we need ruby stuff, not go stuff

note:
- ruby 2.3 because json library that fpm seemingly wants to use
  doesn't work with 2.4 (ruby/json#303)
- for some reason apt-get update no longer needed

.circleci/config.yml

@@ -48,9 +48,8 @@ jobs:
       - run: scripts/qa/end2end.sh
 
   deploy:
-    working_directory: /go/src/github.com/grafana/metrictank
     docker:
-      - image: circleci/golang:1.9.2
+      - image: circleci/ruby:2.3
     steps:
       - checkout
       - attach_workspace:

scripts/build_packages.sh

@@ -8,7 +8,6 @@ BUILD_TMP=$CODE_DIR/build_tmp # used for temporary data used to construct the pa
 mkdir $BUILD_TMP
 mkdir $BUILD_PKG
 
-sudo apt-get update # otherwise the below install command doesn't work
 sudo apt-get install rpm # to be able to make rpms
 
 ARCH="$(uname -m)"

scripts/depends.sh

@@ -4,6 +4,5 @@ set -x
 DIR=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
 cd ${DIR}
 
-sudo apt install rubygems ruby-dev
-sudo gem install bundler
+which bundler &>/dev/null || sudo gem install bundler
 bundle install