CI: use hex.pm images and refresh

.circleci/config.yml

@@ -1,59 +1,66 @@
+version: 2
+
 defaults: &defaults
   working_directory: ~/repo
-  docker:
-    - image: nervesproject/nerves_system_br:latest
   environment:
-    ENV: CI
-    MIX_ENV: test
-    ELIXIR_VERSION: 1.11.2-otp-23
     LC_ALL: C.UTF-8
 
-install_elixir: &install_elixir
-  run:
-    name: Install Elixir
-    command: |
-      wget https://repo.hex.pm/builds/elixir/v$ELIXIR_VERSION.zip
-      unzip -d /usr/local/elixir v$ELIXIR_VERSION.zip
-      echo 'export PATH=/usr/local/elixir/bin:$PATH' >> $BASH_ENV
-
 install_hex_rebar: &install_hex_rebar
   run:
     name: Install hex and rebar
     command: |
       mix local.hex --force
       mix local.rebar --force
 
-install_nerves_bootstrap: &install_nerves_bootstrap
+install_system_deps: &install_system_deps
   run:
-    name: Install nerves_bootstrap
+    name: Install system dependencies
     command: |
-      mix archive.install hex nerves_bootstrap "~> 1.0" --force
-
-version: 2
+        apk add fwup --repository=http://dl-cdn.alpinelinux.org/alpine/edge/community
 
 jobs:
-  build:
+  build_elixir_1_11_otp_23:
+    docker:
+      - image: hexpm/elixir:1.11.3-erlang-23.2.2-alpine-3.12.1
     <<: *defaults
     steps:
       - checkout
-      - <<: *install_elixir
       - <<: *install_hex_rebar
-      - <<: *install_nerves_bootstrap
+      - <<: *install_system_deps
       - restore_cache:
           keys:
             - v1-mix-cache-{{ checksum "mix.lock" }}
       - run: mix deps.get
+      - run: mix format --check-formatted
       # SUDO=true -> disable autodetection of a host build and the "helpful"
       # call to sudo
-      - run: SUDO=true mix compile
-      - run: mix test
-      - run: mix format --check-formatted
-      - run: mix hex.build
+      - run: SUDO=true mix compile --warnings-as-errors
       - run: mix docs
-      - run: mix dialyzer --halt-exit-status
+      - run: mix hex.build
+      - run: mix test
+      - run: mix dialyzer
       - save_cache:
           key: v1-mix-cache-{{ checksum "mix.lock" }}
           paths:
             - _build
             - deps
 
+  build_elixir_1_10_otp_23:
+    docker:
+      - image: hexpm/elixir:1.10.4-erlang-23.1.2-alpine-3.12.1
+    <<: *defaults
+    steps:
+      - checkout
+      - <<: *install_hex_rebar
+      - <<: *install_system_deps
+      - run: mix deps.get
+      - run: SUDO=true mix compile
+      - run: mix test
+
+workflows:
+  version: 2
+  build_test:
+    jobs:
+      - build_elixir_1_11_otp_23
+      - build_elixir_1_10_otp_23
+