Adds ubuntu based Dockerfile

.travis.yml

@@ -1,8 +1,17 @@
 language: crystal
 
+env:
+  # Path to 'hadolint' binary
+  HADOLINT: "${HOME}/hadolint"
+
+install:
+  # Download hadolint binary and set it as executable
+  - curl -sL -o ${HADOLINT} "https://github.com/hadolint/hadolint/releases/download/v1.17.5/hadolint-$(uname -s)-$(uname -m)"
+    && chmod 700 ${HADOLINT}
 script:
   - crystal spec
   - crystal tool format --check
+  - git ls-files --exclude='Dockerfile*' --ignored | xargs --max-lines=1 ${HADOLINT}
 
 addons:
   apt:

Dockerfile

@@ -1,13 +1,24 @@
-FROM jrei/crystal-alpine as builder
+FROM ubuntu:19.04
 
 WORKDIR /build
 
 COPY . .
 
-RUN shards install && shards build --release --static
+# Add the key for the crystal debian repo
+ADD https://keybase.io/crystal/pgp_keys.asc /tmp/crystal.gpg
 
-FROM scratch
+# Install gnupg for the apt-key operation and openssl for our TLS stuff
+RUN apt-get update && \
+	apt-get install  --yes --no-install-recommends gnupg=2.2.12-1ubuntu3 libssl-dev=1.1.1b-1ubuntu2.4 && \
+	# See https://crystal-lang.org/install/
+	apt-key add /tmp/crystal.gpg && \
+	echo "deb https://dist.crystal-lang.org/apt crystal main" > /etc/apt/sources.list.d/crystal.list && \
+	apt-get update && \
+	apt-get install --no-install-recommends --yes crystal=0.33.0-1 pdftk=2.02-5 && \
+	# Cleanup
+	apt-get clean && \
+	rm -rf /var/lib/apt/lists/*
 
-COPY --from=builder /build/bin/muse-dl /
+RUN shards install && shards build --release
 
-ENTRYPOINT ["/muse-dl"]
+ENTRYPOINT ["/build/bin/muse-dl"]