Remove imagemagick dependency

Dockerfile

@@ -1,45 +1,55 @@
 FROM debian:stretch
 
-MAINTAINER buildmaster@rocket.chat
+LABEL maintainer="buildmaster@rocket.chat"
 
-RUN apt-get update \
-	&& apt-get install -y \
-		gpg \
-    && rm -rf /var/lib/apt/lists/*
+ENV NODE_VERSION 8.15.1
+ENV NODE_ENV production
+
+# based on node:8-stretch-slim: https://github.com/nodejs/docker-node/blob/master/8/stretch-slim/Dockerfile
+RUN buildDeps='xz-utils' \
+  && ARCH= && dpkgArch="$(dpkg --print-architecture)" \
+  && case "${dpkgArch##*-}" in \
+    amd64) ARCH='x64';; \
+    ppc64el) ARCH='ppc64le';; \
+    s390x) ARCH='s390x';; \
+    arm64) ARCH='arm64';; \
+    armhf) ARCH='armv7l';; \
+    i386) ARCH='x86';; \
+    *) echo "unsupported architecture"; exit 1 ;; \
+  esac \
+  && set -ex \
+  && apt-get update && apt-get install -y ca-certificates curl wget gnupg dirmngr $buildDeps --no-install-recommends \
+  && rm -rf /var/lib/apt/lists/* \
+  # gpg keys listed at https://github.com/nodejs/node#release-keys
+  && for key in \
+    94AE36675C464D64BAFA68DD7434390BDBE9B9C5 \
+    FD3A5288F042B6850C66B31F09FE44734EB7990E \
+    71DCFD284A79C3B38668286BC97EC7A07EDE3FC1 \
+    DD8F2338BAE7501E3DD5AC78C273792F7D83545D \
+    C4F0DFFF4E8C1A8236409D08E73BC641CC11F4C8 \
+    B9AE9905FFD7803F25714661B63B535A4C206CA9 \
+    77984A986EBC2AA786BC0F66B01FBB92821C587A \
+    8FCCA13FEF1D0C2E91008E09770F7A9A5AE15600 \
+    4ED778F539E3634C779C87C6D7062848A1AB005C \
+    A48C2BEE680E841632CD4E44F07496B3EB3C1762 \
+    B9E2F5981AA6E0CD28160D9FF13993A75599653C \
+  ; do \
+    gpg --batch --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys "$key" || \
+    gpg --batch --keyserver hkp://ipv4.pool.sks-keyservers.net --recv-keys "$key" || \
+    gpg --batch --keyserver hkp://pgp.mit.edu:80 --recv-keys "$key" ; \
+  done \
+  && curl -fsSLO --compressed "https://nodejs.org/dist/v$NODE_VERSION/node-v$NODE_VERSION-linux-$ARCH.tar.xz" \
+  && curl -fsSLO --compressed "https://nodejs.org/dist/v$NODE_VERSION/SHASUMS256.txt.asc" \
+  && gpg --batch --decrypt --output SHASUMS256.txt SHASUMS256.txt.asc \
+  && grep " node-v$NODE_VERSION-linux-$ARCH.tar.xz\$" SHASUMS256.txt | sha256sum -c - \
+  && tar -xJf "node-v$NODE_VERSION-linux-$ARCH.tar.xz" -C /usr/local --strip-components=1 --no-same-owner \
+  && rm "node-v$NODE_VERSION-linux-$ARCH.tar.xz" SHASUMS256.txt.asc SHASUMS256.txt \
+  && apt-get purge -y --auto-remove $buildDeps \
+  && ln -s /usr/local/bin/node /usr/local/bin/nodejs
 
 # gpg: key 4FD08014: public key "Rocket.Chat Buildmaster <buildmaster@rocket.chat>" imported
 RUN gpg --keyserver ha.pool.sks-keyservers.net --recv-keys 0E163286C20D07B9787EBE9FD7F9D0414FD08104
 
-# gpg keys listed at https://github.com/nodejs/node
-RUN set -ex \
- && for key in \
-      94AE36675C464D64BAFA68DD7434390BDBE9B9C5 \
-      FD3A5288F042B6850C66B31F09FE44734EB7990E \
-      71DCFD284A79C3B38668286BC97EC7A07EDE3FC1 \
-      DD8F2338BAE7501E3DD5AC78C273792F7D83545D \
-      C4F0DFFF4E8C1A8236409D08E73BC641CC11F4C8 \
-      B9AE9905FFD7803F25714661B63B535A4C206CA9 \
-      77984A986EBC2AA786BC0F66B01FBB92821C587A \
-      8FCCA13FEF1D0C2E91008E09770F7A9A5AE15600 \
-      4ED778F539E3634C779C87C6D7062848A1AB005C \
-      A48C2BEE680E841632CD4E44F07496B3EB3C1762 \
-      B9E2F5981AA6E0CD28160D9FF13993A75599653C \
-    ; do \
-    gpg --keyserver pool.sks-keyservers.net --recv-keys "$key"; \
-    done
-
-ENV NODE_VERSION 8.15.1
-ENV NODE_ENV production
-
-RUN set -x \
- && apt-get update && apt-get install -y curl ca-certificates imagemagick --no-install-recommends \
- && rm -rf /var/lib/apt/lists/* \
- && curl -SLO "https://nodejs.org/dist/v$NODE_VERSION/node-v$NODE_VERSION-linux-x64.tar.gz" \
- && curl -SLO "https://nodejs.org/dist/v$NODE_VERSION/SHASUMS256.txt.asc" \
- && gpg --verify SHASUMS256.txt.asc \
- && grep " node-v$NODE_VERSION-linux-x64.tar.gz\$" SHASUMS256.txt.asc | sha256sum -c - \
- && tar -xzf "node-v$NODE_VERSION-linux-x64.tar.gz" -C /usr/local --strip-components=1 \
- && rm "node-v$NODE_VERSION-linux-x64.tar.gz" SHASUMS256.txt.asc \
- && npm cache clear --force \
+RUN npm cache clear --force \
  && groupadd -g 65533 -r rocketchat \
  && useradd -u 65533 -r -g rocketchat rocketchat