diff --git a/.travis.yml b/.travis.yml
index c7171ba7..a5c6de5c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,6 +2,7 @@ language: bash
 services: docker
 
 env:
+  - VERSION=3.4
   - VERSION=3.3
   - VERSION=3.2
   - VERSION=3.1
diff --git a/3.4/Dockerfile b/3.4/Dockerfile
new file mode 100644
index 00000000..23ad7eee
--- /dev/null
+++ b/3.4/Dockerfile
@@ -0,0 +1,90 @@
+FROM ruby:2.4-slim
+
+# add our user and group first to make sure their IDs get assigned consistently, regardless of whatever dependencies get added
+RUN groupadd -r redmine && useradd -r -g redmine redmine
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+		ca-certificates \
+		wget \
+	&& rm -rf /var/lib/apt/lists/*
+
+# grab gosu for easy step-down from root
+ENV GOSU_VERSION 1.7
+RUN set -x \
+	&& wget -O /usr/local/bin/gosu "https://github.com/tianon/gosu/releases/download/$GOSU_VERSION/gosu-$(dpkg --print-architecture)" \
+	&& wget -O /usr/local/bin/gosu.asc "https://github.com/tianon/gosu/releases/download/$GOSU_VERSION/gosu-$(dpkg --print-architecture).asc" \
+	&& export GNUPGHOME="$(mktemp -d)" \
+	&& gpg --keyserver ha.pool.sks-keyservers.net --recv-keys B42F6819007F00F88E364FD4036A9C25BF357DD4 \
+	&& gpg --batch --verify /usr/local/bin/gosu.asc /usr/local/bin/gosu \
+	&& rm -r "$GNUPGHOME" /usr/local/bin/gosu.asc \
+	&& chmod +x /usr/local/bin/gosu \
+	&& gosu nobody true
+
+# grab tini for signal processing and zombie killing
+ENV TINI_VERSION v0.9.0
+RUN set -x \
+	&& wget -O /usr/local/bin/tini "https://github.com/krallin/tini/releases/download/$TINI_VERSION/tini" \
+	&& wget -O /usr/local/bin/tini.asc "https://github.com/krallin/tini/releases/download/$TINI_VERSION/tini.asc" \
+	&& export GNUPGHOME="$(mktemp -d)" \
+	&& gpg --keyserver ha.pool.sks-keyservers.net --recv-keys 6380DC428747F6C393FEACA59A84159D7001A4E5 \
+	&& gpg --batch --verify /usr/local/bin/tini.asc /usr/local/bin/tini \
+	&& rm -r "$GNUPGHOME" /usr/local/bin/tini.asc \
+	&& chmod +x /usr/local/bin/tini \
+	&& tini -h
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+		imagemagick \
+		libmysqlclient18 \
+		libpq5 \
+		libsqlite3-0 \
+		\
+		bzr \
+		git \
+		mercurial \
+		openssh-client \
+		subversion \
+	&& rm -rf /var/lib/apt/lists/*
+
+ENV RAILS_ENV production
+WORKDIR /usr/src/redmine
+
+ENV REDMINE_VERSION 3.4.1
+ENV REDMINE_DOWNLOAD_MD5 79b07289c0b591e81180d017dbf6ebf4
+
+RUN wget -O redmine.tar.gz "https://www.redmine.org/releases/redmine-${REDMINE_VERSION}.tar.gz" \
+	&& echo "$REDMINE_DOWNLOAD_MD5 redmine.tar.gz" | md5sum -c - \
+	&& tar -xvf redmine.tar.gz --strip-components=1 \
+	&& rm redmine.tar.gz files/delete.me log/delete.me \
+	&& mkdir -p tmp/pdf public/plugin_assets \
+	&& chown -R redmine:redmine ./
+
+RUN buildDeps=' \
+		gcc \
+		libmagickcore-dev \
+		libmagickwand-dev \
+		libmysqlclient-dev \
+		libpq-dev \
+		libsqlite3-dev \
+		make \
+		patch \
+	' \
+	&& set -ex \
+	&& apt-get update && apt-get install -y $buildDeps --no-install-recommends \
+	&& rm -rf /var/lib/apt/lists/* \
+	&& bundle install --without development test \
+	&& for adapter in mysql2 postgresql sqlite3; do \
+		echo "$RAILS_ENV:" > ./config/database.yml; \
+		echo "  adapter: $adapter" >> ./config/database.yml; \
+		bundle install --without development test; \
+	done \
+	&& rm ./config/database.yml \
+	&& apt-get purge -y --auto-remove $buildDeps
+
+
+VOLUME /usr/src/redmine/files
+
+COPY docker-entrypoint.sh /
+ENTRYPOINT ["/docker-entrypoint.sh"]
+
+EXPOSE 3000
+CMD ["rails", "server", "-b", "0.0.0.0"]
diff --git a/3.4/docker-entrypoint.sh b/3.4/docker-entrypoint.sh
new file mode 100755
index 00000000..6c70881c
--- /dev/null
+++ b/3.4/docker-entrypoint.sh
@@ -0,0 +1,130 @@
+#!/bin/bash
+set -e
+
+# usage: file_env VAR [DEFAULT]
+#    ie: file_env 'XYZ_DB_PASSWORD' 'example'
+# (will allow for "$XYZ_DB_PASSWORD_FILE" to fill in the value of
+#  "$XYZ_DB_PASSWORD" from a file, especially for Docker's secrets feature)
+file_env() {
+	local var="$1"
+	local fileVar="${var}_FILE"
+	local def="${2:-}"
+	if [ "${!var:-}" ] && [ "${!fileVar:-}" ]; then
+		echo >&2 "error: both $var and $fileVar are set (but are exclusive)"
+		exit 1
+	fi
+	local val="$def"
+	if [ "${!var:-}" ]; then
+		val="${!var}"
+	elif [ "${!fileVar:-}" ]; then
+		val="$(< "${!fileVar}")"
+	fi
+	export "$var"="$val"
+	unset "$fileVar"
+}
+
+case "$1" in
+	rails|rake|passenger)
+		if [ ! -f './config/database.yml' ]; then
+			file_env 'REDMINE_DB_MYSQL'
+			file_env 'REDMINE_DB_POSTGRES'
+			
+			if [ "$MYSQL_PORT_3306_TCP" ] && [ -z "$REDMINE_DB_MYSQL" ]; then
+				export REDMINE_DB_MYSQL='mysql'
+			elif [ "$POSTGRES_PORT_5432_TCP" ] && [ -z "$REDMINE_DB_POSTGRES" ]; then
+				export REDMINE_DB_POSTGRES='postgres'
+			fi
+			
+			if [ "$REDMINE_DB_MYSQL" ]; then
+				adapter='mysql2'
+				host="$REDMINE_DB_MYSQL"
+				file_env 'REDMINE_DB_PORT' '3306'
+				file_env 'REDMINE_DB_USERNAME' "${MYSQL_ENV_MYSQL_USER:-root}"
+				file_env 'REDMINE_DB_PASSWORD' "${MYSQL_ENV_MYSQL_PASSWORD:-${MYSQL_ENV_MYSQL_ROOT_PASSWORD:-}}"
+				file_env 'REDMINE_DB_DATABASE' "${MYSQL_ENV_MYSQL_DATABASE:-${MYSQL_ENV_MYSQL_USER:-redmine}}"
+				file_env 'REDMINE_DB_ENCODING' ''
+			elif [ "$REDMINE_DB_POSTGRES" ]; then
+				adapter='postgresql'
+				host="$REDMINE_DB_POSTGRES"
+				file_env 'REDMINE_DB_PORT' '5432'
+				file_env 'REDMINE_DB_USERNAME' "${POSTGRES_ENV_POSTGRES_USER:-postgres}"
+				file_env 'REDMINE_DB_PASSWORD' "${POSTGRES_ENV_POSTGRES_PASSWORD}"
+				file_env 'REDMINE_DB_DATABASE' "${POSTGRES_ENV_POSTGRES_DB:-${REDMINE_DB_USERNAME:-}}"
+				file_env 'REDMINE_DB_ENCODING' 'utf8'
+			else
+				echo >&2
+				echo >&2 'warning: missing REDMINE_DB_MYSQL or REDMINE_DB_POSTGRES environment variables'
+				echo >&2
+				echo >&2 '*** Using sqlite3 as fallback. ***'
+				echo >&2
+				
+				adapter='sqlite3'
+				host='localhost'
+				file_env 'REDMINE_DB_PORT' ''
+				file_env 'REDMINE_DB_USERNAME' 'redmine'
+				file_env 'REDMINE_DB_PASSWORD' ''
+				file_env 'REDMINE_DB_DATABASE' 'sqlite/redmine.db'
+				file_env 'REDMINE_DB_ENCODING' 'utf8'
+				
+				mkdir -p "$(dirname "$REDMINE_DB_DATABASE")"
+				chown -R redmine:redmine "$(dirname "$REDMINE_DB_DATABASE")"
+			fi
+			
+			REDMINE_DB_ADAPTER="$adapter"
+			REDMINE_DB_HOST="$host"
+			echo "$RAILS_ENV:" > config/database.yml
+			for var in \
+				adapter \
+				host \
+				port \
+				username \
+				password \
+				database \
+				encoding \
+			; do
+				env="REDMINE_DB_${var^^}"
+				val="${!env}"
+				[ -n "$val" ] || continue
+				echo "  $var: \"$val\"" >> config/database.yml
+			done
+		fi
+		
+		# ensure the right database adapter is active in the Gemfile.lock
+		bundle install --without development test
+		
+		if [ ! -s config/secrets.yml ]; then
+			file_env 'REDMINE_SECRET_KEY_BASE'
+			if [ "$REDMINE_SECRET_KEY_BASE" ]; then
+				cat > 'config/secrets.yml' <<-YML
+					$RAILS_ENV:
+					  secret_key_base: "$REDMINE_SECRET_KEY_BASE"
+				YML
+			elif [ ! -f /usr/src/redmine/config/initializers/secret_token.rb ]; then
+				rake generate_secret_token
+			fi
+		fi
+		if [ "$1" != 'rake' -a -z "$REDMINE_NO_DB_MIGRATE" ]; then
+			gosu redmine rake db:migrate
+		fi
+		
+		# https://www.redmine.org/projects/redmine/wiki/RedmineInstall#Step-8-File-system-permissions
+		chown -R redmine:redmine files log public/plugin_assets
+		chmod -R 755 files log tmp public/plugin_assets
+		
+		if [ "$1" != 'rake' -a -n "$REDMINE_PLUGINS_MIGRATE" ]; then
+			gosu redmine rake redmine:plugins:migrate
+		fi
+		
+		# remove PID file to enable restarting the container
+		rm -f /usr/src/redmine/tmp/pids/server.pid
+		
+		if [ "$1" = 'passenger' ]; then
+			# Don't fear the reaper.
+			set -- tini -- "$@"
+		fi
+		
+		set -- gosu redmine "$@"
+		;;
+esac
+
+exec "$@"
diff --git a/3.4/passenger/Dockerfile b/3.4/passenger/Dockerfile
new file mode 100644
index 00000000..28f2e88e
--- /dev/null
+++ b/3.4/passenger/Dockerfile
@@ -0,0 +1,18 @@
+FROM redmine:3.4
+
+ENV PASSENGER_VERSION 5.1.5
+
+RUN buildDeps=' \
+		make \
+	' \
+	&& set -x \
+	&& apt-get update && apt-get install -y --no-install-recommends $buildDeps && rm -rf /var/lib/apt/lists/* \
+	&& gem install passenger --version "$PASSENGER_VERSION" \
+	&& apt-get purge -y --auto-remove $buildDeps
+
+# pre-download the PassengerAgent and the NGINX engine
+RUN set -x \
+	&& passenger-config install-agent \
+	&& passenger-config download-nginx-engine
+
+CMD ["passenger", "start"]
diff --git a/Dockerfile.template b/Dockerfile.template
index 9b81bba2..087a0447 100644
--- a/Dockerfile.template
+++ b/Dockerfile.template
@@ -1,4 +1,4 @@
-FROM ruby:2.2-slim
+FROM ruby:%%RUBY_VERSION%%-slim
 
 # add our user and group first to make sure their IDs get assigned consistently, regardless of whatever dependencies get added
 RUN groupadd -r redmine && useradd -r -g redmine redmine
diff --git a/generate-stackbrew-library.sh b/generate-stackbrew-library.sh
index 352f79d4..9554ed60 100755
--- a/generate-stackbrew-library.sh
+++ b/generate-stackbrew-library.sh
@@ -2,8 +2,7 @@
 set -eu
 
 declare -A aliases=(
-	[3.3]='3 latest'
-	[2.6]='2'
+	[3.4]='3 latest'
 )
 
 self="$(basename "$BASH_SOURCE")"
@@ -12,6 +11,9 @@ cd "$(dirname "$(readlink -f "$BASH_SOURCE")")"
 versions=( */ )
 versions=( "${versions[@]%/}" )
 
+# sort version numbers with highest first
+IFS=$'\n'; versions=( $(echo "${versions[*]}" | sort -rV) ); unset IFS
+
 # get the most recent commit which modified any of "$@"
 fileCommit() {
 	git log -1 --format='format:%H' HEAD -- "$@"
diff --git a/update.sh b/update.sh
index 2d24c151..3bcf6fda 100755
--- a/update.sh
+++ b/update.sh
@@ -1,6 +1,14 @@
 #!/bin/bash
 set -eo pipefail
 
+# see https://www.redmine.org/projects/redmine/wiki/redmineinstall
+defaultRubyVersion='2.4'
+declare -A rubyVersions=(
+	[3.3]='2.2'
+	[3.2]='2.2'
+	[3.1]='2.2'
+)
+
 cd "$(dirname "$(readlink -f "$BASH_SOURCE")")"
 
 versions=( "$@" )
@@ -18,17 +26,24 @@ travisEnv=
 for version in "${versions[@]}"; do
 	fullVersion="$(echo $versionsPage | sed -r "s/.*($version\.[0-9]+)\.tar\.gz[^.].*/\1/" | sort -V | tail -1)"
 	md5="$(curl -fsSL "$relasesUrl/redmine-$fullVersion.tar.gz.md5" | cut -d' ' -f1)"
-	
+
+	rubyVersion="${rubyVersions[$version]:-$defaultRubyVersion}"
+
 	(
 		set -x
-		
+
 		cp docker-entrypoint.sh "$version/"
-		sed 's/%%REDMINE_DOWNLOAD_MD5%%/'"$md5"'/; s/%%REDMINE_VERSION%%/'"$fullVersion"'/' Dockerfile.template > "$version/Dockerfile"
-		
+		sed -e 's/%%REDMINE_VERSION%%/'"$fullVersion"'/' \
+			-e 's/%%RUBY_VERSION%%/'"$rubyVersion"'/' \
+			-e 's/%%REDMINE_DOWNLOAD_MD5%%/'"$md5"'/' \
+			Dockerfile.template > "$version/Dockerfile"
+
 		mkdir -p "$version/passenger"
-		sed 's/%%REDMINE%%/redmine:'"$version"'/; s/%%PASSENGER_VERSION%%/'"$passenger"'/' Dockerfile-passenger.template > "$version/passenger/Dockerfile"
+		sed -e 's/%%REDMINE%%/redmine:'"$version"'/' \
+			-e 's/%%PASSENGER_VERSION%%/'"$passenger"'/' \
+			Dockerfile-passenger.template > "$version/passenger/Dockerfile"
 	)
-	
+
 	travisEnv='\n  - VERSION='"$version$travisEnv"
 done