Try with tectonic and update Dockerfile

Dockerfile

@@ -1,34 +1,23 @@
 FROM ubuntu:19.04
 
-# set environment encoding and some base utils
-ENV LANG C.UTF-8
-ENV DEBIAN_FRONTEND=noninteractive
-RUN apt-get update && apt-get install -y wget curl git
-
-# should we add --no-install-recommends?
-
-# texlive install
-RUN apt-get install -y xzdec texlive-full latexmk
-
-# texlive update and install reledmac
-RUN tlmgr init-usertree
-RUN tlmgr option repository http:https://mirror.ctan.org/systems/texlive/tlnet
-RUN tlmgr update --self
-RUN tlmgr install reledmac
-
-# Manual install libertine
-RUN wget http:https://mirrors.ctan.org/install/fonts/libertine.tds.zip
-WORKDIR /texmf
-RUN unzip /libertine.tds.zip
-RUN texhash
-RUN updmap --user --enable Map=libertine.map
+# set environment encoding and system dependencies
+RUN apt-get update && apt-get install -y \
+ # system utils
+ wget curl git \
+ # tectonic deps
+ libfontconfig1-dev libgraphite2-dev libharfbuzz-dev libicu-dev libssl-dev zlib1g-dev \
+ # python and libxml
+ libxml2-dev libxslt-dev python3.7-dev python3-pip 
+
+# Install rust
+RUN curl -f -L https://static.rust-lang.org/rustup.sh -O \
+ && sh rustup.sh -y
+# Install tectonic
+RUN $HOME/.cargo/bin/cargo install tectonic
 
 # Java
 RUN apt-get install -y default-jre
 
-# Python and pip
-RUN apt-get install -y python3.6 python3-pip
-
 # App directory and install
 RUN mkdir -p /usr/src/app
 WORKDIR /usr/src/app
@@ -38,12 +27,12 @@ RUN mkdir upload static static/output logs cache
 
 # Copy in the app content
 COPY requirements.txt /usr/src/app/
-RUN python3.6 -m pip install --no-cache-dir -r requirements.txt
+RUN pip3 install --no-cache-dir -r requirements.txt
 
 COPY . /usr/src/app
 
 COPY texmf/ /root/texmf
 
 EXPOSE 80
 
-CMD gunicorn --worker-class eventlet -w 1 -b 0.0.0.0:80 service:app
+CMD gunicorn -w 1 -b 0.0.0.0:5000 app:app