major refactorings and improvements

Dockerfile

@@ -0,0 +1,54 @@
+ARG ARCH
+FROM amd64/alpine:3.12.3@sha256:074d3636ebda6dd446d0d00304c4454f468237fdacf08fb0eeac90bdbfa1bac7 AS base-amd64
+FROM arm32v7/alpine:3.12.3@sha256:299294be8699c1b323c137f972fd0aa5eaa4b95489c213091dcf46ef39b6c810 AS base-arm
+FROM arm64v8/alpine:3.12.3@sha256:549694ea68340c26d1d85c00039aa11ad835be279bfd475ff4284b705f92c24e AS base-arm64
+FROM base-${ARCH}
+
+ENTRYPOINT ["/sbin/tini","--","/usr/local/searx/dockerfiles/docker-entrypoint.sh"]
+EXPOSE 8080
+VOLUME /etc/searx
+VOLUME /var/log/uwsgi
+
+RUN addgroup searx && adduser -D -h /usr/local/searx -s /bin/sh -G searx searx
+
+ENV SEARX_VERSION="v0.18.0"
+ENV INSTANCE_NAME=searx
+
+WORKDIR /usr/local/searx
+
+RUN apk upgrade --no-cache \
+ && apk add --no-cache -t build-dependencies \
+    build-base="0.5-r2" \
+    py3-setuptools="47.0.0-r0" \
+    python3-dev="3.8.5-r0" \
+    libffi-dev="3.3-r2" \
+    libxslt-dev="1.1.34-r0" \
+    libxml2-dev="2.9.10-r5" \
+    openssl-dev="1.1.1i-r0" \
+    tar="1.32-r1" \
+    git="2.26.2-r0" \
+    curl="7.69.1-r3" \
+ && apk add --no-cache \
+    ca-certificates="20191127-r4" \
+    su-exec="0.2-r1" \
+    python3="3.8.5-r0" \
+    py3-pip="20.1.1-r0" \
+    libxml2="2.9.10-r5" \
+    libxslt="1.1.34-r0" \
+    openssl="1.1.1i-r0" \
+    tini="0.19.0-r0" \
+    uwsgi="2.0.18-r8" \
+    uwsgi-python3="2.0.18-r8" \
+    brotli="1.0.9-r1" \
+ && curl -L "https://github.com/searx/searx/archive/${SEARX_VERSION}.tar.gz" | tar xvz --strip 1 && chown -R searx:searx * \
+ && pip3 install --upgrade pip \
+ && pip3 install --no-cache -r requirements.txt \
+ && apk del build-dependencies \
+ && rm -rf /root/.cache
+
+RUN su searx -c "/usr/bin/python3 -m compileall -q searx"; \
+    touch -c searx/settings.yml; \
+    touch -c dockerfiles/uwsgi.ini; \
+    find /usr/local/searx/searx/static -a \( -name '*.html' -o -name '*.css' -o -name '*.js' \
+    -o -name '*.svg' -o -name '*.ttf' -o -name '*.eot' \) \
+    -type f -exec gzip -9 -k {} \+ -exec brotli --best {} \+