Merge pull request #5 from Monitoring-Projects/optimization/docker-pi…

…p-no-cache-dir-install

use `--no-cache-dir` flag to `pip` in dockerfiles to save space

Dockerfile

@@ -47,7 +47,7 @@ COPY patches/alerts.py /opt/elastalert/elastalert/alerts.py
 RUN mkdir -p /opt/elastalert/rules/ /opt/elastalert/server_data/tests/ \
     && chown -R node:node /opt
 
-RUN pip3 install --upgrade pip
+RUN pip3 install --no-cache-dir --upgrade pip
 
 USER node
 
@@ -63,7 +63,7 @@ RUN sed -i 's/jira>=1.0.10,<1.0.15/jira>=2.0.0/g' requirements.txt && \
     sed -i 's/py-zabbix==1.1.3/py-zabbix>=1.1.3/g' requirements.txt && \
     sed -i 's/requests>=2.0.0/requests>=2.10.0/g' requirements.txt && \
     sed -i 's/twilio==6.0.0/twilio>=6.0.0,<6.1/g' requirements.txt && \
-    pip3 install -r requirements.txt --user
+    pip3 install --no-cache-dir -r requirements.txt --user
 
 WORKDIR /opt/elastalert-server