Simple Shell Script: Dead Docker Containers - docker

Question

I have a very simple Docker container that runs a bash shell script that returns something. My Dockerfile:
# Docker image to get stats from a rest interface using CURL and JSON parsing
FROM ubuntu
RUN apt-get update
# Install curl and jq, a lightweight command-line JSON processor
RUN apt-get install -y curl jq
COPY ./stats.sh /
# Make sure script has execute permissions for root
RUN chmod 500 stats.sh
# Define a custom entrypoint to execute stats commands easily within the container,
# using environment substitution and the like...
ENTRYPOINT ["/stats.sh"]
CMD ["info"]
The stats.sh looks like this:
#!/bin/bash
# ElasticSearch
## Get the total size of the elasticsearch DB in bytes
## Requires the elasticsearch container to be linked with alias 'elasticsearch'
function es_size() {
local size=$(curl $ELASTICSEARCH_PORT_9200_TCP_ADDR:$ELASTICSEARCH_PORT_9200_TCP_PORT/_stats/_all 2>/dev/null|jq ._all.total.store.size_in_bytes)
echo $size
}
if [[ "$1" == "info" ]]; then
echo "Check stats.sh for available commands"
elif [[ "$1" == "es_size" ]]; then
es_size
else
echo "Unknown command: $#"
fi
So basically, I have a Docker container that I will run with --rm to exit immediately after running and returning the value I want. More precise, I run it from another shell script (in the host) with:
local size=$(docker run --name stats-es-size --rm --link $esName:elasticsearch $ENV_DOCKER_REST_STATS_IMAGE:$ENV_DOCKER_REST_STATS_VERSION es_size)
Now I'm running this periodically to gather statistics, once a minute. While it works well in general, I end up getting containers with status Dead about once a day.
Can anybody tell me what I might be doing wrong? Is there some problem with my approach or why do my containers die with a certain frequency?