Add export script

.gitignore

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+stats.json

README.md

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+
+Ultra-light docker monitor
+=========================
+
+This light tool permits:
+ - to export docker container memory usage in a JSON file `stats.json`
+ - display curves of the memory usages using the JSON file
+
+The export and the display are two different parts. This allow to run the display in another machine.
+
+
+
+Setup the stats export
+----------------------
+
+To add it to the cron tab:
+
+	crontab -e
+
+The add new line (to run the check once per hour)
+
+	*/10 * * * * /path.io/docker-stats-histo/save_docker_stats.sh >>/dev/null  2>&1
+
+
+**Note:**
+ - Normaly cron send task outputs (echo) via mail. As the MTA (Mail Transfert Agent), may not be set up,
+the crontab line redirect the outputs into `/dev/null`. Can also be a path to a log file.
+ - No sudo is needed, crontab is called with current user.
+
+
+Display stats
+-------------
+
+To be done...

save_docker_stats.sh

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+#!/usr/bin/env bash
+
+set -eu
+
+
+SCRIPT_PATH="$( cd "$(dirname "$0")" >/dev/null 2>&1 ; pwd -P )"
+OUTPUT="stats.json"
+
+# Move in repo folder
+pushd ${SCRIPT_PATH} > /dev/null
+
+
+# If file does not exist, create it with JSON bracket
+if [ ! -f $OUTPUT ]; then
+    echo "[" >> ${OUTPUT}
+fi
+
+# Append stat data
+now=$(date -Iseconds)
+echo "{" >> ${OUTPUT}
+echo "	\"data\": \"${now}\"" >> ${OUTPUT}
+/snap/bin/docker stats --no-stream --format "	,\"{{.Name}}\": \"{{.MemUsage}}\"" >> ${OUTPUT}
+
+echo "}," >> ${OUTPUT}
+
+
+# Back to  original path
+popd