Add "elasticsearch"

elasticsearch/Dockerfile

@@ -0,0 +1,5 @@
+FROM elasticsearch
+
+COPY docker-healthcheck /usr/local/bin/
+
+HEALTHCHECK CMD ["docker-healthcheck"]

elasticsearch/docker-healthcheck

@@ -0,0 +1,16 @@
+#!/bin/bash
+set -eo pipefail
+
+host="$(hostname --ip-address || echo '127.0.0.1')"
+
+if health="$(curl -fsSL "http://$host:9200/_cat/health?h=status")"; then
+	health="$(echo "$health" | sed -r 's/^[[:space:]]+|[[:space:]]+$//g')" # trim whitespace (otherwise we'll have "green ")
+	if [ "$health" = 'green' ]; then
+		exit 0
+	fi
+	echo >&2 "unexpected health status: $health"
+fi
+
+# If the probe returns 2 ("starting") when the container has already moved out of the "starting" state then it is treated as "unhealthy" instead.
+# https://github.com/docker/docker/blob/dcc65376bac8e73bb5930fce4cddc2350bb7baa2/docs/reference/builder.md#healthcheck
+exit 2