Add "mongo"

mongo/Dockerfile

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

mongo/docker-healthcheck

@@ -0,0 +1,10 @@
+#!/bin/bash
+set -eo pipefail
+
+if mongo --quiet localhost --eval 'quit(db.runCommand({ ping: 1 }).ok ? 0 : 2)'; then
+	exit 0
+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