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README.md

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-# Google Cloud Datastore Emulator
+# Google Cloud Datastore Emulator
+
+A [Google Cloud Datastore Emulator](https://cloud.google.com/datastore/docs/tools/datastore-emulator/) container image. The image is meant to be used for creating an standalone emulator for testing.
+
+- [`171.0` (Dockerfile)](https://github.com/SingularitiesCR/datastore-emulator-docker/blob/171.0/Dockerfile)
+
+## Custom commands
+
+This image contains a script named `start-datastore` (included in the PATH). This script is used to initialize the Datastore emulator.
+
+### Starting an emulator
+
+By default, the following command is called:
+
+```sh
+start-datastore
+```
+
+## Creating a Datastore emulator with Docker Compose
+
+The easiest way to create an emulator with this image is by using [Docker Compose](https://docs.docker.com/compose). The following snippet can be used as a `docker-compose.yml` for a datastore emulator:
+
+```YAML
+version: "2"
+
+services:
+  datastore:
+    image: singularities/datastore
+    environment:
+      - DATASTORE_PROJECT_ID=project-test
+      - DATASTORE_LISTEN_ADDRESS=0.0.0.0:8081
+    ports:
+      - "8081:8081"
+```
+
+### Persistence
+
+The image has a volume mounted at `/opt/data`. To maintain states between restarts, mount a volume at this location.