chore: updated README

README.md

@@ -1,2 +1,133 @@
 # gcp-pubsub-emulator
+[![1] ![2] ![3]](https://github.com/ivanmarban/gcp-pubsub-emulator/pkgs/container/gcp-pubsub-emulator)
+![GitHub Workflow Status (with event)](https://img.shields.io/github/actions/workflow/status/ivanmarban/gcp-pubsub-emulator/build-test-push.yaml?logo=github&label=Build)
+
 A Docker container image of GCP PubSub emulator
+
+## Installation
+
+A pre-built Docker container is available from grhc.io:
+
+```
+docker run --rm -ti -p 8085:8085 --name pubsub ghcr.io/ivanmarban/gcp-pubsub-emulator:latest
+```
+
+Or, if you prefer to build it yourself:
+```
+git clone https://github.com/ivanmarban/gcp-pubsub-emulator.git
+cd gcp-pubsub-emulator
+docker build --build-arg GOOGLE_CLOUD_SDK_VERSION=453.0.0 -t gcp-cloud-emulator:latest .
+```
+Where `GOOGLE_CLOUD_SDK_VERSION` corresponds for version of Google Cloud SDK
+
+## Prerequisites
+
+- Docker runtime
+
+## Usage
+
+After running the above `docker run` command, the container will start and configure automatically following resources:
+
+- project id: `myproject`
+- topic: `mytopic`
+- subscription: `mysubscription`
+- emulator listening port: `8085`
+
+## Configuration
+
+If the default configuration does not meet your needs, you can tune it using environment variables.
+
+### Environment variables
+
+| Parameter Name       | Description                                                                | Default value                                                               |
+|----------------------|----------------------------------------------------------------------------|-----------------------------------------------------------------------------|
+| PUBSUB_PORT          | Port number to run the emulator                                            | 8085                                                                        |
+| PUBSUB_PROJECT       | The project id                                                             | myproject                                                                   |
+| PUBSUB_SETUP         | A json representation of topics & subscriptions to be created              | {"topics":[{"name":"mytopic","subscriptions":[{"name":"mysubscription"}]}]} |
+| SETUP_RETRIES        | Number of retries of the setup script waiting for the emulator to be ready | 10                                                                          |
+| SETUP_SLEEP_INTERVAL | Specify a duration for which the setup script should sleep between retries | 2                                                                           |
+
+### Topics and subscriptions json schema
+
+```json
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "Topics and subscriptions",
+  "type": "object",
+  "properties": {
+    "topics": {
+      "type": "array",
+      "items": {
+        "type": "object",
+        "properties": {
+          "name": {
+            "type": "string"
+          },
+          "subscriptions": {
+            "type": "array",
+            "items": {
+              "type": "object",
+              "properties": {
+                "name": {
+                  "type": "string"
+                }
+              },
+              "required": [
+                "name"
+              ]
+            }
+          }
+        },
+        "required": [
+          "name",
+          "subscriptions"
+        ]
+      }
+    }
+  },
+  "required": [
+    "topics"
+  ]
+}
+```
+
+## Examples
+
+```
+docker run --rm -ti \
+    -e PUBSUB_PORT=8888 \
+    -e PUBSUB_PROJECT=project1 \
+    -e 'PUBSUB_SETUP={"topics":[{"name":"topic1","subscriptions":[{"name":"subscription1"},{"name":"subscription2"}]}]}' \
+    -e SETUP_RETRIES=5 \
+    -e SETUP_SLEEP_INTERVAL=1 \
+    --name pubsub ghcr.io/ivanmarban/gcp-pubsub-emulator:latest
+```
+
+```yaml
+---
+version: '3.9'
+services:
+  pubsub-emulator:
+    container_name: pubsub
+    image: ghcr.io/ivanmarban/gcp-pubsub-emulator:latest
+    ports:
+      - "8085:8085"
+    environment:
+      PUBSUB_PORT: 8888
+      PUBSUB_PROJECT: project1
+      PUBSUB_SETUP: '{"topics":[{"name":"topic1","subscriptions":[{"name":"subscription1"},{"name":"subscription2"}]}]}'
+      SETUP_RETRIES: 5
+      SETUP_SLEEP_INTERVAL: 1
+    healthcheck:
+      test: curl --fail localhost:8888/v1/projects/project1/subscriptions/subscription2 || exit 1
+      interval: 5s
+      retries: 10
+```
+
+## Special Thanks
+This project was inspired by [marcelcorso/gcloud-pubsub-emulator][4] 
+
+[1]: <https://ghcr-badge.egpl.dev/ivanmarban/gcp-pubsub-emulator/tags?trim=major>
+[2]: <https://ghcr-badge.egpl.dev/ivanmarban/gcp-pubsub-emulator/latest_tag?trim=major&label=latest>
+[3]: <https://ghcr-badge.egpl.dev/ivanmarban/gcp-pubsub-emulator/size>
+[4]: <https://github.com/marcelcorso/gcloud-pubsub-emulator>