gcp-pubsub-emulator

A Docker container image of GCP PubSub emulator

Installation

A pre-built Docker container is available from ghcr.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

Publishing a message:

docker exec pubsub curl -s -X POST 'http://localhost:8085/v1/projects/myproject/topics/mytopic:publish' \
    -H 'Content-Type: application/json' \
    --data '{"messages":[{"attributes":{"attribute1":"value1","attribute2":"value2"},"data":"eyJrZXkiOiAidmFsdWUifQ=="}]}'

• The publish API accepts an array of messages
• The message payload must be base64-encoded

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

{
  "$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 -p 8888:8888 \
    -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

---
version: '3.9'
services:
  pubsub-emulator:
    container_name: pubsub
    image: ghcr.io/ivanmarban/gcp-pubsub-emulator:latest
    ports:
      - "8888:8888"
    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