docker-gatekeeper

A container for a docker-compose environment to help orchestrate startup.

docker run -p 8080:8080 --rm giantrobotlabs/gatekeeper

{
  "Supported operations": {
    "GET": {
      "/": "Show usage.",
      "/services": "Get all registered services.",
      "/services/{service}": "Get the service status record.",
      "/services/{service}/status": "Return the HTTP response for the status."
    },
    "PUT": {
      "/services/{service}/ready": "Set the ready status for a service.",
      "/controls/{control}": "Send a server control. quit = Exit server."
    },
    "POST": {
      "/services/{service}": "Register a service to track status."
    },
    "Responses": {
      "GET /services/{service}": {
        "200": "Service registered.",
        "400": "Service not registered."
      },
      "GET /services/{service}/status": {
        "200": "Service ready",
        "404": "Service not registered.",
        "503": "Service not ready."
      },
      "PUT /controls/{control}": {
        "200": "Success",
        "501": "Control operation not implemented."
      }
    }
  }
}

Description

Sometimes you just need to slow things down. The intent of this container is to help monitor when servers are actually ready in a docker-compose environment. In my case, a test database had to be created before a service could connect to it. Docker compose provides a dependencies stanza to try make sure required containers start up, but sometimes ready isn't really ready. Gatekeeper can help manage this situation.

Instructions

Gatekeeper is a small docker container you can start up in your compose infrastructure to register and indicate ready status for other containers. The container is a small nodejs Restify server. The source contains some scripts that can be used as examples to manage server status.

Basic operation

1. Include gatekeeper image in your Docker compose.yml
2. Register your service for status.
3. Wait for a change in status in your dependent container.
4. Register ready state when the service is ready.

Scripts (using curl):

• register - register a service for status.
• ckready - check the service status on the gatekeeper.
• ready - send the ready status for the service.
• stop - send a remote control signal to stop the gatekeeper.

If you don't need gatekeeper to continue running, you can send it a stop signal to shut it down.

For security reasons, this container is intended for local network access only.