feat(api) Added Status API #167

ab623 · 2023-08-08T12:20:35Z

I have recently picked up learning Go and trying to learn to contribute back into open source. And thought that Sablier would be a good project to get involved in.

I have been putting in the early stages of a status page, which intends to show the status of the services Sablier manages, along with useful information about those services, mainly, the status, expiration time, and remaining time.

I had to make quite a few updates across the solution. I have documented the rationale below

Gin - Updates to include status page. The response payload is designed in a way so that it can be extended with global configs.
KV store - This required an update of a new method to be able to get a value along with expiration information
Instance - Updated structs to store additional state data
Providers - Updated providers with a new function to get the list of managed containers, using label enable = true
Session Manager - Few methods to get the service status

Output:
Calling /api/status :

{
  "managed_services": [
    {
      "name": "whoami-secondary",
      "currentReplicas": 1,
      "desiredReplicas": 1,
      "status": "ready",
      "expires_on": "0001-01-01T00:00:00Z",
      "expires_in": 0
    },
    {
      "name": "whoami-primary",
      "currentReplicas": 0,
      "desiredReplicas": 1,
      "status": "unrecoverable",
      "message": "ready"
      "expires_on": "2023-08-08T11:57:59.3412899Z",
      "expires_in": 260
    }
  ]
}

Potential non-blocking issues:

The status could be refined a bit better depending on if the container is up or down
If a service hasn't been hit for the first time, it shows as ready with no expiry (see whoami-secondary). This has been documented in services started with docker compose won't be stopped by sablier unless hit with a request first #153, and could be a quick fix on startup.

I haven't used Go before, nor any of the libraries such as Gin, so some good feedback and advice would be helpful. I have tired to stick close to the format in the project.

…managed services by Sablier and their expirations

acouvreur · 2023-08-08T13:12:43Z

Hey @ab623, thanks for your contribution, I will be looking it it

…rs on startup.

ab623 · 2023-08-08T15:41:19Z

Thanks @acouvreur. Additionally I just pushed a commit to fix #153. I did it on this branch as it requires the functionality in the initial commits.

This works by checking all managed containers on startup, and if the containers are running already, it just applies the default timeout to them. If a containers is already stopped it just skips it.

This way the containers can start first, and then Sabiler can be started after and the containers that it manages will be brought down after the default timeout.

acouvreur · 2023-08-10T16:53:18Z

So for the status page we have a few things to consider:

Instances that have been started by name
Instances that have been started by group (auto discovery)

If it is started by name, we will only see the status when it's up, because as soon as it's down, the instance will be out of the KV store.

For instances started with the group name, then you can already use the group values to build the status page.
So I think you do not need to add anything to the providers.

What do you think about that?

ab623 · 2023-08-10T20:50:05Z

My implementation already accounts for that and is independent of the calling method.

It looks for the enable label and uses that to track all monitored containers.

Then if it is up, it exists in the KV and pulls the expiration data, if not then the service is down, but the container name is still shown in the output, just with a exited status.

acouvreur

Overall I agree with your changes, but I think we need to generify the usage to instance instead of container.

Also, I believe the startup feature is not as expected. We should review it again. And it should also be enabled through a configuration flag.

acouvreur · 2023-08-11T14:43:00Z

app/instance/instance.go

+	DesiredReplicas int           `json:"desiredReplicas"`
+	Status          string        `json:"status"`
+	Message         string        `json:"message,omitempty"`
+	ExpiresAt       time.Time     `json:"expires_on"`


The property name is ExpiresAt but the json is expires_on
We should use one exclusively

Any preference on this?

acouvreur · 2023-08-11T14:43:42Z

app/http/routes/status.go

+}
+
+func (s *Status) ServeStatus(c *gin.Context) {
+	containers, _ := s.SessionsManager.GetManagedContainers()


It's not always containers, it might be swarm services, kubernetes deployments, etc.
We should use instances instead.

Makes sense here. I only have docker experience. I will look into using instances.

acouvreur · 2023-08-11T14:44:40Z