Minimize expensive API calls #245
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Inspect call is expensive and slow but almost all fields we can extract directly from List Containers. The only one missing info for us is ENV VAR which can be retrieved only from inspect
Destroy event may be lost so users may see non existing containers. To cleanup them we have to refresh all containers periodically.
This will be more lightweight API call than inspect
When new container created event received then register the new container with basic fields: name, image. But we need to request other fields: IPs, ports, etc. To get them add the new container's id to list needsRefresh. Usually few containers are created almost simultaneously so to minimize API calls we try to make a batch update. We'll make a short delay to collect all new containers ids and only then request refresh.
# Conflicts: # connector/docker.go
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The PR is intended to improve performance and minimize expensive API calls.
Docker API has two methods:
ContainersList()and more detailedInspect().The ContainersList() has almost all needed fields except of ENV variables that are shown only in Inspect() response.
So the basic idea of the PR is: what if we'll try to get all fields from ContainersList() but when user opens Single View additionally make Inspect() call to get ENV variables. This also allows us to fetch here other things e.g. #226
Currently ctop works like:
name, registers a container and calls a separate Inspect() or each container to get all other fields.createdevent and callsInspect()to retrieve all fields and only then registers a container.But in fact the only one container field shown in main view is container's name. All other fields are shown only in Single view.
And the
createdevent already contains container's name and image. So we can just register a container directly from event.But in future ctop may receive a new functionality to show other fields directly in main view (e.g. show
imagecolumn). So let's keep the fetching of full info but use cheap ContainersList().Also the PR has additional improvements: Refresh periodically each 5 minutes to remove non existing containers and bulk refresh.