Add new field for Swarm in Docker Engine API

[nishanttotla]

Currently, the /info endpoint for the Swarm API uses DriverStatus field in the Engine API. We would like to create a new field exclusively for Swarm to use.

The current suggestion is to name the field CustomStatus.

Related issues: moby/moby#19277, docker-archive/classicswarm#1625, samalba/dockerclient#215

cc @calavera @vieux

[vieux]

👍

[dnephin]

CustomStatus is not very descriptive. Wouldn't it make sense to use something more descriptive about the values it contains? I assume it's about the node status, so maybe NodeStatus? or ClusterStatus ?

[nishanttotla]

@dnephin The idea is that Docker Engine isn't tied to Swarm only, so we want a more generic "extra info" field that could be used by other tools also. What do you think?

[dnephin]

I think it would still be better to be descriptive, engine can just return nil for the value and it will be omitted from the response.

[nishanttotla]

Fair point, but it bloats the API, and depending on how Swarm evolves, may not be needed later. A general [][2]string field on the other hand will be more flexible.

@calavera what do you think?

[dongluochen]

@nishanttotla Can you provide examples how this field will be used?

[nishanttotla]

The current use case is only for Swarm (as per this issue docker-archive/classicswarm#1625). An example for what this field might contain is as follows:

[][]string{
{"Role", "primary"},
{"Strategy", "spread"},
{"Nodes", "2"},
{" agent-01", "x.x.x.x:2375"},
{" └ Status", "Healthy"},
...
{" agent-02", "x.x.x.x:2375"},
{" └ Status", "Healthy"},
...
}

Essentially the entire cluster-related information with the right formatting, with the understanding that the Engine API will print the list as is.

[calavera]

This has been fixed in #46