docker/swarmkit

package cluster

import (
    "context"
    "fmt"

    "github.com/moby/swarmkit/v2/api"
)

func getCluster(ctx context.Context, c api.ControlClient, input string) (*api.Cluster, error) {
    rg, err := c.GetCluster(ctx, &api.GetClusterRequest{ClusterID: input})
    if err == nil {
        return rg.Cluster, nil
    }
    rl, err := c.ListClusters(ctx,
        &api.ListClustersRequest{
            Filters: &api.ListClustersRequest_Filters{
                Names: []string{input},
            },
        },
    )
    if err != nil {
        return nil, err
    }

    if len(rl.Clusters) == 0 {
        return nil, fmt.Errorf("cluster %s not found", input)
    }

    if l := len(rl.Clusters); l > 1 {
        return nil, fmt.Errorf("cluster %s is ambiguous (%d matches found)", input, l)
    }

    return rl.Clusters[0], nil
}