package sorter import ( "fmt" "github.com/containrrr/watchtower/pkg/container" "time" ) // ByCreated allows a list of Container structs to be sorted by the container's // created date. type ByCreated []container.Container func (c ByCreated) Len() int { return len(c) } func (c ByCreated) Swap(i, j int) { c[i], c[j] = c[j], c[i] } // Less will compare two elements (identified by index) in the Container // list by created-date. func (c ByCreated) Less(i, j int) bool { t1, err := time.Parse(time.RFC3339Nano, c[i].ContainerInfo().Created) if err != nil { t1 = time.Now() } t2, _ := time.Parse(time.RFC3339Nano, c[j].ContainerInfo().Created) if err != nil { t1 = time.Now() } return t1.Before(t2) } // SortByDependencies will sort the list of containers taking into account any // links between containers. Container with no outgoing links will be sorted to // the front of the list while containers with links will be sorted after all // of their dependencies. This sort order ensures that linked containers can // be started in the correct order. func SortByDependencies(containers []container.Container) ([]container.Container, error) { sorter := dependencySorter{} return sorter.Sort(containers) } type dependencySorter struct { unvisited []container.Container marked map[string]bool sorted []container.Container } func (ds *dependencySorter) Sort(containers []container.Container) ([]container.Container, error) { ds.unvisited = containers ds.marked = map[string]bool{} for len(ds.unvisited) > 0 { if err := ds.visit(ds.unvisited[0]); err != nil { return nil, err } } return ds.sorted, nil } func (ds *dependencySorter) visit(c container.Container) error { if _, ok := ds.marked[c.Name()]; ok { return fmt.Errorf("circular reference to %s", c.Name()) } // Mark any visited node so that circular references can be detected ds.marked[c.Name()] = true defer delete(ds.marked, c.Name()) // Recursively visit links for _, linkName := range c.Links() { if linkedContainer := ds.findUnvisited(linkName); linkedContainer != nil { if err := ds.visit(*linkedContainer); err != nil { return err } } } // Move container from unvisited to sorted ds.removeUnvisited(c) ds.sorted = append(ds.sorted, c) return nil } func (ds *dependencySorter) findUnvisited(name string) *container.Container { for _, c := range ds.unvisited { if c.Name() == name { return &c } } return nil } func (ds *dependencySorter) removeUnvisited(c container.Container) { var idx int for i := range ds.unvisited { if ds.unvisited[i].Name() == c.Name() { idx = i break } } ds.unvisited = append(ds.unvisited[0:idx], ds.unvisited[idx+1:]...) }