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Merge pull request #250 from damoon/19-PreferNoSchedule
implement issue-19 add prefer no schedule taint to avoid double draining of pods
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,166 @@ | ||
| package taints | ||
|
|
||
| import ( | ||
| "context" | ||
| "encoding/json" | ||
| "fmt" | ||
|
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||
| log "github.com/sirupsen/logrus" | ||
| v1 "k8s.io/api/core/v1" | ||
| metav1 "k8s.io/apimachinery/pkg/apis/meta/v1" | ||
| "k8s.io/apimachinery/pkg/types" | ||
| "k8s.io/client-go/kubernetes" | ||
| ) | ||
|
|
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| // Taint allows to set soft and hard limitations for scheduling and executing pods on nodes. | ||
| type Taint struct { | ||
| client *kubernetes.Clientset | ||
| nodeID string | ||
| taintName string | ||
| effect v1.TaintEffect | ||
| exists bool | ||
| } | ||
|
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| // New provides a new taint. | ||
| func New(client *kubernetes.Clientset, nodeID, taintName string, effect v1.TaintEffect) *Taint { | ||
| exists, _, _ := taintExists(client, nodeID, taintName) | ||
|
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| return &Taint{ | ||
| client: client, | ||
| nodeID: nodeID, | ||
| taintName: taintName, | ||
| effect: effect, | ||
| exists: exists, | ||
| } | ||
| } | ||
|
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| // Enable creates the taint for a node. Creating an existing taint is a noop. | ||
| func (t *Taint) Enable() { | ||
| if t.taintName == "" { | ||
| return | ||
| } | ||
|
|
||
| if t.exists { | ||
| return | ||
| } | ||
|
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| preferNoSchedule(t.client, t.nodeID, t.taintName, t.effect, true) | ||
|
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| t.exists = true | ||
| } | ||
|
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| // Disable removes the taint for a node. Removing a missing taint is a noop. | ||
| func (t *Taint) Disable() { | ||
| if t.taintName == "" { | ||
| return | ||
| } | ||
|
|
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| if !t.exists { | ||
| return | ||
| } | ||
|
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| preferNoSchedule(t.client, t.nodeID, t.taintName, t.effect, false) | ||
|
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| t.exists = false | ||
| } | ||
|
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| func taintExists(client *kubernetes.Clientset, nodeID, taintName string) (bool, int, *v1.Node) { | ||
| updatedNode, err := client.CoreV1().Nodes().Get(context.TODO(), nodeID, metav1.GetOptions{}) | ||
| if err != nil || updatedNode == nil { | ||
| log.Fatalf("Error reading node %s: %v", nodeID, err) | ||
| } | ||
|
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| for i, taint := range updatedNode.Spec.Taints { | ||
| if taint.Key == taintName { | ||
| return true, i, updatedNode | ||
| } | ||
| } | ||
|
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| return false, 0, updatedNode | ||
| } | ||
|
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| func preferNoSchedule(client *kubernetes.Clientset, nodeID, taintName string, effect v1.TaintEffect, shouldExists bool) { | ||
| taintExists, offset, updatedNode := taintExists(client, nodeID, taintName) | ||
|
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| if taintExists && shouldExists { | ||
| log.Debugf("Taint %v exists already for node %v.", taintName, nodeID) | ||
| return | ||
| } | ||
|
|
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| if !taintExists && !shouldExists { | ||
| log.Debugf("Taint %v already missing for node %v.", taintName, nodeID) | ||
| return | ||
| } | ||
|
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| type patchTaints struct { | ||
| Op string `json:"op"` | ||
| Path string `json:"path"` | ||
| Value interface{} `json:"value,omitempty"` | ||
| } | ||
|
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| taint := v1.Taint{ | ||
| Key: taintName, | ||
| Effect: effect, | ||
| } | ||
|
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| var patches []patchTaints | ||
|
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| if len(updatedNode.Spec.Taints) == 0 { | ||
| // add first taint and ensure to keep current taints | ||
| patches = []patchTaints{ | ||
| { | ||
| Op: "test", | ||
| Path: "/spec", | ||
| Value: updatedNode.Spec, | ||
| }, | ||
| { | ||
| Op: "add", | ||
| Path: "/spec/taints", | ||
| Value: []v1.Taint{}, | ||
| }, | ||
| { | ||
| Op: "add", | ||
| Path: "/spec/taints/-", | ||
| Value: taint, | ||
| }, | ||
| } | ||
| } else if taintExists { | ||
| // remove taint and ensure to test against race conditions | ||
| patches = []patchTaints{ | ||
| { | ||
| Op: "test", | ||
| Path: fmt.Sprintf("/spec/taints/%d", offset), | ||
| Value: taint, | ||
| }, | ||
| { | ||
| Op: "remove", | ||
| Path: fmt.Sprintf("/spec/taints/%d", offset), | ||
| }, | ||
| } | ||
| } else { | ||
| // add missing taint to exsting list | ||
| patches = []patchTaints{ | ||
| { | ||
| Op: "add", | ||
| Path: "/spec/taints/-", | ||
| Value: taint, | ||
| }, | ||
| } | ||
| } | ||
|
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| patchBytes, err := json.Marshal(patches) | ||
| if err != nil { | ||
| log.Fatalf("Error encoding taint patch for node %s: %v", nodeID, err) | ||
| } | ||
|
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| _, err = client.CoreV1().Nodes().Patch(context.TODO(), nodeID, types.JSONPatchType, patchBytes, metav1.PatchOptions{}) | ||
| if err != nil { | ||
| log.Fatalf("Error patching taint for node %s: %v", nodeID, err) | ||
| } | ||
|
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| if shouldExists { | ||
| log.Info("Node taint added") | ||
| } else { | ||
| log.Info("Node taint removed") | ||
| } | ||
| } |