---
title: How to manage lifted codes
---

This document explains how lifted code is managed.
A common use case for this task is developer lifting code from other repositories to `pkg/util/lifted` directory.

- [Steps of lifting code](#steps-of-lifting-code)
- [How to write lifted comments](#how-to-write-lifted-comments)
- [Examples](#examples)

## Steps of lifting code
- Copy code from another repository and save it to a go file under `pkg/util/lifted`.
- Optionally change the lifted code.
- Add lifted comments for the code [as guided](#how-to-write-lifted-comments).
- Run `hack/update-lifted.sh` to update the lifted doc `pkg/util/lifted/doc.go`.

## How to write lifted comments
Lifted comments shall be placed just before the lifted code (could be a func, type, var, or const). Only empty lines and comments are allowed between lifted comments and lifted code.

Lifted comments are composed of one or multi comment lines, each in the format of `+lifted:KEY[=VALUE]`. Value is optional for some keys.

Valid keys are as follows：

- source:

  Key `source` is required. Its value indicates where the code is lifted from.

- changed:

  Key `changed` is optional. It indicates whether the code is changed. Value is optional (`true` or `false`, defaults to `true`). Not adding this key or setting it to `false` means no code change.

## Examples
### Lifting function

Lift function `IsQuotaHugePageResourceName` to `corehelpers.go`:

```go
// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.23/pkg/apis/core/helper/helpers.go#L57-L61

// IsQuotaHugePageResourceName returns true if the resource name has the quota
// related huge page resource prefix.
func IsQuotaHugePageResourceName(name corev1.ResourceName) bool {
	return strings.HasPrefix(string(name), corev1.ResourceHugePagesPrefix) || strings.HasPrefix(string(name), corev1.ResourceRequestsHugePagesPrefix)
}
```

Added in `doc.go`:

```markdown
| lifted file              | source file                                                                                                                   | const/var/type/func                     | changed |
|--------------------------|-------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------|---------|
| corehelpers.go           | https://github.com/kubernetes/kubernetes/blob/release-1.23/pkg/apis/core/helper/helpers.go#L57-L61                            | func IsQuotaHugePageResourceName        | N       |
```

### Changed lifting function

Lift and change function `GetNewReplicaSet` to `deployment.go`

```go
// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.22/pkg/controller/deployment/util/deployment_util.go#L536-L544
// +lifted:changed

// GetNewReplicaSet returns a replica set that matches the intent of the given deployment; get ReplicaSetList from client interface.
// Returns nil if the new replica set doesn't exist yet.
func GetNewReplicaSet(deployment *appsv1.Deployment, f ReplicaSetListFunc) (*appsv1.ReplicaSet, error) {
	rsList, err := ListReplicaSetsByDeployment(deployment, f)
	if err != nil {
		return nil, err
	}
	return FindNewReplicaSet(deployment, rsList), nil
}
```

Added in `doc.go`:

```markdown
| lifted file              | source file                                                                                                                   | const/var/type/func                     | changed |
|--------------------------|-------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------|---------|
| deployment.go            | https://github.com/kubernetes/kubernetes/blob/release-1.22/pkg/controller/deployment/util/deployment_util.go#L536-L544        | func GetNewReplicaSet                   | Y       |
```

### Lifting const

Lift const `isNegativeErrorMsg` to `corevalidation.go  `:

```go
// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.22/pkg/apis/core/validation/validation.go#L59
const isNegativeErrorMsg string = apimachineryvalidation.IsNegativeErrorMsg
```

Added in `doc.go`:

```markdown
| lifted file              | source file                                                                                                                   | const/var/type/func                     | changed |
|--------------------------|-------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------|---------|
| corevalidation.go        | https://github.com/kubernetes/kubernetes/blob/release-1.22/pkg/apis/core/validation/validation.go#L59                         | const isNegativeErrorMsg                | N       |
```

### Lifting type

Lift type `Visitor` to `visitpod.go`:

```go
// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.23/pkg/api/v1/pod/util.go#L82-L83

// Visitor is called with each object name, and returns true if visiting should continue
type Visitor func(name string) (shouldContinue bool)
```

Added in `doc.go`:

```markdown
| lifted file              | source file                                                                                                                   | const/var/type/func                     | changed |
|--------------------------|-------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------|---------|
| visitpod.go              | https://github.com/kubernetes/kubernetes/blob/release-1.23/pkg/api/v1/pod/util.go#L82-L83                                     | type Visitor                            | N       |
```