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Add a util library to parse container image name and data
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,141 @@ | ||
| /* | ||
| Copyright 2020 The Kubernetes Authors. | ||
| Licensed under the Apache License, Version 2.0 (the "License"); | ||
| you may not use this file except in compliance with the License. | ||
| You may obtain a copy of the License at | ||
| http://www.apache.org/licenses/LICENSE-2.0 | ||
| Unless required by applicable law or agreed to in writing, software | ||
| distributed under the License is distributed on an "AS IS" BASIS, | ||
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| See the License for the specific language governing permissions and | ||
| limitations under the License. | ||
| */ | ||
|
|
||
| package container | ||
|
|
||
| import ( | ||
| "fmt" | ||
| "path" | ||
| "regexp" | ||
|
|
||
| // Import the crypto sha256 algorithm for the docker image parser to work | ||
| _ "crypto/sha256" | ||
| // Import the crypto/sha512 algorithm for the docker image parser to work with 384 and 512 sha hashes | ||
| _ "crypto/sha512" | ||
|
|
||
| "github.com/docker/distribution/reference" | ||
| "github.com/pkg/errors" | ||
| ) | ||
|
|
||
| var ( | ||
| ociTagAllowedChars = regexp.MustCompile(`[^-a-zA-Z0-9_\.]`) | ||
| ) | ||
|
|
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| // Image type represents the container image details | ||
| type Image struct { | ||
| Repository string | ||
| Name string | ||
| Tag string | ||
| Digest string | ||
| } | ||
|
|
||
| // ImageFromString parses a docker image string into three parts: repo, tag and digest. | ||
| func ImageFromString(image string) (Image, error) { | ||
| named, err := reference.ParseNamed(image) | ||
| if err != nil { | ||
| return Image{}, fmt.Errorf("couldn't parse image name: %v", err) | ||
| } | ||
|
|
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| var repo, tag, digest string | ||
| _, nameOnly := path.Split(reference.Path(named)) | ||
| if nameOnly != "" { | ||
| // split out the part of the name after the last / | ||
| lenOfCompleteName := len(named.Name()) | ||
| repo = named.Name()[:lenOfCompleteName-len(nameOnly)-1] | ||
| } | ||
|
|
||
| tagged, ok := named.(reference.Tagged) | ||
| if ok { | ||
| tag = tagged.Tag() | ||
| } | ||
|
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| digested, ok := named.(reference.Digested) | ||
| if ok { | ||
| digest = digested.Digest().String() | ||
| } | ||
|
|
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| return Image{Repository: repo, Name: nameOnly, Tag: tag, Digest: digest}, nil | ||
| } | ||
|
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| func (i Image) String() string { | ||
| // repo/name [ ":" tag ] [ "@" digest ] | ||
| ref := fmt.Sprintf("%s/%s", i.Repository, i.Name) | ||
| if i.Tag != "" { | ||
| ref = fmt.Sprintf("%s:%s", ref, i.Tag) | ||
| } | ||
| if i.Digest != "" { | ||
| ref = fmt.Sprintf("%s@%s", ref, i.Digest) | ||
| } | ||
| return ref | ||
| } | ||
|
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| // ModifyImageRepository takes an imageName (e.g., repository/image:tag), and returns an image name with updated repository | ||
| func ModifyImageRepository(imageName, repositoryName string) (string, error) { | ||
| image, err := ImageFromString(imageName) | ||
| if err != nil { | ||
| return "", errors.Wrap(err, "failed to parse image name") | ||
| } | ||
| nameUpdated, err := reference.WithName(path.Join(repositoryName, image.Name)) | ||
| if err != nil { | ||
| return "", errors.Wrap(err, "failed to update repository name") | ||
| } | ||
| if image.Tag != "" { | ||
| retagged, err := reference.WithTag(nameUpdated, image.Tag) | ||
| if err != nil { | ||
| return "", errors.Wrap(err, "failed to parse image tag") | ||
| } | ||
| return reference.FamiliarString(retagged), nil | ||
| } | ||
| return "", errors.New("image must be tagged") | ||
| } | ||
|
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| // ModifyImageTag takes an imageName (e.g., repository/image:tag), and returns an image name with updated tag | ||
| func ModifyImageTag(imageName, tagName string) (string, error) { | ||
| normalisedTagName := SemverToOCIImageTag(tagName) | ||
|
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| namedRef, err := reference.ParseNormalizedNamed(imageName) | ||
| if err != nil { | ||
| return "", errors.Wrap(err, "failed to parse image name") | ||
| } | ||
| // return error if images use digest as version instead of tag | ||
| if _, isCanonical := namedRef.(reference.Canonical); isCanonical { | ||
| return "", errors.New("image uses digest as version, cannot update tag ") | ||
| } | ||
|
|
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| // update the image tag with tagName | ||
| namedTagged, err := reference.WithTag(namedRef, normalisedTagName) | ||
| if err != nil { | ||
| return "", errors.Wrap(err, "failed to update image tag") | ||
| } | ||
|
|
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| return reference.FamiliarString(reference.TagNameOnly(namedTagged)), nil | ||
| } | ||
|
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| // ImageTagIsValid ensures that a given image tag is compliant with the OCI spec | ||
| func ImageTagIsValid(tagName string) bool { | ||
| return !ociTagAllowedChars.MatchString(tagName) | ||
| } | ||
|
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| // SemverToOCIImageTag is a helper function that replaces all | ||
| // non-allowed symbols in tag strings with underscores. | ||
| // Image tag can only contain lowercase and uppercase letters, digits, | ||
| // underscores, periods and dashes. | ||
| // Current usage is for CI images where all of symbols except '+' are valid, | ||
| // but function is for generic usage where input can't be always pre-validated. | ||
| // Taken from k8s.io/cmd/kubeadm/app/util | ||
| func SemverToOCIImageTag(version string) string { | ||
| return ociTagAllowedChars.ReplaceAllString(version, "_") | ||
| } |
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