feat: GPG commit signature verification (#2492) #3242
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…t/2492-gpg-commits
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PR is now feature complete. Will conduct a few more tests before declaring ready for review state. |
…t/2492-gpg-verification
jannfis
changed the title
| @@ -24,6 +24,9 @@ spec: | |||
| - "20" | |||
| - --operation-processors | |||
| - "10" | |||
| env: | |||
| - name: ARGOCD_GPG_ENABLED | |||
| value: "true" | |||
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Should we enable by GPG by default and allow user to use ARGOCD_GPG_ENABLED to disable it? In this case we don't have to touch manifests.
Additionally GPG feature is visible in UI even if feature is disabled. Why should we let user disable it at all?
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I think a kill switch for the GPG feature is good for various reasons. For one, there is a slight performance impact of the feature, so people can switch it off if they won't require it. Second reason is, if there is a severe security issue found in Git's GnuPG implementation, or in the way we verify commits, disabling the feature for good by the kill switch could be a viable workaround until a fix is available.
But I agree, we can change semantics to enable the feature by default without touching the manifests. Shall I change it?
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I have changed the default behaviour to GPG feature being enabled and reverted the manifest changes. It still can be disabled using kill switch ARGOCD_GPG_ENABLED=false, for whatever reasons there might be.
…t/2492-gpg-verification
…t/2492-gpg-verification
| // Remove files that do not exist in ConfigMap anymore | ||
| err = filepath.Walk(destPath, func(path string, info os.FileInfo, err error) error { | ||
| if info.IsDir() { | ||
| return nil | ||
| } | ||
| if err != nil { | ||
| log.Warnf("Error walking path %s: %v", path, err) | ||
| } | ||
| p := filepath.Base(path) | ||
| if _, ok := cm.Data[p]; !ok { | ||
| log.Infof("Removing file '%s'", path) | ||
| err := os.Remove(path) | ||
| if err != nil { | ||
| log.Warnf("Failed to remove file %s: %v", path, err) | ||
| } | ||
| } | ||
| return nil | ||
| }) | ||
| if err != nil { | ||
| log.Fatalf("Error: %v", err) | ||
| } | ||
| // Create or update files that are specified in ConfigMap |
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@alexmt FYI, I've also added functionality to delete files from the file system which do not exist in the config map anymore. This makes local/manual testing possible.
Summary
This PR addresses #2492 and adds support for GPG signature verification on Git commits as well as basic management of GPG public keys to ArgoCD. GPG signature verification can be controlled on a per-project level by defining a list of key IDs in the project spec. The controller will only sync to those commits that are signed by one of the allowed key IDs, otherwise will refuse to sync.
Feature toggle and knobs
In order for this feature to be active, it must be explicitly switched on. To switch on GPG features, the environment variable
ARGOCD_GPG_ENABLEDmust be non-empty and set to values other thanfalseorno. The environment needs to be set for the containers of theargocd-server,argocd-controllerandargocd-repo-serverpods. It is not enabled by default for now.The following additional environment variables control the features' behaviour:
ARGOCD_GPG_DATA_PATH(default:/app/config/gpg/source) must be set to the path where the ConfigMap containing the GPG public keys is mounted at (valid only for theargocd-repo-serverpod)ARGOCD_GNUPGHOME(default:/app/config/gpg/keys) can be set to where the GPG keyring will be stored. This path must be available r/w and must not reside on a persistent volume.Completeness
argocd projfor manipulating signature keys and signature verification enforcementContainerize test suite so toolchain is similar (chore: Containerize complete build & test toolchain #3245)General design principles
Functionalities of this feature have been designed to follow the least-privilege concept of ArgoCD, and are split across the API server, Repository Server and Application Controller components.
git verify-commiton the target revision it checks out on behalf of application controller, if instructed by controller to do sogit verify-commit) in the answer to the controllerEach repository server instance will create a GPG keyring and a private key upon initialization, both of which are transient and only valid
for the lifecycle of the pod instance. The private key is used for building the GPG trust database within the pod, and for nothing else. It is
not intended to be used elsewhere.
This design assumes trust between all ArgoCD components - especially the controller trusting the repo server - and also assumes trust into the K8s cluster ArgoCD is running in.
Introduced changes
New API for key management
The API supports the basic operations of adding, removing and listing configured GPG keys.
New gpg command in the CLI
GPG keys can be managed through the following new commands:
argocd gpg listlists all configured GPG public keysargocd gpg get <keyid>retrieves the configured GPG public key with key ID<keyid>argocd gpg add --from <path>adds one or more GPG public keys stored in file<path>to ArgoCD. The data in<path>can be either binary or ASCII-armored.argocd gpg rm <keyid>removes the GPG public key from server's configurationNew ConfigMap resource
ArgoCD stores the GPG public key data in a new ConfigMap resource named
argocd-gpg-keys-cm. The ConfigMap contains entries in the form of<KeyID>: <KeyData>and must be mounted to theargocd-repo-serverpod, to make the public keys consumable by the repository server.New property "signatureKeys" in AppProject CRD
The property
signatureKeysin custom resourceAppProjectis used to enforce verification of GPG commit signatures on a per-project level. The property takes an array ofSignatureKeyobjects, which currently only has a single propertyKeyIDof type string. To have a project enforce signature validation, use the followingOther
New dependencies
This code uses
fsnotifypackage from https://github.com/fsnotify/fsnotify, which is released under revised BSD license.Checklist: