feat: add imagePullSecrets support for container-based skills

[ppeau]

Closes #1222

Problem

Container-based skills using krane to pull OCI images had no way to authenticate against private registries (Artifactory, ACR, ECR, etc.). The imagePullSecrets defined on the agent deployment were not passed to the skills-init init container, causing authentication failures like:
No matching credentials were found for "docker.artifactory.dev.example.com"
Error: pulling ...: Authentication is required

Solution

Follows the approach discussed in #1222 by @s10gopal:

1. Added an imagePullSecrets field under spec.skills accepting a list of kubernetes.io/dockerconfigjson secrets
2. When imagePullSecrets is set, a new docker-auth-init init container is prepended — it merges all referenced secrets into a single config.json using jq
3. The skills-init container reads that merged config via the DOCKER_CONFIG env var, which krane picks up automatically when pulling skill images

Changes

• go/api/v1alpha2/agent_types.go: add ImagePullSecrets []corev1.LocalObjectReference to SkillForAgent struct
• go/api/v1alpha2/zz_generated.deepcopy.go: regenerated DeepCopy for new field
• go/core/internal/controller/translator/agent/adk_api_translator.go: buildSkillsInitContainer now returns []Container, prepends docker-auth-init when imagePullSecrets are present
• docker/skills-init/Dockerfile: add jq to the Alpine base image
• .gitattributes: enforce LF line endings on *.sh.tmpl files (prevents shell script breakage on Windows contributors)

Usage

apiVersion: kagent.dev/v1alpha2
kind: Agent
spec:
  skills:
    refs:
      - private-registry.example.com/my-org/my-skill:v1
    imagePullSecrets:
      - name: my-registry-secret  # kubernetes.io/dockerconfigjson secret

Testing

Validated end-to-end on a local Kubernetes cluster with a private registry protected by htpasswd authentication:

Skill image hosted on the private registry, inaccessible without credentials
Agent configured with imagePullSecrets referencing a dockerconfigjson secret
docker-auth-init merged the credentials, skills-init pulled the image successfully via krane
Skill was correctly loaded and executed by the agent

[Copilot]

Pull request overview

Adds first-class support for authenticating OCI pulls for container-based skills by allowing agents to reference kubernetes.io/dockerconfigjson secrets and wiring those credentials into the skills-init workflow.

Changes:

• Extend the Agent/SandboxAgent spec.skills schema and Go types with imagePullSecrets.
• Update the agent manifest translation to optionally prepend a docker-auth-init initContainer that merges multiple dockerconfigjson secrets into a single Docker config.json, and set DOCKER_CONFIG for skills-init.
• Update the skills-init image to include jq, and add unit/e2e coverage for the new behavior.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
helm/kagent-crds/templates/kagent.dev_sandboxagents.yaml	Exposes spec.skills.imagePullSecrets in the Helm-rendered SandboxAgent CRD schema.
helm/kagent-crds/templates/kagent.dev_agents.yaml	Exposes spec.skills.imagePullSecrets in the Helm-rendered Agent CRD schema.
go/core/test/e2e/invoke_api_test.go	Adds an e2e test verifying docker-auth-init is injected and the agent still functions end-to-end.
go/core/internal/controller/translator/agent/manifest_builder.go	Passes ImagePullSecrets through and adapts to buildSkillsInitContainer returning multiple init containers.
go/core/internal/controller/translator/agent/git_skills_test.go	Adds translator unit tests validating volumes/mounts/env for imagePullSecrets.
go/core/internal/controller/translator/agent/adk_api_translator.go	Implements docker-auth-init, merge script generation, volume/mount wiring, and DOCKER_CONFIG env injection.
go/api/v1alpha2/zz_generated.deepcopy.go	Regenerates DeepCopy to include the new ImagePullSecrets field.
go/api/v1alpha2/agent_types.go	Adds ImagePullSecrets []LocalObjectReference to SkillForAgent.
go/api/config/crd/bases/kagent.dev_sandboxagents.yaml	Updates the base CRD schema for SandboxAgent to include imagePullSecrets.
go/api/config/crd/bases/kagent.dev_agents.yaml	Updates the base CRD schema for Agent to include imagePullSecrets.
docker/skills-init/Dockerfile	Installs jq so the merge init container can build a combined Docker config.
.gitattributes	Forces LF endings for *.sh.tmpl to avoid cross-platform template/script breakage.

---

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[Copilot]

buildSkillsInitContainer now returns a slice of containers, but the receiving variable is still named container, which makes the call site harder to read. Consider renaming it to containers (or similar) to reflect the type and avoid confusion.

[Copilot]

Volume names are derived from the Secret name ("pull-secret-" + secret.Name). Kubernetes Secret names may contain characters (notably '.') and/or length that are invalid for Pod volume names, which can make the generated Deployment fail admission. Consider generating a safe volume name (e.g., index-based or hashed) and keep the SecretName field pointing at the original secret.

[Copilot]

imagePullSecrets entries with an empty Name (LocalObjectReference allows this) or repeated names will currently produce invalid SecretVolumeSource.SecretName values and/or duplicate volume names. It would be safer to validate that every reference has a non-empty name and to de-duplicate (or error) before creating volumes/mounts.

Suggested change

	// Shared EmptyDir volume for the merged Docker config.
	volumes = append(volumes, corev1.Volume{
	Name: "kagent-docker-config",
	VolumeSource: corev1.VolumeSource{
	EmptyDir: &corev1.EmptyDirVolumeSource{},
	},
	})
	// Mount each imagePullSecret as a read-only directory under /docker-secrets/<name>.
	authInitVolumeMounts := []corev1.VolumeMount{
	{Name: "kagent-docker-config", MountPath: "/docker-config-out"},
	}
	for _, secret := range imagePullSecrets {
	volName := "pull-secret-" + secret.Name
	volumes = append(volumes, corev1.Volume{
	Name: volName,
	VolumeSource: corev1.VolumeSource{
	Secret: &corev1.SecretVolumeSource{
	SecretName: secret.Name,
	},
	},
	})
	authInitVolumeMounts = append(authInitVolumeMounts, corev1.VolumeMount{
	Name: volName,
	MountPath: "/docker-secrets/" + secret.Name,
	ReadOnly: true,
	})
	}
	mergeScript := buildDockerAuthMergeScript(imagePullSecrets)
	dockerAuthInitContainer := corev1.Container{
	Name: "docker-auth-init",
	Image: DefaultSkillsInitImageConfig.Image(),
	Command: []string{"/bin/sh", "-c", mergeScript},
	VolumeMounts: authInitVolumeMounts,
	}
	containers = append(containers, dockerAuthInitContainer)
	// Mount the merged config into skills-init so krane picks it up via DOCKER_CONFIG.
	volumeMounts = append(volumeMounts, corev1.VolumeMount{
	Name: "kagent-docker-config",
	MountPath: "/.kagent/.docker",
	ReadOnly: true,
	})
	validImagePullSecrets := make([]corev1.LocalObjectReference, 0, len(imagePullSecrets))
	seenImagePullSecrets := make(map[string]struct{}, len(imagePullSecrets))
	for _, secret := range imagePullSecrets {
	if secret.Name == "" {
	continue
	}
	if _, seen := seenImagePullSecrets[secret.Name]; seen {
	continue
	}
	seenImagePullSecrets[secret.Name] = struct{}{}
	validImagePullSecrets = append(validImagePullSecrets, secret)
	}
	if len(validImagePullSecrets) > 0 {
	// Shared EmptyDir volume for the merged Docker config.
	volumes = append(volumes, corev1.Volume{
	Name: "kagent-docker-config",
	VolumeSource: corev1.VolumeSource{
	EmptyDir: &corev1.EmptyDirVolumeSource{},
	},
	})
	// Mount each imagePullSecret as a read-only directory under /docker-secrets/<name>.
	authInitVolumeMounts := []corev1.VolumeMount{
	{Name: "kagent-docker-config", MountPath: "/docker-config-out"},
	}
	for _, secret := range validImagePullSecrets {
	volName := "pull-secret-" + secret.Name
	volumes = append(volumes, corev1.Volume{
	Name: volName,
	VolumeSource: corev1.VolumeSource{
	Secret: &corev1.SecretVolumeSource{
	SecretName: secret.Name,
	},
	},
	})
	authInitVolumeMounts = append(authInitVolumeMounts, corev1.VolumeMount{
	Name: volName,
	MountPath: "/docker-secrets/" + secret.Name,
	ReadOnly: true,
	})
	}
	mergeScript := buildDockerAuthMergeScript(validImagePullSecrets)
	dockerAuthInitContainer := corev1.Container{
	Name: "docker-auth-init",
	Image: DefaultSkillsInitImageConfig.Image(),
	Command: []string{"/bin/sh", "-c", mergeScript},
	VolumeMounts: authInitVolumeMounts,
	}
	containers = append(containers, dockerAuthInitContainer)
	// Mount the merged config into skills-init so krane picks it up via DOCKER_CONFIG.
	volumeMounts = append(volumeMounts, corev1.VolumeMount{
	Name: "kagent-docker-config",
	MountPath: "/.kagent/.docker",
	ReadOnly: true,
	})
	}

[Copilot]

docker-auth-init is created without SecurityContext or resource requirements, while skills-init uses the pod/deployment securityContext and configured resources. This can cause PodSecurity admission failures or unexpected resource usage differences. Consider applying the same initSecCtx and resources (or a deliberate minimal set) to docker-auth-init as well.

Suggested change

	Name: "docker-auth-init",
	Image: DefaultSkillsInitImageConfig.Image(),
	Command: []string{"/bin/sh", "-c", mergeScript},
	VolumeMounts: authInitVolumeMounts,
	Name: "docker-auth-init",
	Image: DefaultSkillsInitImageConfig.Image(),
	Command: []string{"/bin/sh", "-c", mergeScript},
	VolumeMounts: authInitVolumeMounts,
	SecurityContext: initSecCtx,
	Resources: resources,

[EItanya]

Overall this makes sense, but before we go down the road of adding a new API, is there anyway we can re-use the ImagePullSecrets which already get used for image pulling, or do those remain on the node and never mounted into the pod themselves?

[ppeau]

Hi @EItanya, great question. We actually explored reusing the existing deployment imagePullSecrets first before adding a new field.

On the technical side, imagePullSecrets defined on a pod spec are consumed exclusively by the kubelet to pull container images. They are never mounted into the pod or made accessible to running containers. This means krane, executing inside the skills-init init container, has no way to read those credentials. We hit this wall directly during testing.

Even if it were technically possible, there is a design reason why it would not be the right approach in enterprise environments. The registry used to deploy the kagent system and the registry hosting skill images are typically owned by completely different teams with different security boundaries. The platform/ops team manages the kagent deployment and its registry credentials, while the line-of-business team produces and owns the skill images, hosted in their own private registry (Artifactory, ACR, ECR, etc.). Reusing the deployment imagePullSecrets would couple these two security contexts together, violate the principle of least privilege, and make skills effectively unusable for any team whose registry differs from the one used to deploy kagent. That is the common case at scale.

The new imagePullSecrets field under spec.skills directly mirrors the standard Kubernetes pattern where a pod can reference multiple imagePullSecrets for different registries. It introduces no new concept, just applies the same model at the skill level.

Happy to discuss further if needed!

[EItanya]

Hi @EItanya, great question. We actually explored reusing the existing deployment imagePullSecrets first before adding a new field.

On the technical side, imagePullSecrets defined on a pod spec are consumed exclusively by the kubelet to pull container images. They are never mounted into the pod or made accessible to running containers. This means krane, executing inside the skills-init init container, has no way to read those credentials. We hit this wall directly during testing.

Even if it were technically possible, there is a design reason why it would not be the right approach in enterprise environments. The registry used to deploy the kagent system and the registry hosting skill images are typically owned by completely different teams with different security boundaries. The platform/ops team manages the kagent deployment and its registry credentials, while the line-of-business team produces and owns the skill images, hosted in their own private registry (Artifactory, ACR, ECR, etc.). Reusing the deployment imagePullSecrets would couple these two security contexts together, violate the principle of least privilege, and make skills effectively unusable for any team whose registry differs from the one used to deploy kagent. That is the common case at scale.

The new imagePullSecrets field under spec.skills directly mirrors the standard Kubernetes pattern where a pod can reference multiple imagePullSecrets for different registries. It introduces no new concept, just applies the same model at the skill level.

Happy to discuss further if needed!

Ok I buy that logic. What do you think about renaming the field to PullSecrets instead ImagePullSecrets since these aren't really images

[ppeau]

Hi @EItanya, great question. We actually explored reusing the existing deployment imagePullSecrets first before adding a new field.
On the technical side, imagePullSecrets defined on a pod spec are consumed exclusively by the kubelet to pull container images. They are never mounted into the pod or made accessible to running containers. This means krane, executing inside the skills-init init container, has no way to read those credentials. We hit this wall directly during testing.
Even if it were technically possible, there is a design reason why it would not be the right approach in enterprise environments. The registry used to deploy the kagent system and the registry hosting skill images are typically owned by completely different teams with different security boundaries. The platform/ops team manages the kagent deployment and its registry credentials, while the line-of-business team produces and owns the skill images, hosted in their own private registry (Artifactory, ACR, ECR, etc.). Reusing the deployment imagePullSecrets would couple these two security contexts together, violate the principle of least privilege, and make skills effectively unusable for any team whose registry differs from the one used to deploy kagent. That is the common case at scale.
The new imagePullSecrets field under spec.skills directly mirrors the standard Kubernetes pattern where a pod can reference multiple imagePullSecrets for different registries. It introduces no new concept, just applies the same model at the skill level.
Happy to discuss further if needed!

Ok I buy that logic. What do you think about renaming the field to PullSecrets instead ImagePullSecrets since these aren't really images

Good point, I can see both sides here.

For keeping imagePullSecrets: Skills are stored and pulled as OCI artifacts using the exact same kubernetes.io/dockerconfigjson secrets as normal container images. The name imagePullSecrets is the standard Kubernetes convention, so it feels familiar right away. Anyone who’s used Kubernetes already knows what it means and how to set it up.

For renaming to pullSecrets: Skills aren’t executed as containers, they’re more like content or configuration that gets pulled. The original imagePullSecrets name is specifically tied to pulling runnable container images at the pod level, so using it in this context could feel a bit overloaded. pullSecrets is more neutral and probably more accurate here.

Both options are valid.
I’m happy to go with pullSecrets if you prefer it.

Just say the word and I’ll rename the field right away. 👍

[EItanya]

Hi @EItanya, great question. We actually explored reusing the existing deployment imagePullSecrets first before adding a new field.
On the technical side, imagePullSecrets defined on a pod spec are consumed exclusively by the kubelet to pull container images. They are never mounted into the pod or made accessible to running containers. This means krane, executing inside the skills-init init container, has no way to read those credentials. We hit this wall directly during testing.
Even if it were technically possible, there is a design reason why it would not be the right approach in enterprise environments. The registry used to deploy the kagent system and the registry hosting skill images are typically owned by completely different teams with different security boundaries. The platform/ops team manages the kagent deployment and its registry credentials, while the line-of-business team produces and owns the skill images, hosted in their own private registry (Artifactory, ACR, ECR, etc.). Reusing the deployment imagePullSecrets would couple these two security contexts together, violate the principle of least privilege, and make skills effectively unusable for any team whose registry differs from the one used to deploy kagent. That is the common case at scale.
The new imagePullSecrets field under spec.skills directly mirrors the standard Kubernetes pattern where a pod can reference multiple imagePullSecrets for different registries. It introduces no new concept, just applies the same model at the skill level.
Happy to discuss further if needed!

Ok I buy that logic. What do you think about renaming the field to PullSecrets instead ImagePullSecrets since these aren't really images

Good point, I can see both sides here.

For keeping imagePullSecrets: Skills are stored and pulled as OCI artifacts using the exact same kubernetes.io/dockerconfigjson secrets as normal container images. The name imagePullSecrets is the standard Kubernetes convention, so it feels familiar right away. Anyone who’s used Kubernetes already knows what it means and how to set it up.

For renaming to pullSecrets: Skills aren’t executed as containers, they’re more like content or configuration that gets pulled. The original imagePullSecrets name is specifically tied to pulling runnable container images at the pod level, so using it in this context could feel a bit overloaded. pullSecrets is more neutral and probably more accurate here.

Both options are valid. I’m happy to go with pullSecrets if you prefer it.

Just say the word and I’ll rename the field right away. 👍

Ok I buy that logic, let's stick with it for now. Just resolve merge conflicts and we'll get this merged

[ppeau]

Hi @EItanya, great question. We actually explored reusing the existing deployment imagePullSecrets first before adding a new field.
On the technical side, imagePullSecrets defined on a pod spec are consumed exclusively by the kubelet to pull container images. They are never mounted into the pod or made accessible to running containers. This means krane, executing inside the skills-init init container, has no way to read those credentials. We hit this wall directly during testing.
Even if it were technically possible, there is a design reason why it would not be the right approach in enterprise environments. The registry used to deploy the kagent system and the registry hosting skill images are typically owned by completely different teams with different security boundaries. The platform/ops team manages the kagent deployment and its registry credentials, while the line-of-business team produces and owns the skill images, hosted in their own private registry (Artifactory, ACR, ECR, etc.). Reusing the deployment imagePullSecrets would couple these two security contexts together, violate the principle of least privilege, and make skills effectively unusable for any team whose registry differs from the one used to deploy kagent. That is the common case at scale.
The new imagePullSecrets field under spec.skills directly mirrors the standard Kubernetes pattern where a pod can reference multiple imagePullSecrets for different registries. It introduces no new concept, just applies the same model at the skill level.
Happy to discuss further if needed!

Ok I buy that logic. What do you think about renaming the field to PullSecrets instead ImagePullSecrets since these aren't really images

Good point, I can see both sides here.
For keeping imagePullSecrets: Skills are stored and pulled as OCI artifacts using the exact same kubernetes.io/dockerconfigjson secrets as normal container images. The name imagePullSecrets is the standard Kubernetes convention, so it feels familiar right away. Anyone who’s used Kubernetes already knows what it means and how to set it up.
For renaming to pullSecrets: Skills aren’t executed as containers, they’re more like content or configuration that gets pulled. The original imagePullSecrets name is specifically tied to pulling runnable container images at the pod level, so using it in this context could feel a bit overloaded. pullSecrets is more neutral and probably more accurate here.
Both options are valid. I’m happy to go with pullSecrets if you prefer it.
Just say the word and I’ll rename the field right away. 👍

Ok I buy that logic, let's stick with it for now. Just resolve merge conflicts and we'll get this merged

Done! ✅
I’ve resolved the merge conflicts.

[EItanya]

Sorry for the continue reviews, is there anyway you could put this into a tmpl file similar to this existing one. In the future I want to move away from these scripts altogether, but I think they're a bit simpler to understand for now.

[ppeau]

Perfect, I'll check that out right away. I'll get back to you as soon as it's ready.

[ppeau]

Hi @Eltanya, done! The docker-auth-init script has been moved to a dedicated docker-auth-init.sh.tmpl file, following the same pattern as skills-init.sh.tmpl (//go:embed + template.Must + typed data struct). All existing tests pass including the imagePullSecrets ones.

I'll let you resolve the conversation if it looks good to you 👍