SOPS: Secrets OPerationS - Kubernetes Operator

Operator which manages Kubernetes Secret Resources created from user defined SopsSecrets CRs, inspired by Bitnami SealedSecrets and sops. SopsSecret CR defines multiple kubernetes Secret resources. It supports managing kubernetes Secrets with annotations and labels, that allows using these kubernetes secrets as Jenkins Credentials. The SopsSecret resources can be deployed by Flux GitOps CD and encrypted using sops for AWS, GCP, Azure or on-prem hosted kubernetes clusters. Using sops greatly simplifies changing encrypted files stored in git repository.

Versioning

Requirements for building operator from source code

Requirements for building operator from source code can be found in .tool-versions, this file can be used with asdf

Operator Installation

Helm repository

Add helm repository for chart installation:

helm repo add sops https://isindir.github.io/sops-secrets-operator/

AWS

• Create KMS key
• Create AWS Role which can be used by operator to decrypt CR data structure, follow sops documentation
• Deploy CRD:

kubectl apply -f config/crd/bases/isindir.github.com_sopssecrets.yaml

NOTE: to grant access to aws for sops-secret-operator - kiam, kube2iam or IAM roles for service accounts can be used.

• Deploy helm chart:

kubectl create namespace sops

helm repo add sops https://isindir.github.io/sops-secrets-operator/
helm upgrade --install sops sops/sops-secrets-operator --namespace sops

Age

• Create age reference keys.txt file, create kubernetes secret from it.
• Deploy helm chart:
  • Use secretsAsFiles to specify the secret which contains the keys.txt.
  • Use extraEnv and specify mounted keys.txt path SOPS_AGE_KEY_FILE environment variable.

See example:

...
secretsAsFiles:
- mountPath: /etc/sops-age-key-file
  name: sops-age-key-file
  secretName: sops-age-key-file
extraEnv:
- name: SOPS_AGE_KEY_FILE
  value: /etc/sops-age-key-file/key
...

• Also see: Local testing using age

References:

• Age git repository
• SOPS Age documentation

PGP

For instructions on how-to configure PGP keys for operator, see Preparing GPG keys

Then install operator:

kubectl create namespace sops

kubectl apply -f docs/gpg/1.yaml --namespace sops
kubectl apply -f docs/gpg/2.yaml --namespace sops

kubectl apply -f config/crd/bases/isindir.github.com_sopssecrets.yaml

helm repo add sops https://isindir.github.io/sops-secrets-operator/
helm upgrade --install sops sops/sops-secrets-operator \
  --namespace sops --set gpg.enabled=true

Azure

Outline

• Create a KeyVault if you don't have one already
• Create a Key in that KeyVault
• Create Service principal with permissions to use the key for Encryption/Decryption
  • follow the SOPS documentation
• Either put Tenant ID, Client ID and Client Secret for the Service Principal in your custom values.yaml file or create a Kubernetes Secret with the same information and put the name of that secret in your values.yaml. Enable Azure in the Helm Chart by setting azure.enabled: true in values.yaml.

Login info in values.yaml

cat <<EOF > azure_values.yaml
azure:
  enabled: true
  tenantId: 6ec4c881-32ee-4340-a456-d6ca65a42193
  clientId: 9c325550-b264-4aee-ab6f-719771adda28
  clientSecret: 'YOUR_CLIENT_SECRET'
EOF

kubectl create namespace sops

helm repo add sops https://isindir.github.io/sops-secrets-operator/
helm upgrade --install sops sops/sops-secrets-operator \
  --namespace sops -f azure_values.yaml

Use pre-existing secret for Azure login

cat <<EOF > azure_secret.yaml
kind: Secret
apiVersion: v1
metadata:
  name: azure-sp-credentials
type: Opaque
stringData:
  clientId: 9c325550-b264-4aee-ab6f-719771adda28
  tenantId: 6ec4c881-32ee-4340-a456-d6ca65a42193
  clientSecret: 'YOUR_CLIENT_SECRET'
EOF

cat <<EOF > azure_values.yaml
azure:
  enabled: true
  existingSecret: azure-sp-credentials
EOF

kubectl create namespace sops
kubectl apply -n sops -f azure_secret.yaml

helm repo add sops https://isindir.github.io/sops-secrets-operator/
helm upgrade --install sops sops/sops-secrets-operator \
  --namespace sops -f azure_values.yaml

SopsSecret Custom Resource File creation

• create SopsSecret file, for example:

cat >jenkins-secrets.yaml <<EOF
apiVersion: isindir.github.com/v1alpha3
kind: SopsSecret
metadata:
  name: example-sopssecret
spec:
  # suspend reconciliation of the sops secret object
  suspend: false
  secretTemplates:
    - name: my-secret-name-1
      labels:
        label1: value1
      annotations:
        key1: value1
      stringData:
        data-name0: data-value0
      data:
        data-name1: ZGF0YS12YWx1ZTE=
    - name: jenkins-secret
      labels:
        "jenkins.io/credentials-type": "usernamePassword"
      annotations:
        "jenkins.io/credentials-description": "credentials from Kubernetes"
      stringData:
        username: myUsername
        password: 'Pa$$word'
    - name: some-token
      stringData:
        token: Wb4ziZdELkdUf6m6KtNd7iRjjQRvSeJno5meH4NAGHFmpqJyEsekZ2WjX232s4Gj
    - name: docker-login
      type: 'kubernetes.io/dockerconfigjson'
      stringData:
        .dockerconfigjson: '{"auths":{"index.docker.io":{"username":"imyuser","password":"mypass","email":"myuser@abc.com","auth":"aW15dXNlcjpteXBhc3M="}}}'
EOF

• Encrypt file using sops and AWS kms key:

sops --encrypt \
  --kms 'arn:aws:kms:<region>:<account>:alias/<key-alias-name>' \
  --encrypted-suffix='Templates' jenkins-secrets.yaml \
  > jenkins-secrets.enc.yaml

or

sops --encrypt \
  --kms 'arn:aws:kms:<region>:<account>:alias/<key-alias-name>' \
  --encrypted-regex='^(data)$' jenkins-secrets.yaml \
  > jenkins-secrets.enc.yaml

NOTE: after using regex sops --encrypted-regex resulting file may be inapplicable to the kubernetes cluster, use this feature with care

• Encrypt file using sops and GCP KMS key:

sops --encrypt \
  --gcp-kms 'projects/<project-name>/locations/<location>/keyRings/<keyring-name>/cryptoKeys/<key-name>' \
  --encrypted-suffix='Templates' jenkins-secrets.yaml \
  > jenkins-secrets.enc.yaml

• Encrypt file using sops and Azure Keyvault key:

sops --encrypt \
  --azure-kv 'https://<vault-url>/keys/<key-name>/<key-version>' \
  --encrypted-suffix='Templates' jenkins-secrets.yaml \
  > jenkins-secrets.enc.yaml

• Encrypt file using sops and PGP key:

sops --encrypt \
  --pgp '<pgp-finger-print>' \
  --encrypted-suffix='Templates' jenkins-secrets.yaml \
  > jenkins-secrets.enc.yaml

Note: Multiple keys can be used to encrypt secrets. At the time of decryption access to one of these is needed. For more information see sops documentation.

Changing ownership of existing secrets

If there is a need to re-own existing Secrets by SopsSecret, following annotation should be added to the target kubernetes native secret:

...
metadata:
  annotations:
    "sopssecret/managed": "true"
...

previously not managed secret will be replaced by SopsSecret owned at the next rescheduled reconciliation event.

Example procedure to upgrade from one SopsSecret API version to another

Please see document here: SopsSecret API and Operator Upgrade

License

Mozilla Public License Version 2.0

Known Issues

• sops-secrets-operator is not using standard sops library decryption interface function, modified upstream function is used to decrypt data which ignores enc signature field in sops metadata. This means if some encrypted fields are removed or changed to plain text - it still will be able to decrypt the resource.This is due to the fact that when Kubernetes resource is applied it is always mutated by Kubernetes, for example resource version is generated and added to the resource. But any mutation invalidates sops metadata enc field and standard decryption function fails.
• sops-secrets-operator by design is not wrapping encrypted object to some field in spec. This was deliberate decision for the simplicity of the operations - ability to directly encrypt the whole SopsSecret resource using sops cli. This causes side effects like: if the user of the k8s cluster (which runs sops-secrets-operator) has RBAC access to read secrets in some namespace - it allows directly applying encrypted SopsSecret resource to that namespaces and getting access to the secret material. This operator was only designed to protect access to the secret material from git repository.
• sops-secrets-operator is not strictly following Kubernetes OpenAPI naming conventions. This is due to the fact that sops generates substructures in encrypted file with incompatible to OpenAPI names (containing underscore symbols, where it should be lowerCamelCase for OpenAPI compatibility).

Links

Projects and tools inspired development of sops-secrets-operator:

• sops
  • Configuring AWS KMS for use with sops
  • helm secrets plugin
• kube2iam
  • kiam - in ABANDONED mode now
• Flux GitOps CD - flux supports sops out of the box
  • Flux github repositories
  • Flux sops native integration documentation
• Jenkins Configuration as Code
  • Jenkins - Kubernetes Credentials Provider
  • Jenkins Kubernetes Plugin
• Bitnami SealedSecrets
  • Using sealed secrets with Flux
• kubebuilder
  • operator-sdk

Alternative tools

• Kubernetes external secrets
• Vault Secrets Operator
• Sealed Secrets
• Secrets Store CSI driver
• Kamus
• Tesoro
• Sops Operator