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HashiCorp Vault

HCP Vault

Hashicorp Vault

External Secrets Operator integrates with HashiCorp Vault for secret management.

The KV Secrets Engine is the only one supported by this provider. For other secrets engines, please refer to the Vault Generator.

Example

First, create a SecretStore with a vault backend. For the sake of simplicity we'll use a static token root:

apiVersion: external-secrets.io/v1beta1
kind: SecretStore
metadata:
  name: vault-backend
spec:
  provider:
    vault:
      server: "http://my.vault.server:8200"
      path: "secret"
      # Version is the Vault KV secret engine version.
      # This can be either "v1" or "v2", defaults to "v2"
      version: "v2"
      auth:
        # points to a secret that contains a vault token
        # https://www.vaultproject.io/docs/auth/token
        tokenSecretRef:
          name: "vault-token"
          key: "token"
---
apiVersion: v1
kind: Secret
metadata:
  name: vault-token
data:
  token: cm9vdA== # "root"
NOTE: In case of a ClusterSecretStore, Be sure to provide namespace for tokenSecretRef with the namespace of the secret that we just created.

Then create a simple k/v pair at path secret/foo:

vault kv put secret/foo my-value=s3cr3t

Can check kv version using following and check for Options column, it should indicate [version:2]:

vault secrets list -detailed

If you are using version: 1, just remember to update your SecretStore manifest appropriately

Now create a ExternalSecret that uses the above SecretStore:

apiVersion: external-secrets.io/v1beta1
kind: ExternalSecret
metadata:
  name: vault-example
spec:
  refreshInterval: "15s"
  secretStoreRef:
    name: vault-backend
    kind: SecretStore
  target:
    name: example-sync
  data:
  - secretKey: foobar
    remoteRef:
      key: foo
      property: my-value

  # metadataPolicy to fetch all the labels in JSON format
  - secretKey: tags
    remoteRef:
      metadataPolicy: Fetch 
      key: foo

  # metadataPolicy to fetch a specific label (dev) from the source secret
  - secretKey: developer
    remoteRef:
      metadataPolicy: Fetch 
      key: foo
      property: dev

---
# will create a secret with:
kind: Secret
metadata:
  name: example-sync
data:
  foobar: czNjcjN0

Keep in mind that fetching the labels with metadataPolicy: Fetch only works with KV sercrets engine version v2.

Fetching Raw Values

You can fetch all key/value pairs for a given path If you leave the remoteRef.property empty. This returns the json-encoded secret value for that path.

apiVersion: external-secrets.io/v1beta1
kind: ExternalSecret
metadata:
  name: vault-example
spec:
  # ...
  data:
  - secretKey: foobar
    remoteRef:
      key: /dev/package.json

Nested Values

Vault supports nested key/value pairs. You can specify a gjson expression at remoteRef.property to get a nested value.

Given the following secret - assume its path is /dev/config: 

{
  "foo": {
    "nested": {
      "bar": "mysecret"
    }
  }
}

You can set the remoteRef.property to point to the nested key using a gjson expression. 

apiVersion: external-secrets.io/v1beta1
kind: ExternalSecret
metadata:
  name: vault-example
spec:
  # ...
  data:
  - secretKey: foobar
    remoteRef:
      key: /dev/config
      property: foo.nested.bar
---
# creates a secret with:
# foobar=mysecret

If you would set the remoteRef.property to just foo then you would get the json-encoded value of that property: {"nested":{"bar":"mysecret"}}.

Multiple nested Values

You can extract multiple keys from a nested secret using dataFrom.

Given the following secret - assume its path is /dev/config: 

{
  "foo": {
    "nested": {
      "bar": "mysecret",
      "baz": "bang"
    }
  }
}

You can set the remoteRef.property to point to the nested key using a gjson expression. 

apiVersion: external-secrets.io/v1beta1
kind: ExternalSecret
metadata:
  name: vault-example
spec:
  # ...
  dataFrom:
  - extract:
      key: /dev/config
      property: foo.nested

That results in a secret with these values: 

bar=mysecret
baz=bang

Getting multiple secrets

You can extract multiple secrets from Hashicorp vault by using dataFrom.Find

Currently, dataFrom.Find allows users to fetch secret names that match a given regexp pattern, or fetch secrets whose custom_metadata tags match a predefined set.

Warning

The way hashicorp Vault currently allows LIST operations is through the existence of a secret metadata. If you delete the secret, you will also need to delete the secret's metadata or this will currently make Find operations fail.

Given the following secret - assume its path is /dev/config: 

{
  "foo": {
    "nested": {
      "bar": "mysecret",
      "baz": "bang"
    }
  }
}

Also consider the following secret has the following custom_metadata: 

{
  "environment": "dev",
  "component": "app-1"
}

It is possible to find this secret by all the following possibilities: 

apiVersion: external-secrets.io/v1beta1
kind: ExternalSecret
metadata:
  name: vault-example
spec:
  # ...
  dataFrom:
  - find: #will return every secret with 'dev' in it (including paths)
      name:
        regexp: dev
  - find: #will return every secret matching environment:dev tags from dev/ folder and beyond
      tags:
        environment: dev
will generate a secret with: 
{
  "dev_config":"{\"foo\":{\"nested\":{\"bar\":\"mysecret\",\"baz\":\"bang\"}}}"
}

Currently, Find operations are recursive throughout a given vault folder, starting on provider.Path definition. It is recommended to narrow down the scope of search by setting a find.path variable. This is also useful to automatically reduce the resulting secret key names: 

apiVersion: external-secrets.io/v1beta1
kind: ExternalSecret
metadata:
  name: vault-example
spec:
  # ...
  dataFrom:
  - find: #will return every secret from dev/ folder
      path: dev
      name:
        regexp: ".*"
  - find: #will return every secret matching environment:dev tags from dev/ folder
      path: dev
      tags:
        environment: dev
Will generate a secret with: 
{
  "config":"{\"foo\": {\"nested\": {\"bar\": \"mysecret\",\"baz\": \"bang\"}}}"
}

Authentication

We support five different modes for authentication: token-based, appRole, kubernetes-native, ldap, jwt/oidc and awsAuth, each one comes with it's own trade-offs. Depending on the authentication method you need to adapt your environment.

Token-based authentication

A static token is stored in a Kind=Secret and is used to authenticate with vault.

apiVersion: external-secrets.io/v1beta1
kind: SecretStore
metadata:
  name: vault-backend
  namespace: example
spec:
  provider:
    vault:
      server: "https://vault.acme.org"
      path: "secret"
      version: "v2"
      auth:
        # points to a secret that contains a vault token
        # https://www.vaultproject.io/docs/auth/token
        tokenSecretRef:
          name: "my-secret"
          key: "vault-token"
NOTE: In case of a ClusterSecretStore, Be sure to provide namespace in tokenSecretRef with the namespace where the secret resides.

AppRole authentication example

AppRole authentication reads the secret id from a Kind=Secret and uses the specified roleId to aquire a temporary token to fetch secrets.

apiVersion: external-secrets.io/v1beta1
kind: SecretStore
metadata:
  name: vault-backend
  namespace: example
spec:
  provider:
    vault:
      server: "https://vault.acme.org"
      path: "secret"
      version: "v2"
      auth:
        # VaultAppRole authenticates with Vault using the
        # App Role auth mechanism
        # https://www.vaultproject.io/docs/auth/approle
        appRole:
          # Path where the App Role authentication backend is mounted
          path: "approle"
          # RoleID configured in the App Role authentication backend
          roleId: "db02de05-fa39-4855-059b-67221c5c2f63"
          # Reference to a key in a K8 Secret that contains the App Role SecretId
          secretRef:
            name: "my-secret"
            key: "secret-id"
NOTE: In case of a ClusterSecretStore, Be sure to provide namespace in secretRef with the namespace where the secret resides.

Kubernetes authentication

Kubernetes-native authentication has three options of obtaining credentials for vault:

  1. by using a service account jwt referenced in serviceAccountRef
  2. by using the jwt from a Kind=Secret referenced by the secretRef
  3. by using transient credentials from the mounted service account token within the external-secrets operator

apiVersion: external-secrets.io/v1beta1
kind: SecretStore
metadata:
  name: vault-backend
  namespace: example
spec:
  provider:
    vault:
      server: "https://vault.acme.org"
      path: "secret"
      version: "v2"
      auth:
        # Authenticate against Vault using a Kubernetes ServiceAccount
        # token stored in a Secret.
        # https://www.vaultproject.io/docs/auth/kubernetes
        kubernetes:
          # Path where the Kubernetes authentication backend is mounted in Vault
          mountPath: "kubernetes"
          # A required field containing the Vault Role to assume.
          role: "demo"
          # Optional service account field containing the name
          # of a kubernetes ServiceAccount
          serviceAccountRef:
            name: "my-sa"
          # Optional secret field containing a Kubernetes ServiceAccount JWT
          #  used for authenticating with Vault
          secretRef:
            name: "my-secret"
            key: "vault"
NOTE: In case of a ClusterSecretStore, Be sure to provide namespace in serviceAccountRef or in secretRef, if used.

LDAP authentication

LDAP authentication uses username/password pair to get an access token. Username is stored directly in a Kind=SecretStore or Kind=ClusterSecretStore resource, password is stored in a Kind=Secret referenced by the secretRef.

apiVersion: external-secrets.io/v1beta1
kind: SecretStore
metadata:
  name: vault-backend
  namespace: example
spec:
  provider:
    vault:
      server: "https://vault.acme.org"
      path: "secret"
      version: "v2"
      auth:
        # VaultLdap authenticates with Vault using the LDAP auth mechanism
        # https://www.vaultproject.io/docs/auth/ldap
        ldap:
          # Path where the LDAP authentication backend is mounted
          path: "ldap"
          # LDAP username
          username: "username"
          secretRef:
            name: "my-secret"
            key: "ldap-password"
NOTE: In case of a ClusterSecretStore, Be sure to provide namespace in secretRef with the namespace where the secret resides.

JWT/OIDC authentication

JWT/OIDC uses either a JWT token stored in a Kind=Secret and referenced by the secretRef or a temporary Kubernetes service account token retrieved via the TokenRequest API. Optionally a role field can be defined in a Kind=SecretStore or Kind=ClusterSecretStore resource.

apiVersion: external-secrets.io/v1beta1
kind: SecretStore
metadata:
  name: vault-backend
  namespace: example
spec:
  provider:
    vault:
      server: "https://vault.acme.org"
      path: "secret"
      version: "v2"
      auth:
        # VaultJwt authenticates with Vault using the JWT/OIDC auth mechanism
        # https://www.vaultproject.io/docs/auth/jwt
        jwt:
          # Path where the JWT authentication backend is mounted
          path: "jwt"
          # JWT role configured in a Vault server, optional.
          role: "vault-jwt-role"

          # Retrieve JWT token from a Kubernetes secret
          secretRef:
            name: "my-secret"
            key: "jwt-token"

          # ... or retrieve a Kubernetes service account token via the `TokenRequest` API
          kubernetesServiceAccountToken:
            serviceAccountRef:
              name: "my-sa"
            # `audiences` defaults to `["vault"]` it not supplied
            audiences:
            - vault
            # `expirationSeconds` defaults to 10 minutes if not supplied
            expirationSeconds: 600
NOTE: In case of a ClusterSecretStore, Be sure to provide namespace in secretRef with the namespace where the secret resides.

AWS IAM authentication

AWS IAM uses either a set of AWS Programmatic access credentials stored in a Kind=Secret and referenced by the secretRef or by getting the authentication token from an IRSA enabled service account

Access Key ID & Secret Access Key

You can store Access Key ID & Secret Access Key in a Kind=Secret and reference it from a SecretStore.

apiVersion: external-secrets.io/v1beta1
kind: SecretStore
metadata:
  name: vault-backend-aws-iam
spec:
  provider:
    vault:
      server: "http://my.vault.server:8200"
      path: secret
      version: v2
      namespace: <vault_namespace>
      auth:
        iam:
          # Path where the AWS auth method is enabled in Vault, e.g: "aws/". Defaults to aws
          path: aws
          # AWS Region. Defaults to us-east-1
          region: us-east-1
          # optional: assume role before fetching secrets
          role: arn:aws:iam::1234567890:role/role-a
          # Vault Role. In vault, a role describes an identity with a set of permissions, groups, or policies you want to attach a user of the secrets engine
          vaultRole: vault-role-for-aws-iam-auth
          # Optional. Placeholder to supply header X-Vault-AWS-IAM-Server-ID. It is an additional (optional) header used by Vault IAM auth method to mitigate against different types of replay attacks. More details here: https://developer.hashicorp.com/vault/docs/auth/aws
          vaultAwsIamServerID: example-vaultAwsIamServerID
          secretRef: #Use this method when you have static AWS creds.
            accessKeyIDSecretRef:
              name: vault-iam-creds-secret
              key: access-key
            secretAccessKeySecretRef:
              name: vault-iam-creds-secret
              key: secret-access-key
            sessionTokenSecretRef:
              name: vault-iam-creds-secret
              key: secret-session-token

NOTE: In case of a ClusterSecretStore, Be sure to provide namespace in accessKeyIDSecretRef, secretAccessKeySecretRef with the namespaces where the secrets reside.

EKS Service Account credentials

This feature lets you use short-lived service account tokens to authenticate with AWS. You must have Service Account Volume Projection enabled - it is by default on EKS. See EKS guide on how to set up IAM roles for service accounts.

The big advantage of this approach is that ESO runs without any credentials.

apiVersion: v1
kind: ServiceAccount
metadata:
  annotations:
    eks.amazonaws.com/role-arn: arn:aws:iam::123456789012:role/my-irsa-enabled-role
  name: my-serviceaccount
  namespace: default

Reference the service account from above in the Secret Store:

apiVersion: external-secrets.io/v1beta1
kind: SecretStore
metadata:
  name: vault-backend-aws-iam
spec:
  provider:
    vault:
      server: "http://my.vault.server:8200"
      path: secret
      version: v2
      namespace: <vault_namespace>
      auth:
        iam:
          # Path where the AWS auth method is enabled in Vault, e.g: "aws/". Defaults to aws
          path: aws
          # AWS Region. Defaults to us-east-1
          region: us-east-1
          # Vault Role. In vault, a role describes an identity with a set of permissions, groups, or policies you want to attach a user of the secrets engine
          vaultRole: vault-role-for-aws-iam-auth
          # Optional. Placeholder to supply header X-Vault-AWS-IAM-Server-ID. It is an additional (optional) header used by Vault IAM auth method to mitigate against different types of replay attacks. More details here: https://developer.hashicorp.com/vault/docs/auth/aws
          vaultAwsIamServerID: example-vaultAwsIamServerID
          jwt:
            serviceAccountRef:
              name: my-serviceaccount #Provide service account with IRSA enabled

Controller's Pod Identity

This is basicially a zero-configuration authentication approach that inherits the credentials from the controller's pod identity

This approach assumes that appropriate IRSA setup is done controller's pod (i.e. IRSA enabled IAM role is created appropriately and controller's service account is annotated appropriately with the annotation "eks.amazonaws.com/role-arn" to enable IRSA)

apiVersion: external-secrets.io/v1beta1
kind: SecretStore
metadata:
  name: vault-backend-aws-iam
spec:
  provider:
    vault:
      server: "http://my.vault.server:8200"
      path: secret
      version: v2
      namespace: <vault_namespace>
      auth:
        iam:
          # Path where the AWS auth method is enabled in Vault, e.g: "aws/". Defaults to aws
          path: aws
          # AWS Region. Defaults to us-east-1
          region: us-east-1
          # Vault Role. In vault, a role describes an identity with a set of permissions, groups, or policies you want to attach a user of the secrets engine
          vaultRole: vault-role-for-aws-iam-auth
          # Optional. Placeholder to supply header X-Vault-AWS-IAM-Server-ID. It is an additional (optional) header used by Vault IAM auth method to mitigate against different types of replay attacks. More details here: https://developer.hashicorp.com/vault/docs/auth/aws
          vaultAwsIamServerID: example-vaultAwsIamServerID

NOTE: In case of a ClusterSecretStore, Be sure to provide namespace for serviceAccountRef with the namespace where the service account resides.

apiVersion: external-secrets.io/v1beta1
kind: SecretStore
metadata:
  name: vault-backend
  namespace: example
spec:
  provider:
    vault:
      server: "https://vault.acme.org"
      path: "secret"
      version: "v2"
      auth:
        # VaultJwt authenticates with Vault using the JWT/OIDC auth mechanism
        # https://www.vaultproject.io/docs/auth/jwt
        jwt:
          # Path where the JWT authentication backend is mounted
          path: "jwt"
          # JWT role configured in a Vault server, optional.
          role: "vault-jwt-role"

          # Retrieve JWT token from a Kubernetes secret
          secretRef:
            name: "my-secret"
            key: "jwt-token"

          # ... or retrieve a Kubernetes service account token via the `TokenRequest` API
          kubernetesServiceAccountToken:
            serviceAccountRef:
              name: "my-sa"
            # `audiences` defaults to `["vault"]` it not supplied
            audiences:
            - vault
            # `expirationSeconds` defaults to 10 minutes if not supplied
            expirationSeconds: 600
NOTE: In case of a ClusterSecretStore, Be sure to provide namespace in secretRef with the namespace where the secret resides.

PushSecret

Vault supports PushSecret features which allow you to sync a given kubernetes secret key into a hashicorp vault secret. In order to do so, it is expected that the secret key is a valid JSON object.

In order to use PushSecret, you need to give create, read and update permissions to the path where you want to push secrets to for both data and metadata of the secret. Use it with care!

Here is an example on how to set it up: 

apiVersion: v1
kind: Secret
metadata:
  name: source-secret
  namespace: default
stringData:
  source-key: "{\"foo\":\"bar\"}" # Needs to be a JSON
---
apiVersion: external-secrets.io/v1alpha1
kind: PushSecret
metadata:
  name: pushsecret-example
  namespace: default
spec:
  refreshInterval: 10s # Refresh interval for which push secret will reconcile
  secretStoreRefs: # A list of secret stores to push secrets to
    - name: vault-secretstore
      kind: SecretStore
  selector:
    secret:
      name: source-secret # Source Kubernetes secret to be pushed
  data:
    - match:
        secretKey: source-key # Source Kubernetes secret key containing the vault secret (in JSON format)
        remoteRef:
          remoteKey: vault/secret # path to vault secret. This path is appended with the vault-store path.

Vault Enterprise

Eventual Consistency and Performance Standby Nodes

When using Vault Enterprise with performance standby nodes, any follower can handle read requests immediately after the provider has authenticated. Since Vault becomes eventually consistent in this mode, these requests can fail if the login has not yet propagated to each server's local state.

Below are two different solutions to this scenario. You'll need to review them and pick the best fit for your environment and Vault configuration.

Vault Namespaces

Vault namespaces are an enterprise feature that support multi-tenancy. You can specify a vault namespace using the namespace property when you define a SecretStore:

apiVersion: external-secrets.io/v1beta1
kind: SecretStore
metadata:
  name: vault-backend
spec:
  provider:
    vault:
      server: "http://my.vault.server:8200"
      # See https://www.vaultproject.io/docs/enterprise/namespaces
      namespace: "ns1"
      path: "secret"
      version: "v2"
      auth:
        # ...

Read Your Writes

Vault 1.10.0 and later encodes information in the token to detect the case when a server is behind. If a Vault server does not have information about the provided token, Vault returns a 412 error so clients know to retry.

A method supported in versions Vault 1.7 and later is to utilize the X-Vault-Index header returned on all write requests (including logins). Passing this header back on subsequent requests instructs the Vault client to retry the request until the server has an index greater than or equal to that returned with the last write. Obviously though, this has a performance hit because the read is blocked until the follower's local state has caught up.

Forward Inconsistent

Vault also supports proxying inconsistent requests to the current cluster leader for immediate read-after-write consistency.

Vault 1.10.0 and later support a replication configuration that detects when forwarding should occur and does it transparently to the client.

In Vault 1.7 forwarding can be achieved by setting the X-Vault-Inconsistent header to forward-active-node. By default, this behavior is disabled and must be explicitly enabled in the server's replication configuration.