Credentials in Kestra – Secure Authentication to External Systems

Authenticate to external systems securely.

Credentials – Server to Server authentication for Flows

Credentials are a reusable way to configure server-to-server authentication credentials once and use it across tasks.

Instead of embedding token minting/refresh logic in each plugin, Kestra can mint and refresh access tokens at runtime and you reference them in your workflow with a simple expression.

Many APIs are moving away from long-lived static API keys toward short-lived tokens (e.g. OAuth 2.0), which improves security and simplifies rotation and revocation.

For simple static values (API keys, usernames/passwords), use Secrets directly.

Sensitive material used by a credential (client secrets, private keys, certificates) is referenced via Secrets so it can be stored in external or read-only secret managers (e.g., Secrets Manager or Read-only Secrets) and never appears in plain text in the credential config.

Availability and scope

Credentials can be accessed and created at:

• Tenant level (reusable across namespaces in that tenant)
• Namespace level (scoped to a single namespace)

During setup, Kestra lets you test token retrieval from the UI to ensure your configuration is correct.

Use a credential in a flow

Use the credential() Pebble function to retrieve the current access token for a credential key.

id: api_call
namespace: company.team
 
tasks:
 - id: request
 type: io.kestra.plugin.core.http.Request
 uri: https://api.example.com/v1/ping
 method: GET
 auth:
 type: BEARER
 token: "{{ credential('my_oauth') }}"

credential() returns the access token only.

For non-sensitive configuration (e.g., hostnames, table names, feature flags), prefer Variables.

Credential types

Credentials cover common server-to-server authentication patterns, including:

• OAuth2 client_credentials (generic)
• OAuth2 JWT Bearer extension grant (jwt_bearer, RFC 7523)
• OAuth2 private_key_jwt (client authentication)
• GitHub App

Credentials can reference sensitive inputs via existing Secrets (e.g., client secrets, private keys, certificates), including secrets stored in an external or read-only secrets manager.

Example: Google service account with JWT Bearer

The following example shows how to use a Google Cloud service account with an OAuth2 JWT Bearer credential in Kestra.

1. Create a service account in Google Cloud

In Google Cloud:

1. Go to IAM & Admin -> Service Accounts.
2. Create a new service account and grant it only the roles required for your use case.
3. Open the service account, go to Keys, and create a new JSON key.
4. Download the JSON key file.

From that JSON file, you will use:

• client_email
• private_key
• private_key_id
• token_uri

For more information, see the Google service account guide.

2. Create a secret for the private key

Store the private key from the downloaded JSON in a Kestra secret rather than embedding it directly in the credential.

For example, create a secret named GCP_PRIVATE_KEY with the value of the private_key field from the JSON file.

You can manage that secret from the Kestra UI or by using an external Secrets Manager.

3. Create the credential in Kestra

In the Credentials UI, create a new credential with the following values:

• Credential Type: OAUTH2
• Auth Config Type: JWT_BEARER
• Token Endpoint: https://oauth2.googleapis.com/token
• Issuer: the client_email value from the JSON key
• Subject: use the service account email for a standard service account flow; for Google Workspace domain-wide delegation, use the delegated user instead
• Private Key: reference the GCP_PRIVATE_KEY secret
• Key ID: the private_key_id value from the JSON key
• Algorithm: RS256
• Additional Claims: add a scope claim containing the Google OAuth scopes required by the API, for example https://www.googleapis.com/auth/cloud-platform.read-only

For Google service accounts, the scope must be included in the JWT claims. If you need multiple scopes, provide them as a single space-delimited string in the scope claim, for example:

https://www.googleapis.com/auth/cloud-platform.read-only https://www.googleapis.com/auth/bigquery.readonly

4. Use the credential in a flow

Once the credential is saved, you can use it in a flow with the credential() Pebble function.

The example below calls the Google Cloud Resource Manager API and sends the access token as a Bearer token in the request header:

id: google_api_with_credential
namespace: company.team
 
inputs:
 - id: project_id
 type: STRING
 
tasks:
 - id: request
 type: io.kestra.plugin.core.http.Request
 method: GET
 uri: "https://cloudresourcemanager.googleapis.com/v1/projects/{{ inputs.project_id }}"
 options:
 auth:
 type: BEARER
 token: "{{ credential('gcp-service-account') }}"
 
 - id: log_result
 type: io.kestra.plugin.core.log.Log
 message: |
 code={{ outputs.request.code }}
 body={{ outputs.request.body }}

If the service account has the required permissions on the target project, the request should return 200 and the project metadata in the response body.

Token lifecycle and caching

• Tokens are not persisted.
• The token cache is in-memory only (when enabled).
• Tokens are retrieved during task execution and refreshed based on the Refresh before expiry setting configured on the credential.
• Token caching can be enabled or disabled per credential.

Credential hygiene

• Least privilege: scope credentials to the smallest set of permissions required.
• Rotate regularly: prefer short-lived tokens where possible; rotate long-lived keys.
• Avoid leaking values: don’t print tokens or derived values (e.g., substrings) to logs; see Best Practices for Secrets.