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Client Configuration

When Nessie is integrated into a broader data processing environment, authentication settings need to be provided in a way specific to the tool used.

Nessie client configuration options

See also Authentication Settings below.

Common settings

Property Description
nessie.uri Config property name (“nessie.uri”) for the Nessie service URL.
nessie.authentication.type ID of the authentication provider to use, default is no authentication.

Valid values are BASIC, BEARER, OAUTH2 and AWS.

The value is matched against the values returned as the supported auth-type by implementations of (NessieAuthenticationProvider) across all available authentication providers.

Note that “basic” HTTP authentication is not considered secure, use BEARER instead.
nessie.ref Name of the initial Nessie reference, usually main.
nessie.ref.hash Commit ID (hash) on “nessie.ref”, usually not specified.
nessie.tracing Enable adding the HTTP headers of an active OpenTracing span to all Nessie requests. Disabled by default.
nessie.client-builder-name Name of the Nessie client to use. If not specified, the implementation prefers the new Java HTTP client ( JavaHttp), if running on Java 11 or newer, or the Java URLConnection client. The Apache HTTP client ( ApacheHttp) can be used, if it has been made available on the classpath.
nessie.client-builder-impl Similar to “nessie.client-builder-name”, but uses a class name.

Deprecated Prefer using Nessie client implementation names, configured via “nessie.client-builder-name”.
nessie.enable-api-compatibility-check Enables API compatibility check when creating the Nessie client. The default is true.

You can also control this setting by setting the system property nessie.client.enable-api-compatibility-check to true or false.
nessie.client-api-version Explicitly specify the Nessie API version number to use. The default for this setting depends on the client being used.

Network settings

Property Description
nessie.transport.read-timeout Network level read timeout in milliseconds. When running with Java 11, this becomes a request timeout. Default is 25000 ms.
nessie.transport.connect-timeout Network level connect timeout in milliseconds, default is 5000.
nessie.transport.disable-compression Config property name (“nessie.transport.disable-compression”) to disable compression on the network layer, if set to true.
nessie.ssl.no-certificate-verification Optional, disables certificate verifications, if set to true. Can be useful for testing purposes, not recommended for production systems.
nessie.ssl.cipher-suites Optional, list of comma-separated cipher suites for SSL connections.

This parameter only works on Java 11 and newer with the Java HTTP client.
nessie.ssl.protocols Optional, list of comma-separated protocols for SSL connections.

This parameter only works on Java 11 and newer with the Java HTTP client.
nessie.ssl.sni-hosts Optional, comma-separated list of SNI host names for SSL connections.

This parameter only works on Java 11 and newer with the Java HTTP client.
nessie.ssl.sni-matcher Optional, a single SNI matcher for SSL connections.

Takes a single SNI hostname matcher, a regular expression representing the SNI hostnames to match.

This parameter only works on Java 11 and newer with the Java HTTP client.

HTTP settings

Property Description
nessie.http2-upgrade Optional, allow HTTP/2 upgrade, if set to true.

This parameter only works on Java 11 and newer with the Java HTTP client.
nessie.http-redirects Optional, specify how redirects are handled.

* NEVER: Never redirect.
* ALWAYS: Always redirect.
* NORMAL: Always redirect, except from HTTPS URLs to HTTP URLs.

This parameter only works on Java 11 and newer with the Java HTTP client.

Bearer authentication settings

See also Authentication Settings below.

Property Description
nessie.authentication.token Token used for BEARER authentication.

OAuth2 settings

See also Authentication Settings below.

Property Description
nessie.authentication.oauth2.issuer-url OAuth2 issuer URL.

The root URL of the OpenID Connect identity issuer provider, which will be used for discovering supported endpoints and their locations. For Keycloak, this is typically the realm URL: https://<keycloak-server>/realms/<realm-name>.

Endpoint discovery is performed using the OpenID Connect Discovery metadata published by the issuer. See OpenID Connect Discovery 1.0 for more information.

Either this property or (nessie.authentication.oauth2.token-endpoint) must be set.
nessie.authentication.oauth2.token-endpoint URL of the OAuth2 token endpoint. For Keycloak, this is typically https://<keycloak-server>/realms/<realm-name>/protocol/openid-connect/token .

Either this property or (nessie.authentication.oauth2.issuer-url) must be set. In case it is not set, the token endpoint will be discovered from the issuer URL (nessie.authentication.oauth2.issuer-url), using the OpenID Connect Discovery metadata published by the issuer.
nessie.authentication.oauth2.auth-endpoint URL of the OAuth2 authorization endpoint. For Keycloak, this is typically https://<keycloak-server>/realms/<realm-name>/protocol/openid-connect/auth .

If using the “authorization_code” grant type, either this property or (nessie.authentication.oauth2.issuer-url) must be set. In case it is not set, the authorization endpoint will be discovered from the issuer URL (nessie.authentication.oauth2.issuer-url), using the OpenID Connect Discovery metadata published by the issuer.
nessie.authentication.oauth2.device-auth-endpoint URL of the OAuth2 device authorization endpoint. For Keycloak, this is typically http://<keycloak-server>/realms/<realm-name>/protocol/openid-connect/auth/device .

If using the “Device Code” grant type, either this property or (nessie.authentication.oauth2.issuer-url) must be set.
nessie.authentication.oauth2.grant-type The grant type to use when authenticating against the OAuth2 server. Valid values are:

* “client_credentials”
* “password”
* “authorization_code”
* “device_code”

Optional, defaults to “client_credentials”.

Depending on the grant type, different properties must be provided.

For the “client_credentials” grant type, the following properties must be provided:

* token endpoint (nessie.authentication.oauth2.token-endpoint) or issuer URL (nessie.authentication.oauth2.issuer-url)
* client ID (nessie.authentication.oauth2.client-id)
* client secret (nessie.authentication.oauth2.client-secret) (if required)

For the “password” grant type, the following properties must be provided:

* token endpoint (nessie.authentication.oauth2.token-endpoint) or issuer URL (nessie.authentication.oauth2.issuer-url)
* client ID (nessie.authentication.oauth2.client-id)
* client secret (nessie.authentication.oauth2.client-secret) (if required)
* username (nessie.authentication.oauth2.username)
* password (nessie.authentication.oauth2.password)

For the “authorization_code” grant type, the following properties must be provided:

* token endpoint (nessie.authentication.oauth2.token-endpoint) or issuer URL (nessie.authentication.oauth2.issuer-url)
* authorization endpoint (nessie.authentication.oauth2.auth-endpoint) or issuer URL (nessie.authentication.oauth2.issuer-url)
* client ID (nessie.authentication.oauth2.client-id)
* client secret (nessie.authentication.oauth2.client-secret) (if required)

For the “device_code” grant type, the following properties must be provided:

* token endpoint (nessie.authentication.oauth2.token-endpoint) or issuer URL (nessie.authentication.oauth2.issuer-url)
* device authorization endpoint (nessie.authentication.oauth2.device-auth-endpoint) or issuer URL (nessie.authentication.oauth2.issuer-url)
* client ID (nessie.authentication.oauth2.client-id)
* client secret (nessie.authentication.oauth2.client-secret) (if required)

Both client and user must be properly configured with appropriate permissions in the OAuth2 server for the authentication to succeed.
nessie.authentication.oauth2.client-id Client ID to use when authenticating against the OAuth2 server. Required if using OAuth2 authentication, ignored otherwise.
nessie.authentication.oauth2.client-secret Client secret to use when authenticating against the OAuth2 server. Required if using OAuth2 authentication, ignored otherwise.
nessie.authentication.oauth2.username Username to use when authenticating against the OAuth2 server. Required if using OAuth2 authentication and “password” grant type, ignored otherwise.
nessie.authentication.oauth2.password Password to use when authenticating against the OAuth2 server. Required if using OAuth2 authentication and the “password” grant type, ignored otherwise.
nessie.authentication.oauth2.default-access-token-lifespan Default access token lifespan; if the OAuth2 server returns an access token without specifying its expiration time, this value will be used.

Optional, defaults to “PT1M”. Must be a valid ISO-8601 duration.
nessie.authentication.oauth2.default-refresh-token-lifespan Default refresh token lifespan. If the OAuth2 server returns a refresh token without specifying its expiration time, this value will be used.

Optional, defaults to “PT30M”. Must be a valid ISO-8601 duration.
nessie.authentication.oauth2.refresh-safety-window Refresh safety window to use; a new token will be fetched when the current token’s remaining lifespan is less than this value. Optional, defaults to “PT10S”. Must be a valid ISO-8601 duration.
nessie.authentication.oauth2.preemptive-token-refresh-idle-timeout Defines for how long the OAuth2 provider should keep the tokens fresh, if the client is not being actively used. Setting this value too high may cause an excessive usage of network I/O and thread resources; conversely, when setting it too low, if the client is used again, the calling thread may block if the tokens are expired and need to be renewed synchronously. Optional, defaults to “PT30S”. Must be a valid ISO-8601 duration.
nessie.authentication.oauth2.background-thread-idle-timeout Defines how long the background thread should be kept running if the client is not being actively used, or no token refreshes are being executed. Optional, defaults to “PT30S”. Setting this value too high will cause the background thread to keep running even if the client is not used anymore, potentially leaking thread and memory resources; conversely, setting it too low could cause the background thread to be restarted too often. Must be a valid ISO-8601 duration.
nessie.authentication.oauth2.client-scopes Space-separated list of scopes to include in each request to the OAuth2 server. Optional, defaults to empty (no scopes).

The scope names will not be validated by the Nessie client; make sure they are valid according to RFC 6749 Section 3.3 .
nessie.authentication.oauth2.token-exchange.enabled Enable OAuth2 token exchange. If enabled, each access token obtained from the OAuth2 server will be exchanged for a new token, using the token endpoint and the token exchange grant type, as defined in RFC 8693.
nessie.authentication.oauth2.token-exchange.issuer-url For token exchanges only. The root URL of an alternate OpenID Connect identity issuer provider, to use when exchanging tokens only.

If neither this property nor “nessie.authentication.oauth2.token-exchange.token-endpoint” are defined, the global token endpoint will be used. This means that the same authorization server will be used for both the initial token request and the token exchange.

Endpoint discovery is performed using the OpenID Connect Discovery metadata published by the issuer. See OpenID Connect Discovery 1.0 for more information.

See: NessieConfigConstants#CONF_NESSIE_OAUTH2_TOKEN_EXCHANGE_ISSUER_URL
nessie.authentication.oauth2.token-exchange.token-endpoint For token exchanges only. The URL of an alternate OAuth2 token endpoint to use when exchanging tokens only.

If neither this property nor “nessie.authentication.oauth2.token-exchange.issuer-url” are defined, the global token endpoint will be used. This means that the same authorization server will be used for both the initial token request and the token exchange.
nessie.authentication.oauth2.token-exchange.client-id For token exchanges only. An alternate client ID to use. If not provided, the global client ID will be used. If provided, and if the client is confidential, then its secret must be provided as well with “nessie.authentication.oauth2.token-exchange.client-secret” – the global client secret will NOT be used.
nessie.authentication.oauth2.token-exchange.client-secret For token exchanges only. The client secret to use, if “nessie.authentication.oauth2.token-exchange.client-id” is defined and the token exchange client is confidential.
nessie.authentication.oauth2.token-exchange.resource For token exchanges only. A URI that indicates the target service or resource where the client intends to use the requested security token. Optional.
nessie.authentication.oauth2.token-exchange.audience For token exchanges only. The logical name of the target service where the client intends to use the requested security token. This serves a purpose similar to the resource parameter but with the client providing a logical name for the target service.
nessie.authentication.oauth2.token-exchange.scopes For token exchanges only. Space-separated list of scopes to include in each token exchange request to the OAuth2 server. Optional. If undefined, the global scopes configured through (nessie.authentication.oauth2.client-scopes) will be used. If defined and null or empty, no scopes will be used.

The scope names will not be validated by the Nessie client; make sure they are valid according to RFC 6749 Section 3.3 .
nessie.authentication.oauth2.token-exchange.subject-token For token exchanges only. The subject token to exchange.

By default, the client will use its current access token as the subject token. But if this property is set, the client will use the static token provided here instead.
nessie.authentication.oauth2.token-exchange.subject-token-type For token exchanges only. The type of the subject token. By default, urn:ietf:params:oauth:token-type:access_token .

If “nessie.authentication.oauth2.token-exchange.subject-token” is set, this property will be used to define the type of the provided subject token. If that property not set, this property will define the type of the access token obtained by the client – in this case, please note that if an incorrect token type is provided, the token exchange could fail.
nessie.authentication.oauth2.token-exchange.actor-token For token exchanges only. The actor token to exchange.

By default, the client will not use an actor token. But if this property is set, the client will use the static token provided here as the actor token.
nessie.authentication.oauth2.token-exchange.actor-token-type For token exchanges only. The type of the actor token. By default, urn:ietf:params:oauth:token-type:access_token .

If “nessie.authentication.oauth2.token-exchange.actor-token” is set, this property will be used to define the type of the provided subject token. If that property not set, this property will define the type of the access token obtained by the client – in this case, please note that if an incorrect token type is provided, the token exchange could fail.
nessie.authentication.oauth2.auth-code-flow.web-port Port of the OAuth2 authorization code flow web server.

When running a client inside a container make sure to specify a port and forward the port to the container host.

The port used for the internal web server that listens for the authorization code callback. This is only used if the grant type to use is “authorization_code”.

Optional; if not present, a random port will be used.
nessie.authentication.oauth2.auth-code-flow.timeout Defines how long the client should wait for the authorization code flow to complete. This is only used if the grant type to use is “authorization_code”. Optional, defaults to “PT5M”.
nessie.authentication.oauth2.device-code-flow.timeout Defines how long the client should wait for the device code flow to complete. This is only used if the grant type to use is “device_code”. Optional, defaults to “PT5M”.
nessie.authentication.oauth2.device-code-flow.poll-interval Defines how often the client should poll the OAuth2 server for the device code flow to complete. This is only used if the grant type to use is “device_code”. Optional, defaults to “PT5S”.

AWS authentication settings

Additional AWS authentication configuration should be provided via standard AWS configuration files.

See also Authentication Settings below.

Property Description
nessie.authentication.aws.region AWS region used for AWS authentication, must be configured to the same region as the Nessie setver.
nessie.authentication.aws.profile AWS profile name used for AWS authentication (optional).

Basic authentication settings

See also Authentication Settings below.

Property Description
nessie.authentication.username Username used for the insecure BASIC authentication.

Deprecated “basic” HTTP authentication is not considered secure. Use (nessie.authentication.token) instead.
nessie.authentication.password Password used for the insecure BASIC authentication.

Deprecated “basic” HTTP authentication is not considered secure. Use (nessie.authentication.token) instead.

Java 11 connection pool options

The Java 11 HTTP client can be configured using Java system properties. Since Java’s HttpClient API does not support the configuration of these properties programmatically, Nessie cannot expose those via its configuration mechanism.

System property Meaning
jdk.httpclient.connectionPoolSize The size of the HTTP connection pool.Defaults to 0, which means the number of connections is unlimited.
jdk.httpclient.keepalive.timeout Number of seconds an idle HTTP connection will be kept alive. Defaults is 1200 seconds.
jdk.httpclient.receiveBufferSize Size of the network level receive buffer size. Defaults to 0, which means the operating system defaults apply.
jdk.httpclient.sendBufferSize Size of the network level send buffer size. Defaults to 0, which means the operating system defaults apply.

Note

See Javadoc of javax.net.ssl.SSLParameters for valid options/values for the configuration parameters starting with nessie.ssl..

Note

See Javadoc of org.projectnessie.client.NessieConfigConstants as well.

Note

In case you run into issues with Nessie’s new HTTP client for Java 11 and newer, you can try to use the legacy URLConnection based HTTP client by setting the system property or configuration option nessie.client-builder-name to URLConnection.

Spark

When Nessie is used in Spark-based environments (with Iceberg the Nessie authentication settings are configured via Spark session properties (Replace <catalog_name> with the name of your catalog).

// local spark instance, assuming NONE authentication
conf.set("spark.sql.catalog.<catalog_name>", "org.apache.iceberg.spark.SparkCatalog")
    .set("spark.sql.catalog.<catalog_name>.authentication.type", "NONE")
    .set(...);
spark = SparkSession.builder()
                    .master("local[2]")
                    .config(conf)
                    .getOrCreate();
# local spark instance, assuming NONE authentication
spark = SparkSession.builder \
        .config("spark.sql.catalog.<catalog_name>", "org.apache.iceberg.spark.SparkCatalog") \
        .config("spark.sql.catalog.<catalog_name>.authentication.type", "NONE") \
        .config(...) 
        .getOrCreate()

Property Prefixes

The spark.sql.catalog.<catalog_name> prefix identifies properties for the Nessie catalog. The <catalog_name> part is just the name of the catalog in this case (not to be confused with the Nessie project name).

Multiple Nessie catalogs can be configured in the same Spark environment, each with its own set of configuration properties and its own property name prefix.

When Nessie is used in Flink with Iceberg, the Nessie authentication settings are configured when creating the Nessie catalog in Flink (Replace <catalog_name> with the name of your catalog):

table_env.execute_sql(
        """CREATE CATALOG <catalog_name> WITH (
        'type'='iceberg',
        'catalog-impl'='org.apache.iceberg.nessie.NessieCatalog',
        'authentication.type'='NONE')""")

Authentication Settings

The sections below discuss specific authentication settings. The property names are shown without environment-specific prefixes for brevity. Nonetheless, in practice the property names should be given appropriate prefixes (as in the examples above) for them to be recognized by the tools and Nessie code.

The value of the authentication.type property can be one of the following:

  • NONE (default)
  • BEARER
  • OAUTH2
  • AWS

Authentication Type NONE

For the Authentication Type NONE only the authentication.type property needs to be set.

This is also the default authentication type if nothing else is configured.

Authentication Type BEARER

For the BEARER Authentication Type the authentication.token property should be set to a valid OpenID token.

This authentication type is recommended only when the issued access token has a lifespan large enough to cover the duration of the entire Nessie client’s session. Once the token is expired, the Nessie client will not be able to refresh it and will have to be restarted, with a different token. If the token needs to be refreshed periodically, then the OAUTH2 authentication type should be preferred to this one.

Authentication Type OAUTH2

The OAUTH2 Authentication Type is able to authenticate against an OAuth2 server and obtain a valid access token. Only Bearer access tokens are currently supported. The access token is then used to authenticate against Nessie. The client will automatically refresh the access token. This authentication type is recommended when the access token has a lifespan shorter than the Nessie client’s session lifespan.

Note that the Nessie server must be configured to accept OAuth2 tokens from the same server. For example, if the OAuth2 server is Keycloak, this can be done by defining the following properties in the application.properties file of the Nessie server:

nessie.server.authentication.enabled=true
quarkus.oidc.auth-server-url=https://<keycloak-server>/realms/<realm-name>

The most important property is authentication.oauth2.grant-type, which defines the grant type to use when authenticating against the OAuth2 server. Valid values are:

The full list of available properties is shown hereafter. Depending on the grant type, some of them must be provided:

  • For the “client_credentials” grant type, at least the following properties must be provided:
  • authentication.oauth2.issuer-url or authentication.oauth2.token-endpoint
  • authentication.oauth2.client-id
  • authentication.oauth2.client-secret
  • For the “password” grant type, at least the following properties must be provided:
  • authentication.oauth2.issuer-url or authentication.oauth2.token-endpoint
  • authentication.oauth2.client-id
  • authentication.oauth2.client-secret
  • authentication.oauth2.username
  • authentication.oauth2.password
  • For the “authorization_code” grant type, at least the following properties must be provided:
  • authentication.oauth2.issuer-url, or both authentication.oauth2.token-endpoint and authentication.oauth2.auth-endpoint
  • authentication.oauth2.client-id
  • authentication.oauth2.client-secret
  • authentication.oauth2.auth-endpoint
  • For the “device_code” grant type, at least the following properties must be provided:
  • authentication.oauth2.issuer-url, or both authentication.oauth2.token-endpoint and authentication.oauth2.deivce-auth-endpoint
  • authentication.oauth2.client-id
  • authentication.oauth2.client-secret
  • authentication.oauth2.auth-endpoint

Here are the available properties for the OAUTH2 authentication type:

  • authentication.oauth2.issuer-url: The root URL of the OpenID Connect identity issuer provider, which will be used for discovering supported endpoints and their locations. For Keycloak, this is typically the realm URL: https://<keycloak-server>/realms/<realm-name>. Optional. Either this property or the authentication.oauth2.token-endpoint property must be provided. Endpoint discovery is performed using the OpenID Connect Discovery metadata published by the issuer. See OpenID Connect Discovery 1.0 for more information.

  • authentication.oauth2.token-endpoint: the URL of the OAuth2 token endpoint. For Keycloak, this is typically https://<keycloak-server>/realms/<realm-name>/protocol/openid-connect/token. Optional. Either this property or the authentication.oauth2.issuer-url property must be provided.

  • authentication.oauth2.auth-endpoint: the URL of the OAuth2 auth endpoint. For Keycloak, this is typically https://<keycloak-server>/realms/<realm-name>/protocol/openid-connect/auth. If using the “authorization_code” grant type, either this property or the authentication.oauth2.issuer-url property must be provided.

  • authentication.oauth2.device-auth-endpoint: the URL of the OAuth2 device auth endpoint. For Keycloak, this is typically https://<keycloak-server>/realms/<realm-name>/protocol/openid-connect/auth/device. If using the “device_code” grant type, either this property or the authentication.oauth2.issuer-url property must be provided.

  • authentication.oauth2.client-id: the client ID to use when authenticating against the OAuth2 server. Required.

  • authentication.oauth2.client-secret: the client secret to use when authenticating against the OAuth2 server. Required.

  • authentication.oauth2.username: the username to use when authenticating against the OAuth2 server. Required if using the “password” grant type.

  • authentication.oauth2.password: the password to use when authenticating against the OAuth2 server. Required if using the “password” grant type.

  • authentication.oauth2.default-access-token-lifespan: the default access token lifespan; if the OAuth2 server returns an access token without specifying its expiration time, this value will be used. Optional, defaults to PT1M (1 minute). Must be a valid ISO-8601 duration.

  • authentication.oauth2.default-refresh-token-lifespan: the default refresh token lifespan; if the OAuth2 server returns a refresh token without specifying its expiration time, this value will be used. Optional, defaults to PT30M (30 minutes). Must be a valid ISO-8601 duration.

  • authentication.oauth2.refresh-safety-window: the refresh safety window to use; a new token will be fetched when the current token’s remaining lifespan is less than this value. Optional, defaults to PT10S (10 seconds). Must be a valid ISO-8601 duration.

  • authentication.oauth2.client-scopes: space-separated list of scopes to include in each request to the OAuth2 server. Optional, defaults to empty (no scopes). The scope names will not be validated by the Nessie client; make sure they are valid according to RFC 6749 Section 3.3.

  • authentication.oauth2.token-exchange-enabled: if set to true, the Nessie client will attempt to exchange access tokens for refresh tokens whenever appropriate. This, however, can only work if the OAuth2 server supports token exchange. Optional, defaults to true (enabled). Note that recent versions of Keycloak support token exchange, but it is disabled by default. See Using token exchange for more information and how to enable this feature.

  • authentication.oauth2.preemptive-token-refresh-idle-timeout: for how long the Nessie client should keep the tokens fresh, if the client is not being actively used. Setting this value too high may cause an excessive usage of network I/O and thread resources; conversely, when setting it too low, if the client is used again, the calling thread may block if the tokens are expired and need to be renewed synchronously. Optional, defaults to PT30S (30 seconds). Must be a valid ISO-8601 duration.

  • authentication.oauth2.background-thread-idle-timeout: how long the Nessie client should keep a background thread alive, if the client is not being actively used, or no token refreshes are being executed. Setting this value too high will cause the background thread to keep running even if the client is not used anymore, potentially leaking thread and memory resources; conversely, setting it too low could cause the background thread to be restarted too often. Optional, defaults to PT30S (30 seconds). Must be a valid ISO-8601 duration.

  • authentication.oauth2.auth-code-flow.web-port: The port used for the embedded web server that listens for the authorization code callback. This is only used if the grant type to use is “authorization_code”. Optional; if not present, a random port will be used.

  • authentication.oauth2.auth-code-flow.timeout: How long the client should wait for the authorization code flow to complete. This is only used if the grant type to use is “authorization_code”. Optional, defaults to PT5M (5 minutes). Must be a valid ISO-8601 duration.

  • authentication.oauth2.device-code-flow.timeout: How long the client should wait for the device code flow to complete. This is only used if the grant type to use is “device_code”. Optional, defaults to PT5M (5 minutes). Must be a valid ISO-8601 duration.

  • authentication.oauth2.device-code-flow.poll-interval: How often the client should poll the device authorization endpoint for a token. This is only used if the grant type to use is “device_code”. Optional, defaults to PT5S (5 seconds). Must be a valid ISO-8601 duration.

Which grant type to use?

The “client_credentials” grant type is the simplest one, but it requires the client to be granted enough permissions to access the Nessie server on behalf of the user. This is not always possible, and should be avoided if the resource owner (the user) is a human.

The “password” grant type is also simple, but it requires passing the user’s password to the client, which may not be acceptable in some cases for security reasons.

For real users trying to authenticate within a terminal session, such as a Spark shell, the “authorization_code” grant type is recommended. It requires the user to authenticate in a browser window, thus sparing the need to provide the user’s password directly to the client. The user will be prompted to authenticate in a separate browser window, and the Nessie client will be notified when the authentication is complete.

If the terminal session is running remotely however, on inside an embedded device, then the “authorization_code” grant type may not be suitable, as the browser and the terminal session must be running on the same machine. In this case, the “device_code” grant type is recommended. Similar to the “authorization_code” grant type, it requires the user to authenticate in a browser window, but it does not require the browser and the terminal session to be running on the same machine. The user will be prompted to authenticate in a local browser window, and the remote Nessie client will poll the OAuth2 server for the authentication status, until the authentication is complete.