Plugin SPI¶
Plugin interface¶
get_versions()¶
Returns all available versions of the plugin. Depending on the plugin, this version may map directly to the HDFS version, or it may not; check your plugin’s documentation. It is responsibility of the plugin to make sure that all required images for each hadoop version are available, as well as configs and whatever else that plugin needs to create the Hadoop cluster.
Returns: list of strings representing plugin versions
Example return value: [“1.2.1”, “2.3.0”, “2.4.1”]
get_configs( hadoop_version )¶
Lists all configs supported by the plugin with descriptions, defaults, and targets for which this config is applicable.
Returns: list of configs
Example return value: ((“JobTracker heap size”, “JobTracker heap size, in MB”, “int”, “512”, “mapreduce”, “node”, True, 1))
get_node_processes( hadoop_version )¶
Returns all supported services and node processes for a given Hadoop version. Each node process belongs to a single service and that relationship is reflected in the returned dict object. See example for details.
Returns: dictionary having entries (service -> list of processes)
Example return value: {“mapreduce”: [“tasktracker”, “jobtracker”], “hdfs”: [“datanode”, “namenode”]}
get_required_image_tags( hadoop_version )¶
Lists tags that should be added to OpenStack Image via Image Registry. Tags are used to filter Images by plugin and hadoop version.
Returns: list of tags
Example return value: [“tag1”, “some_other_tag”, ...]
validate( cluster )¶
Validates a given cluster object. Raises a SaharaException with a meaningful message in the case of validation failure.
Returns: None
Example exception: <NotSingleNameNodeException {code=’NOT_SINGLE_NAME_NODE’, message=’Hadoop cluster should contain only 1 NameNode instance. Actual NN count is 2’ }>
validate_scaling( cluster, existing, additional )¶
To be improved.
Validates a given cluster before scaling operation.
Returns: list of validation_errors
update_infra( cluster )¶
This method is no longer used now that Sahara utilizes Heat for OpenStack resource provisioning, and is not currently utilized by any plugin.
Returns: None
configure_cluster( cluster )¶
Configures cluster on the VMs provisioned by sahara. In this function the plugin should perform all actions like adjusting OS, installing required packages (including Hadoop, if needed), configuring Hadoop, etc.
Returns: None
start_cluster( cluster )¶
Start already configured cluster. This method is guaranteed to be called only on a cluster which was already prepared with configure_cluster(...) call.
Returns: None
scale_cluster( cluster, instances )¶
Scale an existing cluster with additional instances. The instances argument is a list of ready-to-configure instances. Plugin should do all configuration operations in this method and start all services on those instances.
Returns: None
get_edp_engine( cluster, job_type )¶
Returns an EDP job engine object that supports the specified job_type on the given cluster, or None if there is no support. The EDP job engine object returned must implement the interface described in Elastic Data Processing (EDP) SPI. The job_type is a String matching one of the job types listed in Job Types.
Returns: an EDP job engine object or None
decommission_nodes( cluster, instances )¶
Scale cluster down by removing a list of instances. The plugin should stop services on the provided list of instances. The plugin also may need to update some configurations on other instances when nodes are removed; if so, this method must perform that reconfiguration.
Returns: None
on_terminate_cluster( cluster )¶
When user terminates cluster, sahara simply shuts down all the cluster VMs. This method is guaranteed to be invoked before that, allowing the plugin to do some clean-up.
Returns: None
get_open_ports( node_group )¶
When user requests sahara to automatically create a security group for the
node group (auto_security_group property set to True), sahara will call
this plugin method to get a list of ports that need to be opened.
Returns: list of ports to be open in auto security group for the given node group
get_edp_job_types( versions )¶
Optional method, which provides the ability to see all supported job types for specified plugin versions.
Returns: dict with supported job types for specified versions of plugin
recommend_configs( self, cluster, scaling=False )¶
Optional method, which provides recommendations for cluster configuration before creating/scaling operation.
get_image_arguments( self, hadoop_version ):¶
Optional method, which gets the argument set taken by the plugin’s image generator, or NotImplemented if the plugin does not provide image generation support. See Image Generation.
Returns: A sequence with items of type sahara.plugins.images.ImageArgument.
pack_image( self, hadoop_version, remote, reconcile=True, ... ):¶
Optional method which packs an image for registration in Glance and use by Sahara. This method is called from the image generation CLI rather than from the Sahara api or engine service. See Image Generation.
Returns: None (modifies the image pointed to by the remote in-place.)
validate_images( self, cluster, reconcile=True, image_arguments=None ):¶
Validates the image to be used to create a cluster, to ensure that it meets the specifications of the plugin. See Image Generation.
Returns: None; may raise a sahara.plugins.exceptions.ImageValidationError
Object Model¶
Here is a description of all the objects involved in the API.
Notes:
- clusters and node_groups have ‘extra’ fields allowing the plugin to persist any supplementary info about the cluster.
- node_process is just a process that runs on some node in cluster.
Example list of node processes:
- jobtracker
- namenode
- tasktracker
- datanode
- Each plugin may have different names for the same processes.
Config¶
An object, describing one configuration entry
| Property | Type | Description |
|---|---|---|
| name | string | Config name. |
| description | string | A hint for user, what this config is used for. |
| config_type | enum | possible values are: ‘string’, ‘integer’, ‘boolean’, ‘enum’. |
| config_values | list | List of possible values, if config_type is enum. |
| default_value | string | Default value for config. |
| applicable_target | string | The target could be either a service returned by get_node_processes(...) call in form of ‘service:<service name>’, or ‘general’. |
| scope | enum | Could be either ‘node’ or ‘cluster’. |
| is_optional | bool | If is_optional is False and no default_value is specified, user must provide a value. |
| priority | int | 1 or 2. A Hint for UI. Configs with priority 1 are always displayed. Priority 2 means user should click a button to see the config. |
User Input¶
Value provided by user for a specific config.
| Property | Type | Description |
|---|---|---|
| config | config | A config object for which this user_input is provided. |
| value | ... | Value for the config. Type depends on Config type. |
Instance¶
An instance created for cluster.
| Property | Type | Description |
|---|---|---|
| instance_id | string | Unique instance identifier. |
| instance_name | string | OpenStack instance name. |
| internal_ip | string | IP to communicate with other instances. |
| management_ip | string | IP of instance, accessible outside of internal network. |
| volumes | list | List of volumes attached to instance. Empty if ephemeral drive is used. |
| nova_info | object | Nova instance object. |
| username | string | Username, that sahara uses for establishing remote connections to instance. |
| hostname | string | Same as instance_name. |
| fqdn | string | Fully qualified domain name for this instance. |
| remote | helpers | Object with helpers for performing remote operations. |
Node Group¶
Group of instances.
| Property | Type | Description |
|---|---|---|
| name | string | Name of this Node Group in Cluster. |
| flavor_id | string | OpenStack Flavor used to boot instances. |
| image_id | string | Image id used to boot instances. |
| node_processes | list | List of processes running on each instance. |
| node_configs | dict | Configs dictionary, applied to instances. |
| volumes_per_node | int | Number of volumes mounted to each instance. 0 means use ephemeral drive. |
| volumes_size | int | Size of each volume (GB). |
| volumes_mount_prefix | string | Prefix added to mount path of each volume. |
| floating_ip_pool | string | Floating IP Pool name. All instances in the Node Group will have Floating IPs assigned from this pool. |
| count | int | Number of instances in this Node Group. |
| username | string | Username used by sahara to establish remote connections to instances. |
| configuration | dict | Merged dictionary of node configurations and cluster configurations. |
| storage_paths | list | List of directories where storage should be placed. |
Cluster¶
Contains all relevant info about cluster. This object is is provided to the plugin for both cluster creation and scaling. The “Cluster Lifecycle” section below further specifies which fields are filled at which moment.
| Property | Type | Description |
|---|---|---|
| name | string | Cluster name. |
| project_id | string | OpenStack Project id where this Cluster is available. |
| plugin_name | string | Plugin name. |
| hadoop_version | string | Hadoop version running on instances. |
| default_image_id | string | OpenStack image used to boot instances. |
| node_groups | list | List of Node Groups. |
| cluster_configs | dict | Dictionary of Cluster scoped configurations. |
| cluster_template_id | string | Cluster Template used for Node Groups and Configurations. |
| user_keypair_id | string | OpenStack keypair added to instances to make them accessible for user. |
| neutron_management_network | string | Neutron network ID. Instances will get fixed IPs in this network if ‘use_neutron’ config is set to True. |
| anti_affinity | list | List of processes that will be run on different hosts. |
| description | string | Cluster Description. |
| info | dict | Dictionary for additional information. |
Validation Error¶
Describes what is wrong with one of the values provided by user.
| Property | Type | Description |
|---|---|---|
| config | config | A config object that is not valid. |
| error_message | string | Message that describes what exactly is wrong. |