Returns all versions of Hadoop that could be used with the plugin. 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 - Hadoop versions
Example return value: (“Apache Hadoop 1.1.1”, “CDH 3”, “HDP 1.2”)
Lists all configs supported by 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))
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”]}
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”, ...]
Validates a given cluster object. Raises SaharaException with meaningful message.
Returns: None
Example exception: <NotSingleNameNodeException {code=’NOT_SINGLE_NAME_NODE’, message=’Hadoop cluster should contain only 1 NameNode instance. Actual NN count is 2’ }>
To be improved.
Validates a given cluster before scaling operation.
Returns: list of validation_errors
Plugin has a chance to change cluster description here. Specifically, plugin must specify image for VMs could change VMs specs in any way it needs. For instance, plugin can ask for additional VMs for the management tool.
Returns: None
Configures cluster on provisioned by Sahara VMs. In this function plugin should perform all actions like adjusting OS, installing required packages (including Hadoop, if needed), configuring Hadoop, etc.
Returns: None
Start already configured cluster. This method is guaranteed to be called only on cluster which was already prepared with configure_cluster(...) call.
Returns: None
Scale an existing Cluster with additional instances. 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
Scale cluster down by removing a list of instances. Plugin should stop services on a provided list of instances. Plugin also may want to update some configurations on other instances, so this method is the right place to do that.
Returns: None
Provides plugin with ability to create cluster based on plugin-specific config. Sahara expects plugin to fill in all the required fields. The last argument is the function that plugin should call to save the Cluster Template. See “Cluster Lifecycle for Config File Mode” section below for clarification.
When user terminates cluster, Sahara simply shuts down all the cluster VMs. This method is guaranteed to be invoked before that, allowing plugin to do some clean-up.
Returns: None
Returns the instance object for the host running the Oozie server (this service may be referenced by a vendor-dependent identifier)
Returns: The Oozie server instance object
Returns the URI for access to the mapred resource manager (e.g Hadoop 1.x - jobtracker, Hadoop 2.x - yarn resource manager)
Returns: The resource manager URI
Here is a description of all the objects involved in the API.
Notes:
Example list of node processes:
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 should 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. |
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. |
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 |
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. |
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. |
| tenant_id | string | OpenStack Tenant 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. |
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. |