Core Framework & Executor types

Describes a master. This will probably have more fields in the future which might be used, for example, to link a framework web UI to a master web UI.

Describes a slave. Note that the slaveInfoSlaveID field is only available after a slave is registered with the master, and is made available here to facilitate re-registration. If checkpoint is set, the slave is checkpointing its own information and potentially frameworks' information (if a framework has checkpointing enabled).

Describes a framework. If the user field is set to an empty string Mesos will automagically set it to the current user. Note that the ID is only available after a framework has registered, however, it is included here in order to facilitate scheduler failover (i.e., if it is set then the SchedulerDriver expects the scheduler is performing failover). The amount of time that the master will wait for the scheduler to failover before removing the framework is specified by frameworkFailoverTimeout. If frameworkCheckpoint is set, framework pid, executor pids and status updates are checkpointed to disk by the slaves. Checkpointing allows a restarted slave to reconnect with old executors and recover status updates, at the cost of disk I/O. The frameworkRole field is used to group frameworks for allocation decisions, depending on the allocation policy being used. If the frameworkHostname field is set to an empty string Mesos will automagically set it to the current hostname.

Describes some resources available on a slave. An offer only contains resources from a single slave.

Describes a request for resources that can be used by a framework to proactively influence the allocator.

Describes a task. Passed from the scheduler all the way to an executor (see SchedulerDriver::launchTasks and Executor::launchTask).

A different executor can be used to launch this task, and subsequent tasks meant for the same executor can reuse the same ExecutorInfo struct.

Describes a command, executed via:

/bin/sh -c value

Any URIs specified are fetched before executing the command. If the executable field for an uri is set, executable file permission is set on the downloaded file. Otherwise, if the downloaded file has a recognized archive extension (currently [compressed] tar and zip) it is extracted into the executor's working directory. In addition, any environment variables are set before executing the command (so they can be used to "parameterize" your command).

Describes a resource on a machine. A resource can take on one of three types: scalar (double), a list of finite and discrete ranges (e.g., [1-10, 20-30]), or a set of items.

N.B. there is a slight deviation from the C++ API: the Haskell bindings convert Text values into a single element Set value in order to avoid having to expose yet another data type.

Indicates the state of the scheduler and executor driver after function calls.

Describes the current status of a task.

Describes possible task states. IMPORTANT: Mesos assumes tasks that enter terminal states (see below) imply the task is no longer running and thus clean up any thing associated with the task (ultimately offering any resources being consumed by that task to another task).

A unique ID assigned to a framework. A framework can reuse this ID in order to do failover.

A unique ID assigned to a slave. Currently, a slave gets a new ID whenever it (re)registers with Mesos. Framework writers shouldn't assume any binding between a slave ID and and a hostname.

A unique ID assigned to an offer.

A framework generated ID to distinguish a task. The ID must remain unique while the task is active. However, a framework can reuse an ID _only_ if a previous task with the same ID has reached a terminal state (e.g., Finished, Lost, Killed, etc.). See isTerminal for a utility function to simplify checking task state.

A framework generated ID to distinguish an executor. Only one executor with the same ID can be active on the same slave at a time.

A slave generated ID to distinguish a container. The ID must be unique between any active or completed containers on the slave. In particular, containers for different runs of the same (framework, executor) pair must be unique.

Describes a snapshot of the resource usage for an executor.

Resource usage is for an executor. For tasks launched with an explicit executor, the executor id is provided. For tasks launched without an executor, our internal executor will be used. In this case, we provide the task id here instead, in order to make this message easier for schedulers to work with.

Credential used for authentication.

NOTE: credentialPrincipal is used for authenticating the framework with the master. This is different from frameworkUser which is used to determine the user under which the framework's executors/tasks are run.