MongoDB
=======

DICE TOSCA library supports three MongoDB configurations: standalone,
replicated cluster and sharded cluster.

.. note::

   Currently, only standalone MongoDB setup is fully supported. Replicated
   and sharded setups require that inter-cluster authentication is properly
   configured and we are missing a few crucial pieces of infrastructure that
   would allow us to configure it (most critical is component that can
   produce server certificates on demand, like Hashicorp Vault).

Standalone server is the simplest option. We only need a VM that will host the
mongo. By default, mongo installation does not allow unauthenticated access
and in order to start using the installation we need to define some databases
and users that can use the databases.

Mongo types also support DMon monitoring. In order to monitor the mongo
instance, simply set ``monitoring.enabled`` property to ``true``. Note that
no user database is monitored automatically. If database should be monitored,
we need to explicitly enabled monitoring on it. Note that database cannot be
monitored if mongo that contains the database is not monitored. By default,
monitoring is disabled.

In the example below, we defined mongo instance with two databases that can be
used by user single user. The first database is monitored while the second one
is not.

.. code-block:: yaml

   node_templates:

     ${MONGO}_firewall:
       type: dice.firewall_rules.mongo.Common

     ${MONGO}_vm:
       type: dice.hosts.ubuntu.${HOST_SIZE}
       relationships:
         - type: dice.relationships.ProtectedBy
           target: ${MONGO}_firewall

     ${MONGO}:
       type: dice.components.mongo.Server
       properties:
         monitoring:
           enabled: true
       relationships:
         - type: dice.relationships.ContainedIn
           target: ${MONGO}_vm

     ${MONGO}_db1:
       type: dice.components.mongo.DB
       properties:
         name: ${MONGO_DB_NAME_1}
         monitoring:
           enabled: true
       relationships:
         - type: dice.relationships.ContainedIn
           target: ${MONGO}

     ${MONGO}_db2:
       type: dice.components.mongo.DB
       properties:
         name: ${MONGO_DB_NAME_2}
       relationships:
         - type: dice.relationships.ContainedIn
           target: ${MONGO}

     ${MONGO}_user:
       type: dice.components.mongo.User
       properties:
         username: ${MONGO_USER}
       relationships:
         - type: dice.relationships.mongo.HasRightsToUse
           target: ${MONGO}_db1
         - type: dice.relationships.mongo.HasRightsToUse
           target: ${MONGO}_db2
         - type: dice.relationships.ContainedIn
           target: ${MONGO}


Preparing replicated cluster is a bit more complicated, since we need to
inform orchestrator about mongo nodes that form a replicated set:

.. code-block:: yaml

   node_templates:

     ${MONGO}_firewall:
       type: dice.firewall_rules.mongo.Common

     ${MONGO}_vm:
       type: dice.hosts.ubuntu.${HOST_SIZE}
       instances:
         deploy: ${REPLICA_SERVER_COUNT}
       relationships:
         - type: dice.relationships.ProtectedBy
           target: ${MONGO}_firewall

     ${MONGO}:
       type: dice.components.mongo.ReplicaServer
       relationships:
         - type: dice.relationships.ContainedIn
           target: ${MONGO}_vm

     ${MONGO}_replica_set:
       type: dice.components.mongo.Group
       relationships:
         - type: dice.relationships.mongo.ComposedOf
           target: ${MONGO}


Cluster setup that should be used in production environments where we expect
a heavy load should take advantage of sharding. Setting up such cluster is a
bit fiddly, but provided types should make preparing blueprint relatively
painless.

Sharded cluster consists of configuration servers, shard servers and
router(s) that are then connected into one cluster using DICE provided
relationships.

.. code-block:: yaml

   node_templates:

     ${MONGO}_firewall:
       type: dice.firewall_rules.mongo.Common

     ${MONGO}_config_vms:
       type: dice.hosts.ubuntu.{HOST_SIZE}
       instances:
         deploy: {CONFIG_SERVER_COUNT}
       relationships:
         - type: dice.relationships.ProtectedBy
           target: ${MONGO}_firewall

     ${MONGO}_config:
       type: dice.components.mongo.ConfigServer
       relationships:
         - type: dice.relationships.ContainedIn
           target: ${MONGO}_config_vms

     ${MONGO}_config_replica:
       type: dice.components.mongo.Group
       relationships:
         - type: dice.relationships.mongo.ComposedOf
           target: ${MONGO}_config

     ${MONGO}_shard_1_vms:
       type: dice.hosts.ubuntu.{HOST_SIZE}
       instances:
         deploy: {SHARD_1_SERVER_COUNT}
       relationships:
         - type: dice.relationships.ProtectedBy
           target: ${MONGO}_firewall

     ${MONGO}_shard_1:
       type: dice.components.mongo.ShardServer
       relationships:
         - type: dice.relationships.ContainedIn
           target: ${MONGO}_shard_1_vms

     ${MONGO}_shard_1_replica:
       type: dice.components.mongo.Group
       relationships:
         - type: dice.relationships.mongo.ComposedOf
           target: ${MONGO}_shard_1

     ${MONGO}_shard_2_vms:
       type: dice.hosts.ubuntu.{HOST_SIZE}
       instances:
         deploy: {SHARD_2_SERVER_COUNT}
       relationships:
         - type: dice.relationships.ProtectedBy
           target: ${MONGO}_firewall

     ${MONGO}_shard_2:
       type: dice.components.mongo.ShardServer
       relationships:
         - type: dice.relationships.ContainedIn
           target: ${MONGO}_shard_2_vms

     ${MONGO}_shard_2_replica:
       type: dice.components.mongo.Group
       relationships:
         - type: dice.relationships.mongo.ComposedOf
           target: ${MONGO}_shard_2

     ${MONGO}_router_vm:
       type: dice.hosts.ubuntu.{HOST_SIZE}
       relationships:
         - type: dice.relationships.ProtectedBy
           target: ${MONGO}_firewall

     ${MONGO}_router:
       type: dice.components.mongo.Router
       relationships:
         - type: dice.relationships.ContainedIn
           target: ${MONGO}_router_vm
         - type: dice.relationships.mongo.ConfigurationStoredIn
           target: ${MONGO}_config_replica
         - type: dice.relationships.mongo.RoutesTo
           target: ${MONGO}_shard_1_replica
         - type: dice.relationships.mongo.RoutesTo
           target: ${MONGO}_shard_2_replica


Template variables
------------------

  MONGO
    The name of the MongoDB cluster, usually set to *mongo*.

  REPLICA_SERVER_COUNT, SHARD_n_SERVER_COUNT, CONFIG_SERVER_COUNT
    Number of mongo workers that should be used to create
    replica/shard/configuration replica.

  MONGO_DB_NAME_n
    Name of the mongo database that should be created.

  MONGO_USER
    Name of the user that should be added to mongo.

  HOST_SIZE
    Size of the host virtual machine. Available values are *Small*, *Medium*
    and *Large*.