configmgmt.md

Configuration Management

As Open vStorage is completely distributed it uses a distributed configuration management system. There is currently only 1 option as configuration management system:

• Arakoon

The main configuration file

The main config file /opt/OpenvStorage/config/framework.json contains the json {"configuration_store": "arakoon"} and must be available on all Open vStorage nodes. In case of Arakoon there's the above arakoon_cacc.ini file available on all Open vStorage nodes and ALBA backend nodes. This file might be provided by external means (unattended setup) during setup, but is afterwards maintained by the Open vStorage cluster. Whoever is responsible for managing this cluster should make sure that the key __ovs_config contains a raw dump of it's config file. The ovs-watcher-config on Open vStorage nodes or asd-watcher on ALBA backend nodes (referred to as 1st-layer watchers) will monitor availability of this Arakoon (referred to as 1st-layer Arakoon). After ovs-watcher-config boots, it will start all other Arakoons (ovsdb, voldrv, abm, nsm, referred to as 2nd-layer arakoons), which will cause the ovs-watcher-framework and ovs-watcher-voldrv (referred to as 2nd-layer watchers) to start and start up the rest of the framework/voldrv/proxy/... The asd-watcher will when started trigger a start of the asd-manager and the asds. If asd-watcher detects a change in the config Arakoon's config (__ovs_config), it will update it's local arakoon_cacc.ini file and restart the asd-manager automatically. ovs-watcher-config will do the same for the ovs-nodes but will not restart the framework.

Set, get and list configuration keys

The OVS commandline allows to easily list and change the configuration parameters of the cluster:

• ovs config edit some/key: Edit that key in your $EDITOR. If it doesn't exist, the key is created.
• ovs config list some: List all keys with the given prefix.
• ovs config get some/key: Print the content of the given key.

Framework

All framework keys stated below are relative to /ovs/framework. E.g. cluster_id will be /ovs/framework/cluster_id.

Clusterwide key-values

arakoon_clusters = {"ovsdb": "$framework_arakoon_cluster_name",
                    "voldrv": "$storagedriver_arakoon_cluster_name"}
cluster_id = "$cluster_id"
install_time = "$epoch"
rdma = true|false
logging = {"type": "console|file|redis"}
memcache = {"endpoints": ["$endpoint_1", "$endpoint2"],
            "metadata": {"internal": True|False}}
messagequeue = {"endpoints": ["$endpoint_3", "$endpoint_4"],
                "protocol": "amqp",
                "user": "ovs",
                "password": "$unencrypted_password",
                "queues": {"storagedriver": "volumerouter"},
                "metadata": {"internal": True|False}}
paths = {"basedir": "/opt/OpenvStorage",
         "ovsdb": "/opt/OpenvStorage/db"}
plugins/installed = {"backends": ["$plugin_a"],
                     "generic": ["$plugin_b", "$plugin_c"]},
plugins/$plugin_a/config = {"nsm": {"safety": 3,
                                    "maxload": 75}}
stores = {"persistent": "pyrakoon",
          "volatile": "memcache"}
support = {"remote_access": True|False,
           "support_agent": True|False,
           "interval": 60}
webapps = {"html_endpoint": "/",
           "oauth2": {"mode": "local|remote",
                      "authorize_uri": "$autorize_url_for_remote",
                      "client_id": "$client_id_for_remote",
                      "client_secret": "$client_secret_for_remote",
                      "scope": "$scope_for_remote",
                      "token_uri": "$token_uri_for_remote"}}

The /ovs/framework/webapps/oauth2 mode can be either local or remote. When using remote, certain extra keys on how to reach the remote authentication platform should be given.

• authorize_uri: If a user is not logged in, he will be redirected to this page for authenitcation
• client_id: OVS client identification towards remote oauth2 platform
• client_secret: OVS client password for authenitcation to remote oauth2 platform
• scope: Requested scope for OVS users
• token_uri: URI where OVS can request the token

Cluster node specific key-values

hosts/$host_id/ip = "$host_ip"
hosts/$host_id/paths = {"celery": "/usr/bin/celery"}
hosts/$host_id/ports = {"storagedriver": [[26200, 26299]],
                        "mds": [[26300, 26399]],
                        "arakoon": [26400]}
hosts/$host_id/promotecompleted = True|False
hosts/$host_id/setupcompleted = True|False
hosts/$host_id/storagedriver = {"vmware_mode": "ganesha"}
hosts/$host_id/type = "MASTER|EXTRA|UNCONFIGURED"
hosts/$host_id/versions = {"ovs": 4,
                           "$plugin_a": $plugin_a_version}

The $host_id in above keys can be found on the respective node in /etc/openvstorage_id

Arakoon

All arakoon keys stated below are relative to /ovs/arakoon. E.g. ovsdb will be /ovs/arakoon/ovsdb.

$clustername/metadata = {"internal": True|False,
                         "type": "SD|FWK|ABM|NSM",
                         "in_use": True|False}
$clustername/config = "$raw_arakoon_config_format"

Under the hood

Arakoon

As of now, only arakoon is implemented as backend for persistent storage.

Structure

The main Configuration class contains a small number of public functions.

All functions call the _passthrough to offload the implementation to one of the underlying implementation classes.

There is an interface for these implementation classes available should you wish to plug in a different configuration store.

Passthrough

The passthrough function will dynamically call the implementation class its associated function.

The main reason for the passthrough method is to:

• Dynamically switch between stores: the current Framework unittesting mindset is flawed. A number of things are checked at runtime but before the environment variable is set, classes can already import the Configuration class, thus compiling it down with the non-mocked client
• Keep the Configuration statically accessible: mainly to keep legacy alive. The Configuration was statically approached from the start, switching it over the to factory pattern would be too troublesome