Convert Consoles To Use Objects Framework¶

https://blueprints.launchpad.net/nova/+spec/convert-consoles-to-objects

Make consoles to use the objects framework – the current console code does not take advantage of the framework objects, instead it provides some types (console/type.py) to handle them. These types do not provide any features to handle versioning, RPC or any kind of methods to make them useful.

Problem description¶

The current code does not provide any mechanism to handle versioning. Additionally, since RPC cannot handle classes derived from the Python object type, we need to handle a dict “connect_info” between RPC calls and no way is provided to share the state of the console across processes.

Another problem comes with the token, memcached is not a database and cannot guarantee that the expire time will be respected, a token can expire before that limit (eviction). By using the framework objects we can get the opportunity to store the whole state of Console object with a valid token in the database and share the state between process.

For instance bug 1425640 needs to know when an user is connected to a particular port from a number of perspectives: from the compute node, to return the next port defined and not connected; from the proxy to reject new connections on already connected port from the API to let user informed no more port are available.

We will also enhance security by only storing a hash of tokens in the database after to have returned the clean one to the users. Then when users will request to connect a console the token passed will be hashed and compared to the one stored in the database for validation.

A new option will be introduced [workarounds]enable_consoleauth which will allow operators to opt-in to enabling use of both the database and legacy consoleauth backend at the same time. The use case for this is if the operator does not want all of their already existing console authorizations to be invalidated once the database backend is available. Usually, the TTL for console authorizations is short-lived (default is 10 minutes) so invalidating existing consoles should not be a problem in the usual case. However, if an operator has configured much longer TTL, they may want to take advantage of the [workarounds]enable_consoleauth option to allow fall back to consoleauth for already existing consoles. Once all pre-database-backend console authorizations have expired, the operator may set [workarounds]enable_consoleauth back to False and stop running the consoleauth service.

The consoleauth service will be retained for legacy compatibility but in a deprecated status, supported for one release. After the period the consoleauth service can be removed.

Because the new tokens will go in the database we need to consider cells v2. The child cell database is the appropriate place for console connection info because it relates directly to instances. Currently the console connection URLs returned to the user only contain a token. This is not sufficient to determine which cell holds the console connection. An initial idea for handling this was to add the instance uuid to the console proxy URL and use it to target the instance’s cell database for the verification of the origin protocol by the console proxy. However, when we added the instance uuid to the URLs, the Tempest jobs failed on the noVNC tests because noVNC was not able to separate more than one query parameter in the URL, so the ?instance_uuid=<uuid> portion of the URL was being considered as part of the token, the first query parameter token=<token>. So, instead we will resolve the cell database issue by running console proxies per cell instead of global to a deployment, such that the cell database is local to the console proxy. This approach is backward compatible with the existing console proxies and also decreases load on a large deployment by sharding proxies per cell instead of all consoles for the deployment going through one centralized proxy.

Use Cases¶

Developer can take advantage of using the framework objects when adding a new console or features.

Proposed change¶

Define a new ConsoleAuthToken object.
Convert drivers to generate ConsoleAuthToken object.
Define schema and API to store ConsoleAuthToken object in child cell database.
Update code to store ConsoleAuthToken with valid token in database or consoleauth dependant on the switch until consoleauth is removed.
Update proxies to use the database or consoleauth dependant on the switch until consoleauth is removed.
Define a periodic task to clean expired object stored in database; To balance the load and avoid blocking the database during too much time each compute nodes will be responsible to clean connection_info for guests they host.
Add a config option [workarounds]enable_consoleauth defaulting to False that operators can opt-in to if they wish to run the legacy consoleauth service to fall back on if they have configured long TTL for console authorizations and do not wish to have already existing consoles invalidated once the database backend is available.
Update documentation to reflect the new required deployment layout where console proxies are run per cell.
Fix bug 1425640

Alternatives¶

Continue to use memcached as a backend will make the behavior of connection information not previsible since objects can be evicted. Also in order to fix issue 1425640 and 1455252 a scan has to be done to list available ports which is difficult when using memcached without add specific code to maintain a list of stored keys.

Data model impact¶

A new ConsoleAuthToken model needs to be defined with attributes:

instance: an instance which refer the console
host: a string field to handle hostname
port: an int field to handle service number
token_hash: a string field to handle a token or null
access_url: a string field to handle access or null
options: a dict field to handle particular information like usetls, internal_access_path, mode…
expires: a date time to indicate when the token expires or null

The database schema

CREATE TABLE console_connection (
     instance_uuid CHAR(36) NOT NULL,
     host VARCHAR(255) NOT NULL,
     port INT NOT NULL,
     token_hash CHAR(40),
     access_url VARCHAR(255),
     options TEXT,
     expires DATETIME,

     PRIMARY KEY (instance_uuid, host, port),
     INDEX (token, instance_uuid),
     FOREIGN KEY (instance_uuid)
       REFERENCES instances(uuid)
       ON DELETE CASCADE
);

Note

No migration are expected from serialized dicts connection info stored in memcached to the database, during the upgrade clients already connected to consoles will keep their connections until proxy will be restarted. At this step we expect to have the consoleauth service to also have been restarted.

REST API impact¶

None

Security impact¶

In the point of view of tokens we can expect a better security since currently tokens are stored in memcached which does not provide any security layer. Now only hash of tokens will be stored in the database also security policy will enhanced to be the same than other critical components stored in database.

Notifications impact¶

None

Other end user impact¶

When proxyclient will be restartred users will be disconnected from our consoles but should reconnect to it with the same token if not already expired.

Performance Impact¶

The database load will increase but we can expect that with a minimal impact for DBA.

Other deployer impact¶

The consoleauth service must be restarted before proxy services. When proxy will be restarted clients will be disconnected from consoles. consoleauth will continue to work as backend until a deprecated period of one release operator are encouraged to switch on the database backend (see option: console_tokens_backend).

If the deployer choses to use the database to store console connection information the consoleauth service will not be required.

Developer impact¶

None

Upgrade impact¶

New console token authorizations will be stored in the database but already existing consoleauth service token authorizations will continue to work until their TTLs expire, if the operator has set [workarounds]enable_consoleauth = True before upgrading (the default is False). Once all of the old consoleauth service token authorizations have expired, the flag should be disabled and it will no longer be necessary to run the consoleauth service.

Implementation¶

Assignee(s)¶

Primary assignee:: melwitt
Other contributors:: sahid-ferdjaoui

Work Items¶

Convert code to use objects framework
Update consoleauth to take advantage of the database to handle tokens
Fix bug 1425640

Dependencies¶

None

Testing¶

The current code is already tested by functional and unit tests since we do not provide any feature we can consider that the code will be well covered by those tests.

The new version will be tested in the gate.

Documentation Impact¶

The cell deployment layout documentation will be updated to reflect the new requirement that console proxies must be run per cell instead of global to a deployment.

References¶

None

History¶

Revisions¶
Release Name	Description
Liberty	Introduced
Newton	Re-proposed
Pike	Re-proposed
Queens	Re-proposed
Rocky	Re-proposed

Convert Consoles To Use Objects Framework

Convert Consoles To Use Objects Framework¶

Problem description¶

Use Cases¶

Proposed change¶

Alternatives¶

Data model impact¶

REST API impact¶

Security impact¶

Notifications impact¶

Other end user impact¶

Performance Impact¶

Other deployer impact¶

Developer impact¶

Upgrade impact¶

Implementation¶

Assignee(s)¶

Work Items¶

Dependencies¶

Testing¶

Documentation Impact¶

References¶

History¶

Nova Specs

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