* Ensure invalid tunnel agent connections get closed
Connections from reverse tunnel agents were being marked
as invalid by the proxy under certain conditions but would
ultimately never be closed. This could lead to scenarios where
the agent thought things were fine but the proxy considered
that agent unhealthy and unroutable.
Pruning of invalid connections used to occur when a proxy
tried to retrieve a connection for that tunnel. This also
further muddied the point in time at which the proxy could
close a connection as it never explicitly stopped tracking
the connection and closed it at the same time.
To remedy this, connections are explicitly closed by the proxy
and removed from the mapping to stop tracking immediately. In order
to prevent a connection that is servicing an active connection
from being closed the proxy now tracks which connections have
sessions. Closing does not occur when there are any active
sessions to prevent them from being force terminated.
When the proxy receives a heartbeat from an agent it now restores
the connection to a valid state. In the event that too many heart
beats have been missed for an agent, the proxy will now terminate
the connection, again only if it is not serving any sessions.
Fixes#15911
* Add tracing instrumentation for ssh clients/servers
Add tracing context to the existing ProxyHelloSignature to provide
span information across ssh connections. To add span context per
ssh session on top of new connections, the same tracing context is
passed in the first global request of the session.
In order to ensure that tracing context is pulled from and inserted
into the proper context.Context, some interfaces and methods were
changed to take one as the first argument.
- Ensure that the dial request uses proper "server ID" format,
which is <uuid>.<cluster_name>
- Update reverse tunnel agent to handle tunnel connections
to desktops
* Added support for connecting API client through tunnel proxy and web proxy addresses (with identity file).
* Added concurrent dialing logic to dial several possible dialing combinations and seamlessly return the first client to connect.
Anton Miniailo