cs.app.portfwd 20190602

Manage persistent ssh tunnels and port forwards.

Portfwd runs a collection of ssh tunnel commands persistently, each in its own cs.app.svcd <https://pypi.org/project/cs.app.svcd>_ instance with all the visibility and process control that SvcD brings.

It reads tunnel preconditions from special comments within the ssh config file. It uses the configuration options from the config file as the SvcD signature function thus restarting particular ssh tunnels when their specific configuration changes. It has an "automatic" mode (the -A option) which monitors the desired list of tunnels from statuses expressed via cs.app.flag <https://pypi.org/project/cs.app.flag>_ which allows live addition or removal of tunnels as needed.

Function Condition(portfwd, op, invert, *args)

Factory to construct a condition from a specification.

Class FlagCondition

MRO: _PortfwdCondition
A flag based condition.

Function main(argv=None, environ=None)

Command line main programme.

Class PingCondition

MRO: _PortfwdCondition
A ping based condition.

Class Portfwd

MRO: cs.app.flag.FlaggedMixin
An ssh tunnel built on a SvcD.

Method Portfwd.__init__(self, target, ssh_config=None, conditions=(), test_shcmd=None, trace=False, verbose=False, flags=None)

Initialise the Portfwd.

Parameters:

• target: the tunnel name, and also the name of the ssh configuration used
• ssh_config: ssh configuration file if not the default
• conditions: an iterable of Conditions which must hold before the tunnel is set up; the tunnel also aborts if these cease to hold
• test_shcmd: a shell command which must succeed before the tunnel is set up; the tunnel also aborts if this command subsequently fails
• trace: issue tracing messages; default False
• verbose: be verbose; default False
• flags: optional preexisting Flags instance

Class Portfwds

A collection of Portfwd instances and associated control methods.