Cannot access VMs if no floating IPs and custom network

[Adrien Vergé]

On infras with custom network topology (to meet strong security requirements, for instance), VMs can only be accessed through a relay host, proxy or any other artifact. This kind of network configuration should not be an impediment to use Sahara.

Currently Sahara accesses VMs using two methods:
- directly when floating IPs are assigned;
- using a proxy when use_floating_ips=false and use_namespaces=true, the proxy command being hard-coded ('ip netns exec qrouter...')

One should be able to specify a custom proxy command in conf, to enable Sahara to reach VMs via SSH and HTTP.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/131142

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/131142
Committed: https://git.openstack.org/cgit/openstack/sahara/commit/?id=d901039ea1d8567db92ef2bd454e239119455118
Submitter: Jenkins
Branch: master

commit d901039ea1d8567db92ef2bd454e239119455118
Author: Adrien Vergé <email address hidden>
Date: Tue Oct 21 16:48:02 2014 +0200

    Make proxy command generic and user-definable

    When using Sahara with use_floating_ips=false, instances are accessed
    through a proxy (both for SSH and HTTP connections). Currently Sahara
    reaches them using a hard-coded proxy command. This patch makes this
    command user-definable in the configuration file.

    Changes:
    - Move HTTP adapters logic out of Neutron-related code.
    - Transform the neutron proxy command into a generic one:
        'ip netns exec qrouter-{router_id} nc {host} {port}'
    - Use user-defined proxy command when proxy_command is set in conf;
      the hard-coded proxy command when use_floating_ips=false and
      use_namespaces=true; otherwise no proxy.
    - Add tests for those three possibilities + misconfiguration.

    Examples of use:
    - proxy_command='ip netns exec ns_for_{network_id} nc {host} {port}'
    - proxy_command='ssh proxy-machine-{tenant_id} nc {host} {port}'

    Change-Id: Iac033659e97b1ad935bb7be84de9fc731f787f4b
    Closes-Bug: #1386193