• David Johnson's avatar
    Ubuntu 15 support. · 2baf7655
    David Johnson authored
    Similar to Ubuntu 14, but new and different UIDs, and...
    
    systemd!  systemd has made it into Ubuntu.  This affects our control net
    discovery.  Our /etc/network/interfaces hack marks eth[0-9] as "auto".
    New Ubuntu versions have systemd (or upstart, if your Ubuntu 15 uses
    that -- our images will not) job that waits for any interfaces marked
    auto to come up, and doesn't timeout for 2 mins.  This doesn't work for
    us, because our use of auto is abuse :).
    
    So, we enter a new level of abuse.  We change the systemd unit
    dependencies, making the network-online.target service want (depend on)
    our special ifup-wait-emulab-cnet.service (which looks for /run/cnet to
    get written), instead of on ifup-wait-all-auto.service.  This means
    network-online.target happens as soon as the control net is up, which is
    the primary thing we're concerned about.
    
    Now, if experimenters would ever add their own special "auto" interfaces
    to /etc/network/interfaces, the rest of the startup scripts that depend
    on network-online.target could possibly race (although you would think
    that our control net discovery will be slower than any static
    configuration...).
    
    But for now, this solution appealed more that "faking" that eth[0-9] are
    all up by writing the right files --- or by finding a better mechanism
    instead of abusing "auto".
    2baf7655
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