Update default ISO path to prefer an ISO that's next to the boot2docker CLI binary

[tianon]

This is especially important for places like the Windows installer, where we want people to be able to install boot2docker 1.3 from an installer, and it includes the right ISO, so when they boot their VM, it should also be boot2docker 1.3, without any extra work or extra downloading.

[tianon]

I wonder if we should be doing an EvalSymlinks on this os.Args[0] first so that we can have this work for OS X too (without putting the ISO in /usr/local/bin or similar).

[tianon]

I'm gonna update with EvalSymlinks logic.

[bfirsh]

When they run boot2docker.app, it puts it in the right place, doesn't it? Can't the installer do this?

[tianon]

Updated with much more correct logic.

@bfirsh technically, the start.sh script could copy it over for Windows, but I really think both of those are hacky - if I explicitly install Boot2Docker 1.3, then boot2docker up should boot Boot2Docker 1.3 for me, IMO

[tianon]

(unless I do an explicit boot2docker --iso=some-other-iso up)

[tianon]

Anyone else want to weigh in? :)

[tianon]

C'mon you 27 members of the peanut gallery watching this repo, surely some of you have opinions on this; let's have 'em! 😉

[gmlewis]

My $0.02 - I don't like programs to dictate where I put my executables... and I certainly don't want an ISO where I put the executable.

[tianon]

Right, this isn't really dictating that. This is essentially just a bonus feature for if you happen to put your executable next to an ISO you want to use, like the Windows installer does. Everyone else will probably put it in /usr/local/bin or ~/bin and thus never run into this (and thus the default for them will stay ~/.boot2docker/boot2docker.iso and require using boot2docker download etc).

Essentially, what we're dictating with this change is that if you install with the installers, you can update with the installers and actually have stuff update properly.

[gmlewis]

OK, in that case, LGTM.

[daghack]

It makes a lot of sense to me, and is certainly a convenience.

[SvenDowideit]

yes, this needs documentation, and i might have a tweak for osx - I'll make an update PR when i've finished testing

[SvenDowideit]

Linux

• if you only have a ~/.boot2docker/boot2docker.iso is works the same as always
• you can optionally throw your iso into /usr/local/bin/boot2docker.iso assuming thats where you throw your cli binary, and all users will use that iso instead.

Windows

• if you have an existing iso in ~/.boot2docker/ it will be used on your existing vm until you delete it (during which time, the cli help will lie to you, but b2d info will tell you the truth), after that, by default, it'll use the iso in C:/Progra...
• new users will have it always use the shared iso, and will need to set flags, or profile file to change it.

OSX

• essentially the same as Linux

[SvenDowideit]

and so LGTM, with a followup PR coming