Creating linked_dirs in Capistrano 3 fails - capistrano

Question

I am attempting to set up Capistrano with a SilverStripe build and am running into a few troubles setting up the shared directories.
I set the linked_dirs in deploy.rb with the following:
set :linked_dirs, %w{assets vendor}
Since adding this line I get the following error:
[617afa7f] Command: /usr/bin/env mkdir -p /var/www/website/releases/20160215083713 /var/www/website/releases/20160215083713
INFO [617afa7f] Finished in 0.250 seconds with exit status 0 (successful).
DEBUG [88c3de20] Running /usr/bin/env [ -L /var/www/website/releases/20160215083713/assets ] as capistrano#128.199.231.152
DEBUG [88c3de20] Command: [ -L /var/www/website/releases/20160215083713/assets ]
DEBUG [88c3de20] Finished in 0.258 seconds with exit status 1 (failed).
DEBUG [3d61c1c4] Running /usr/bin/env [ -d /var/www/website/releases/20160215083713/assets ] as capistrano#128.199.231.152
DEBUG [3d61c1c4] Command: [ -d /var/www/website/releases/20160215083713/assets ]
DEBUG [3d61c1c4] Finished in 0.254 seconds with exit status 1 (failed).
INFO [3016a8cd] Running /usr/bin/env ln -s /var/www/website/shared/assets /var/www/website/releases/20160215083713/assets as capistrano#128.199.231.152
I am a mega noob when it comes to Capistrano and a semi noob when it comes to server configuration and permissions, so any pointers would be appreciated.

Answer 1

It probably hasn't actually failed. One thing to know about Capistrano is that (success) and (failed) are actually returning the result of the exit status, (success) if 0 and (failed) if non-0.
If we look at the command in question, it says that /usr/bin/env [ -L /var/www/website/releases/20160215083713/assets ] failed. This command is saying "return 0 if /var/www/website/releases/20160215083713/assets exists and is a link (-L). This fails, but that just means it returns non-0, thus the link needs to be created. Note that the next command also fails (-d) with asserting that the path is a directory. And the last line in your output is actually creating the link in question.
You can see the test in the Capistrano codebase here: https://github.com/capistrano/capistrano/blob/master/lib/capistrano/tasks/deploy.rake#L128
You can clean up and simplify the output with https://github.com/mattbrictson/airbrussh. This is developed by one of the primary Capistrano devs.
As a sidenote, similarly all the green text in your terminal is stdout and the red text is stderr. This can also be confusing.