[17.06] Delete node attachments when node is removed

[dperny]

When a node is removed, delete all of its attachment tasks, so that any
networks being used by those tasks can be successfully removed.

Provides a workaround to the state where a node with attachments is
somehow removed from the cluster while attached to a network, preventing
the network from being removed. Does not fix many other related bugs.

Includes a unit test for the function that removes node attachment
tasks.

Signed-off-by: Drew Erny drew.erny@docker.com

[andrewhsu]

@dperny was this with a cherry-pick command? e.g.

$ git cherry-pick -s -x badbeef

If so, did it go in clean or did you have to resolve conflicts?

reference: backport of #2409 Delete node attachments when node is removed

[dperny]

@andrewhsu the cherry-pick was clean, and done with

git cherry-pick <commitidihaveforgotten>

I passed no flags.

[andrewhsu]

@dperny if you could redo the commit with the git cherry-pick -s -x flags that would make future selves easier to track source of code. I usually put the cherry-pick command in the PR description along with statement of whether it went clean or not.

[dperny]

@andrewhsu does this commit message look more your speed?

[andrewhsu]

LGTM

[codecov]

Codecov Report

Merging #2414 into bump_v17.06 will decrease coverage by 0.02%.
The diff coverage is 59.09%.

@@               Coverage Diff               @@
##           bump_v17.06    #2414      +/-   ##
===============================================
- Coverage        59.91%   59.89%   -0.03%     
===============================================
  Files              120      120              
  Lines            25106    25128      +22     
===============================================
+ Hits             15043    15051       +8     
- Misses            8726     8743      +17     
+ Partials          1337     1334       -3