Workaround for Cobra.Command handling of PersistentPreRunE

[chungers]

The command pkg used, Cobra.Command, only executes the first PersistentPreRunE function, searching from the bottom up the command tree (from leaf subcommands up to the root).

This creates a problem where for commands like infrakit manager inspect, only the PersistentPreRunE of the manager subcommand is executed, leaving the top level one (where the log level is set) not run at all. As a result, for deeply nested commands, --log doesn't have any effects.

This PR adds a convenient function upTree that is called by the leaf PersistetPreRunE to recurse up the tree and then executing some function in top-to-bottom order. This is probably better than patching/forking the library, and not calling the helper function just follows standard Cobra command behavior.

Signed-off-by: David Chung david.chung@docker.com

[codecov-io]

Current coverage is 65.40% (diff: 100%)

Merging #372 into master will decrease coverage by 0.04%

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