skeema / skeema / 25889702098

92%

Build Type

push

github

Committed by evanelias

Commit Message

host option: support external command shellouts directly

Skeema has always supported use of external commands for obtaining hostnames
via the host-wrapper option, which is designed to be configured a single time
generically in a top-level directory. However, that option requires that the
host option is still set in the appropriate subdir .skeema files -- even
if just set to a dummy/placeholder value, so that Skeema still knows which
dirs are supposed to map to hosts.

That host-wrapper setup can be unnecessarily confusing for cases where it is
more desirable to define the external command directly in each .skeema file
that should map to hosts, or in cases where there is only a single host-level
directory anyway.

This commit augments the host option accordingly, to provide a simpler
alternative to host-wrapper for these situations. Now, any value wrapped in
`backticks` is treated as an external shell command to execute. The command's
STDOUT is captured for use as the list of hostnames, just like host-wrapper's
functionality, but without needing to configure that separate option.

In the backtick-wrapped value, the following placeholder variables are
supported for dynamic interpolation:

  {ENVIRONMENT}: The environment name from the command-line
  {DIRNAME}:     Base name (last path component) of the dir being processed
  {DIRPATH}:     Full path of the dir being processed
  {SCHEMA}:      Schema name being processed, if constant or $ENV

To be clear, this commit does NOT deprecate the host-wrapper option, nor fully
replace all of its use-cases. In situations where a common service-discovery
program should be configured for schema repo containing many distinct database
clusters, the best approach for that situation is to stay with host-wrapper in
a top-level .skeema option file, and subdirs that define host as service-
discovery lookup keys.

In contrast, use of the new host=`...` functionality makes more sense in cases
where each subdir uses a diffe... (continued)

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38 of 43 new or added lines in 3 files covered. (88.37%)

2 existing lines in 1 file now uncovered.

10962 of 11852 relevant lines covered (92.49%)

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