#21189 Better diagnostics for when empty digests / captures occur for `adhoc_tool`, `shell_command`, and friends New discussion created by tdyas Background The Problem Pants does not error or warn when output digests captured by the shell backend or produced by the "wrap as" target types (e.g.,

experimental_wrap_as_resources

) are empty. This can occur, for example, because a file capture glob failed to capture a missing file for

adhoc_tool

or

shell_command

or the user specified an incorrect glob for the

outputs

field of a "wrap as" target type which was then not matched against the inputs. Motivation As reported in #21156, a user recently encountered an issue where a file which they expected to be in the execution sandbox was missing. In their reproduction, the output digest of the relevant

shell_command

target was the path

cpp/hello_cpp

(but was captured via the glob

"hello_cpp"

given the `shell_command`'s working directory was

cpp

). The user then tried to use an

experimental_wrap_as_resources

target to convert that output into a

resources

target for consumption by a

python_test

target. The

outputs

glob was specified as

hello_cpp

and not

cpp/hello_cpp

since the user was not aware of how the working directory support on

shell_command

changes where the output is captured. This incorrect glob caused the

experimental_wrap_as_resources

to produce an empty digest as output. Pants did not provide any diagnostics to the user about this case. Arguably, Pants probably should provide some error or warning when globs do not match in these cases since the user clearly expected something to be there. Not doing so results in "silent failures" which are hard to debug if you are not a Pants maintainer. (Indeed, I had to add debug logging to rule code and run from Pants sources in order to track down the issue.) Ideas Some ideas for better diagnostics: 1. For

adhoc_tool

and

shell_command

target types, Pants should by default verify that all

output_files

and

output_directories

globs in fact match captured files / directories from the process execution. • Add an

outputs_match_error_behavior

field on

adhoc_tool

and

shell_command

which takes the values

error

,

warn

,

ignore

to set what diagnostics occur if globs do not match.

error

is the default. • Add an

outputs_match_mode

field on

adhoc_tool

and

shell_command

which takes the values

any

and

all

to set whether at least one glob needs to match or whether all globs need to match.

all

is the default. 1. For "wrap as" target types (e.g.,

experimental_wrap_as_resources

), Pants should by default verify that the

outputs

globs in fact match files which produced by the input targets. • Add an

outputs_match_error_behavior

field on

adhoc_tool

and

shell_command

which takes the values

error

,

warn

,

ignore

to set what diagnostics occur if globs do not match.

error

is the default. • Add an

outputs_match_mode

field on

adhoc_tool

and

shell_command

which takes the values

any

and

all

to set whether at least one glob needs to match or whether all globs need to match.

all

is the default. 1. Should there be global options to set the defaults for

outputs_match_error_behavior

and

outputs_match_mode

? 2. Are there better names for these? 3. What other ideas may help for diagnostics? • Maybe Pants should log the files in the digest involved in

adhoc_tool

,

shell_command

, and "wrap_as" targets at debug level? pantsbuild/pants