Fix json parsing bug with plugins that don't provide args #5489
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This fixes a bug with JSON agent configuration parsing where the AST for the plugin stanza had unnecessary flattening originating from hcl parsing library. The workaround fixes the AST by popping off the flattened element and wrapping it in a list. The workaround comes from similar code in terraform. There were no existing test cases for json parsing so I added a few.
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I would suggest placing test content in a testdata directory. testdata directory is special:
The go tool will ignore a directory named "testdata", making it available to hold ancillary data needed by the tests.
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Done, noting that we use both testdata/ and other different names for test fixtures, should be made consistent in a future PR
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Also maybe document how you generated this file? This is neat.
command/agent/config_parse.go
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| // Deal with json->hcl AST parsing incorrectness when directly nested | ||
| // items show up as additional keys. This currently only affects plugin | ||
| // configuration because args is not necessary. All other fields in the config | ||
| // have multiple keys and parse from json into the AST correctly. |
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While I agree with the outcome (this is the only place to add now), I disagree with the rationale.
It's true that other config stanzas require multiple entries, but a user may still set one field only triggering this condition and without unwrapLegacyHCLObjectKeysFromJSON call, the error message might not be comprehensible. However, given this is only relevant for deeply nested entries, it affects few other keys at most.
Beyond 0.9, we want to increase our test coverage. I noticed that other parse* functions have list = list.Elem() call that's missing here, correctly so but not sure why. Also, I noticed that it's easy to get parser to crash with simple config files, like:
# basic client stanza
{"client": {"server_join": {"retry_max": 3}}}
# sentinel path that seems similar to this one
{"sentinel": {
"import": {"custom-plugin": {"path": "/custom-path"}}
}}
In both of these cases, list = list.Elem() causes us to get an empty list that causes a crash when indexed. The pattern causing them affect many stanzes here.
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agreed, there are more lingering bugs in json parsing. Found this open ticket from 2016 :( #1290. Let's track this for the next minor release, +1 for more test cases
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Fixed the wording of the comment
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I'm going to lock this pull request because it has been closed for 120 days ⏳. This helps our maintainers find and focus on the active contributions. |
This fixes a bug with JSON agent configuration parsing where the AST
for the plugin stanza had unnecessary flattening originating from hcl parsing.
The workaround fixes the AST by popping off the flattened element and wrapping
it in a list. The workaround comes from similar code in terraform
There were no existing test cases for json parsing so I added a few.
fixes #5484