Fix HCL2 panics when parsing undefined variables #10326
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Update hcl/v2 to point to https://github.com/hashicorp/hcl/commits/nomad-v2.9.1+tweaks1
With the updated undefined variable code, we attempt to pick the text of
`${....}` verbatim from the hcl body. Previously, we'd attempt to
regenerate the string from the AST and pray it matches input; the
generation is lossy, as the same AST can represent multiple variations
(e.g. `${v.0}` and `${v[0]}` have the same HCLv2 AST). In this change,
we attempt to go back to the hcl2 source and find the string snippet
corresponding to the variable reference.
| v := "${" + expr + "}" | ||
| UndefinedVariable: func(t hcl.Traversal) (cty.Value, hcl.Diagnostics) { | ||
| body := c.ParseConfig.Body | ||
| start := t.SourceRange().Start.Byte |
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Just for my own clarity here, because the the docs on hcl.Traversal aren't very easy to drop into and come away with a solid understanding... the SourceRange starts right after the ${ we're evaluating and stops either at the } or the end of the body? Just want to make sure that's guaranteed so that the slicing below can't panic.
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Imperially, Start.Byte is the offset first non-white space character after ${, and End.Byte is the offset of the first whitespace or }.
It's an error if ${ is present without a corresponding }. I was being a bit more defensive though.
This fixes a regression in #10326, to handle unquoted unknown variables. The HCL job may contain unquoted undefined variable references without ${...} wrapping, e.g. value = meta.node_class. In 1.0.4, this got parsed as value = "${meta.node_class}". This code performs a scan to find the relevant ${ and }, and only tries to find the closest ones with whitespace as the only separator.
Fix HCL2 panics when parsing undefined variables
This fixes a regression in #10326, to handle unquoted unknown variables. The HCL job may contain unquoted undefined variable references without ${...} wrapping, e.g. value = meta.node_class. In 1.0.4, this got parsed as value = "${meta.node_class}". This code performs a scan to find the relevant ${ and }, and only tries to find the closest ones with whitespace as the only separator.
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This PR fixes a panic related to parsing undefined "variables" appearing in HCL2 - HCL2 parser is meant to leave unknown variable references intact (e.g.
${VAR}). However, some attributes can be sophisticated e.g.${attr.something-with-dots["and_indexing"].3}and the code didn't handle them resulting into a panic.This PR makes two core changes:
First it updates hcl2 to be base on v2.9.1 with some nomad tweaks:
nomad-v2.9.1+tweaks1. This branch is the same as before, but picks up the feedback we got in hashicorp/hcl#413Secondly, with the updated undefined variable code, we attempt to pick the text of
${....}verbatim from the hcl body. Previously, we'd attempt to regenerate the string from the AST and pray it matches input; the generation is lossy, as the same AST can represent multiple variations (e.g.${v.0}and${v[0]}have the same HCLv2 AST). In this change, we attempt to go back to the hcl2 source and find the string snippet corresponding to the variable reference.Fixes #10316
Fixes #9956