add arbitrary expression to CelExpression#115
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Signed-off-by: zirain <[email protected]>
Signed-off-by: zirain <[email protected]>
Signed-off-by: zirain <[email protected]>
| cel.expr.CheckedExpr cel_expr_checked = 4; | ||
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| // Expression in abstract syntax tree (AST) form. | ||
| // This's useful when there's no control plane(e.g. XDS from file). |
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Sorry, I don't fully understand what's the realtionship between having a dynamic control-plane and having it in a file.
Can you shed some light here?
Also, are there any constraints for this field, or is there some format that needs to be used?
Will a generic string, e.g. "abc", make sense in this case?
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Previous context is here, suggested by @yanavlasov.
I agree with that it's hard to send cel.expr.CheckedExpr when uses using file for xds instead of a control plane, or maybe I missed something.
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it's a little painful to write something like following:
expression:
parsed_expr:
expr:
id: 4
call_expr:
function: _!=_
args:
- id: 3
select_expr:
field: id
operand:
id: 2
select_expr:
field: node
operand:
id: 1
ident_expr:
name: xds
- id: 5
const_expr:
string_value: "node_name"
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The use case is simple deployment or tests where it is easier to make Envoy parse the CEL expression, rather than having to specify the AST proto.
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I agree it's easier, but it is unclear what the format that is used here (perhaps add a link).
FWIW, I hope it is being validated, and the config is rejected if the string is invalid.
3 participants
this's suggested by @yanavlasov in envoyproxy/envoy#38182 (comment)
it's useful in envoy when there's no control plane.
cc @yanavlasov @htuch