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consul/command/helpers/decode_shim.go

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feat(cli): enable to delete config entry from an input file (#13677) * feat(cli): enable to delete config entry from an input file - A new flag to config delete to delete a config entry in a valid config file, e.g., config delete -filename intention-allow.hcl - Updated flag validation; -filename and -kind can't be set at the same time - Move decode config entry method from config_write.go to helpers.go for reusing ParseConfigEntry() - add changelog Co-authored-by: Dan Upton <daniel@floppy.co>
2022-07-11 14:13:40 +00:00
package helpers
command: ensure that the json form of config entries can be submitted with 'consul config write' (#6290) The json decoder inside of the HCLv1 hcl.Decode function behaves unexpectedly when decoding generically into a map[string]interface{} as is done for 'consul config write' pre-submit decoding. This results in some subtle (service-router Match and Destinations being separated) and some not so subtle (service-resolver subsets and failover panic if multiple subsets are referenced) bugs when subsequently passed through mapstructure to finish decoding. Given that HCLv1 is basically frozen and the HCL part of it is fine instead of trying to figure out what the underlying bug is in the json decoder for our purposes just sniff the byte slice and selectively use the stdlib json decoder for JSON and hcl decoder for HCL.
2019-08-07 21:41:33 +00:00
import (
"encoding/json"
"unicode"
"unicode/utf8"
"github.com/hashicorp/hcl"
)
// hclDecode is a modified version of hcl.Decode just for the super general
// purposes here. There's some strange bug in how hcl.Decode decodes json where
//
// { "sub" : { "v1" : { "field" : "value1" }, "v2" : { "field" : "value2" } } }
//
// hcl.Decode-s into:
//
// map[string]interface {}{
// "sub":[]map[string]interface {}{
// map[string]interface {}{
// "v1":[]map[string]interface {}{
// map[string]interface {}{
// "field":"value1"
// }
// }
// },
// map[string]interface {}{
// "v2":[]map[string]interface {}{
// map[string]interface {}{
// "field":"value2"
// }
// }
// }
// }
// }
//
// but json.Unmarshal-s into the more expected:
//
// map[string]interface {}{
// "sub":map[string]interface {}{
// "v1":map[string]interface {}{
// "field":"value1"
// },
// "v2":map[string]interface {}{
// "field":"value2"
// }
// }
// }
//
// The strange part is that the following HCL:
//
// sub { "v1" = { field = "value1" }, "v2" = { field = "value2" } }
//
// hcl.Decode-s into:
//
// map[string]interface {}{
// "sub":[]map[string]interface {}{
// map[string]interface {}{
// "v1":[]map[string]interface {}{
// map[string]interface {}{
// "field":"value1"
// }
// },
// "v2":[]map[string]interface {}{
// map[string]interface {}{
// "field":"value2"
// }
// }
// }
// }
// }
//
// Which is the "correct" value assuming you did the patch-slice-of-maps correction.
//
// Given that HCLv1 is basically frozen and the HCL part of it is fine instead
// of trying to track down a weird bug we'll bypass the weird JSON decoder and just use
// the stdlib one.
func hclDecode(out interface{}, in string) error {
data := []byte(in)
if isHCL(data) {
return hcl.Decode(out, in)
}
return json.Unmarshal(data, out)
}
// this is an inlined variant of hcl.lexMode()
func isHCL(v []byte) bool {
var (
r rune
w int
offset int
)
for {
r, w = utf8.DecodeRune(v[offset:])
offset += w
if unicode.IsSpace(r) {
continue
}
if r == '{' {
return false
}
break
}
return true
}