Invalid warning Variable substitution using $VAR will be deprecated in favor of ${VAR} and ${env:VAR}, please update $$

[arielvalentin]

Component(s)

No response

What happened?

Description

When using ottl transform processor with a capture group, the following warning is emitted in the logs:

{
"level":"warn",
"ts":1717553616.784837,
"caller":"expandconverter@v0.101.0/expand.go:73",
"msg":"Variable substitution using $VAR will be deprecated in favor of ${VAR} and ${env:VAR}, please update $$",
"variable":"$"
}

Steps to Reproduce

Create a transform processor that uses replace pattern with a capture group substitution like this:

error_mode: ignore
trace_statements:
  - context: span
    statements:
      - |-
        replace_pattern(attributes["baz"], "^(foo|bar)-.*", "$$1")

Expected Result

No warnings are printed

Actual Result

{
"level":"warn",
"ts":1717553616.784837,
"caller":"expandconverter@v0.101.0/expand.go:73",
"msg":"Variable substitution using $VAR will be deprecated in favor of ${VAR} and ${env:VAR}, please update $$",
"variable":"$"
}

Collector version

v0.101.0

Environment information

Environment

OS: (e.g., "Ubuntu 20.04")
Compiler(if manually compiled): (e.g., "go 14.2")

OpenTelemetry Collector configuration

No response

Log output

No response

Additional context

No response

[crobert-1]

This is a warning that you need to update your configuration to use the the alternate format, as the configuration you're using for environment variables, $$1 in your case, is going to be deprecated.

For your config, $$1 should be ${$1}, I believe.

[arielvalentin]

@crobert-1 is that in the release notes?

When will that be reflected in the documentation?

https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/ce5c28fe653317cbc1ae930bb04ef214169929d7/pkg/ottl/ottlfuncs/README.md#replace_pattern

[crobert-1]

It looks like the update wasn't included in the release notes.

PR: #9162
Relevant issue: #9162

You're correct though, that documentation is definitely out of date now. Thanks for linking!

[github-actions]

Pinging code owners for pkg/ottl: @TylerHelmuth @kentquirk @bogdandrutu @evan-bradley. See Adding Labels via Comments if you do not have permissions to add labels yourself.

[crobert-1]

Actually, I may be wrong here, it may be an incorrect warning. I forgot about the special casing around $$1 here. I'll defer to the OTTL code owners to decide if this is a bug in confmap or out of date documentation here 👍

[evan-bradley]

This is a legitimate issue. It's possible confmap is being too aggressive with checks and ignoring $$, but it could also be that now OTTL can move toward not requiring $$. I need to double-check the handling before I can say for sure.

[TylerHelmuth]

This is happening bc of

opentelemetry-collector/confmap/converter/expandconverter/expand.go

Line 87 in 9907ba5

msg := fmt.Sprintf("Variable substitution using $VAR will be deprecated in favor of ${VAR} and ${env:VAR}, please update $%s", str)

, which now has a valid logger.

That check needs a better regex - right now it is checking for a string starting with a $, not if it is also a valid env var name.

[crobert-1]

@TylerHelmuth and @evan-bradley - Should this issue be moved to core then to fix the expand converter logic? (Since this isn't an OTTL issue, or any contrib component)

[TylerHelmuth]

Ya