replace: '{{ .Value | urldecode }}' doesn't decode a value (it doesn't work)

[fadeevab]

Describe the bug

replace stage with the replace: '{{ .Value | urldecode }}' doesn't decode a matched value (it doesn't work).

[inspect: replace stage]: none.

For the reference, {{ .Value | upper }} works as expected.

Documentation: urldecode

To Reproduce

promtail, version 2.9.8 (branch: release-2.9.x, revision: 94e0029)

Steps to reproduce the behavior:

cat my2.log | promtail --stdin --dry-run --config.file=./promtail2.yml  --inspect

my2.log test log:

asdf%40gmail.com
lflfl%40gmail.com

promtail2.yml config:

server:
  http_listen_port: 9088
  grpc_listen_port: 0

clients:
  - url: http://127.0.0.2:3100/loki/api/v1/push

scrape_configs:
  - job_name: some job
    pipeline_stages:
      - replace:
          expression: '(.+)'
          replace: '{{ .Value | urldecode }}'

Expected behavior
Emails asdf%40gmail.com and lflfl%40gmail.com should be converted into asdf@gmail.com and lflfl@gmail.com.

Environment:

• Infrastructure: bare-metal

[rgroothuijsen]

It does get a little confusing; the function is defined for LoqQL line formatting, but not for the template code used in Promtail. At a glance it appears many of these functions are only allowed in the former.

[fadeevab]

It does get a little confusing; the function is defined for LoqQL line formatting, but not for the template code used in Promtail. At a glance it appears many of these functions are only allowed in the former.

It looks like a bug of a "copy-paste flavor" because 2 similar function maps exist in 2 different places... I speculate that more functions could be added to the 2nd function map to make it work. (?)