Remove comments of config.string.

[mashhurs]

Release notes

Environment ${VAR} in config.string comments will no longer be evaluated.

What does this PR do?

if config.string of pipeline config has ENV ${VAR} in its comments and ${VAR} is not set, pipeline may not start which is meaningless. This change introduces a logic to remove comments of config.string.
Note that other keys, such as pipeline.id are YAML definitions where their comments will be wiped out by YAML:safe_load.

Why is it important/What is the impact to the user?

Users who have ${VAR} comments in config.string currently need to set ${VAR} env variable. They are no longer required after this change.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] I have made corresponding change to the default configuration files (and/or docker env variables)
• I have added tests that prove my fix is effective or that my feature works

Author's Checklist

• [ ]

How to test this PR locally

• pull current PR
• add following config to the pipeline.yml

   - pipeline.id: "test #id1" # test
     config.string: |
       input { generator { count => 10 } } #id${PIPELINE_WORKERS}"
       output {
         # pipeline.workers: "${PIPELINE_WORKERS}"
         stdout { codec => dots } # output
       } # pipeline.workers: "${PIPELINE_WORKERS}"
       # pipeline.workers: "${PIPELINE_WORKERS}"
  

• without this change LS would complain to set the PIPELINE_WORKERS
• after this change LS doesn't ask to set the PIPELINE_WORKERS

Related issues

• Closes Commented out variable substitutions may still be evaluated in pipelines.yml #16008

Use cases

Screenshots

Logs

[mashhurs]

review note: we keep new lines even though they are empty because when something goes wrong in config, error displays the line with specific error position.

[mashhurs]

review note: currently only config.string may contain the comments. YAML::safe_load removes the comments from other keys such as pipeline.id.

[donoghuc]

I'm still learning what is acceptable under these pipeline definitions.... Would it be possible to have string literals with a # char inside? Perhaps something like

filter {
  mutate { add_field => { "test_field" => "This is real data # not a comment" } }
}

In that case, would we mangle this using this regex?

[jsvd]

it would:

jruby-9.4.9.0 :010 > line = 'mutate { add_field => { "test_field" => "This is real data # not a comment" } }'
 => "mutate { add_field => { \"test_field\" => \"This is real data # not a comment\" } }" 
jruby-9.4.9.0 :011 > line.match?(/(?<!['"]) #/) ? line.gsub(/ (?<!['"])#.*/, '') : line
 => "mutate { add_field => { \"test_field\" => \"This is real data" 

same with ruby code that may have a #:

jruby-9.4.9.0 :008 > line = 'filter { ruby { code => "puts # 1" } }  # test'
 => "filter { ruby { code => \"puts # 1\" } }  # test" 
jruby-9.4.9.0 :009 > line.match?(/(?<!['"]) #/) ? line.gsub(/ (?<!['"])#.*/, '') : line
 => "filter { ruby { code => \"puts"

[mashhurs]

Wow! This is more than I initially thought. I have revised a logic but honestly I would avoid adding such complex art which touches user's config. Maybe we document that commenting env ${VAR} is not allowed for config.string?

Example pipelines.yml:

- pipeline.id: "test #id1" # test
  config.string: |
    input { 
      generator { count => 10 } #id${PIPELINE_WORKERS}"
      beats {
        port => 5555 # intentional comment contains "${BEATS_DEV_PORT}" variable, shouldn't break functionalities
        host => "127.0.0.1"
      }
      # another intentional comment contains "${BEATS_PROD_HOST}" variable, shouldn't break functionalities
    }
    filter {
      mutate { add_field => { "oopsy" => "This is real data # not a ' comment, oopsy" } }
      mutate {
        add_field => {
          'doopsy' => "This is real data # not a ' comment, doopsy" # pipeline.workers: "${PIPELINE_WORKERS}"
        }
        add_tag => [ "doopsy_tag", "${ENV_TAG}" ] # "${ENV_TAG_ANOTHER}
      }
      mutate {
        add_field => {
          "hoopsy" => 
            'This is real data # not a " comment, hoopsy'
        }
      }
    mutate { add_field => { "loopsy" => "This is real data # not a ' escape comment, \\" loopsy" } }
      mutate { add_field => { "woopsy" => 'This is real data # not a " comment, ${ENV_TAG_ANOTHER} whoopsy' } } # "${ENV_TAG_ANOTHER} } }
    }
    output {
      stdout { } # output
    } # pipeline.workers: "${PIPELINE_WORKERS}"
    # pipeline.workers: "${PIPELINE_WORKERS}"

  #  pipeline.workers: "${PIPELINE_WORKERS}"

[jsvd]

Agreed, it's a very high hanging fruit for very little return in terms of user experience. +1 on documenting this limitation and closing the PR

[donoghuc]

I agree, i was looking back at the discussion around this issue trying to get the context. It seemed to me at first glance that the behavior of doing interpolation here is correct. Specifically the flow seemed to be that variables would be interpolated before generating the config. At that point there would be no concept of what is a comment vs config in the template input.

I do see how this may be a frustrating edge case, but it is one that is probably not worth introducing magic around.

[mashhurs]

Thanks for the feedback! I have added doc changes with the PR-16689 and that closes both current PR and upstream issue.

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarQube

[elasticmachine]

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[mashhurs]

Closing as this PR covers doc changes.