[Logstash] Add guard against missing elements in codec payload

[robbavey]

Proposed commit message

Add guard against missing elements in codec payload

Due to a bug in Logstash (elastic/logstash#16410), when configuring a codec with optional settings, the stats do not get generated, causing the data collection for codecs, and thus plugins to fail.

This commit adds a guard to the retrieval of encode and decode to ensure that the CEL input does not fail when encountering this issue.

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• I have verified that Kibana version constraints are current according to guidelines.

How to test this PR locally

Setup Logstash Integration to point to a working Logstash instance, the Logstash pipeline should include a codec that is configured with an optional parameter, eg

input { 
  stdin {
    codec => json { id => "json" }
  }
}

Navigate to the Pipeline Details Overview page, and verify that there is data for this pipeline. There should be entries in the input and codec sections of the page.

Related issues

elastic/logstash#16410

[elasticmachine]

🚀 Benchmarks report

Package logstash 👍(0) 💚(1) 💔(1)

Expand to view

Data stream	Previous EPS	New EPS	Diff (%)	Result
log	6134.97	5128.21	-1006.76 (-16.41%)	💔

To see the full report comment with /test benchmark fullreport

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 5337088

[botelastic]

Hi! We just realized that we haven't looked into this PR in a while. We're sorry! We're labeling this issue as Stale to make it hit our filters and make sure we get back to it as soon as possible. In the meantime, it'd be extremely helpful if you could take a look at it as well and confirm its relevance. A simple comment with a nice emoji will be enough :+1. Thank you for your contribution!

[consulthys]

LGTM

[elastic-vault-github-plugin-prod]

Package logstash - 2.4.11 containing this change is available at https://epr.elastic.co/search?package=logstash