[CoreDNS] Add CoreDNS package

[legoguy1000]

What does this PR do?

Add CoreDNS package

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.

Author's Checklist

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[elasticmachine]

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• Start Time: 2022-10-08T14:21:25.698+0000

• Duration: 15 min 20 sec

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Passed	13
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Total	13

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[elasticmachine]

Pinging @elastic/security-external-integrations (Team:Security-External Integrations)

[andrewkroh]

Great to see CoreDNS support coming to Agent.

I think this package would benefit from a system test the runs the real CoreDNS in a container, and then sends in some queries from another container using dig to simulate requests and possibly some errors. I used a setup like this in the hashicorp_vault package and it makes verifying compatibility with new versions easier.

This would also setup the package to have a metrics data_stream added that uses the prometheus input to collect data from https://coredns.io/plugins/metrics/. (Also did this in hashicorp_vault.)

[legoguy1000]

Great to see CoreDNS support coming to Agent.

I think this package would benefit from a system test the runs the real CoreDNS in a container, and then sends in some queries from another container using dig to simulate requests and possibly some errors. I used a setup like this in the hashicorp_vault package and it makes verifying compatibility with new versions easier.

This would also setup the package to have a metrics data_stream added that uses the prometheus input to collect data from https://coredns.io/plugins/metrics/. (Also did this in hashicorp_vault.)

I was going to do this but couldn't get CoreDNS to log to a file within a container so with the current inputs wouldn't really allow for reading from the container STDOUT unless I'm missing something

[andrewkroh]

I would tee the stdout from the CoreDNS process to a file that the system tests can consume. For example

integrations/packages/hashicorp_vault/_dev/deploy/docker/docker-compose.yml

Line 27 in db0aeeb

docker-entrypoint.sh server -dev 2>&1 | tee /service_logs/log.json

[legoguy1000]

I would tee the stdout from the CoreDNS process to a file that the system tests can consume. For example

integrations/packages/hashicorp_vault/_dev/deploy/docker/docker-compose.yml

Line 27 in db0aeeb

docker-entrypoint.sh server -dev 2>&1 | tee /service_logs/log.json

entrypoint: /coredns -conf /config/Corefile 2>&1 | tee /tmp/coredns.log results in 2022/10/04 02:17:01 extra command line arguments: [2>&1 | tee /tmp/coredns.log] so still need to find away around it in order to use the coredns image instead of just the alpine.

[andrewkroh]

The coredns image is bult FROM scratch and only holds the coredns binary and ca-certs. How about as a workaround building an image based on something small like debian-slim? coredns is only single binary so the Dockerfile should be fairly simple.

[legoguy1000]

The coredns image is bult FROM scratch and only holds the coredns binary and ca-certs. How about as a workaround building an image based on something small like debian-slim? coredns is only single binary so the Dockerfile should be fairly simple.

That worked. Just need to figure out the errors now with the agent.

[legoguy1000]

@andrewkroh fixed tests. ready for review

[andrewkroh]

LGTM. Can you please include a screenshot of the dashboard in the package.

[andrewkroh]

LGTM 🚢

[andrewkroh]

/test

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🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	100.0% (1/1)	💚
Files	100.0% (2/2)	💚 2.726
Classes	100.0% (2/2)	💚 2.726
Methods	95.455% (21/22)	👍 5.583
Lines	85.492% (165/193)	👎 -6.159
Conditionals	100.0% (0/0)	💚