[8.10](backport #3415) elastic-agent install: Only uninstall when Agent is installed

[mergify]

This is an automatic backport of pull request #3415 done by Mergify.
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	modified:   internal/pkg/agent/cmd/install.go

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	both modified:   internal/pkg/agent/install/install.go

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[elasticmachine]

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• Start Time: 2023-10-12T11:52:26.472+0000

• Duration: 28 min 46 sec

Test stats 🧪

Test	Results
Failed	0
Passed	6317
Skipped	55
Total	6372

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[elasticmachine]

🌐 Coverage report

Name	Metrics % (covered/total)	Diff
Packages	98.765% (80/81)	👍
Files	67.944% (195/287)	👍
Classes	66.234% (357/539)	👍
Methods	53.125% (1122/2112)	👍
Lines	38.605% (12759/33050)	👎 -0.039
Conditionals	100.0% (0/0)	💚

[ycombinator]

Several integration tests failed in Buildkite with errors like this one:

    fixture.go:365: >> running agent with: [/tmp/TestInstallWithEndpointSecurityAndRemoveEndpointIntegrationunprotected3086036477/001/elastic-agent-8.10.2-SNAPSHOT-linux-arm64/elastic-agent install --force --non-interactive --url https://408087213e8b4d0ba301c330386e040e.fleet.eastus2.azure.qa.cld.elstc.co:9243 --enrollment-token WmZ2YnpZb0JHT3NOYTB5bHpvb1o6VWhmV0Jpa0JUUU94N20teEZGTUh5QQ==]
    endpoint_security_test.go:358: Installing in non-interactive mode.
        Error: failed to copy source directory (/tmp/TestInstallWithEndpointSecurityAndRemoveEndpointIntegrationunprotected3086036477/001/elastic-agent-8.10.2-SNAPSHOT-linux-arm64) to destination (/opt/Elastic/Agent): symlink data/elastic-agent-2ee5e9/elastic-agent /opt/Elastic/Agent/elastic-agent: file exists

Maybe some previous test didn't finish cleanup? Re-running the Buildkite build to see if this is a transient error...

[ycombinator]

The build is failing again with the same errors as before: #3472 (comment).

 upgrade_test.go:507: Agent installation output: "Installing in non-interactive mode.\nError: failed to copy source directory (/tmp/TestStandaloneUpgradeToSpecificSnapshotBuild2358091522/001/elastic-agent-8.10.2-SNAPSHOT-linux-arm64) to destination (/opt/Elastic/Agent): symlink data/elastic-agent-896177/elastic-agent /opt/Elastic/Agent/elastic-agent: file exists\nFor help, please see our troubleshooting guide at https://www.elastic.co/guide/en/fleet/8.10/fleet-troubleshooting.html\n"

This makes me think there's some PR fixing the testing framework's fixture uninstallation code that probably hasn't been backported to the 8.10 branch. @cmacknz @pchila can you think of any such PR?

[pchila]

@ycombinator I can't think of any recent PRs that could have affected this behavior. We still rely on the fixture for uninstalling at the end of a test. I am wondering if in some of our testcases we don't detect the agent as "installed" and with this change we have some stuff that is left over...

[ycombinator]

Thanks @pchila. Just strange that we're only seeing this on 8.10 and not on main. As you said, perhaps there's some cleanup code that's present on main but didn't get backported to 8.10. I'll investigate. Thanks!

[mergify]

This pull request has not been merged yet. Could you please review and merge it @ycombinator? 🙏

[ycombinator]

I'm going to revisit this PR once #3495 is merged.

[elasticmachine]

Pinging @elastic/elastic-agent (Team:Elastic-Agent)

[mergify]

This pull request has not been merged yet. Could you please review and merge it @ycombinator? 🙏