Split Agent and Installer custom action DLLs

[clarkb7]

What does this PR do?

Splits the CustomActions project into AgentCustomActions (For the Agent) and InstallerCustomActions (For the fleet automation Installer) projects.

This PR only moves the sfxca entrypoints (marked by [CustomAction]) into the new projects. Follow up PRs will start moving individual CA implementations into the separate projects, as necessary.

The CustomActions project will remain to contain common code between the MSIs, such as starting services, configuring services, configuring permissions, etc. While the individual projects will contain the unique parts like paths, property names, service names, etc. and the entrypoints.

The sfx.CA.DLL generated for each MSI will contain both the common CustomActions.dll as well as the per-project [Agent|Installer]CustomActions.dll.

Sets OMNIBUS_TARGET env var in invoke task to target MSI being configured by WixSetup. This var is already set during CI builds, so it is mainly relevant for local builds.

Motivation

Allow custom actions with only slightly different implementations to share a name (e.g. ReadInstallState, StopDDServices) without causing name collision errors during makesfxca. Duplicating the entrypoints with a prefix (.e.g. Agent_ReadInstallState and Installer_ReadInstallState) would bring us closer to the makesfxca limit of 127 custom action entrypoints.

Allow each MSI to define their own custom actions, and keep their unique logic separate, without mixing implementations in the same source file.

https://datadoghq.atlassian.net/browse/WINA-967

Additional Notes

Possible Drawbacks / Trade-offs

Running the same custom action code with different inputs (different service names) can be handled by using MSI tables for input rather than putting the values in the CA code. The former being what the built-in and WiX actions do in many cases. This would also be beneficial for reducing code in our merge modules. This is not a technique we use in our MSI right now so it would require more detailed investigation, see https://datadoghq.atlassian.net/browse/WINA-723.

Describe how to test/QA your changes

no functional changes, just a refactor, has E2E test coverage

[agent-platform-auto-pr]

[Fast Unit Tests Report]

On pipeline 42931548 (CI Visibility). The following jobs did not run any unit tests:

Jobs:

• tests_deb-arm64-py3
• tests_deb-x64-py3
• tests_flavor_dogstatsd_deb-x64
• tests_flavor_heroku_deb-x64
• tests_flavor_iot_deb-x64
• tests_rpm-arm64-py3
• tests_rpm-x64-py3
• tests_windows-x64

If you modified Go files and expected unit tests to run in these jobs, please double check the job logs. If you think tests should have been executed reach out to #agent-devx-help

[pr-commenter]

Regression Detector

Regression Detector Results

Run ID: f7ee4b40-6450-4597-a879-5d85796918fa Metrics dashboard Target profiles

Baseline: 5dae124
Comparison: e949499

Performance changes are noted in the perf column of each table:

• ✅ = significantly better comparison variant performance
• ❌ = significantly worse comparison variant performance
• ➖ = no significant change in performance

No significant changes in experiment optimization goals

Confidence level: 90.00%
Effect size tolerance: |Δ mean %| ≥ 5.00%

There were no significant changes in experiment optimization goals at this confidence level and effect size tolerance.

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI	links
➖	basic_py_check	% cpu utilization	+1.96	[-0.69, +4.61]	Logs
➖	otel_to_otel_logs	ingress throughput	+0.92	[+0.11, +1.74]	Logs
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	+0.67	[-0.13, +1.47]	Logs
➖	idle	memory utilization	+0.24	[+0.21, +0.27]	Logs
➖	file_tree	memory utilization	+0.19	[+0.13, +0.25]	Logs
➖	tcp_dd_logs_filter_exclude	ingress throughput	+0.00	[-0.01, +0.01]	Logs
➖	uds_dogstatsd_to_api	ingress throughput	+0.00	[-0.01, +0.01]	Logs
➖	pycheck_lots_of_tags	% cpu utilization	-0.70	[-3.12, +1.72]	Logs
➖	tcp_syslog_to_blackhole	ingress throughput	-1.10	[-13.93, +11.72]	Logs

Bounds Checks

perf	experiment	bounds_check_name	replicates_passed
✅	idle	memory_usage	10/10

Explanation

A regression test is an A/B test of target performance in a repeatable rig, where "performance" is measured as "comparison variant minus baseline variant" for an optimization goal (e.g., ingress throughput). Due to intrinsic variability in measuring that goal, we can only estimate its mean value for each experiment; we report uncertainty in that value as a 90.00% confidence interval denoted "Δ mean % CI".

For each experiment, we decide whether a change in performance is a "regression" -- a change worth investigating further -- if all of the following criteria are true:

1. Its estimated |Δ mean %| ≥ 5.00%, indicating the change is big enough to merit a closer look.

2. Its 90.00% confidence interval "Δ mean % CI" does not contain zero, indicating that if our statistical model is accurate, there is at least a 90.00% chance there is a difference in performance between baseline and comparison variants.

3. Its configuration does not mark it "erratic".

[clarkb7]

/merge

[dd-devflow]

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