[AMLII-2036] Add check for readonly file systems

[soberpeach]

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What does this PR do?

Returns a valid launcher even if agent is in a readonly file system. Errors are handled gracefully instead of causing a panic.

Motivation

Bug discovered when then agent was run in a readonly filesystem.

Additional Notes

Possible Drawbacks / Trade-offs

Describe how to test/QA your changes

Run the agent with logs enabled and make the agent logs run directory readonly (directory is located at /opt/datadog-agent-/run on mac) and ensure the agent doesn't panic on startup.

[pr-commenter[bot]]

Test changes on VM

Use this command from test-infra-definitions to manually test this PR changes on a VM:

inv create-vm --pipeline-id=44457772 --os-family=ubuntu

Note: This applies to commit f2245b3f

[pr-commenter[bot]]

Regression Detector

Regression Detector Results

Run ID: 17ffab5a-75b6-4749-80e0-e9b925242fae Metrics dashboard Target profiles

Baseline: 8599a94b76a9968510da2783080bd3ce076e086b Comparison: f2245b3f2569e320b71f1a0c34edf82c71d0fe81

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	trials	links
➖	otel_to_otel_logs	ingress throughput	+1.08	[+0.25, +1.92]	1	Logs
➖	uds_dogstatsd_to_api	ingress throughput	-0.00	[-0.00, +0.00]	1	Logs
➖	tcp_dd_logs_filter_exclude	ingress throughput	-0.00	[-0.01, +0.01]	1	Logs
➖	idle	memory utilization	-0.04	[-0.08, +0.00]	1	Logs
➖	tcp_syslog_to_blackhole	ingress throughput	-0.08	[-0.14, -0.03]	1	Logs
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	-0.13	[-0.88, +0.63]	1	Logs
➖	basic_py_check	% cpu utilization	-0.18	[-2.95, +2.60]	1	Logs
➖	file_tree	memory utilization	-0.59	[-0.70, -0.47]	1	Logs
➖	pycheck_lots_of_tags	% cpu utilization	-0.75	[-3.42, +1.92]	1	Logs

Bounds Checks

perf	experiment	bounds_check_name	replicates_passed
❌	idle	memory_usage	8/10

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".

[soberpeach]

/merge

[dd-devflow[bot]]

:steam_locomotive: MergeQueue: pull request added to the queue

The median merge time in main is 23m.

Use /merge -c to cancel this operation!