Enhance logging in cases where we have 0 memory recommendations

[plkokanov]

What this PR does / why we need it:
This PR further enhances logging added in #322 in cases where vpa-recommender recommends 0 memory resources. I have chosen to only log cases when recommendations are 0 as these are the recommendations that we have observed when the issue occurs.

Here are the enhancements:

• The internal histogram representation will be printed when 0 recommendations occur
• Recommendations of each estimator are printed, not only the last one in the chain
• Logging is only done when the target estimator recommends 0 memory to reduce amounts of logs - no logs are printed for lower bound and upper bound estimators
• The histogram and checkpoint will be printed on single lines so that they can be easily identified in plutono and not be mixed up with other log lines

Here's what an example log would look like:

W1017 16:24:46.291415   92393 estimator.go:133] Computed "memory" resources for VPA "foo/bar" were 0 in percentile estimator of "targetEstimator"!
W1017 16:24:46.291842   92393 estimator.go:194] Computed "memory" resources for VPA "foo/bar" were 0 after applying margin in margin estimator of "targetEstimator", they were 0 before that
W1017 16:24:46.291864   92393 estimator.go:212] Computed "memory" resources for VPA "foo/bar" were below minimum in min resource estimator of "targetEstimator"! Computed 0, minimum is 400000000.
W1017 16:24:46.291916   92393 estimator.go:240] The memory histogram for VPA "foo/bar" is empty!
W1017 16:24:46.291998   92393 estimator.go:243] Here's the string representation of the memory histogram for VPA "foo/bar": referenceTimestamp: 0001-01-01 00:00:00 +0000 UTC, halfLife: 24h0m0s; minBucket: 175, maxBucket: 0, totalWeight: 0.0000; %-tile value: ; 0: 0.0000; 5: 0.0000; 10: 0.0000; 15: 0.0000; 20: 0.0000; 25: 0.0000; 30: 0.0000; 35: 0.0000; 40: 0.0000; 45: 0.0000; 50: 0.0000; 55: 0.0000; 60: 0.0000; 65: 0.0000; 70: 0.0000; 75: 0.0000; 80: 0.0000; 85: 0.0000; 90: 0.0000; 95: 0.0000; 100: 0.0000; buckets value; 0: 0.0000; 1: 0.0000; 2: 0.0000; 3: 0.0000; 4: 0.0000; 5: 0.0000; 6: 0.0000; 7: 0.0000; 8: 0.0000; 9: 0.0000; 10: 0.0000; 11: 0.0000; 12: 0.0000; 13: 0.0000; 14: 0.0000; 15: 0.0000; 16: 0.0000; 17: 0.0000; 18: 0.0000; 19: 0.0000; 20: 0.0000; 21: 0.0000; 22: 0.0000; 23: 0.0000; 24: 0.0000; 25: 0.0000; 26: 0.0000; 27: 0.0000; 28: 0.0000; 29: 0.0000; 30: 0.0000; 31: 0.0000; 32: 0.0000; 33: 0.0000; 34: 0.0000; 35: 0.0000; 36: 0.0000; 37: 0.0000; 38: 0.0000; 39: 0.0000; 40: 0.0000; 41: 0.0000; 42: 0.0000; 43: 0.0000; 44: 0.0000; 45: 0.0000; 46: 0.0000; 47: 0.0000; 48: 0.0000; 49: 0.0000; 50: 0.0000; 51: 0.0000; 52: 0.0000; 53: 0.0000; 54: 0.0000; 55: 0.0000; 56: 0.0000; 57: 0.0000; 58: 0.0000; 59: 0.0000; 60: 0.0000; 61: 0.0000; 62: 0.0000; 63: 0.0000; 64: 0.0000; 65: 0.0000; 66: 0.0000; 67: 0.0000; 68: 0.0000; 69: 0.0000; 70: 0.0000; 71: 0.0000; 72: 0.0000; 73: 0.0000; 74: 0.0000; 75: 0.0000; 76: 0.0000; 77: 0.0000; 78: 0.0000; 79: 0.0000; 80: 0.0000; 81: 0.0000; 82: 0.0000; 83: 0.0000; 84: 0.0000; 85: 0.0000; 86: 0.0000; 87: 0.0000; 88: 0.0000; 89: 0.0000; 90: 0.0000; 91: 0.0000; 92: 0.0000; 93: 0.0000; 94: 0.0000; 95: 0.0000; 96: 0.0000; 97: 0.0000; 98: 0.0000; 99: 0.0000; 100: 0.0000; 101: 0.0000; 102: 0.0000; 103: 0.0000; 104: 0.0000; 105: 0.0000; 106: 0.0000; 107: 0.0000; 108: 0.0000; 109: 0.0000; 110: 0.0000; 111: 0.0000; 112: 0.0000; 113: 0.0000; 114: 0.0000; 115: 0.0000; 116: 0.0000; 117: 0.0000; 118: 0.0000; 119: 0.0000; 120: 0.0000; 121: 0.0000; 122: 0.0000; 123: 0.0000; 124: 0.0000; 125: 0.0000; 126: 0.0000; 127: 0.0000; 128: 0.0000; 129: 0.0000; 130: 0.0000; 131: 0.0000; 132: 0.0000; 133: 0.0000; 134: 0.0000; 135: 0.0000; 136: 0.0000; 137: 0.0000; 138: 0.0000; 139: 0.0000; 140: 0.0000; 141: 0.0000; 142: 0.0000; 143: 0.0000; 144: 0.0000; 145: 0.0000; 146: 0.0000; 147: 0.0000; 148: 0.0000; 149: 0.0000; 150: 0.0000; 151: 0.0000; 152: 0.0000; 153: 0.0000; 154: 0.0000; 155: 0.0000; 156: 0.0000; 157: 0.0000; 158: 0.0000; 159: 0.0000; 160: 0.0000; 161: 0.0000; 162: 0.0000; 163: 0.0000; 164: 0.0000; 165: 0.0000; 166: 0.0000; 167: 0.0000; 168: 0.0000; 169: 0.0000; 170: 0.0000; 171: 0.0000; 172: 0.0000; 173: 0.0000; 174: 0.0000; 175: 0.0000
W1017 16:24:46.292089   92393 estimator.go:251] Here's the checkpoint/state for VPA "foo/bar": {"lastUpdateTime":"2024-10-17T13:24:46Z","version":"v3","cpuHistogram":{"referenceTimestamp":null},"memoryHistogram":{"referenceTimestamp":null},"firstSampleStart":null,"lastSampleStart":null}

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:
/cc @voelzmo @ialidzhikov

Release note:

Enhance logging in case we have 0 memory recommendations.

[ialidzhikov]

The changes look fine.

I was wondering how to handle the versioning. We released v1.2.1. Right now the version points to v1.3.0-dev.

autoscaler/vertical-pod-autoscaler/common/version.go

Line 20 in 48da8ca

const VerticalPodAutoscalerVersion = "1.3.0-dev"

We should rather update to version somehow to make it clear that it is the 2nd patch on top of the v1.2.1 upstream release.

Maybe something like 1.2.1-build.2 or 1.2.1-2. According to the semver regex these are valid semver versions.

[voelzmo]

/lgtm

Thanks for the change!

[plkokanov]

According to the CICD docs the options for bumping the version for the release trait are: bump_major, bump_minor, bump_patch and noop.

For the version trait we have the choices of: noop, finalize, inject-commit-hash, inject-commit-hash-nodash, inject-timestamp, inject-branch-name and use-branch-name. For releases we currently use the finalize option which (I think) removes the suffix from the version - v1.3.0-dev becomes v1.3.0

If we use noop in both places we could maintain the version name ourselves and maybe even automate the bump with the write-vpa-version.sh script. I'll check to see if there are more options tomorrow.

Anyway, I would propose to do it in a separate PR.