README
¶
complexity package
Pure, stateless functions for scoring VM migration complexity. No dependency on the HTTP layer or database — designed to be unit-tested in isolation.
Score scale
Scores express how much effort a migration is expected to require. Two independent dimensions are scored: OS type and disk size.
| Score | Label | Meaning |
|---|---|---|
| 0 | Unknown | OS not recognised; complexity cannot be assessed |
| 1 | Easy | Straightforward migration, minimal intervention expected |
| 2 | Medium | Standard migration, some attention required |
| 3 | Hard | Complex migration, significant effort expected |
| 4 | White Glove | Requires manual intervention and special handling |
OS scores run 0–4. Disk scores run 1–4 (unknown does not apply to disk size).
OS classification
ClassifyOS(osName string) Score performs case-insensitive substring matching against OSDifficultyScores. If no keyword matches, the OS receives score 0 (unknown).
The full keyword-to-score mapping:
Score 1 — Easy
| OS family | Matched versions |
|---|---|
| Red Hat Enterprise Linux | 6, 7, 8, 9, 10 |
| Red Hat Fedora | all |
| CentOS | 6, 7, 8, 9 |
| Oracle Linux | 6, 7, 8, 9 |
| Rocky Linux | 8, 9 |
Score 2 — Medium
| OS family | Matched versions |
|---|---|
| Red Hat Enterprise Linux | 4, 5 |
| CentOS | 4, 5 |
| Oracle Linux | 4, 5 |
| SUSE Linux Enterprise | 12, 15 |
| Microsoft Windows Server | 2016, 2019, 2022, 2025 |
| Microsoft Windows | 10, 11 |
Score 3 — Hard
| OS family | Matched versions |
|---|---|
| SUSE Linux Enterprise | 8, 9, 10, 11 |
| SUSE openSUSE | all |
| AlmaLinux | 8, 9 |
| Ubuntu Linux | 18.04, 20.04, 22.04, 24.04, generic |
| Debian GNU/Linux | 5–12 |
| Microsoft Windows Server | 2000, 2003, 2008, 2008 R2, 2012, 2012 R2 |
| Microsoft Windows | XP, Vista, 7, 8 |
| Oracle Solaris | 10, 11 |
| FreeBSD | all |
| VMware Photon OS | all |
| Amazon Linux 2 | all |
| CoreOS Linux | all |
| Apple macOS | all |
Score 4 — White Glove
| OS family | Matched versions |
|---|---|
| Microsoft SQL | all (database workload) |
Score 0 — Unknown
Any OS name that does not match a keyword in the table above. Examples: "Other (64-bit)", "Other Linux (64-bit)", unrecognised custom distributions.
Disk size classification
ScoreDiskTierLabel(label string) Score maps the pre-computed tier labels produced by the agent (stored in vms.diskSizeTier) to numeric scores.
| Tier label | Size range | Score |
|---|---|---|
| Easy (0-10TB) | ≤ 10 TB provisioned | 1 |
| Medium (10-20TB) | ≤ 20 TB provisioned | 2 |
| Hard (20-50TB) | ≤ 50 TB provisioned | 3 |
| White Glove (>50TB) | > 50 TB provisioned | 4 |
DiskSizeRangeRatings() returns the same map with keys trimmed to the numeric range only (e.g. "0-10TB") for use in API responses.
Functions
| Function | Returns | Description |
|---|---|---|
ClassifyOS(osName) |
Score |
Score for a single OS name string |
OSBreakdown(entries) |
[]OSDifficultyEntry |
VM counts aggregated by score (0–4), always 5 entries |
OSNameBreakdown(entries) |
[]OSNameEntry |
One entry per distinct OS name with its score and VM count |
OSRatings(entries) |
map[string]Score |
OS name → score map (no VM counts) |
ScoreDiskTierLabel(label) |
Score |
Score for a single disk tier label |
DiskBreakdown(tiers) |
[]DiskComplexityEntry |
VM counts and total TB aggregated by score (1–4), always 4 entries |
DiskSizeRangeRatings() |
map[string]Score |
Static tier label → score lookup with range-only keys |
Documentation
¶
Overview ¶
Package complexity provides pure, stateless functions for scoring VM migration complexity. It has no dependency on the HTTP layer or database and is designed to be unit-tested in isolation.
Two independent scoring dimensions are supported:
OS complexity (scores 0–4): derived by substring-matching the VM's OS name against OSDifficultyScores. Score 1 is the least complex; score 0 means the OS is unknown and complexity can not be assessed.
Disk complexity (scores 1–4): derived from the pre-computed disk-size tier labels stored in the inventory by the agent. Score 1 is the least complex; score 4 is the most complex.
Index ¶
Constants ¶
This section is empty.
Variables ¶
var DiskScores = []Score{1, 2, 3, 4}
DiskScores lists all valid disk complexity scores in canonical order.
var DiskSizeScores = map[string]Score{
"Easy (0-10TB)": 1,
"Medium (10-20TB)": 2,
"Hard (20-50TB)": 3,
"White Glove (>50TB)": 4,
}
DiskSizeScores maps the pre-computed inventory tier label strings (produced by the agent) to numeric complexity scores. The thresholds follow complexity.md:
Score 1 — provisioned disk ≤ 10 TB Score 2 — provisioned disk ≤ 20 TB Score 3 — provisioned disk ≤ 50 TB Score 4 — provisioned disk > 50 TB
Edit this map to adjust disk complexity scoring.
var OSDifficultyScores = map[string]Score{
"Red Hat Enterprise Linux 4": 2,
"Red Hat Enterprise Linux 5": 2,
"Red Hat Enterprise Linux 6": 1,
"Red Hat Enterprise Linux 7": 1,
"Red Hat Enterprise Linux 8": 1,
"Red Hat Enterprise Linux 9": 1,
"Red Hat Enterprise Linux 10": 1,
"Red Hat Fedora": 1,
"CentOS 4": 2,
"CentOS 5": 2,
"CentOS 6": 1,
"CentOS 7": 1,
"CentOS 8": 1,
"CentOS 9": 1,
"Oracle Linux 4": 2,
"Oracle Linux 5": 2,
"Oracle Linux 6": 1,
"Oracle Linux 7": 1,
"Oracle Linux 8": 1,
"Oracle Linux 9": 1,
"Rocky Linux 8": 1,
"Rocky Linux 9": 1,
"AlmaLinux 8": 3,
"AlmaLinux 9": 3,
"SUSE Linux Enterprise 8": 3,
"SUSE Linux Enterprise 9": 3,
"SUSE Linux Enterprise 10": 3,
"SUSE Linux Enterprise 11": 3,
"SUSE Linux Enterprise 12": 2,
"SUSE Linux Enterprise 15": 2,
"SUSE openSUSE": 3,
"Ubuntu Linux 18.04": 3,
"Ubuntu Linux 20.04": 3,
"Ubuntu Linux 22.04": 3,
"Ubuntu Linux 24.04": 3,
"Ubuntu Linux": 3,
"Debian GNU/Linux 5": 3,
"Debian GNU/Linux 6": 3,
"Debian GNU/Linux 7": 3,
"Debian GNU/Linux 8": 3,
"Debian GNU/Linux 9": 3,
"Debian GNU/Linux 10": 3,
"Debian GNU/Linux 11": 3,
"Debian GNU/Linux 12": 3,
"Microsoft Windows Server 2000": 3,
"Microsoft Windows Server 2003": 3,
"Microsoft Windows Server 2008 R2": 3,
"Microsoft Windows Server 2008": 3,
"Microsoft Windows Server 2012 R2": 3,
"Microsoft Windows Server 2012": 3,
"Microsoft Windows Server 2016": 2,
"Microsoft Windows Server 2019": 2,
"Microsoft Windows Server 2022": 2,
"Microsoft Windows Server 2025": 2,
"Microsoft Windows XP": 3,
"Microsoft Windows Vista": 3,
"Microsoft Windows 7": 3,
"Microsoft Windows 8": 3,
"Microsoft Windows 10": 2,
"Microsoft Windows 11": 2,
"Oracle Solaris 10": 3,
"Oracle Solaris 11": 3,
"FreeBSD": 3,
"VMware Photon OS": 3,
"Amazon Linux 2": 3,
"CoreOS Linux": 3,
"Apple macOS": 3,
"Microsoft SQL": 4,
}
OSDifficultyScores maps OS name substrings to numeric complexity scores. ClassifyOS checks whether each key is a case-insensitive substring of the VM's OS name.
When multiple keys match the same OS name, all matching keys carry the same score, so non-deterministic map iteration order does not affect the result.
Score semantics:
0 = unknown (no key matched) 1 = score 1 easiest 2 = score 2 3 = score 3 4 = score 4 hardest
var OSScores = []Score{0, 1, 2, 3, 4}
OSScores lists all valid OS complexity scores in canonical order.
Functions ¶
func DiskSizeRangeRatings ¶
DiskSizeRangeRatings returns the DiskSizeScores map with keys reformatted to contain only the numeric range portion of each tier label (e.g. "Easy (0-10TB)" becomes "0-10TB"). Use this when exposing the lookup table in API responses so that UI-level label words ("Easy", "Hard", etc.) do not bleed into the data layer.
Types ¶
type DiskComplexityEntry ¶
DiskComplexityEntry is one row in the disk complexity breakdown.
func DiskBreakdown ¶
func DiskBreakdown(tiers []DiskTierInput) []DiskComplexityEntry
DiskBreakdown maps pre-computed inventory tier labels to numeric scores and returns a slice of DiskComplexityEntry in canonical score order (1–4). All four scores are always present; absent scores carry VMCount == 0 and TotalSizeTB == 0.
type DiskTierInput ¶
type DiskTierInput struct {
Label string // Tier label as stored in the inventory (key in vms.diskSizeTier)
VMCount int
TotalSizeTB float64
}
DiskTierInput represents a pre-computed disk size tier from the inventory.
type OSDifficultyEntry ¶
OSDifficultyEntry is one row in the OS complexity breakdown.
func OSBreakdown ¶
func OSBreakdown(osEntries []VMOsEntry) []OSDifficultyEntry
OSBreakdown classifies each OS entry by numeric score and returns a slice of OSDifficultyEntry in canonical score order (0–4). All five scores are always present; absent scores carry VMCount == 0.
type OSNameEntry ¶ added in v0.8.0
OSNameEntry is one row in the per-OS-name complexity breakdown.
func OSNameBreakdown ¶ added in v0.8.0
func OSNameBreakdown(osEntries []VMOsEntry) []OSNameEntry
OSNameBreakdown returns one OSNameEntry per distinct OS name in osEntries.
type Score ¶
type Score = int
Score is a numeric complexity level. Lower values indicate simpler migrations. OS scores run 0–4; disk scores run 1–4.
func ClassifyOS ¶
ClassifyOS returns the numeric complexity score for the given OS name by checking whether each key in OSDifficultyScores appears as a case-insensitive substring of osName. Returns 0 if no key matches (unknown).
func ScoreDiskTierLabel ¶
ScoreDiskTierLabel returns the numeric score for an inventory disk tier label. Returns 0 if the label is not in DiskSizeScores.
Source Files