cloudflare/pint
Publicmirrored from https://github.com/cloudflare/pintAvailable
internal/checks/alerts_comparison.go
151lines · modecode
| 1 | package checks |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | |
| 6 | "github.com/cloudflare/pint/internal/discovery" |
| 7 | "github.com/cloudflare/pint/internal/parser" |
| 8 | "github.com/cloudflare/pint/internal/parser/utils" |
| 9 | |
| 10 | promParser "github.com/prometheus/prometheus/promql/parser" |
| 11 | ) |
| 12 | |
| 13 | const ( |
| 14 | ComparisonCheckName = "alerts/comparison" |
| 15 | ComparisonCheckDetails = `Prometheus alerting rules will trigger an alert for each query that returns *any* result. |
| 16 | Unless you do want an alert to always fire you should write your query in a way that returns results only when some condition is met. |
| 17 | In most cases this can be achieved by having some condition in the query expression. |
| 18 | For example ` + "`" + `up == 0` + "`" + " or " + "`" + "rate(error_total[2m]) > 0" + "`." + ` |
| 19 | Be careful as some PromQL operations will cause the query to always return the results, for example using the [bool modifier](https://prometheus.io/docs/prometheus/latest/querying/operators/#comparison-binary-operators).` |
| 20 | ) |
| 21 | |
| 22 | func NewComparisonCheck() ComparisonCheck { |
| 23 | return ComparisonCheck{} |
| 24 | } |
| 25 | |
| 26 | type ComparisonCheck struct{} |
| 27 | |
| 28 | func (c ComparisonCheck) Meta() CheckMeta { |
| 29 | return CheckMeta{ |
| 30 | States: []discovery.ChangeType{ |
| 31 | discovery.Noop, |
| 32 | discovery.Added, |
| 33 | discovery.Modified, |
| 34 | discovery.Moved, |
| 35 | }, |
| 36 | IsOnline: false, |
| 37 | } |
| 38 | } |
| 39 | |
| 40 | func (c ComparisonCheck) String() string { |
| 41 | return ComparisonCheckName |
| 42 | } |
| 43 | |
| 44 | func (c ComparisonCheck) Reporter() string { |
| 45 | return ComparisonCheckName |
| 46 | } |
| 47 | |
| 48 | func (c ComparisonCheck) Check(_ context.Context, _ discovery.Path, rule parser.Rule, _ []discovery.Entry) (problems []Problem) { |
| 49 | if rule.AlertingRule == nil { |
| 50 | return problems |
| 51 | } |
| 52 | |
| 53 | if rule.AlertingRule.Expr.SyntaxError != nil { |
| 54 | return problems |
| 55 | } |
| 56 | |
| 57 | expr := rule.Expr().Query |
| 58 | |
| 59 | if n := utils.HasOuterBinaryExpr(expr); n != nil && n.Op == promParser.LOR { |
| 60 | if (hasComparision(n.LHS) == nil || hasComparision(n.RHS) == nil) && !isAbsent(n.LHS) && !isAbsent(n.RHS) { |
| 61 | problems = append(problems, Problem{ |
| 62 | Lines: rule.AlertingRule.Expr.Value.Lines, |
| 63 | Reporter: c.Reporter(), |
| 64 | Text: "Alert query uses `or` operator with one side of the query that will always return a result, this alert will always fire.", |
| 65 | Details: ComparisonCheckDetails, |
| 66 | Severity: rewriteSeverity(Warning, n.LHS, n.RHS), |
| 67 | }) |
| 68 | } |
| 69 | } |
| 70 | |
| 71 | if n := hasComparision(expr.Expr); n != nil { |
| 72 | if n.ReturnBool && hasComparision(n.LHS) == nil && hasComparision(n.RHS) == nil { |
| 73 | problems = append(problems, Problem{ |
| 74 | Lines: rule.AlertingRule.Expr.Value.Lines, |
| 75 | Reporter: c.Reporter(), |
| 76 | Text: "Alert query uses `bool` modifier for comparison, this means it will always return a result and the alert will always fire.", |
| 77 | Details: ComparisonCheckDetails, |
| 78 | Severity: Bug, |
| 79 | }) |
| 80 | } |
| 81 | return problems |
| 82 | } |
| 83 | |
| 84 | if hasAbsent(expr) { |
| 85 | return problems |
| 86 | } |
| 87 | |
| 88 | problems = append(problems, Problem{ |
| 89 | Lines: rule.AlertingRule.Expr.Value.Lines, |
| 90 | Reporter: c.Reporter(), |
| 91 | Text: "Alert query doesn't have any condition, it will always fire if the metric exists.", |
| 92 | Details: ComparisonCheckDetails, |
| 93 | Severity: Warning, |
| 94 | }) |
| 95 | |
| 96 | return problems |
| 97 | } |
| 98 | |
| 99 | func hasComparision(n promParser.Node) *promParser.BinaryExpr { |
| 100 | if node, ok := n.(*promParser.BinaryExpr); ok { |
| 101 | if node.Op.IsComparisonOperator() { |
| 102 | return node |
| 103 | } |
| 104 | if node.Op == promParser.LUNLESS { |
| 105 | return node |
| 106 | } |
| 107 | } |
| 108 | |
| 109 | for _, child := range promParser.Children(n) { |
| 110 | if node := hasComparision(child); node != nil { |
| 111 | return node |
| 112 | } |
| 113 | } |
| 114 | |
| 115 | return nil |
| 116 | } |
| 117 | |
| 118 | func isAbsent(node promParser.Node) bool { |
| 119 | if node, ok := node.(*promParser.Call); ok && (node.Func.Name == "absent") { |
| 120 | return true |
| 121 | } |
| 122 | |
| 123 | for _, child := range promParser.Children(node) { |
| 124 | if isAbsent(child) { |
| 125 | return true |
| 126 | } |
| 127 | } |
| 128 | |
| 129 | return false |
| 130 | } |
| 131 | |
| 132 | func hasAbsent(n *parser.PromQLNode) bool { |
| 133 | if isAbsent(n.Expr) { |
| 134 | return true |
| 135 | } |
| 136 | for _, child := range n.Children { |
| 137 | if hasAbsent(child) { |
| 138 | return true |
| 139 | } |
| 140 | } |
| 141 | return false |
| 142 | } |
| 143 | |
| 144 | func rewriteSeverity(s Severity, nodes ...promParser.Node) Severity { |
| 145 | for _, node := range nodes { |
| 146 | if n, ok := node.(*promParser.Call); ok && n.Func.Name == "vector" { |
| 147 | return Bug |
| 148 | } |
| 149 | } |
| 150 | return s |
| 151 | } |
| 152 | |