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adding feature flag, promql-negative-offset

Browse source 
Signed-off-by: schou <pschou@users.noreply.github.com>
This commit is contained in:
schou 2021-02-21 13:03:58 -05:00
parent 851acf86ee
commit 22cd48868a
6 changed files with 60 additions and 6 deletions
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7
cmd/prometheus/main.go
View file

@ -117,7 +117,8 @@ type flagConfig struct {
featureList []string
// These options are extracted from featureList
// for ease of use.
enablePromQLAtModifier bool
enablePromQLAtModifier bool
enablePromQLNegativeOffset bool
prometheusURL string
corsRegexString string
@ -134,6 +135,9 @@ func (c *flagConfig) setFeatureListOptions(logger log.Logger) error {
case "promql-at-modifier":
c.enablePromQLAtModifier = true
level.Info(logger).Log("msg", "Experimental promql-at-modifier enabled")
case "promql-negative-offset":
c.enablePromQLNegativeOffset = true
level.Info(logger).Log("msg", "Experimental promql-negative-offset enabled")
case "remote-write-receiver":
c.web.RemoteWriteReceiver = true
level.Info(logger).Log("msg", "Experimental remote-write-receiver enabled")
@ -441,6 +445,7 @@ func main() {
LookbackDelta: time.Duration(cfg.lookbackDelta),
NoStepSubqueryIntervalFn: noStepSubqueryInterval.Get,
EnableAtModifier: cfg.enablePromQLAtModifier,
EnableNegativeOffset: cfg.enablePromQLNegativeOffset,
}
queryEngine = promql.NewEngine(opts)

6
docs/disabled_features.md
View file

@ -18,6 +18,12 @@ They may be enabled by default in future versions.
The `@` modifier lets you specify the evaluation time for instant vector selectors,
range vector selectors, and subqueries. More details can be found [here](querying/basics.md#modifier).
## Negative offset in PromQL
`--enable-feature=promql-negative-offset`
In contrast to the positive offset modifier, the negative offset modifier lets one shift a vector into the future. An example in which one may want to use a negative offset is: when reviewing past data and making temporal comparisons with earlier data and later data. More details can be found [here](querying/basics.md#offset-modifier).
## Remote Write Receiver
`--enable-feature=remote-write-receiver`

8
docs/querying/basics.md
View file

@ -204,11 +204,17 @@ The same works for range vectors. This returns the 5-minute rate that
rate(http_requests_total[5m] offset 1w)
For comparisons with temporal shifts forward and backward, a negative offset
For comparisons with temporal shifts forward in time, a negative offset
can be specified:
rate(http_requests_total[5m] offset -1w)
This negative offset is disabled by default since it breaks the invariant
that PromQL does not look ahead of the evaluation time for samples. This
feature is enabled by setting `--enable-feature=promql-negative-offset`
flag. See [disabled features](../disabled_features.md) for more details
about this flag.
### @ modifier
The `@` modifier allows changing the evaluation time for individual instant

29
promql/engine.go
View file

@ -211,6 +211,9 @@ type EngineOpts struct {
// EnableAtModifier if true enables @ modifier. Disabled otherwise.
EnableAtModifier bool
// EnableNegativeOffset if true enables negative (-) offset values. Disabled otherwise.
EnableNegativeOffset bool
}
// Engine handles the lifetime of queries from beginning to end.
@ -226,6 +229,7 @@ type Engine struct {
lookbackDelta time.Duration
noStepSubqueryIntervalFn func(rangeMillis int64) int64
enableAtModifier bool
enableNegativeOffset bool
}
// NewEngine returns a new engine.
@ -307,6 +311,7 @@ func NewEngine(opts EngineOpts) *Engine {
lookbackDelta: opts.LookbackDelta,
noStepSubqueryIntervalFn: opts.NoStepSubqueryIntervalFn,
enableAtModifier: opts.EnableAtModifier,
enableNegativeOffset: opts.EnableNegativeOffset,
}
}
@ -388,9 +393,10 @@ func (ng *Engine) newQuery(q storage.Queryable, expr parser.Expr, start, end tim
}
var ErrValidationAtModifierDisabled = errors.New("@ modifier is disabled")
var ErrValidationNegativeOffsetDisabled = errors.New("negative offset is disabled")
func (ng *Engine) validateOpts(expr parser.Expr) error {
if ng.enableAtModifier {
if ng.enableAtModifier && ng.enableNegativeOffset {
return nil
}
@ -398,23 +404,38 @@ func (ng *Engine) validateOpts(expr parser.Expr) error {
parser.Inspect(expr, func(node parser.Node, path []parser.Node) error {
switch n := node.(type) {
case *parser.VectorSelector:
if n.Timestamp != nil || n.StartOrEnd == parser.START || n.StartOrEnd == parser.END {
if !ng.enableAtModifier &&
(n.Timestamp != nil || n.StartOrEnd == parser.START || n.StartOrEnd == parser.END) {
validationErr = ErrValidationAtModifierDisabled
return validationErr
}
if !ng.enableNegativeOffset && n.OriginalOffset < 0 {
validationErr = ErrValidationNegativeOffsetDisabled
return validationErr
}
case *parser.MatrixSelector:
vs := n.VectorSelector.(*parser.VectorSelector)
if vs.Timestamp != nil || vs.StartOrEnd == parser.START || vs.StartOrEnd == parser.END {
if !ng.enableAtModifier &&
(vs.Timestamp != nil || vs.StartOrEnd == parser.START || vs.StartOrEnd == parser.END) {
validationErr = ErrValidationAtModifierDisabled
return validationErr
}
if !ng.enableNegativeOffset && vs.OriginalOffset < 0 {
validationErr = ErrValidationNegativeOffsetDisabled
return validationErr
}
case *parser.SubqueryExpr:
if n.Timestamp != nil || n.StartOrEnd == parser.START || n.StartOrEnd == parser.END {
if !ng.enableAtModifier &&
(n.Timestamp != nil || n.StartOrEnd == parser.START || n.StartOrEnd == parser.END) {
validationErr = ErrValidationAtModifierDisabled
return validationErr
}
if !ng.enableNegativeOffset && n.OriginalOffset < 0 {
validationErr = ErrValidationNegativeOffsetDisabled
return validationErr
}
}
return nil
})

12
promql/engine_test.go
View file

@ -2299,6 +2299,18 @@ func TestEngineOptsValidation(t *testing.T) {
}, {
opts: EngineOpts{EnableAtModifier: true},
query: "rate(metric[1h:1m] @ end())",
}, {
opts: EngineOpts{EnableNegativeOffset: false},
query: "metric offset -1s", fail: true, expError: ErrValidationNegativeOffsetDisabled,
}, {
opts: EngineOpts{EnableNegativeOffset: true},
query: "metric offset -1s",
}, {
opts: EngineOpts{EnableAtModifier: true, EnableNegativeOffset: true},
query: "metric @ 100 offset -2m",
}, {
opts: EngineOpts{EnableAtModifier: true, EnableNegativeOffset: true},
query: "metric offset -2m @ 100",
},
}

4
web/api/v1/api.go
View file

@ -370,6 +370,8 @@ func (api *API) query(r *http.Request) (result apiFuncResult) {
qry, err := api.QueryEngine.NewInstantQuery(api.Queryable, r.FormValue("query"), ts)
if err == promql.ErrValidationAtModifierDisabled {
err = errors.New("@ modifier is disabled, use --enable-feature=promql-at-modifier to enable it")
} else if err == promql.ErrValidationNegativeOffsetDisabled {
err = errors.New("negative offset is disabled, use --enable-feature=promql-negative-offset to enable it")
}
if err != nil {
return invalidParamError(err, "query")
@ -448,6 +450,8 @@ func (api *API) queryRange(r *http.Request) (result apiFuncResult) {
qry, err := api.QueryEngine.NewRangeQuery(api.Queryable, r.FormValue("query"), start, end, step)
if err == promql.ErrValidationAtModifierDisabled {
err = errors.New("@ modifier is disabled, use --enable-feature=promql-at-modifier to enable it")
} else if err == promql.ErrValidationNegativeOffsetDisabled {
err = errors.New("negative offset is disabled, use --enable-feature=promql-negative-offset to enable it")
}
if err != nil {
return apiFuncResult{nil, &apiError{errorBadData, err}, nil, nil}