This is archived documentation for InfluxData product versions that are no longer maintained. For newer documentation, see the latest InfluxData documentation.
An HTTPOutNode caches the most recent data for each group it has received.
The cached data is available at the given endpoint. The endpoint is the relative path from the API endpoint of the running task. For example if the task endpoint is at "/task/<task_name>" and endpoint is "top10", then the data can be requested from "/task/<task_name>/top10".
Example:
stream
|window()
.period(10s)
.every(5s)
|top('value', 10)
//Publish the top 10 results over the last 10s updated every 5s.
|httpOut('top10')
Index
Properties
Chaining Methods
- Alert
- Bottom
- Count
- Deadman
- Derivative
- Distinct
- Eval
- First
- GroupBy
- HttpOut
- InfluxDBOut
- Join
- Last
- Log
- Max
- Mean
- Median
- Min
- Percentile
- Sample
- Shift
- Spread
- Stats
- Stddev
- Sum
- Top
- Union
- Where
- Window
Chaining Methods
Chaining methods create a new node in the pipeline as a child of the calling node.
They do not modify the calling node.
Chaining methods are marked using the |
operator.
Alert
Create an alert node, which can trigger alerts.
node|alert()
Returns: AlertNode
Bottom
Select the bottom num
points for field
and sort by any extra tags or fields.
node|bottom(num int64, field string, fieldsAndTags ...string)
Returns: InfluxQLNode
Count
Count the number of points.
node|count(field string)
Returns: InfluxQLNode
Deadman
Helper function for creating an alert on low throughput, aka deadman's switch.
- Threshold – trigger alert if throughput drops below threshold in points/interval.
- Interval – how often to check the throughput.
- Expressions – optional list of expressions to also evaluate. Useful for time of day alerting.
Example:
var data = stream
|from()...
// Trigger critical alert if the throughput drops below 100 points per 10s and checked every 10s.
data
|deadman(100.0, 10s)
//Do normal processing of data
data...
The above is equivalent to this Example:
var data = stream
|from()...
// Trigger critical alert if the throughput drops below 100 points per 10s and checked every 10s.
data
|stats(10s)
|derivative('emitted')
.unit(10s)
.nonNegative()
|alert()
.id('node \'stream0\' in task \'{{ .TaskName }}\'')
.message('{{ .ID }} is {{ if eq .Level "OK" }}alive{{ else }}dead{{ end }}: {{ index .Fields "emitted" | printf "%0.3f" }} points/10s.')
.crit(lamdba: "emitted" <= 100.0)
//Do normal processing of data
data...
The id
and message
alert properties can be configured globally via the 'deadman' configuration section.
Since the AlertNode is the last piece it can be further modified as normal. Example:
var data = stream
|from()...
// Trigger critical alert if the throughput drops below 100 points per 1s and checked every 10s.
data
|deadman(100.0, 10s)
.slack()
.channel('#dead_tasks')
//Do normal processing of data
data...
You can specify additional lambda expressions to further constrain when the deadman's switch is triggered. Example:
var data = stream
|from()...
// Trigger critical alert if the throughput drops below 100 points per 10s and checked every 10s.
// Only trigger the alert if the time of day is between 8am-5pm.
data
|deadman(100.0, 10s, lambda: hour("time") >= 8 AND hour("time") <= 17)
//Do normal processing of data
data...
node|deadman(threshold float64, interval time.Duration, expr ...tick.Node)
Returns: AlertNode
Derivative
Create a new node that computes the derivative of adjacent points.
node|derivative(field string)
Returns: DerivativeNode
Distinct
Produce batch of only the distinct points.
node|distinct(field string)
Returns: InfluxQLNode
Eval
Create an eval node that will evaluate the given transformation function to each data point. A list of expressions may be provided and will be evaluated in the order they are given and results of previous expressions are made available to later expressions.
node|eval(expressions ...tick.Node)
Returns: EvalNode
First
Select the first point.
node|first(field string)
Returns: InfluxQLNode
GroupBy
Group the data by a set of tags.
Can pass literal * to group by all dimensions. Example:
|groupBy(*)
node|groupBy(tag ...interface{})
Returns: GroupByNode
HttpOut
Create an http output node that caches the most recent data it has received. The cached data is available at the given endpoint. The endpoint is the relative path from the API endpoint of the running task. For example if the task endpoint is at "/api/v1/task/<task_name>" and endpoint is "top10", then the data can be requested from "/api/v1/task/<task_name>/top10".
node|httpOut(endpoint string)
Returns: HTTPOutNode
InfluxDBOut
Create an influxdb output node that will store the incoming data into InfluxDB.
node|influxDBOut()
Returns: InfluxDBOutNode
Join
Join this node with other nodes. The data is joined on timestamp.
node|join(others ...Node)
Returns: JoinNode
Last
Select the last point.
node|last(field string)
Returns: InfluxQLNode
Log
Create a node that logs all data it receives.
node|log()
Returns: LogNode
Max
Select the maximum point.
node|max(field string)
Returns: InfluxQLNode
Mean
Compute the mean of the data.
node|mean(field string)
Returns: InfluxQLNode
Median
Compute the median of the data. Note, this method is not a selector, if you want the median point use .percentile(field, 50.0).
node|median(field string)
Returns: InfluxQLNode
Min
Select the minimum point.
node|min(field string)
Returns: InfluxQLNode
Percentile
Select a point at the given percentile. This is a selector function, no interpolation between points is performed.
node|percentile(field string, percentile float64)
Returns: InfluxQLNode
Sample
Create a new node that samples the incoming points or batches.
One point will be emitted every count or duration specified.
node|sample(rate interface{})
Returns: SampleNode
Shift
Create a new node that shifts the incoming points or batches in time.
node|shift(shift time.Duration)
Returns: ShiftNode
Spread
Compute the difference between min and max points.
node|spread(field string)
Returns: InfluxQLNode
Stats
Create a new stream of data that contains the internal statistics of the node. The interval represents how often to emit the statistics based on real time. This means the interval time is independent of the times of the data points the source node is receiving.
node|stats(interval time.Duration)
Returns: StatsNode
Stddev
Compute the standard deviation.
node|stddev(field string)
Returns: InfluxQLNode
Sum
Compute the sum of all values.
node|sum(field string)
Returns: InfluxQLNode
Top
Select the top num
points for field
and sort by any extra tags or fields.
node|top(num int64, field string, fieldsAndTags ...string)
Returns: InfluxQLNode
Union
Perform the union of this node and all other given nodes.
node|union(node ...Node)
Returns: UnionNode
Where
Create a new node that filters the data stream by a given expression.
node|where(expression tick.Node)
Returns: WhereNode
Window
Create a new node that windows the stream by time.
NOTE: Window can only be applied to stream edges.
node|window()
Returns: WindowNode