Kapacitor cannot send alert

Kapacitor and influxdb version : latest in docker hub

So I am testing alerting for system using Kapacitor, but it cannot write any alert into file log.

My Kapacitor's config:
`

[logging]
file = "/var/log/kapacitor/kapacitor.log"
level = "CRITICAL"

[[influxdb]]
enabled = true
default = true
name = "localhost"
urls = ["http://172.17.0.1:8086"]
username = ""
password = ""
timeout = 0
insecure-skip-verify = false
startup-timeout = "5m"
disable-subscriptions = false
subscription-mode = "cluster"
subscription-protocol = "http"
subscriptions-sync-interval = "1m0s"
kapacitor-hostname = ""
http-port = 0
udp-bind = ""
udp-buffer = 1000
udp-read-buffer = 0

[influxdb.subscriptions]
my_database = [ "default" ]`

My TICKscript:

`

ID: chronograf-v1-1e6206a2-5898-4434-9772-20736583a12a
Error:
Template:
Type: stream
Status: enabled
Executing: true
Created: 18 Apr 18 07:30 UTC
Modified: 18 Apr 18 08:21 UTC
LastEnabled: 18 Apr 18 08:21 UTC
Databases Retention Policies: ["zcloud"."autogen"]
TICKscript:
stream
|from()
.database('mydb')
.retentionPolicy('autogen')
.measurement('mymeasurement')
.groupBy(*)
|window()
.period(10s)
.every(10s)
.align()
|mean('wind_speed')
.as('value')
|alert()
.warn(lambda: "value" >= 7.5)
.warnReset(lambda: "usage_idle" < 7.5)
.message(' {{.ID}}')
.log('/tmp/alerts.log')

DOT:
digraph chronograf-v1-1e6206a2-5898-4434-9772-20736583a12a {
graph [throughput="0.00 points/s"];

stream0 [avg_exec_time_ns="0s" errors="0" working_cardinality="0" ];
stream0 -> from1 [processed="0"];

from1 [avg_exec_time_ns="0s" errors="0" working_cardinality="0" ];
from1 -> window2 [processed="0"];

window2 [avg_exec_time_ns="0s" errors="0" working_cardinality="0" ];
window2 -> mean3 [processed="0"];

mean3 [avg_exec_time_ns="0s" errors="0" working_cardinality="0" ];
mean3 -> alert4 [processed="0"];

alert4 [alerts_triggered="0" avg_exec_time_ns="0s" crits_triggered="0"
errors="0" infos_triggered="0" oks_triggered="0" warns_triggered="0"
working_cardinality="0" ];
}`

My influx's subscriptions:

`

> show subscriptions
name: _internal
retention_policy name mode destinations
---------------- ---- ---- ------------
monitor kapacitor-25336acf-a3d2-4a7b-b382-fbeabc97eb61 ANY [http://ab0221805079:9092]
monitor kapacitor-fe287e2d-ac2d-46c2-8d95-10c9ae2719f4 ANY [http://ab0221805079:9092]

name: mydb
retention_policy name mode destinations
---------------- ---- ---- ------------
autogen kapacitor-25336acf-a3d2-4a7b-b382-fbeabc97eb61 ANY [http://ab0221805079:9092]
autogen kapacitor-fe287e2d-ac2d-46c2-8d95-10c9ae2719f4 ANY [http://ab0221805079:9092]

name: chronograf
retention_policy name mode destinations
---------------- ---- ---- ------------
autogen kapacitor-fe287e2d-ac2d-46c2-8d95-10c9ae2719f4 ANY [http://ab0221805079:9092]
`

Start with the Kapacitor configuration, TICKscript, and InfluxDB subscription output in the issue. Check why the task graph shows zero processed points and zero alerts, then verify that a triggered alert is written to /tmp/alerts.log; done means the alert pipeline processes data and produces the expected log entry.

Written by the indexing model from the issue text.