If file output cannot write to stdout it does not write to other files

[NomNomSu]

Bug report

Telegraf is not saving from [[inputs.sqlserver]] to [[outputs.file]] when running it as Windows service but it works correctly when running it from command line. Service was ran on administrator account so it had administrator priviledges.

Relevant telegraf.conf:

[global_tags]
  # dc = "us-east-1" # will tag all metrics with dc=us-east-1
  # rack = "1a"

# Configuration for telegraf agent
[agent]
  interval = "5s"
  round_interval = true
  metric_buffer_limit = 1000
  flush_buffer_when_full = true
  collection_jitter = "0s"
  flush_interval = "10s"
  flush_jitter = "0s"
  debug = true
  quiet = false
  logfile = "C:/Program Files/Telegraf/telegraf.log"
  hostname = ""


###############################################################################
#                                  OUTPUTS                                    #
###############################################################################

[[outputs.file]]
  ## Files to write to, "stdout" is a specially handled file.
  files = ["stdout", "C:/temp/sql/sqlperf.out"]
  data_format = "json"
  json_timestamp_units = "1ns"


###############################################################################
#                                  INPUTS                                     #
###############################################################################

[[inputs.sqlserver]]
  servers = [
    "Server=localhost\\servername;Port=1433;User Id=telegraf;Password=***********;app name=telegraf;log=1;",
  ]

System info:

Telegraf 1.5.3
Telegraf v1.7.0~0a02363c

Windows Server 2012 R2
Telegraf Running as service with --config parameter

Steps to reproduce:

1. Create config with [[inputs.sqlserver]] and [[outputs.file]]
2. Create windows service in powershell with command: $path/telegraf.exe --service install --config $path\telegraf.conf
3. Run service

Expected behavior:

output file is created and data is written to file

Actual behavior:

output file is created but file has always 0 bytes

Additional info:

when the same config is run from command line using $path/telegraf.exe --config $path/telegraf.conf file is created and data is written correctly.

With debug on, telegraf log when running from command line:

2018-04-13T08:56:18Z D! Attempting connection to output: file
2018-04-13T08:56:18Z D! Successfully connected to output: file
2018-04-13T08:56:18Z I! Starting Telegraf v1.7.0~0a02363c
2018-04-13T08:56:18Z I! Loaded outputs: file
2018-04-13T08:56:18Z I! Loaded inputs: inputs.sqlserver
2018-04-13T08:56:18Z I! Tags enabled: host=****
2018-04-13T08:56:18Z I! Agent Config: Interval:5s, Quiet:false, Hostname:"****", Flush Interval:10s
2018-04-13T08:56:30Z D! Output [file] buffer fullness: 627 / 1000 metrics.
2018-04-13T08:56:31Z D! Output [file] wrote batch of 627 metrics in 1.0210848s

With debug on, telegraf log when running as service:

2018-04-13T08:52:13Z D! Attempting connection to output: file
2018-04-13T08:52:13Z D! Successfully connected to output: file
2018-04-13T08:52:13Z I! Starting Telegraf v1.7.0~0a02363c
2018-04-13T08:52:13Z I! Loaded outputs: file
2018-04-13T08:52:13Z I! Loaded inputs: inputs.sqlserver
2018-04-13T08:52:13Z I! Tags enabled: host=*****
2018-04-13T08:52:13Z I! Agent Config: Interval:5s, Quiet:false, Hostname:"*****", Flush Interval:10s

[danielnelson]

Does it help if you remove the "stdout" file from the file output?

[NomNomSu]

Yes it does, thanks a lot!

[danielnelson]

To fix this we should warn if stdout is not available, but not stop output to all files.