in_head: a simple plugin to read a file.

[nokute78]

I added a new input plugin, in_head.
This plugin read a file from head regularly.

We can get some sensor state by reading a file.
e.g How to read RPi2 GPIO state.

$ cat /sys/class/gpio/gpio25/value

So, this plugin may collect such sensor state.

This plugin needs in_head.conf.
You can configure filepath, intervals and buffer size to read.

$ bin/fluent-bit -i head -o stdout -c ../../in_head.conf -V
Fluent-Bit v0.7.0
Copyright (C) Treasure Data

[2016/01/29 22:45:46] [ info] Configuration
 flush time     : 5 seconds
 input plugins  : head 
 collectors     : 
[2016/01/29 22:45:46] [ info] starting engine
[2016/01/29 22:45:46] [debug] Head config: buf_size=256 path=/proc/uptime
[2016/01/29 22:45:46] [debug] Head config: interval_sec=1 interval_nsec=0
[2016/01/29 22:45:46] [debug] in_head_init read_len=0 buf_size=8
[2016/01/29 22:45:46] [debug] [stats] register in plugin: head
[2016/01/29 22:45:46] [debug] [stats] register out plugin: stdout
[2016/01/29 22:45:47] [debug] in_head_collect read_len=20 buf_size=256
[2016/01/29 22:45:48] [debug] in_head_collect read_len=20 buf_size=256
[2016/01/29 22:45:49] [debug] in_head_collect read_len=20 buf_size=256
[2016/01/29 22:45:50] [debug] in_head_collect read_len=20 buf_size=256
[2016/01/29 22:45:51] [debug] [thread 0x2584210] created
[0] [1454075147, {"head"=>"155706.38 142978.31"}]
[1] [1454075148, {"head"=>"155707.38 142979.25"}]
[2] [1454075149, {"head"=>"155708.38 142980.23"}]
[3] [1454075150, {"head"=>"155709.38 142981.20"}]
[2016/01/29 22:45:51] [debug] [thread 0x2584210] ended
[2016/01/29 22:45:51] [debug] in_head_collect read_len=20 buf_size=256
[2016/01/29 22:45:51] [debug] [stats] dump
{"input_plugins":{"head":{"data":[{"time":1454075147,"bytes":0,"events":1},{"time":1454075148,"bytes":0,"events":1},{"time":1454075149,"bytes":0,"events":1}]}},"output_plugins":{"stdout":{"data":[]}}}

Thanks!

Signed-off-by: nokute78 [email protected]

[edsiper]

On this line, you are setting a NULL character in the wrong position, e.g:

{"head":"96996.47 187893.47\u0000"}

two workarounds:

• right position: head_config->buf[head_config->buf_len] = '\0';
• since you are packaging directly to msgpack, there is no need for this.

so I think number 2 is better.

[edsiper]

better to get rid of that line, if the read(2) call reads the maximum allowed by the buffer, it will generate an overflow. At the end it's not required.

[edsiper]

thanks for this contribution!, the plugin looks pretty good, I just added a small note that needs to be fixed, so then it can be merged.

[nokute78]

Thank you for reviewing.
I deleted the wrong null termination.

[edsiper]

merged, thanks!