The "collector_configuration_directory" option requires an absolute path

[bernd]

Problem description

The value of the collector_configuration_directory config option needs to be an absolute path. I tried to use .cache/config as value. Writing the config file worked but starting the collector didn't because it couldn't find the file.

Filebeat error log:

Exiting: error loading config file: stat .cache/config/filebeat-6.3.0.conf: no such file or directory

Sidecar output:

$ ./build/1.0.0/linux/amd64/graylog-sidecar -c local.yml 
INFO[0000] Using node-id: 1c4a8275-ffeb-4c27-8cfb-cd23ff5a52e8 
INFO[0000] Starting signal distributor                  
INFO[0005] Adding process runner for: filebeat-6.3.0    
INFO[0005] [filebeat-6.3.0] Configuration change detected, rewriting configuration file. 
INFO[0005] [filebeat-6.3.0] Starting (exec driver)      
ERRO[0006] [filebeat-6.3.0] Backend finished unexpectedly, trying to restart 1/3. 
INFO[0006] [filebeat-6.3.0] Starting (exec driver)      
ERRO[0007] [filebeat-6.3.0] Backend finished unexpectedly, trying to restart 2/3. 
INFO[0007] [filebeat-6.3.0] Starting (exec driver)      
ERRO[0008] [filebeat-6.3.0] Backend finished unexpectedly, trying to restart 3/3. 
INFO[0008] [filebeat-6.3.0] Starting (exec driver)      
ERRO[0009] [filebeat-6.3.0] Unable to start collector after 3 tries, giving up! 

I think we should either require an absolute path and warn the user if the path is not absolute or change the code to handle relative paths.

Steps to reproduce the problem

1. Use relative path for collector_configuration_directory config option
2. Start sidecar
3. Assign configuration
4. Watch collector startup fail

Environment

• Sidecar Version: 1.0.0-alpha.9