Problem
The agent is not starting and there are no logs
Solution
Look for the message sudo: sorry, you must have a tty to run sudo
If the Agent does not start and there are no logs available, have a look at /var/log/messages or /var/log/syslog and look for the message sudo: sorry, you must have a tty to run sudo.
When using old Linux versions, sometimes the nri-agent user fails to execute a service because it does not have any TTY attached.
To fix this problem, edit your /etc/sudoers file with the visudo command and comment or remove the following line:
Defaults requiretty
After exiting and saving the file, restart the newrelic-infra service.
Check the agent's permission to open the log_file
It is possible that the log file you are using was created when the agent was running as root, and now the nri-agent user does not have permissions to write it.
To solve this, you need to change the owner of the log file or just change the log_file entry in the /etc/newrelic-infra.yml configuration file. Our installation scripts create the /var/log/newrelic-infra/ folder for that purpose, so a recommended value would be:
log_file: /var/log/newrelic-infra/newrelic-infra.log