* Fix to improve hostname handling
If config_db.json is missing hostname entry, hostname-config.sh ends
up deleting existing entry too and hostname changes to default 'localhost'
* default hostname to 'sonic` if missing in config file
We noticed in tests/production that there is a low probability failure
where /etc/hosts could have some garbage characters before the entry for
local host name. The consequence is that all sudo command would be very
slow. In extreme cases it would prevent some services from starting
properly.
I suspect that the /etc/hosts file might be opened by some process causing
the issue. Editing contents with new file level and replace the whole file
should be safer.
Signed-off-by: Ying Xie <ying.xie@microsoft.com>
- What I did
This fix removes the possibility of 'localhost' entry getting removed from /etc/hosts file by hostname-config service.
Without this change, whenever we change the hostname from 'localhost' to any other name on the config_db.json and reload the config, /etc/hosts file will only have the new hostname on it. But there are multiple sonic utilities (eg: swssconfig) which relies on the hard coded 'localhost' name and they tend to stop working.
- How I did it
Added a new check on hostname-config.sh script to avid blindly deleting the line containing the old hostname from /etc/hosts file. Now it will delete the old hostname only if its not localhost or when the hostname is not changing.
- How to verify it
Bring up SONiC on a device with hostname as localhost
Edit /etc/sonic/config_db.json to update the 'hostname' filed under DEVICE_METADATA from "hostname" : "localhost" --> "hostname" : "sonic"
run config reload -y to reflect the hostname change done on config_db.json file.
cat /etc/hosts and check whether both 127.0.0.1 localhost and 127.0.0.1 sonic entry are present on the file.
ping localhost should work fine.
- Description for the changelog
Make hostname-config service more robust in handling SONiC hostname change from localhost to anything else.
