Closed mopfeffe closed 4 years ago
arvindsv
commented
9 years ago Sort of related to #599? Maybe making both hostname and IP configurable? Of course, we have to consider the implications of an agent being setup with a made-up hostname and IP address. Does it matter?
mopfeffe
commented
9 years ago Does seems related to #599 – which is much more generally addressing the agent IP address presented to the server for server communication to the agent.
I’m actually quite new to go-cd, so I actually don’t understand the use of the hostname once it reaches the go server. Is that for information only? Is the name actually used or just displayed on the server web site for administrators to see?
--Moshe
From: Aravind SV [mailto:notifications@github.com] Sent: Monday, August 31, 2015 3:09 PM To: gocd/gocd Cc: Moshe Pfeffer (mopfeffe) Subject: Re: [gocd] Hostname returned in SystemUtils.java performs dns lookup.. (#1462)
Sort of related to #599https://github.com/gocd/gocd/issues/599? Maybe making both hostname and IP configurable? Of course, we have to consider the implications of an agent being setup with a made-up hostname and IP address. Does it matter?
— Reply to this email directly or view it on GitHubhttps://github.com/gocd/gocd/issues/1462#issuecomment-136353445.
grahamc
commented
9 years ago The way it is doing the hostname lookup, it should be returning the entry in /etc/hosts which you're supposed to define when you set the hostname. IMHO this isn't a bug in GoCD but in the configuration of your system.
ex, the debian instructions: https://wiki.debian.org/HowTo/ChangeHostname#Core_networking
thusly, the local IP should always resolve promptly.
grahamc
commented
9 years ago @arvindsv re: made up hostnames and made up IPs:
arvindsv
commented
9 years ago @grahamc: About it should be considered potentially made up and "user data": You're right.
The server knows the "real" IP (at least the server-side ingress IP) that the connection came in from, just in case an administrator wants to track an agent down, which claims to be a made-up IP which doesn't belong in the network. Should the agents page show that too, then? Today, it is not.
arvindsv
commented
9 years ago I’m actually quite new to go-cd, so I actually don’t understand the use of the hostname once it reaches the go server. Is that for information only? Is the name actually used or just displayed on the server web site for administrators to see?
As far as I can recall, it's just used for information purposes. /cc @jyotisingh: Is that right?
grahamc
commented
9 years ago @arvindsv I suspect having the real IP display in the "Details" page for an agent would be helpful. I'm not sure it has a good use case on the main screen. Along these lines, I think having the "first connected' datetime displayed there too, but I don't want to start adding work to this issue :).
stale[bot]
commented
4 years ago This issue has been automatically marked as stale because it has not had activity in the last 90 days.
If you can still reproduce this error on the master branch using local development environment or on the latest GoCD Release, please reply with all of the information you have about it in order to keep the issue open.
Thank you for all your contributions.
To get the host name, SystemUtil.java is using public static String getLocalhostName() { try { return InetAddress.getLocalHost().getHostName(); } catch (UnknownHostException e) { throw new RuntimeException(e); } } See:
https://github.com/gocd/gocd/blob/f52a72f9b7c23919470dbdbc47139ef1dc95acf8/base/src/com/thoughtworks/go/util/SystemUtil.java#L46
This causes a DNS lookup on the IP address, which may return something other than the hostname (or may fail if the IP address is not registered in the DNS (causing go agent to send unknonw-host-NNN as the hostname). I would consider that perhaps InetAddress.getHostName() might be a good option to use in case this fails, or perhaps just replace InetAddress.getLocalHost().getHostname() with InetAddress.getHostName() instead...