Gabriel Petrovay's questions

I am running a GCE instance and on it I have a Kubernetes cluster running. An HTTP Load Balancer is also configured to probe the health of the a Kubernetes service running on this instance. But I constantly get this error:

Error: Server Error

The server encountered a temporary error and could not complete your request. Please try again in 30 seconds.

So I wonder if the health check associated with the load balancer is running/configured correctly.

Where can I find or how can I enable the log files of such a health checker?

The instance is running Debian.

Is there a way to detect when a server is completely up (i.e. finished all the kernel startup tasks)? This is a Google Compute Engine Instance.

Nov 18 10:58:51 image-name google: No startup script found in metadata.
Nov 18 10:58:53 image-name kernel: [   27.491829] aufs au_opts_verify:1570:docker[2414]: dirperm1 breaks the protection by the permission bits on the lower branch
Nov 18 10:58:53 image-name kernel: [   27.703142] aufs au_opts_verify:1570:docker[2414]: dirperm1 breaks the protection by the permission bits on the lower branch
Nov 18 10:58:53 image-name kernel: [   27.735867] aufs au_opts_verify:1570:docker[2414]: dirperm1 breaks the protection by the permission bits on the lower branch
Nov 18 10:58:53 image-name kernel: [   27.771732] aufs au_opts_verify:1570:docker[2260]: dirperm1 breaks the protection by the permission bits on the lower branch
Nov 18 10:58:53 image-name kernel: [   27.797540] device vethfa3ab85 entered promiscuous mode
Nov 18 10:58:53 image-name kernel: [   27.804420] IPv6: ADDRCONF(NETDEV_UP): vethfa3ab85: link is not ready
Nov 18 10:58:53 image-name kernel: [   28.028306] IPv6: ADDRCONF(NETDEV_CHANGE): vethfa3ab85: link becomes ready
Nov 18 10:58:53 image-name kernel: [   28.035505] docker0: port 1(vethfa3ab85) entered forwarding state
Nov 18 10:58:53 image-name kernel: [   28.041963] docker0: port 1(vethfa3ab85) entered forwarding state
Nov 18 10:58:53 image-name kernel: [   28.048532] IPv6: ADDRCONF(NETDEV_CHANGE): docker0: link becomes ready
Nov 18 10:58:54 image-name kernel: [   28.980082] IPv6: eth0: IPv6 duplicate address fe80::42:acff:fe11:1 detected!
Nov 18 10:59:08 image-name kernel: [   43.068094] docker0: port 1(vethfa3ab85) entered forwarding state
Nov 18 10:59:53 image-name kernel: [   87.944452] aufs au_opts_verify:1570:docker[2864]: dirperm1 breaks the protection by the permission bits on the lower branch
Nov 18 10:59:53 image-name kernel: [   88.001012] aufs au_opts_verify:1570:docker[2864]: dirperm1 breaks the protection by the permission bits on the lower branch
Nov 18 10:59:53 image-name kernel: [   88.049510] aufs au_opts_verify:1570:docker[2815]: dirperm1 breaks the protection by the permission bits on the lower branch

My problem is that I can connect to it using SSH when kernel progress is below 30% and some processes are not yet started. I want to detect somehow if the server has completed startup.

I have postfix installed on my machine. I also use the generic maps to overwrite the email address from ubuntu to [email protected]:

/etc/postfix/generic
    ubuntu     [email protected]

With this generic mapping the email comes from "Ubuntu" <[email protected]>. But I also want to overwrite the the From Name of the sender to Server1 such that I receive emails from: "Server1" <[email protected]>.

How do I configure this in postfix?

I have a Ubuntu server with the users: ubuntu and user

I connect to each of the users using ssh -A (to pass my local machine keys to SSH). From any of the users I can connect to the SSH server of Github:

$ ssh -T [email protected]
...
Hi gabipetrovay! You've successfully authenticated, but GitHub does not provide shell access.

But when I try to connect from ubuntu using sudo, on behalf of user

sudo -E -u user ssh -T [email protected]

I get a Permission denied (publickey) error.

Using the -vv option for ssh I can see that when running with sudo on behalf of user from ubuntu the key on my machine is not offered to the ssh server. As a comparison:

directly form user:

debug2: key: /Users/gabriel/.ssh/id_rsa (0x7fbf09390020),
debug2: key: /home/mono/.ssh/id_rsa ((nil)),
debug2: key: /home/mono/.ssh/id_dsa ((nil)),
debug2: key: /home/mono/.ssh/id_ecdsa ((nil)),
debug2: key: /home/mono/.ssh/id_ed25519 ((nil)),

from ubuntu using sudo -u user:

debug2: key: /home/mono/.ssh/id_rsa ((nil)),
debug2: key: /home/mono/.ssh/id_dsa ((nil)),
debug2: key: /home/mono/.ssh/id_ecdsa ((nil)),
debug2: key: /home/mono/.ssh/id_ed25519 ((nil)),

So it seems that through sudo the SSH_AUTH_SOCK socket is not considered.

I have also added Defaults env_keep+=SSH_AUTH_SOCK to /etc/sudoers but it still does not work.

How can I achieve this? I need to execute ssh and git commands from user ubuntu on behalf of the user user.

I would like to disable the PrintLastLog option for only one run of the ssh command.

I tried to pass it using the -o option:

 ssh -q -o PrintLastLog=no localhost

but I get:

command-line: line 0: Bad configuration option: printlastlog

I also don't see the PrintLastLog option in the SSH_CONFIG(5) man file. Are there options that are special and cannot be passed as command line flags?

The reason for the question is that I need to ssh to several servers from a script, and I don't want the MOTD/login message clogging up the log output from the script.

I have a Ubuntu web server that uses iptables PREROUTING to forward port 80 to 8000.

So the web process listens on port 8000. Now I want to make a curl from the same server to a web application running on it. But this issues a Connection refused:

$ curl http://my.webite.com/on/same/server
curl: (7) Failed connect to my.webite.com:80; Connection refused

curl-ing on port 8000 works (but it must work on port 80).

I also made sure that that web server listens on all interfaces (not only on the physical one):

$ netstat -ntl | grep LISTEN
...
tcp        0      0 0.0.0.0:8000            0.0.0.0:*               LISTEN
...

The domain of my app (my.webite.com) also resolves to the physical interface IP.

Why do I get the Connection refused?

The file I want to modify belongs to root. I want to change this file with a sudo-er

sudo sed -i 's/Accept .* LC_\*$/& GIT_*/' /etc/ssh/sshd_config

(trying to append GIT_* to the Accept sshd config directive)

But the file remains unchanged:

$ grep Accept /etc/ssh/sshd_config 
AcceptEnv LANG LC_*