Add an option for Gardenctl to enable global log level

[neo-liang-sap]

In #234, gardenerLogger is introduced, the log level could be specified via:

var logger = gardenerlogger.NewLogger("info")

We would like to check whether it is possible to add an option for gardenctl commandline e.g. gardenctl -v=info to specify globally the log level.

[neo-liang-sap]

/assign

[danielfoehrKn]

It would be nice if logging on the debug level would include verbose output for the ssh command itself (not only gardenctl ssh)

[tedteng]

It would be nice if logging on the debug level would include verbose output for the ssh command itself (not only gardenctl ssh)

will take care of that. I already enable this in my local code when I development , will open PR for that.

[tedteng]

@danielfoehrKn Please have a look PR: check #264. I was also want to set the global flag before, but working on another ticket which allow non-operator ssh node via gardenctl, doesn't have time working on that. Base on the global flag concept, two enhance in this PR.

1. ssh Verbose mode

Bastion host instance running.
Waiting 60 seconds for Bastion SSH port open
=> nc: connectx to 54.93.202.72 port 22 (tcp) failed: Connection refused

=> nc: connectx to 54.93.202.72 port 22 (tcp) failed: Connection refused

=> Connection to 54.93.202.72 port 22 [tcp/*] succeeded!

Opened SSH Port on Bastion
SSH gardener@54.93.202.72 => gardener@ip-10-250-10-22.eu-central-1.compute.internalOpenSSH_8.1p1, LibreSSL 2.7.3
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 47: Applying options for *
debug1: Executing proxy command: exec ssh -W ip-10-250-10-22.eu-central-1.compute.internal:22 -i /Users/i333/.garden/cache/canary-virtual/projects/i333/zegfzwjhzh/key -o IdentitiesOnly=yes -o ConnectionAttempts=2 -o StrictHostKeyChecking=no gardener@54.93.202.72
debug1: identity file /Users/i333/.garden/cache/canary-virtual/projects/i333/zegfzwjhzh/key type -1
debug1: identity file /Users/i333/.garden/cache/canary-virtual/projects/i333/zegfzwjhzh/key-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.1
Warning: Permanently added '54.93.202.72' (ED25519) to the list of known hosts.
debug1: Remote protocol version 2.0, remote software version OpenSSH_8.2p1 Debian-4
debug1: match: OpenSSH_8.2p1 Debian-4 pat OpenSSH* compat 0x04000000
debug1: Authenticating to ip-10-250-10-22.eu-central-1.compute.internal:22 as 'gardener'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: curve25519-sha256@libssh.org
debug1: kex: host key algorithm: ssh-ed25519
debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
...

2. Error msg enhance
   I try adopt logger.Debugf but not too much useful information as before, maybe I get wrong ways when use logger.Debugf

gg target -g ttt -p i333878 -t zegfzwjhzh -d
Garden:
KUBECONFIG=/Users/i333878/gardener_kubeconfig/ttt/kubeconfig
time="2020-08-20T08:42:35+08:00" level=debug msg="secrets \"seed-aws-eu1\" is forbidden: User \"system:serviceaccount:garden-i333878:robot\" cannot get resource \"secrets\" in API group \"\" in the namespace \"garden\""
exit status 2

after change, it looks like this when we call ErrorCheck, the error msg will display the error file and lines

gg target -g ttt -p i333xxx -t zegfzwjhzh -d
Garden:
KUBECONFIG=/Users/i333xxx/gardener_kubeconfig/ttt/kubeconfig
2020/08/20 08:51:51 [error] /Users/i333xxx/Work/tedteng/gardenctl/pkg/cmd/target.go:568 
 secrets "seed-aws-eu1" is forbidden: User "system:serviceaccount:garden-i333xxx:robot" cannot get resource "secrets" in API group "" in the namespace "garden"
exit status 2