Minikube on Centos

I want to have a "mini" version of Kubernetes on my Centos laptop.

I would prefer not to install an Hypervisor, since k8s can use "--vm-driver=none"...
but I give it a try to install VirtualBox https://www.itzgeek.com/how-tos/linux/centos-how-tos/install-virtualbox-4-3-on-centos-7-rhel-7.html

After installing VirtualBox, I can proceed with minikube

https://kubernetes.io/docs/tasks/tools/install-minikube/


curl -Lo minikube https://storage.googleapis.com/minikube/releases/latest/minikube-linux-amd64 \
&& chmod +x minikube

sudo cp minikube /usr/local/bin && rm minikube

minikube version
minikube version: v0.33.1

minikube start

I get "Error parsing version semver: Version string empty"


kubectl cluster-info
kubectl get nodes



I can try also with "minikube start --vm-driver=none", which however requires docker

Coding and cooking

priceless!

Running Centos on Windows

once you have upgraded to Windows PRO, you can install https://docs.docker.com/docker-for-windows/install/ Docker for Windows

Then open your Git Bash shell and run:

winpty docker run --name centos -i -t -d centos

If the container is stopped, you can simply

docker start centos

and login again:

winpty docker exec -ti centos bash


So you can have a "REAL" Centos on Windows... cool...

VirtualBox and Hyper-V on Windows 10 PRO

I have recently installed Windows PRO. During installation of Hyper-V, it duly warns you that you will no longer be able to use VirtualBox. Which is true, because when I start a VM in VirtualBOx I get the message:


WHvCapabilityCodeHypervisorPresent is FALSE! Make sure you have enabled the 'Windows Hypervisor Platform' feature. (VERR_NEM_NOT_AVAILABLE).
VT-x is not available (VERR_VMX_NO_VMX).


Apparently all you need to do to re-enable VirtualBox is:


open CMD as Administrator
bcdedit /set hypervisorlaunchtype off

reboot your machine

To restore Hyper-V you simply run:
bcdedit /set hypervisorlaunchtype on
or
bcdedit /set hypervisorlaunchtype auto


I haven't tested yet but it should work IMHO



bcdedit is this https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/bcdedit-command-line-options

Windows Boot Manager
--------------------
identifier              {bootmgr}
device                  partition=\Device\HarddiskVolume2
path                    \EFI\Microsoft\Boot\bootmgfw.efi
description             Windows Boot Manager
locale                  fr-FR
inherit                 {globalsettings}
badmemoryaccess         Yes
default                 {current}
resumeobject            {b32f6aed-59a4-11e8-b3f7-b9390bbf0244}
displayorder            {current}
toolsdisplayorder       {memdiag}
timeout                 30

Windows Boot Loader
-------------------
identifier              {current}
device                  partition=C:
path                    \WINDOWS\system32\winload.efi
description             Windows 10
locale                  fr-FR
inherit                 {bootloadersettings}
recoverysequence        {b32f6aef-59a4-11e8-b3f7-b9390bbf0244}
displaymessageoverride  Recovery
recoveryenabled         Yes
badmemoryaccess         Yes
isolatedcontext         Yes
allowedinmemorysettings 0x15000075
osdevice                partition=C:
systemroot              \WINDOWS
resumeobject            {b32f6aed-59a4-11e8-b3f7-b9390bbf0244}
nx                      OptIn
bootmenupolicy          Standard
hypervisorlaunchtype    Auto

Installing spring boot CLI and spring cloud on centos

wget http://repo.spring.io/release/org/springframework/boot/spring-boot-cli/2.1.2.RELEASE/spring-boot-cli-2.1.2.RELEASE-bin.zip
unzip spring-boot-cli-2.1.2.RELEASE-bin.zip

vi .bash_profile

export SPRING_HOME=/home/centos/spring-2.1.2.RELEASE/
PATH=$PATH:$SPRING_HOME
export PATH



to test, type:

spring version

Spring CLI v2.1.2.RELEASE

See also https://gist.github.com/diegopacheco/7623d6da015f588e4f11bee17d483569


vi app.groovy

@RestController
class WebApplication {

@RequestMapping("/")
String home() {
"Hello World!"
}

}


spring run app.groovy
curl http://localhost:8080/

Now you can install Spring Cloud:

spring install org.springframework.cloud:spring-cloud-cli:2.0.0.RELEASE



spring cloud configserver

I get

Caused by: java.lang.NoSuchMethodError: org.springframework.cloud.launcher.cli.LauncherCommand$LauncherOptionHandler.option(Ljava/util/Collection;Ljava/lang/String;)Ljoptsimple/OptionSpecBuilder;


ridiculous....
see here https://github.com/spring-cloud/spring-cloud-cli/issues/80


If I install an older version of Spring CLI, it works:
http://repo.spring.io/release/org/springframework/boot/spring-boot-cli/2.0.0.RELEASE/spring-boot-cli-2.0.0.RELEASE-bin.zip



More information on the Spring Cloud command here https://spring.io/blog/2016/11/02/introducing-the-spring-cloud-cli-launcher

WELD is a holy piece of crap

All of a sudden I get this, and the HTML page is basically blank


2019-01-14 16:21:54,369 WARN [org.jboss.weld.Servlet] (http-/127.0.0.1:8180-1) WELD-000714 HttpContextLifecycle guard leak detected. The Servlet container is not fully compliant. The value was 1
2019-01-14 16:21:54,370 WARN [org.jboss.weld.Context] (http-/127.0.0.1:8180-1) WELD-000223 Bean store leak was detected during org.jboss.weld.context.http.HttpRequestContextImpl association: org.apache.catalina.connector.RequestFacade@6da1f69f
2019-01-14 16:21:54,371 WARN [org.jboss.weld.Context] (http-/127.0.0.1:8180-1) WELD-000223 Bean store leak was detected during org.jboss.weld.context.http.HttpSessionContextImpl association: org.apache.catalina.connector.RequestFacade@6da1f69f


I am just using some javax.inject.Inject and javax.ejb.Stateless annotations.


After undoing all and redoing one step at a time, it all works.


I have enabled weld logging in standalone.xml

<logger category="org.jboss.weld"><level name="DEBUG"/></logger>


but this doesn't help much.

THey say one should hook in the BeanManager to examine its content, but I find this unpractical.
They should really provide a managemen/monitoring console, like the /beans endpoint in SpringBoot.

Once more, Java EE proves to be inferior to Spring.

apache httpd on centos

sudo yum install httpd mod_ssl
systemctl status httpd
systemctl start httpd
Job for httpd.service failed because the control process exited with error code. See "systemctl status httpd.service" and "journalctl -xe" for details.
systemctl status httpd.service

httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Sat 2018-04-28 02:58:49 CEST; 12s ago
     Docs: man:httpd(8)
           man:apachectl(8)
  Process: 25955 ExecStop=/bin/kill -WINCH ${MAINPID} (code=exited, status=1/FAILURE)
  Process: 25951 ExecStart=/usr/sbin/httpd $OPTIONS -DFOREGROUND (code=exited, status=1/FAILURE)
 Main PID: 25951 (code=exited, status=1/FAILURE)

sudo su -
cd /var/log/httpd/
less error_log

[Sat Apr 28 02:58:49.199587 2018] [core:notice] [pid 25951] SELinux policy enabled; httpd running as context system_u:system_r:httpd_t:s0
[Sat Apr 28 02:58:49.222124 2018] [suexec:notice] [pid 25951] AH01232: suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)
[Sat Apr 28 02:58:49.223152 2018] [ssl:emerg] [pid 25951] (13)Permission denied: AH02201: Init: Can't open server certificate file /home/centos/myapp/mysitename.crt
[Sat Apr 28 02:58:49.223168 2018] [ssl:emerg] [pid 25951] AH02312: Fatal error initialising mod_ssl, exiting.

less /etc/httpd/conf/httpd.conf

<VirtualHost *:443>
  DocumentRoot /var/www/website
  ServerName www.yourdomain.com
  SSLEngine on
  SSLCertificateFile "/home/centos/myapp/mysitename.crt"
  SSLCertificateKeyFile "/home/centos/myapp/mysitename.key"
</VirtualHost>

sudo /usr/sbin/httpd -S

AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using localhost.localdomain. Set the 'ServerName' directive globally to suppress this message
VirtualHost configuration:
*:443                  is a NameVirtualHost
         default server www.yourdomain.com (/etc/httpd/conf/httpd.conf:107)
         port 443 namevhost www.yourdomain.com (/etc/httpd/conf/httpd.conf:107)
         port 443 namevhost localhost.localdomain (/etc/httpd/conf.d/ssl.conf:56)
ServerRoot: "/etc/httpd"
Main DocumentRoot: "/var/www/html"
Main ErrorLog: "/etc/httpd/logs/error_log"
Mutex default: dir="/run/httpd/" mechanism=default 
Mutex mpm-accept: using_defaults
Mutex authdigest-opaque: using_defaults
Mutex proxy-balancer-shm: using_defaults
Mutex rewrite-map: using_defaults
Mutex authdigest-client: using_defaults
Mutex ssl-stapling: using_defaults
Mutex proxy: using_defaults
Mutex authn-socache: using_defaults
Mutex ssl-cache: using_defaults
PidFile: "/run/httpd/httpd.pid"
Define: _RH_HAS_HTTPPROTOCOLOPTIONS
Define: DUMP_VHOSTS
Define: DUMP_RUN_CFG
User: name="apache" id=48
Group: name="apache" id=48

See also http://www.javamonamour.org/2018/02/apache.html

jcmd GC.heap_dump File exists

The instructions here https://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/tooldescr006.html say:

Create a heap dump (hprof dump)

jcmd GC.heap_dump filename=Myheapdump


This is wrong. First, you need a PID; second, you should not provide filename=bla but simply bla:


Correct example:

/usr/lib/jvm/java-openjdk/bin/jcmd 50513 GC.heap_dump /u01/users/admrun/nexus3_02.hprof


if you run simply

/usr/lib/jvm/java-openjdk/bin/jcmd 50513 GC.heap_dump filename=bla.hprof

it doesn't create a bla.hprof but rather a "filename" file.... and the second time you run it you get a "File exists" message.

Confusing and frustrating!