Hard&Soft experiments

Logback in Quarkus

Jul 222023

Quarkus framework has its own logging system, based on JBoss logging. There is a more or less simple system with configuration via properties (or yaml). In simple cases, features from default Quarkus logging are enough, but for complex cases, like MDC, log separation, etc standard Quarkus logging capability is insufficient.

Another thing that brings some problems is tests, especially in gradle, because there is no way to specify the logging level by package name for tests (at least it doesn’t work for me up to Quarkus v. 3.2.0).

So at least one solution – use another logging framework you like. It can be Logback, Log4J or even JUL. By the way, there is already developed option for using logback.xml as a log configuration source, but only in a static way – transcode logback.xml into standard Quarkus logging settings at the build stage.

In this case for using another logging framework we need to replace the existing one.

Remove unnecessary packages from the build: build.gradle

configurations.all {
 exclude group: 'org.jboss.logging', module: 'jboss-logmanager-embedded'
 exclude group: 'org.jboss.logging', module: 'commons-logging-jboss-logging'
 exclude group: 'org.jboss.slf4j', module: 'slf4j-jboss-logmanager'
 exclude group: 'org.slf4j', module: 'slf4j-jdk14'
}

Add required dependencies: build.gradle

dependencies {
...
 implementation "org.slf4j:slf4j-api:${slf4jVersion}"
 implementation "ch.qos.logback:logback-core:${logbackVersion}"
 implementation "ch.qos.logback:logback-classic:${logbackVersion}"
...
}

Use the required logging provider on the application start command

java -Dorg.jboss.logging.provider=slf4j -jar quarkus-runner.jar

Also sometimes we need to tune logging in gradle test task: build.gradle

test {
  systemProperty "java.util.logging.manager", "org.jboss.logmanager.LogManager"
  systemProperty "org.jboss.logging.provider", "slf4j"
// one file for multimodule project
  systemProperty 'logback.configurationFile', "${rootDir}/src/test/resources/logback-test.xml"
}

Java: how not to write programs – AtomicInteger

Java, Programming No Responses »

Apr 182020

One time I needed to use a counter for some heavy loaded process in multithread environment. As usual, I use the class java.util.concurrent.atomic.AtomicInteger, the methods incrementAndGet and decrementAndGet. But when I put these methods in only two places, absolutely synchronized by calls (increment and decrement counter in short time gap), I got a strange behavior with the counter – it constantly goes down to negative values. When I tried to view source code (OpenJDK 8), I saw this:

/**
     * Atomically increments by one the current value.
     *
     * @return the updated value
     */
    public final int incrementAndGet() {
        return unsafe.getAndAddInt(this, valueOffset, 1) + 1;
    }

So, instead of incrementing value concurrently and returning new value after this, we have a function call, which returns a current value and increments value by one in the same place. May be this function (getAndAddInt) really increments value of AtomicInteger… or may be not, in this place we don’t know, because we know nothing about new value – we simply return old value + 1.

I found the same behavior in OpenJDK11 source code:

public final int incrementAndGet() {
    return U.getAndAddInt(this, VALUE, 1) + 1;
}

And the same code up to OpenJDK14: https://github.com/openjdk/jdk14u/blob/master/src/java.base/share/classes/java/util/concurrent/atomic/AtomicInteger.java

Moreover, I wrote simple code with a volatile field and two methods for increasing/decreasing this field with ReentrantLock. And using this methods in the same places, where I used AtomicInteger methods, I got a different result – my counter was increased and decreased and had more plausible value, than AtomicInteger.

Connect to XenServer VM screen via VNC

XenServer No Responses »

May 192018

For connect to virtual machine screen via VNC you need:

Retrieve VM domain number (execute in XenServer console):

xe vm-list params=dom-id name-label=[vm name] | grep dom-id

Retrieve VNC port for this domain (execute in XenServer console):
```
xenstore-read /local/domain/[domain]/console/vnc-port
```
Make remote connection ([port] – last two digits from previous output), execute in remote console:
```
vncviewer -via root@[xenserver] localhost:[port]
```

All together from remote console xen_vm_screen.sh:

#!/bin/bash
XEN_HOST=$1
VM=$2
XEN_USER=root
DOMAIN=`ssh $XEN_USER@$XEN_HOST "xe vm-list params=dom-id name-label=$VM | awk -F ':' '{gsub(/[ \t]+/, \"\", \\\$2); print \\\$2}'"`
VM_PORT=`ssh $XEN_USER@$XEN_HOST "xenstore-read /local/domain/$DOMAIN/console/vnc-port"`
vncviewer -via $XEN_USER@$XEN_HOST localhost:${VM_PORT:2:2}

Execute it as:

bash ./xen_vm_screen.sh vm_host_name vm_name

Cisco SCP: Privilege denied

Cisco No Responses »

Sep 072016

Based on: Cisco SCP getting privileged denied

Sometime when you initiate copy via SCP to router/switch, you get:

Privilege denied

instead of copy process.
But SCP on device already enabled.

For fix this error you need add to device configuration

aaa authorization exec default local none

MDADM: Convert RAID5 to RAID10

Linux, RAID No Responses »

Sep 042016

Based on Changing a RAID-10 into a RAID-5

It is usually assumed that the best HDD organization on a backup server is a RAID5, since it provides a fairly good price/volume. Unfortunately, increasing of disk count affect to some RAID5 disadvantages, in particular the in reliability and recovery speed. For example if the server has RAID5 of 6 (six) SATA disk drives (even it’s reliable enough, such as WD Re), with one disk replacement, array recovery time is about 10 hours (in my case). At the recovery time reservation is absent, the load on the disks are increased, that increases the probability of failure of the remaining disks, and if all the disks have same series, the probability of another disk will deteriorate during the recovery, increase even more.
In this regard, it was decided to convert the existing disk array from RAID5 to RAID10 with the addition of two drives, that in theory should lead to increasing of server performance and improving reliability.

Setup HP switches via command line (CLI)

HP 3 Responses »

Jul 192016

Inspired by: Начальная настройка коммутатора HP 1910 серии

It is well known and has been emphasized by HP, many HP switches (HPE) are configured through the web-interface. A little less known is that a full customization for large number of switches is also possible via command line (for example, 1910, 1920).

Access to HP ILO2 via OpenSSH v6.2 and higher

HP ILO, Linux 1 Response »

Feb 272016

When you try to access HP ILO2 console via some new version of OpenSSH you have error.
For OpenSSH v.6# ssh ilouser@iloserver Received disconnect from iloserver: 2: Client Disconnect
Solution: add option -o MACs=hmac-sha1 to ssh:
# ssh -o MACs=hmac-sha1 ilouser@iloserver ilouser@iloserver's password:

For OpenSSH v.7# ssh ilouser@iloserver Unable to negotiate with UNKNOWN: no matching key exchange method found. Their offer: diffie-hellman-group1-sha1
Solution: add option -o KexAlgorithms=diffie-hellman-group1-sha1 -o MACs=hmac-sha1 to ssh:
# ssh -o KexAlgorithms=diffie-hellman-group1-sha1 -o MACs=hmac-sha1 ilouser@iloserver ilouser@iloserver's password:

Access to HP ILO remote console via SSH

HP ILO, Linux 2 Responses »

Feb 272016

From Pinoy UNIX Administrations

There are times when you want to have a quick access to the remote console of a server like HP’s ILO but you don’t want (not able) to open a web browser just to access it. But there is an ability to access it via SSH (text console only).

Open a ssh connection to the ILO’s IP address.
# ssh ilo_admin@ip_address
Enter your ILO admin account and password. After that you will see the ILO prompt.
hpILO->
To access the remote console of the server at the ILO prompt type “TEXTCONS”
hpILO->TEXTCONS
You will be presented with the Login: console. Enter your root or user account of the server to gain access.
Login:

Upgrade UniFi AP via command line

WiFi No Responses »

Apr 182014

Sometimes when you upgrade firmware of access points (AP) through the UniFi controller interface, AP hung in Upgrading state (eg UniFi AP PRO).
When you restart AP, it does not change state and AP does not reach.
In this case, you need to upgrade AP firmware via command line.
It is assumed the server is installed on Linux

Determine controller version and firmware code:
Version: execute command on the server
```
ls -l /usr/lib/unifi/dl/firmware/BZ2/
```
resulting directory is version number

Firmware code determined by the table:
Continue reading »

Install puppet to the XenServer

VM, XenServer No Responses »

Aug 072013

In file /etc/yum.repos.d/CentOS-Base.repo in section [base] set enabled=1

sed -i 's/enabled=0/enabled=1/g' /etc/yum.repos.d/CentOS-Base.repo

For XenServer 6.2, 6.5 in file /etc/yum.repos.d/Citrix.repo in section [citrix] set enabled=0

sed -i 's/enabled=1/enabled=0/g' /etc/yum.repos.d/Citrix.repo

 rpm -Uvh http://dl.fedoraproject.org/pub/epel/5/$(uname -i)/epel-release-5-4.noarch.rpm
 cd /tmp
 wget https://yum.puppetlabs.com/el/5/products/$(uname -i)/puppetlabs-release-5-10.noarch.rpm
 rpm -Uvh puppetlabs-release-5-10.noarch.rpm
 yum install puppet

set up /etc/puppet/puppet.conf, after that:

 chkconfig puppet on
 /etc/init.d/puppet start

I Also recommend using a xs_patcher to make XenServer up to date.

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