Docker-CE: Setting up a tomcat in less than a minute and running your JSP…

Last time i wrote about processes and files of a docker container hosting the docker example
Next step was to run a tomcat with a small application inside.

This can be done with theses commands:
  1. Get tomcat from the docker library:
    # docker pull tomcat
    Using default tag: latest
    latest: Pulling from library/tomcat
    3e17c6eae66c: Pull complete
    fdfb54153de7: Pull complete
    a4ca6e73242a: Pull complete
    5161d2a139e2: Pull complete
    7659b327f9ec: Pull complete
    ce47e69f11ad: Pull complete
    7d946df3a3d8: Pull (more...)

Docker-Swarm: Running a minimal webserver in a swarm

In my last posting to docker swarm i created a swarm on virtualbox with alpine linux with a hdd footprint of 290MB per node:
There are some tutorials out there with running a nginx or a java webserver in a container but >100MB for each node seems far to much for my tests.

So i decided to create a application which listens on port 8080 with netcat. I created a directory ncweb with

Docker-Swarm: One manager, two nodes with Alpine Linux

After creating a Alpine Linux VM inside virtualbox and after adding docker because of the small disk footprint (Alpine Linux: 170MB | with docker: 280MB) i performed the following steps to create a docker swarm:
  • cloning the vm twice
  • assigning a static ip to the manager node
  • create new MACs for the network interface cards on the nodes 

Then i followed the tutorial but without running the docker-machine commands, because i have (more...)

OpenJDK 9: Limitations/shortcomings of the Jshell

Jshell is a quite powerful tool to do some quick explorations and to write some scripts.

If found the following limitations:
  • No syntax highlighting
  • Only comments with // are allowed
    if you open a script file with
      *  My comments
    this will work only many warnings.
    |  Error:
    |  illegal start of expression
    |   * Copyright (c) 1995, 2008, Oracle and/or its affiliates. All rights reserved.
    |   ^
    |  Error:

Docker-CE: Creating a small Linux as base OS for running a Docker cluster

After some first steps with docker i wanted to run more than one docker node. The problem is, that i have very limited resources on my laptop.
  • CoreOS (see here)
    consumes about 600MB diskspace
  • UbuntuCore (see here)
    consumes about 1.9GB diskspace
To setup CoreOS you have to learn ignition - otherwise every change is lost after a reboot. For UbuntuCore you have to use an UbuntuOne account to get it running.

I (more...)

Docker-CE: Get Started Tutorial – processes / files / HTTP headers

Inside my docker installation on ubuntu server i performed the official docker tutorial part 2: "containers"

Ok. Not really interesting, because the tutorial describes all steps very well (except the point, that you have to install python3-pip and you have to run pip3 and not pip).

Here the interesting part:

After i started the container ("docker run -p 4000:80 friendlyhello") i got the following:
root@ubuntuserver:/var/lib/docker/image# docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS                  (more...)

Docker-CE: initial configuration

After installing docker to a ubuntu server i was keen what kind of processes and files are there.
# ps x|grep docker
 5852 ?        Ssl    0:05 /usr/bin/dockerd -H fd://
 5867 ?        Ssl    0:04 docker-containerd --config /var/run/docker/containerd/containerd.toml
So the inital configuration is not stored in /etc.

The configuration file looks like this:
# cat /var/run/docker/containerd/containerd.toml
root = "/var/lib/docker/containerd/daemon"
state = "/var/run/docker/containerd/daemon"
subreaper = false
oom_score = -500

  address = "/var/run/docker/containerd/docker-containerd.sock"

Oracle SOA Suite 12c: database configuration

After the running the rcu i was keen what was created inside the database. The installation showed some additional tablespaces:
select tablespace_name from dba_tablespaces; 

13 Zeilen gewählt.
Ok. Not really exciting.
But the list of the created tables was quite impressing:
select OWNER,TABLE_NAME from all_tables where owner like 'DEV%';

OWNER                TABLE_NAME                             
-------------------- ----------------------------------------
DEV_MDS              MDS_PURGE_PATHS                        
DEV_SOAINFRA         AQ$_IP_QTAB_G                          
DEV_SOAINFRA         (more...)

Docker-CE on Ubuntu 17.10 (Artful Aardvark)

Today docker is only added to the repositories up to ubuntu version 17.04:

If you want to run docker on 17.10 you have to perform the following steps:
After that 
# docker run hello-world
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
9a0669468bf7: Pull complete
Digest: sha256:cf2f6d004a59f7c18ec89df311cf0f6a1c714ec924eebcbfdd759a669b90e711
Status: (more...)

Oracle SOA Suite 12c: rcu from a remote host / database configuration

First step is to configure the database on your Oracle Linux server which hosts your database:
[root@localhost admin]# firewall-cmd --permanent --zone public --add-port=1521/tcp
Then run the rcu:
schroff@zerberus:/home/data/opt/oracle/Middleware/Oracle_Home/oracle_common/bin$ ./rcu

    RCU-Logdatei: /tmp/RCU2017-10-14_22-36_851447466/logs/rcu.log
The startup screen:
 Connect to you database:
 Connection successful:
 Certified database?!
 Choose the SOA Suite components:

 Password definition for all created schemas:
 Variables (take a look here)
 Creation of tablespaces:

 Create schemas:
The end:

Microservices: Ubuntu Core: Building your own snap application

After the installation of ubuntu core and running caddy webserver from a repository  i was wondering how to build my own snap package.

The tutorial shows how to build GNU Hello into a snap packages:
and this tutorial works fine.
But this does not really help, if you have a command, which you can not build with autotools or ant or ....
A complete list can be found here.

So my plan:

Oracle Database 12c on Oracle Linux: Firewall configuration to access Enterprise Manager on http://host:5500/em

If you have installed your database on Oracle Linux, first step is to access the enterprise manager via port 5500 (https://localhost:5500/em). If you want to access this URL from another host, you have to check and change the firewall settings:

[root@localhost system]# service firewalld status
Redirecting to /bin/systemctl status firewalld.service
● firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
   Active: active (running) since So (more...)

Oracle SOA Suite 12c: rcu fails on Oracle Linux

Next step after setting up a database is running the rcu script to create the soa suite schema inside the database. But this step fails with an ugly exception:

[oracle@localhost bin]$ pwd
[oracle@localhost bin]$ ./rcu

    RCU-Logdatei: /tmp/RCU2017-10-07_18-13_966788282/logs/rcu.log

Exception in thread "main" java.lang.ExceptionInInitializerError
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(
    at java.lang.reflect.Method.invoke(Method. (more...)

Microservices: Running a webserver (caddy) on Ubuntu Core with snap

After the installation of a ubuntu core system inside virutalbox i was keen how to put a microservice via snap package onto the server.

First a listing of the installed snap packages:
~$ snap list
Name          Version     Rev  Developer  Notes
core          16.04.1     394  canonical  -
pc            16.04-0.8   9    canonical  -
pc-kernel     4.4.0-45-4  37   canonical  -
To get a list of available packages you can use "snap find" + a search (more...)

Microservices: Ubuntu Core and snap – a minimal linux

After some first steps with coreOS
i read about Ubuntu Core, which targets also on a minimal linux. Here an architecture overview from ubuntu:
Ubuntu provides an image for KVM (the link points to an installation howto), but i want to stay with Virtualbox. I followed this tutorial:
unxz ubuntu-core-16-amd64.img.xz
VBoxManage convertdd ubuntu-core-16-amd64.img ubuntu-core-16-amd64.vdi (more...)

Oracle SOA Suite 12c: Installation – Preparing the database

After a successful installation of Oracle 12c database the next step is to create a plugable databse (PDB).
Therefor you have to run the dbca (database creation assistant):

 The first check fails with:
[oracle@localhost ~]$ export ORACLE_SID=soasuite12c
[oracle@localhost ~]$ sqlplus

SQL*Plus: Release Production on Sat Oct 7 17:00:21 2017

Copyright (c) 1982, 2016, Oracle.  All rights reserved.

Enter user-name: bpeladmin
Enter password:
ORA-01034: ORACLE (more...)

AVM Fritz: WLAN Mesh with Powerline Repeater does not work – Part 2

A month ago i tried to get the new WLAN mesh running with my Fritz!Box 7490 and Fritz!Powerline 546E.

Some days ago AVM release a new firmware for the 546E:

But even with the new firmware the powerline adapter does show up with the "mesh symbol" inside the home network overview:

I am wondering, if the WLAN mesh only works by using the powerline connectivity. AVM support pages show up the following advisory:

Contao: How to create a virtual system from your live website

Since a couple of year my sport club runs its website with contao.
Because our webhoster changed the support for php, i have to find a way to do an upgrade without damaging the running website.

The plan:
  1. create a linux host as a vm
  2. install mysql, apache2, php
  3. import the backups
The first step was easy. Inside virtualbox i created an ubuntu 17.10 system.
The second step was not that simple:
add-apt-repository ppa:ondrej/php

Ubuntu 17.10: problems with gnome extensions

After migrating to ubuntu 17.10 the unity desktop is gone and the system starts up with gnome 3.
As i wrote here, there are some problems with window decorations which can be fixed by (re-)moving some directories.

But i still had some problems with gnome extension:
The installation process via the webpage gnome extensions worked fine, but e.g. the system monitor did not show up...

The solution was easy:
apt install vanilla-gnome-desktop

Myths about Wayland (display server protocol / X11 replacement)

If you ask Google abount wayland (which is shipped with ubuntu 17.10 or fedora 26) there are some articles, which are not or no more accurate:

"You can not export any X11 application to a linux host which runs wayland"
Wrong... Just login to other linux machines via "ssh -X"  and run xclock or whatever. It works...

"Screenshots will not work anymore"
Hmmm. Ok. X11 screenshot applications will not work anymore - but (more...)