Context

• CentOS 7.4 default image on Digital Ocean, entry level plan, with 1 GB RAM
• Bitnami Tomcat stack -- local/native installation mode
  

Prerequisites

local$ ssh root@SERVER_IP

swap

add swap if RAM+swap is less than 2 GB
this is a short version of these two guides: Bitnami low memory & Digital Ocean swap guide

# free -m | grep Swap
Swap:   0   0   0
# dd if=/dev/zero of=/myswap count=1024 bs=1MiB
# chmod 600 /swapfile
# ls -lh /swapfile
-rw-------. 1 root root 1.0G Jan 19 19:05 /swapfile
# mkswap /swapfile
Setting up swapspace version 1, size = 1048572 KiB
no label, UUID=ed94f556-38a2-43de-a64b-a3829e85dbd0
# swapon /swapfile
# free -m | grep Swap
Swap:   1023   0  1023
# sysctl vm.swappiness=10
vm.swappiness = 10
# echo "/mnt/swap.0 swap swap defaults 0 0" >> /etc/fstab
# reboot
...

# free -m | grep Swap
Swap:   1023   0  1023

perl

# yum install perl perl-Data-Dumper
# perl
Ctrl+D

• if you get a warning regarding locale settings, perform the fix mentioned here https://wiki.jaumesola.com/CentOS

EPEL repo

needed at least for haveged below

# yum install epel-release

haveged

Without this Tomcat may take forever to start (issue with SessionIdGeneratorBase - createSecureRandom). Details here.

# yum install -y haveged
# chkconfig haveged on
# reboot

Default install

# curl --remote-name --location  https://bitnami.com/redirect/to/168422/bitnami-tomcatstack-8.5.24-2-linux-x64-installer.run
# chmod +x bitnami-tomcatstack-8.5.24-2-linux-x64-installer.run
# ./bitnami-tomcatstack-8.5.24-2-linux-x64-installer.run 

• asks for passwords for MySQL root & Tomcat manager
  

Essential commands

Verify it works

 http://SERVER_IP should show Bitnami's "welcome" page

Start on boot


# cp /opt/tomcatstack-8.5.24-2/ctlscript.sh /etc/init.d/bitnami-tomcat
# vi /etc/init.d/bitnami-tomcat

#!/bin/sh
#
# chkconfig: 2345 80 30
# description: Bitnami services


# chkconfig --add bitnami-tomcat
# reboot


SFTP

Let's Encrypt

Warning

This is a setup I use for development environments, not recommended for production!

Basic VM Install

• Download OVA file from https://bitnami.com/stack/lamp/virtual-machine (version used: PHP 7.1.16-0 64-bit)
  
• In VirtualBox file menu, import appliance (OVA file) & start it
• Wait until coloured screen appears
• Login with bitnami / bitnami
• Set a new password
• Root access: $ sudo su
• Shutdown: $ sudo init 0


Tweak VM resources

By default resources allocated to the VM are quite scarce. Depending on the use it will have and the resources on your host machine you may want to increase them. My setup includes:

• all available CPUs at 80% for better performance
  
• 1 or 2 GB of RAM
• 8 MB of video memory (there's no GUI)
  

Stop the VM for adjusting them.

Configure VM network

bridged mode

With this mode the VM can communicate in all directions. Limitation: the virtual adapter needs to be attached to a physical WiFi (AirPort) adapter. Configure this mode in the VM's Settings - Network - Adapter 1.

host-only adapter

If you don't need the VM to access the internet you can configure it in this way.For that we need to create a host-only adapter. In Global Tools - Host Network Manager create one with default parameters & enable DHCP. The first one gets by default the name vboxnet0 and the IP range 192.168.56.x. Then in VM's Settings - Network - Adapter 1 select Host-only adapter and vboxnet0.

Verify it works

http://192.168.x.x/

Access the VM from the macOS terminal

I find it convenient to have SSH enabled so I can access the VM from a terminal Window. Partly because without GUI the default console is very limited: no window resize, no clipboard integration...
https://docs.bitnami.com/virtual-machine/faq/#how-to-connect-to-the-server-through-ssh

VM:

Install VirtualBox Guest Additions

This is optional but quite convenient in a development setup. Specifically I use the shared folders feature with the host so changes in code I make on macOS are immediately available within the VM.

• In Settings - Storage add a new CD device to the existing controller and leave it empty
• Start the VM

Install dependencies

Install Guest Additions

Enable phpMyAdmin for private IPs

Bitnami docs instruct to use an ssh tunnel to access phpMyAdmin, but I prefer to just allow access from the local network.

replace: Require local by Require ip 192.168

Verify it works: http://192.168.x.x/phpmyadmin/

Install WordPress module

Following this guide: https://docs.bitnami.com/installer/infrastructure/lamp/#how-can-i-add-applications-on-top-of-lamp

Obtain the module download URL from https://bitnami.com/stack/lamp/modules

• language
• Installation folder: /opt/bitnami
• WP admin account data
• MySQL "root" password (see above)
• Blog name
• mail support/SMTP Settings so your application can send notifications via email.  Either GMail or in my case "Custom":
• Username
• Password
• SMTP Host 
• SMTP Port [587]
• Secure connection: None /SSL/TLS
• Development o production environment
  

Context

• CentOS 7.4 default image on Digital Ocean, entry level plan, with 1 GB RAM

• Bitnami LAMP stack -- local/native installation mode
  

Prerequisites

local$ ssh root@SERVER_IP

swap

add swap if RAM+swap is less than 2 GB
this is a short version of these two guides: Bitnami low memory & Digital Ocean swap guide

# free -m | grep Swap
Swap:   0   0   0
# dd if=/dev/zero of=/swapfile count=1024 bs=1MiB
# chmod 600 /swapfile
# ls -lh /swapfile
-rw-------. 1 root root 1.0G Jan 19 19:05 /swapfile
# mkswap /swapfile
Setting up swapspace version 1, size = 1048572 KiB
no label, UUID=ed94f556-38a2-43de-a64b-a3829e85dbd0
# swapon /swapfile
# free -m | grep Swap
Swap:   1023   0  1023
# sysctl vm.swappiness=10
vm.swappiness = 10
# echo "/mnt/swap.0 swap swap defaults 0 0" >> /etc/fstab
# reboot
...

# free -m | grep Swap
Swap:   1023   0  1023

perl

The MySQL installer requires perl and the perl Data::Dumper module.

# yum install perl perl-Data-Dumper
# perl
Ctrl+D

• if you get a warning regarding locale settings, perform the fix mentioned here https://wiki.jaumesola.com/CentOS

create regular user

Default install

$ curl --remote-name --location  https://bitnami.com/redirect/to/181565/bitnami-lampstack-7.1.15-0-linux-x64-installer.run
$ chmod +x bitnami-lampstack-7.1.15-0-linux-x64-installer.run
$ ./bitnami-lampstack-7.1.15-0-linux-x64-installer.run

Essential commands

Verify it works

Start on boot


# cp /home/lampy/lampstack-7.1.15-0/ctlscript.sh /etc/init.d/bitnami-lamp
# vi /etc/init.d/bitnami-lamp

#!/bin/sh
#
# chkconfig: 2345 80 30
# description: Bitnami services


runuser...


# chkconfig --add bitnami-lamp
# reboot


Context

• Product home page https://bitnami.com/stack/tomcat
  
• Assuming installed on /Applications/bitnami-tomcat

Default install

• Install from https://bitnami.com/stack/tomcat
• Start Bitnami Application Manager (BAM) (/Applications/bitnami-tomcat/manager-osx.app)
• Bitnami index page: http://localhost:8080
• Tomcat default URL: http://127.0.0.1:8080/index.jsp
• Tomcat manager: http://127.0.0.1:8080/manager/status (credentials entered at installation time)
  
• phpMyAdmin: http://127.0.0.1:8080/phpmyadmin/ (credentials entered at installation time)
• Guide: https://docs.bitnami.com/installer/infrastructure/tomcat/
• Unix console (sets custom $PATH):
  $ sh /Applications/bitnami-tomcat/use_tomcatstack

• location of apps/sites installed by default: /Applications/bitnami-tomcat/apache-tomcat/webapps/
• docs/
  
• examples/
• host-manager/: Tomcat Virtual Host Manager
• manager/: Tomcat manager above
  
• ROOT/: Bitnami index page & default Tomcat site above
  

Install own app

The guide above has a paragraph "How To Create A Custom Java Application?". That didn't work for me. Instead, much simpler to drop the app's war file to /Applications/bitnami-tomcat/apache-tomcat/webapps/

• E.g. you can try with this "hello world" app. You don't even need to restart any server for this one. Otherwise use BAM.
  

A quick guide of what worked for me. 

Geth is the official implementation that allows you to run an Ethereum node. There are several others.

I installed it with Homebrew based on the official geth guide for macOS.

Homebrew installation:

Geth installation:

Verify (as regular user):

• wait for message "Starting P2P networking"
• interrupt (Ctrl-C)
• check that there are no obvious errors

Warning: this worked for me on macOS as of August 2017. Over time you can expect some/most/all of the information here to have changed.

There are several testnets, a number of them old/deprecated. The latest seem to be Kovan and Rinkeby. Kovan seems to work only with Parity while Rinkeby seems to work only with geth.

You will need to install geth first.

I mostly followed this guide.

I tried first the experimental light mode but I got errors, so I tried with the full mode. Not a big deal at this moment because the size on disk is below 1GB and it took around one hour to download/build with a 2011 macbook Air.

I prefer to make the data directory explicit (where the blockchain files will be stored), so I first create one on a disk of my choice. Also I will work from that directory, so I will assume all commands are entered from it.

intitalise with genesis block

load blockchain 

Wait. You will see the INFO message "Block synchronisation started" then many INFO lines starting with "Imported...". Sync is in progress... 

• Note the 1GB cache, you can use less or more depending on your available memory
• Network id 4 corresponds to the Rinkeby chain
• Blockchain data will be stored in geth/

Check blockchain sync progress

While the node is up & running (the above command) you can get info about the blockchain sync progress (among other data) through the JavaScript console. In another terminal window type:

At the ">" prompt you can type, e.g.

You can double check you are seeing the right data progress by looking at the last block at www.rinkeby.io home page.

Note that the "NOTE...Importing..." messages include a number parameter which is the block being processed.

Getting free (worthless) ether for testing

Create a testing account

Create an account, enter password, get its address (account data will be saved to keystore/):

$ geth --datadir=. account new
...(enter password):..
Address: {559b0e5a899d9ef4c04ee35ccbefab2e6d7f06da}

That is the address I got. In order to use the faucet & get ether into this account, first create a github gist with just the hash in it (remember to prepend with "0x"). In my case:

Now use your gist URL in the faucet feature at www.rinkeby.io

I requested 3 ETH, then I searched etherscan with my address to verify I got them:

https://rinkeby.etherscan.io/address/0x559b0e5a899d9ef4c04ee35ccbefab2e6d7f06da

Next verification step would be to verify that locally we also get the correct balance.

We first verify it is taking the accounts we created (files in keystore/)

> eth.accounts
["0x559b0e5a899d9ef4c04ee35ccbefab2e6d7f06da", "0x62c8681441620cb0574fcee27d6085529067b8da"]

The first one (index 0) is the one I got my 3 ETH, let's see if they are on our local blockchain (balance for account 0):

> web3.fromWei(web3.eth.getBalance(web3.eth.accounts[0]));
3

great!

Now we may keep using geth, or a wallet for a nice UI.

Local macOS configuration

Python & Mercurial

This was tested on macOS El Capitan, with Pyhton 2.7 and Mercurial 4.2.2

Install Hg-Git

It can be installed with Python's package installer pip.

Install pip first:

Enable the extension:

hggit =

SSH key for github

create SSH key (details)

• ssh-keygen -t rsa -b 4096 -C "someone@example.com"

add it to your github account (details)

• $ pbcopy < ~/.ssh/id_rsa.pub

We are building a team that will participate in the startup acceleration program by Bbooster.

This is an intensive program of 4 months (June to September), at the end of which we expect to get funding (65% of the projects got it in past editions and we believe ours is among the best :-).

Ideally full-time on-site in Valencia as a founder, but we are also open to some other kind of collaboration like part-time or remote.

The project will be an internet portal initially focused in the tourism sector and collaborative economy. 

Current team members have expertise in business, marketing and backend development. We need to cover the graphical design/UI/front end area.

Interested? Contact me on Linkedin

This worked for me on version 18.1 Serena Xfce

Install Apache

sudo apt-get install apache2

Verify: open browser with URL http://localhost/

Install PHP 7

Read more

If you administer an email server as I do, it's very useful to have an automated monitoring system that checks often that it works properly.

My first try on any new feature I want to add to my non-fatally-critical systems is to use an external service, specially if it can be done for free. Whereas there is a number of server monitoring services, most don't include roundtrip email monitoring, at least on their free plan. 

The only one I found to include it is...

Read more

You want to force any URL that doesn't include either:

1. HTTPS
2. www subdomain

RewriteEngine On
RewriteBase /

RewriteCond %{HTTP_HOST} ^domain.com$ [NC]
RewriteRule ^(.*)$ https://www.domain.com/$1 [R=301,L]

RewriteCond %{HTTPS} off
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}

comes from part 1

As it already "does something" we will continue with the demo app.

Read more

I use MAMP+Mercurial+Eclipse as PHP development environment on Mac OS X. These are instructions for this environment adapted from https://symfony.com/doc/current/book/installation.html

Read more

Our product intends to save you a significant amount of your time, and spare you the difficulties of a manual process. As explained in my previous post “How to create PDF files from XML with Apache-FOP”, XSL-FO and Apache-FOP provide a free and standard way to create PDF files in a language independent manner.

But there are a number of disadvantages with that approach, e.g.:

• you have to learn XSL-FO (and therefore also XPath and XSL).
• even if you know XSL-FO you do not want to be writing FO templates using a text editor.
• there is some logic that cannot be easily defined using XSL-FO. For example, grouping of data requires you to use the so called Muenchian method , which isn't straightforward to understand.
  

In order to overcome these drawbacks, at J4L Components we have developed J4L FO Designer. The designer is a Visual (WYSIWYG) editor that will generate XSL-FO files for you. This makes the start into the XSL-FO world very easy, and it is also a useful tool for experienced developers since you can create and test XSL-FO files very quickly.

Read more

Este procedimiento sirve para cuando tenemos una cuenta de Gmail y queremos usar Gmail como servicio para gestionar otras cuentas que no son de Google, sin tener que decir a nuestros contactos que hemos cambiado de correo. Es decir para nuestros contactos no cambia nada: siguen usando nuestra dirección de correo que conocen. Para nosotros cambia que usamos el servicio de Gmail para gestionar este correo y, aunque sigue activo, ya no necesitamos usar el servicio del proveedor original.

Repitiendo este procedimiento se pueden integrar varias cuentas externas en una ÚNICA cuenta gratuita de Gmail. También se puede repetir usando varias cuentas independientes de Gmail gratuito. Si se desea un servicio unificado para la gestión de diversas cuentas de una organización con Gmail, deberá contratarse el servicio de pago "Google Apps".

Requisitos

1. Tener una cuenta de Gmail
2. Tener otra cuenta de correo que queremos utilizar con Gmail (cuenta externa)
3. Que la cuenta de correo externa admita redirección o reenvío automático de todos los mensajes recibidos
4. Disponer de los datos conexión SMTP segura (TLS ó SSL) que funcione con esta cuenta (servidor, puerto, usuario, contraseña)

Procedimiento

1. Obtener los datos de conexión de nuestra cuenta externa y averigüar cómo activar la redirección de correos entrantes. Esto puede estar disponible a través de un panel de control o bien tendremos que contactar con nuestro proveedor.
   
   
2. Activar la redirección de nuestro correo externo al correo de gmail. 
   
   
3. En nuestra cuenta de Gmail realizaremos los siguientes pasos:

   • Entrar en la configuración de la cuenta

     

   • Clic en Cuentas e importación y en el apartado "Enviar correo como" , clicar en Añadir otra dirección de correo electrónico

     

   • En la ventana emergente introducir:
     • Nombre del remitente que se desea usar al enviar mensajes con la cuenta externa
     • La cuenta de correo externa
     • IMPORTANTE: desmarcar la casilla "tratar como un alias"
     • Clicar en botón "paso siguiente"

       
   • "Enviar el correo a través de tu servidor SMTP
   • Introducir los datos correspondientes y clicar el botón "Añadir cuenta".
     
   • En caso de problemas comprobar que los datos son correctos / consultar el proveedor de nuestro correo.
     

     

     
     
   • Verificar tu dirección de correo electrónico
     • Clicar en botón "Enviar Verificación"

       

   • Espera a que te llegue el correo de verificación e introduce el código.

     

   • Se cierra la ventana y se actualiza la página de configuración con la nueva cuenta externa añadida. Haz clic ahora en el enlace correspondiente "establecer como predeterminada" junto a la cuenta que acabas de añadir. 
   • Resultado final:

     

     
     
4. A partir de este momento, al redactar un correo nuevo aparecerá tu cuenta externa como remitente en vez de la de Gmail. Si en algún caso quieres usar la de Gmail podrás desplegar el campo del remitente y elegirla.

   

5. Comprobar con otra cuenta que el envío y recepción funcionan correctamente: enviar un correo desde gmail, comprobar que se recibe con el remitente correcto, responderlo y comprobar que la respuesta llega a nuestra cuenta de gmail
   

XML

Nowadays, XML is the native format of many applications, Oracle APEX for example, partly bases its reporting systen on XML. Middleware as Oracle BPEL, SAP PI, IBM Websphere and of course many Web services are also XML based. XML is also being used as exchange format in business to business transactions, for example for e-Invoicing. In these and many other environments there is often the need to create PDF files from XML.

XSL-FO

In the past PDF files would be created using proprietary reporting tools that would use a database as data source. Additionally these tools are programming language specific. Later on the XSL-FO standard allowed for a better way to do it in many cases.

What is new about XSL-FO?
- it is programming language neutral.
- it is a standard so you are not tied to a vendor.
- it uses XML as data source.

Apache FOP

One implementation of the XSL-FO standard is Apache FOP. One important aspect about this implementation is that the Apache license model allows to use it in commercial environment.

Many free/open source products have a license model that puts strong restrictions on the way you may use the software. Not surprisingly there are software companies that do not allow the use in their code any open source software other than Apache Foundation one. So if you use Apache you know you are on the safe side.

Procedure

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I was intrigued about all the buzz around the Rails framework and the Ruby language, so I thought it was the time to check it out by myself and start by learning Ruby. So, as I usually do, I assigned myself some specific learning task: in this case porting the J4L barcoding software from PHP (which in turn was ported from Java).

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During 2010 I worked mostly on this project. J.M.E., the web designer, and I worked with Iker Marcaide to develop the first version of the international money transfer web application, which was launched around June, just in time to win the "HiT Barcelona global technological innovation summit". 

This initial web application was developed using the Zend Framework.

It was very exciting to participate in this project and contribute to its early success!