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https://github.com/svenvc/pharo-server-tools

Tools to deploy and manage headless Pharo servers from the command line
https://github.com/svenvc/pharo-server-tools

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Tools to deploy and manage headless Pharo servers from the command line

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# Pharo Server Tools



Tools to deploy and manage headless Pharo servers from the command line.



## Goal



To deploy and manage a Pharo based server application on a Linux system.

More specifically, Pharo 4 on Ubuntu 14.04 LTS server.



The goal is to integrate well within the standard Linux world,



- create an entry in `/etc/init.d` or `/etc/systemd/system/` for automatic start/stop/restart

- create an entry in `/etc/monit/conf.d` for monitoring with automatic restarts whenever the check fails

- setup logging to daily files

- setup secure REPL access to the running application



This document describes the basic manual installation procedure.

There is also an interactive scaffold script that automates most work.



## Installation



Note that we assume that you operate your machine as a normal user.



````bash

echo $USER

````



Check out the project `pharo-server-tools` from github.

You will need to install git first



````bash

sudo apt-get install git-core 

git clone https://github.com/svenvc/pharo-server-tools.git

````



The following directory structure is used



````bash

~/pharo

~/pharo/bin

~/pharo/bin/pharo-vm

~/pharo/build

````



The script `install-pharo.sh` will download a Pharo 4 image + VM

and move things around to create the directory structure.

This has to be done only once. You will need to install unzip.



````bash

sudo apt-get install unzip

~/pharo-server-tools/install-pharo.sh

````



You can use both a 32 or 64 bit Ubuntu distribution.

However, since the Pharo VM is still a 32 bit application, 

you will need to install some extra libraries in that case.



The standard instructions are



````bash

sudo dpkg --add-architecture i386

sudo apt-get update

sudo apt-get install libc6:i386

sudo apt-get install libssl1.0.0:i386

sudo apt-get install libfreetype6:i386

````



You can use the script `ubuntu-32bit-support-on-64bit.sh` for this.



## Server Application



It is assumed your whole application is packaged using 

one single Metacello configuration that loads all dependencies.



Note that if you want to use the REPL and HTTP monitoring features described here, you need to include NeoConsole as one of your dependencies.



````

project: 'NeoConsole' with: [

  spec 

    className: 'ConfigurationOfNeoConsole';

    repository: 'http://mc.stfx.eu/Neo' ];

````



Furthermore it is assumed that you have a script that actually

starts up your application. This could be as simple as

`MyApp start` but will probably be a bit more involved.



Each server application will eventually be deployed and run

from its own directory under `~/pharo`. From the operational

standpoint this is the only relevant place.



Next we describe the different steps needed

to set everything up manually.

There is also an interactive script to automate all these steps.



````bash

./pharo-server-tools/scaffold.sh

````



Here is an example usage, installing a Pharo HTTP Server, with NeoConsole as sole dependency.



````bash

$ ./scaffold.sh 

This script will setup a new Pharo service under /home/t3/pharo

Service name: pharo-http-server

Image name (empty for service name): 

User (empty for current user): 

Description: Pharo HTTP Server

Metacello repository: http://mc.stfx.eu/Neo

Metacello name: ConfigurationOfNeoConsole

Metacello user (empty for none): 

Metacello password (empty for none): 

Metacello version (empty for stable): 

Metacello group (empty for default): 

Telnet port (empty for 42001): 

Metrics port (empty for 42002): 

Creating custom build script

This script will build a pharo-http-server image

'Installing ConfigurationOfNeoConsole stable'



Loading 8 of ConfigurationOfNeoConsole...

Fetched -> Neo-Console-Core-SvenVanCaekenberghe.15 --- http://mc.stfx.eu/Neo --- http://mc.stfx.eu/Neo

Loaded -> Neo-Console-Core-SvenVanCaekenberghe.15 --- http://mc.stfx.eu/Neo --- cache

...finished 8

Creating custom run/startup script

Creating custom REPL script

Creating custom init.d script

Creating custom systemd.service script

Creating custom monit service check

Done

To install the init.d script do

sudo cp /home/t3/pharo/pharo-http-server/init.d.script /etc/init.d/pharo-http-server

sudo update-rc.d pharo-http-server defaults

To install the systemd.service script do

sudo cp /home/t3/pharo/pharo-http-server/systemd.service.script /etc/systemd/system/pharo-http-server.service

sudo systemctl daemon-reload

sudo systemctl enable pharo-http-server

To install the monit service check do

sudo cp /home/t3/pharo/pharo-http-server/monit-service-check /etc/monit/conf.d/pharo-http-server

````



## Building



Pharo uses an image to hold all the objects and code needed to run

an application. You need to build your custom image by loading

your code into the standard image. This build from source step is

executed in the `~/pharo/build` directory.



Building will be done incrementally in a scratch image called

`build.image`. This is created once or whenever you want to 

completely start over. In the build directory do



````bash

../bin/pharo Pharo.image save build

````



Now edit the build.sh script to refer to load your configuration.

The default just loads NeoConsole for the REPL tool, a dependency

you should add to your own projects. For the demo/tutorial this

will be enough.



````bash

./build.sh

````



After a successful build, copy the image again. Our demo/tutorial

application will be called `pharo-http-server`.



````bash

../bin/pharo build.image save pharo-http-server

````



When you update your code, you execute the last 2 steps again.



## Deploying



### Preparing the deploy directory



Start by creating your deploy directory



````bash

mkdir ~/pharo/pharo-http-server

````



Now move over the customised image and changes files that were

created in the build step



````bash

mv ~/pharo/build/pharo-http-server.* ~/pharo/pharo-http-server

````



To control our application process itself, to start it in the background,

to figure out whether it is running and its process id, to stop it,

we use a helper script called `pharo-ctl.sh`. Copy it 



````bash

cp ~/pharo-server-tools/pharo-ctl.sh ~/pharo/pharo-http-server

````



Next we need a run or startup script. The template is good for the

demo/tutorial, you will probably have to customise it. Copy it



````bash

cp ~/pharo-server-tools/run.st.template ~/pharo/pharo-http-server/run-pharo-http-server.st

````



Here is the script’s contents:



````smalltalk

(NeoConsoleTranscript onFileNamed: 'server-{1}.log') install.



Transcript

  cr;

  show: 'Starting '; show: (NeoConsoleTelnetServer startOn: 42001); cr;

  show: 'Starting '; show: (NeoConsoleMetricDelegate startOn: 42002); cr;

  flush.



(ZnServer defaultOn: 8080)

  logToTranscript;

  logLevel: 2;

  start.

````



The first expression installs a non-interactive transcript that redirects

all Transcript output to files which are organised by day.



Next, the tools from the NeoConsole project are used to start 2 helper services.

The first is a locally bound Telnet server that allows for REPL access 

to a running image which is very useful for debugging and monitoring purposes.

The second is a locally bound HTTP server that gives access to a number

of metrics, named read-only properties, among which is `system.status`.



Finally we start our application, an HTTP server on port 8080, with logging.



We now have everything set up to manually run our application server.

The `pharo-ctl` script always takes 3 arguments, the name of the 

startup script, the desired operation and the name of the image.

Execute it without arguments for help



````bash

./pharo-ctl.sh 

Executing ./pharo-ctl.sh

Working directory /home/sven/pharo/pharo-http-server

Usage: ./pharo-ctl.sh  <command> <image>

    manage a Pharo server

Naming

    script       is used as unique identifier

    script.st    must exist and is the Pharo startup script  

    script.pid   will be used to hold the process id

    image.image  is the Pharo image that will be started

Commands:

    start    start the server in background

    stop     stop the server

    restart  restart the server

    run      run the server in foreground

    pid      print the process id 

````



Note that the extensions `.st` and `.image` are added automatically.



Here is how to start our application



    ./pharo-ctl.sh run-pharo-http-server start pharo-http-server



Note that the image could be started multiple times, like when running N

instances for load balancing, but the startup/run script should be unique,

like `run.0.st`, `run.1.st` and so on. The combination image/script should

be unique on your machine.



To figure out whether it is running and get its process id (PID)



````bash

./pharo-ctl.sh run-pharo-http-server pid pharo-http-server

````



To stop the background process



````bash

./pharo-ctl.sh run-pharo-http-server stop pharo-http-server

````



You can invoke this last command multiple times if you somehow managed 

to start multiple copies.



### Integrating with Linux Init Scripts



You want your application server to be under control of Linux,

so that it will start automatically whenever your machine (re)starts.

System administrators need this so called service entry to learn 

about your application. We will reuse this feature ourselves later on as well.



#### init.d



To do this you have to create a script inside `/etc/init.d`.

Copy the template and update the System V style RC init subsystem:



````bash

sudo cp ~/pharo-server-tools/init.d.template /etc/init.d/pharo-http-server

sudo update-rc.d pharo-http-server defaults

````



Again, the script is more or less ready for our demo/tutorial.

Check the variables at the top, you need to change the `user` in 

the `PHDIR=` and `SU=` lines to the actual user you are using.



If everything is well, Linux can now control your application.



````bash

sudo service pharo-http-server

sudo service pharo-http-server start

sudo service pharo-http-server stop

````



#### systemd



Alternatively, you can use the newer systemd approach.

To do this you have to create a script inside `/etc/systemd/system`.

Copy the template, reload the daemon and enable the service.



````bash

sudo cp ~/pharo-server-tools/systemd.service.template /etc/systemd/system/pharo-http-server.service

sudo systemctl daemon-reload

sudo systemctl enable pharo-http-server

````



Make sure to change the user. Now you can manipulate the service in a standard way.



````bash

sudo systemctl stop pharo-http-server

sudo systemctl start pharo-http-server

sudo systemctl status pharo-http-server

````



### Integrating with monitoring



Your application server might crash or become otherwise unresponsive.

You want automatic monitoring of some external feature of your

application server with the option to restart it should the service check fail.



In our startup script we started a special, locally bound HTTP server just

for this purpose, running on port 42002. The URI `/metrics/system.status` gives

a simple service status indication.



````bash

curl http://localhost:42002/metrics/system.status

````



Which returns a single line of text, like



    Status OK - Clock 2015-08-25T14:21:08.641321+02:00 - Allocated 51,123,436 bytes - 14.63 % free.



We chose to use monit for this purpose.



````bash

sudo apt-get install monit

````



Now copy over the monit-service template corresponding to your choice of startup (init.d or systemd)



_Using init.d_

````bash

sudo cp ~/pharo-server-tools/monit-service-init.d.template /etc/monit/conf.d/pharo-http-server

````



_Using systemd_

````bash

sudo cp ~/pharo-server-tools/monit-service-systemd.template /etc/monit/conf.d/pharo-http-server

````



Edit the file by replace `user` with your username and restart monit, 

after validating validating the syntax.



````bash

sudo service monit syntax

sudo service monit restart

````



The contents of the service check is pretty simple:



````bash

check process pharo-http-server

    with pidfile "/home/user/pharo/pharo-http-server/run-pharo-http-server.pid"

    start program = "/etc/init.d/pharo-http-server start"

    stop program = "/etc/init.d/pharo-http-server stop"

    if failed url http://localhost:42002/metrics/system.status

       timeout 10 seconds retry 3

       then restart 

````



It says to check the specified URL and restart if there is no successful response to it,

retrying 3 times with a timeout of 10 seconds each time. 



Note how we reuse the init script and the PID file.

When using systemd, you will need to modify the start and stop programs accordingly.



Consult monit’s documentation for more options, like email notifications.



### REPL telnet access to a running image



Although log files are a standard way to learn about a running background process,

it is a very primitive interface. You either log too little or too much. 

Often you would just love to have a look inside your running application.



With NeoConsole’s REPL (read-eval-print-loop) telenet access you can do just that.

In our startup script we started a special, locally bound Telnet server

on port 42001.



````bash

telnet localhost 42001



./repl.sh

````



You can use telnet directly or use the repl.sh script.

Here is a transcript of a session with this tool.



````bash

Trying 127.0.0.1...

Connected to localhost.

Escape character is '^]'.

Neo Console Pharo4.0 of 18 March 2013 update 40618

> help

help <command>

known commands are:

  describe

  eval DEFAULT

  get

  help

  history

  quit

> get

known metrics:

  system.status - Simple system status

  memory.total - Total allocated memory

  memory.free - Free memory

  system.date - Current date

  system.time - Current time

  system.timestamp - Current timestamp

  process.count - Current process count

  process.list - Current list of processes

  system.version - Image version info

  system.mcversions - Monticello packages version info

> get system.status

  Status OK - Clock 2015-08-25T14:31:07.769294+02:00 - Allocated 55,551,212 bytes - 11.44 % free.

> 123 factorial



12146304367025329675766243241881295855454217088483382315328918161829235892362167668831156960612640202170735835221294047782591091570411651472186029519906261646730733907419814952960000000000000000000000000000

> 0@0 extent: 10@20



(0@0) corner: (10@20)

> =

self: (0@0) corner: (10@20)

class: Rectangle

origin: (0@0)

corner: (10@20)

> quit

Bye!

Connection closed by foreign host.

````



There is an executable script called repl.sh that helps you remember how to connect

to the telnet REPL service.



## Troubleshooting



Carefully read the run/startup script, the init.d script and the service check script.

Path names and port numbers should match.

Double check that the right processes run (`ps auxw | grep pharo`).



## Resources



The following chapter from the 'Enterprise Pharo, a Web prespective' 

treats the same subject: 

[Deploying a Pharo web application in production](https://ci.inria.fr/pharo-contribution/job/EnterprisePharoBook/lastSuccessfulBuild/artifact/book-result/DeploymentWeb/DeployForProduction.html)