EWD 3 Training Course Part 29: Running QEWD as a Service

Copyright © 2016 M/Gateway Developments Ltd

EWD 3 Training CoursePart 29

Running QEWD as a Service

Rob TweedDirector, M/Gateway Developments Ltd

Twitter: @rtweed


The QEWD Node.js process

• So far we've run it in a Command Prompt or Terminal window– This OK for demonstration– But not for production

• It needs to run as a service– Automatically start at boot time– Restart on error– Pipe console.log to a log file



• Different approaches needed for– Windows– Linux

• Many different options available, but the following are two that seem to work well



• Windows:– NSSM

• Linux– PM2


Windows: NSSM

• http://nssm.cc/

• Free Service Manager for Windows• Works very well with Node.js and QEWD

• Click download and get the latest version– 2.24 (at time of writing these notes)


Install NSSM

• Drill down into the downloaded file– Downloads/nssm-2.24.zip

• Find the /win64 directory– Downloads/nssm-2.24.zip/nssm-2.24/win64/nssm.exe

• Copy nssm.exe to a directory that is already in your PATH for executables, eg:– C:\Program Files\nodejs


Log file for piped output

• Create a suitable directory, eg:– C:\qewd\log

• Create an empty file in it:– qewd.log


Dependency on Caché

• When NSSM starts up, it must wait to make sure Caché has already started– We need the dependency information

• Control Panel:– System and Security

• Administrative Tools– Services


Dependency on Caché

• In the Services Window that opens up, find the Service named:– Caché Controller for Cachexxxx

• Right click on it and select Properties• At the top you'll see the Service Name

– eg: Cache c- intersystems_cache2015-2• Copy this to your clipboard


Start NSSM Installer• In a Command Prompt window type:

nssm install• Application Path:

– C:\Program Files\nodejs\node.exe• Startup Directory:

– C:\ewd3 (or wherever you start ewd-xpress)• Arguments:

– ewd-xpress• Click on Dependencies Tab

– Paste the Caché Service string from clipboard

• Click on I/O tab– Input: leave blank– Output: C:\qewd\log\qewd.log– Error: C:\qewd\log\qewd.log

• Give your new service a name:– QEWD

• Click Install Service


Start the QEWD Service• Switch to the Services window• Click Refresh button• QEWD should appear in the list of services• Right-click on it and select Properties

– Service Status will be stopped– Click Start

• QEWD should now be running– Test by starting the qewd-monitor application


Log File

• Look in C:\qewd\log\qewd.log• You should see all the console.log activity

being piped there


Controlling the Service• Standard Windows Service• Use the Services panel and find QEWD

– Stop– Start– Restart

• If an error occurs that stops the master process, the QEWD service will automatically restart

• The QEWD service will start automatically when Windows is re-booted


NSSM additional features

• Lots more functionality• Worth exploring documentation at

http://nssm.cc

• To edit your service definition:– Open Command Prompt window

nssm edit QEWD


Linux: PM2

• Advanced Node.js Process Manager– http://pm2.keymetrics.io/

• Install:

– -g option makes pm2 available as a command

cd ~sudo npm install –g pm2


Start QEWD as a Service

cd ~/qewdpm2 start qewd.js

Assuming that qewd.js is the name of yourQEWD startup file.


Start QEWD as a Service

cd ~/qewdpm2 start qewd.js

This will be now the PM2 Service name


Monitor PM2 Services

cd ~/qewdpm2 status

Displays the status of all your PM2 Services- online- stopped


Stop the QEWD PM2 Service

cd ~/qewdpm2 stop qewd


Restart the QEWD PM2 Service

cd ~/qewdpm2 start qewd

If you've already started QEWD as a service,and if it appears as stopped in pm2 status,

you don't need to specify the .js file extension


Restart the QEWD PM2 Service

cd ~/qewdpm2 restart qewd

To stop and start QEWD again in 1 command


Logging the output

• PM2 automatically pipes console.log and error output to log files:

– ~/qewd/.pm2/logs

– You should find:• ~/.pm2/logs/qewd-out-0.log


Logging the output

• PM2 automatically pipes console.log and error output to log files:

– ~/qewd/.pm2/logs

– You should find:• ~/.pm2/logs/qewd-out-0.log

This number may vary


Logging the output

• Use the tail command to monitor QEWD activity in real-time

tail –f ~/.pm2/logs/qewd-out-0.log


PM2 will auto-restart QEWD

• If an error brings down the QEWD master process, PM2 will automatically restart it

• Try stopping the master process using qewd-monitor while tailing the log file– Watch it stop and immediately restart

Software

EWD 3 Training Course Part 29: Running QEWD as a Service