Redis Startup issues on Debian Stretch (9) - linux

Actually I'm on my way to switch to debian 9 for the new production servers of the company and want to provision them with ansible. So far, everything works fine, but now I'm stuck with redis-server.
By default, Debian 9 comes with redis version 3.2. I'm installing the package via apt-get install redis-server. After that, redis starts up as a daemon in the background. Now I want to apply some custom configuration, like binding to 2 different IPs (127.0.0.1 and the server IP).
After changing this as well as the daemonize option (to yes), redis is no longer willing to start in the background. Whenever doing either service redis-server start or /etc/init.d/redis-server start, the command just stucks.
journalctl -xe tells me, that the pid file is not readable (redis-server.service: PID file /var/run/redis/redis-server.pid not readable (yet?) after start-post: No such file or directory) even though it should be created according to init.d script:
start)
echo -n "Starting $DESC: "
mkdir -p $RUNDIR
touch $PIDFILE
chown redis:redis $RUNDIR $PIDFILE
chmod 755 $RUNDIR
After all, I can see, that both service redis-server start and /etc/init.d/redis-server are starting the server and I'm also able to connect to the server via redis-cli. But the damn process stucks.
Can anyone help? If you need further information, just let me know. I'll provide what ever possible if this solves the problem!
best
Chris

I had a similar situation on a Centos 7 server.
The resolution was to change supervised from no to auto
# By default Redis does not run as a daemon. Use 'yes' if you need it.
# Note that Redis will write a pid file in /var/run/redis.pid when daemonized.
daemonize yes
# If you run Redis from upstart or systemd, Redis can interact with your
# supervision tree. Options:
# supervised no - no supervision interaction
# supervised upstart - signal upstart by putting Redis into SIGSTOP mode
# supervised systemd - signal systemd by writing READY=1 to $NOTIFY_SOCKET
# supervised auto - detect upstart or systemd method based on
# UPSTART_JOB or NOTIFY_SOCKET environment variables
# Note: these supervision methods only signal "process is ready."
# They do not enable continuous liveness pings back to your supervisor.
supervised auto
When you run the process as daemon it need to interact with systemd for process management (if I read well some documentation).
Thanks

Related

What's difference between these redis starting commands

sudo /etc/init.d/redis-server start
sudo service redis-server start
sudo systemctl start redis-server
sudo redis-server --daemonize yes
The last one is "nearest to the metal", it directly starts the Redis server process with no special options, and is "stand-alone". I would use this type of command when just "messing around" in the Terminal with quick tests and when trying to get an initial configuration tested and running.
The first 3 are all basically wrappers around starting the Redis server process to make it compatible with systemd or other Linux startup systems. They potentially add more layers of management, like:
reporting to the systemctl logs
saving the process id so the process can be killed or restarted
potentially specifying a different config file
potentially waiting for other services to become available before starting Redis
I would prefer one of the first three for routine, every-day, managed starting up of Redis on a production system.

how to restart a nodejs server on linux AWS

So I'm really new into loading the node server on AWS,
basically I followed some guide to start node from etc/init
so I have a file like that in etc/init
menuserver.conf
#!upstart
description "menu-creator server"
start on started mountall
stop on shutdown
# Automatically Respawn:
respawn
respawn limit 99 5
env NODE_ENV=development
# Warning: this runs node as root user, which is a security risk
# in many scenarios, but upstart-ing a process as a non-root user
# is outside the scope of this question
exec node /home/ec2-user/MenuCreator/app.js >> /var/log/yourappname.log 2>&1
I have updated the server code, and wish to restart the server, how to do it?
as I'm just starting out, I don't care so much for the security risks.
I've tried etc/init.d/menuserver restart,
but actually menuserver isn't found in init.d.
looking for a quick way to restart the program, and also for a long term good practice guide for how to setup and restart the server.
(I think I heard Forever is recommended... is it?)
Try setting pm2 on server. You can easily restart server then. Study more about pm2
http://pm2.keymetrics.io/
sudo stop/start/restart service name worked for me,
example:
sudo stop menuserver

Centos 7: Auto restart application if it stopped

I want to auto restart my application "Fiware IoT Agent" if it stopped, the problem is that it depends of Mongo Db Data Base and the Mosquitto broker. My OS is centOS 7
Here is the commands that I use to launch my three application in the following order:
*Mongo:
/usr/local/iot/mongodb-linux-x86_64-3.0.5/bin/mongod --dbpath /usr/local/iot/mongodb-linux-x86_64-3.0.5/data/db$
*Mosquitto broker
/usr/sbin/mosquitto -c /etc/iot/mosquitto.conf &
pid=$!
echo $pid > /var/run/iot/mosquitto.pid
Iot Agent:
than I start my application using this command
export LD_LIBRARY_PATH=/usr/local/iot/lib
/usr/local/iot/bin/iotagent -i 192.168.1.11 -p 80 -v DEBUG -d /usr/local/iot/lib -c /etc/iot/config.json
how can I start my application if it stopped known that it depends of the other two application? If for example Mongo DB stopped, I must be able to restart it and then to restart my application.
CentOS 7 uses systemd. You can create systemd service for each of your applications and specify dependencies between them. And specify "Restart=always" for service which need to be auto restarted.
You can create your own watch dog code. When you start your application get the pid of the process and the pid of mongo DB.
Every couple of second like 10 seconds check that the pid of both process still exist, or you can also make the programs touch a file every couple of seconds as well then check the file modification time to see if the programs are still alive.
If the program hasn't touched the file or if you go jus the pid route and the pid doesn't exist. Then the program has died.
Restart the program and get the new pid and go about again in a forever while loop.

Run Upstart with Forever

We have a series of node.js scripts on an Ubuntu (13.10) server that we want to keep up and running as much as possible, and restart automatically in the event of a server reboot. We've tried a few different techniques, but have yet to find a solution that works.
Setup: None of the scripts run on port 80, instead we run them on ports above 8000.
Node.js files are currently running in /usr/lib/sites/path/Node
We have set them up and running individually using Forever while running in the context of a well privileged (but not root) user, simply by running the following from the context of the folder containing the scripts:
forever start server_process.js
We want to run these scripts at server start up, and have some ability later (if needed) to restart them.
Upstart sounds like it should be the solution, but we've not yet managed to get it working. The following script starts, then stops without indicating why...
description "Our app"
version "1.0"
author "Nautilytics"
start on startup
stop on shutdown
expect fork
env FOREVER_PATH=/usr/bin/forever
env APPLICATION_DIRECTORY=/usr/lib/sites/path/Node
env APPLICATION_START=ourapp.js
env LOG_PATH=/var/log/ourapp.log
chdir /usr/lib/sites/path/Node
script
exec $FOREVER_PATH start --sourceDir $APPLICATION_DIRECTORY -f -v $APPLICATION_START >> $LOG_PATH 2&>1
end script
Through blunt trial and error, a couple of times we have been able to get errors that indicate that other files (required by ourapp.js) could not be found, as if the chdir has not worked or passed through into the forever start.
After scouring the internet for a solution, we decided to stick with nodejs and not use forever for this task. It was much easier and with respawn it does just about everything we needed forever to do for us.
start on runlevel [2345]
stop on shutdown
respawn
script
exec sudo nodejs /usr/lib/sites/path/Node/ourapp.js 2>&1 >> /var/log/ourapp.log
end script
A bit more secure upstart config script might be (hardened-nodejs.conf):
description "Managing and monitoring nodejs application"
# start when filesystem is mounted networking is up
start on (filesystem and net-device-up IFACE!=lo)
# stop on shutting down the system
stop on runlevel [016]
# application environment
# staging and development instances should use hardened-nodejs.override to define environment
env NODE_ENV=production
# respawn the job up to 10 times within a 5 second period.
# If the job exceeds these values, it will be stopped and marked as failed.
respawn
respawn limit 10 5
# ssl-cert group can read certificates
setuid www-data
setgid ssl-cert
exec /usr/bin/nodejs /usr/lib/sites/path/Node/ourapp.js 2>&1 >> /var/log/ourapp.log
One of solutions to run nodejs application listening on a low port might be to use capabilities tools.
If serving over SSL user or group must have read access to the certificate. Check ssl-cert package and this answer for basic concepts.
Have you checked process.cwd()? It could be that your process is running elsewhere.

How do I run a Node.js application as its own process?

What is the best way to deploy Node.js?
I have a Dreamhost VPS (that's what they call a VM), and I have been able to install Node.js and set up a proxy. This works great as long as I keep the SSH connection that I started node with open.
2016 answer: nearly every Linux distribution comes with systemd, which means forever, monit, PM2, etc. are no longer necessary - your OS already handles these tasks.
Make a myapp.service file (replacing 'myapp' with your app's name, obviously):
[Unit]
Description=My app
[Service]
ExecStart=/var/www/myapp/app.js
Restart=always
User=nobody
# Note Debian/Ubuntu uses 'nogroup', RHEL/Fedora uses 'nobody'
Group=nogroup
Environment=PATH=/usr/bin:/usr/local/bin
Environment=NODE_ENV=production
WorkingDirectory=/var/www/myapp
[Install]
WantedBy=multi-user.target
Note if you're new to Unix: /var/www/myapp/app.js should have #!/usr/bin/env node on the very first line and have the executable mode turned on chmod +x myapp.js.
Copy your service file into the /etc/systemd/system folder.
Tell systemd about the new service with systemctl daemon-reload.
Start it with systemctl start myapp.
Enable it to run on boot with systemctl enable myapp.
See logs with journalctl -u myapp
This is taken from How we deploy node apps on Linux, 2018 edition, which also includes commands to generate an AWS/DigitalOcean/Azure CloudConfig to build Linux/node servers (including the .service file).
Use Forever. It runs Node.js programs in separate processes and restarts them if any dies.
Usage:
forever start example.js to start a process.
forever list to see list of all processes started by forever
forever stop example.js to stop the process, or forever stop 0 to stop the process with index 0 (as shown by forever list).
I've written about my deployment method here: Deploying node.js apps
In short:
Use git post-receive hook
Jake for the build tool
Upstart as a service wrapper for node
Monit to monitor and restart applications it they go down
nginx to route requests to different applications on the same server
pm2 does the tricks.
Features are: Monitoring, hot code reload, built-in load balancer, automatic startup script, and resurrect/dump processes.
You can use monit, forever, upstart or systemd to start your server.
You can use Varnish or HAProxy instead of Nginx (Nginx is known not to work with websockets).
As a quick and dirty solution you can use nohup node your_app.js & to prevent your app terminating with your server, but forever, monit and other proposed solutions are better.
I made an Upstart script currently used for my apps:
description "YOUR APP NAME"
author "Capy - http://ecapy.com"
env LOG_FILE=/var/log/node/miapp.log
env APP_DIR=/var/node/miapp
env APP=app.js
env PID_NAME=miapp.pid
env USER=www-data
env GROUP=www-data
env POST_START_MESSAGE_TO_LOG="miapp HAS BEEN STARTED."
env NODE_BIN=/usr/local/bin/node
env PID_PATH=/var/opt/node/run
env SERVER_ENV="production"
######################################################
start on runlevel [2345]
stop on runlevel [016]
respawn
respawn limit 99 5
pre-start script
mkdir -p $PID_PATH
mkdir -p /var/log/node
end script
script
export NODE_ENV=$SERVER_ENV
exec start-stop-daemon --start --chuid $USER:$GROUP --make-pidfile --pidfile $PID_PATH/$PID_NAME --chdir $APP_DIR --exec $NODE_BIN -- $APP >> $LOG_FILE 2>&1
end script
post-start script
echo $POST_START_MESSAGE_TO_LOG >> $LOG_FILE
end script
Customize all before #########, create a file in /etc/init/your-service.conf and paste it there.
Then you can:
start your-service
stop your-service
restart your-service
status your-service
I've written a pretty comprehensive guide to deploying Node.js, with example files:
Tutorial: How to Deploy Node.js Applications, With Examples
It covers things like http-proxy, SSL and Socket.IO.
Here's a longer article on solving this problem with systemd: http://savanne.be/articles/deploying-node-js-with-systemd/
Some things to keep in mind:
Who will start your process monitoring? Forever is a great tool, but it needs a monitoring tool to keep itself running. That's a bit silly, why not just use your init system?
Can you adequately monitor your processes?
Are you running multiple backends? If so, do you have provisions in place to prevent any of them from bringing down the others in terms of resource usage?
Will the service be needed all the time? If not, consider socket activation (see the article).
All of these things are easily done with systemd.
If you have root access you would better set up a daemon so that it runs safe and sound in the background. You can read how to do just that for Debian and Ubuntu in blog post Run Node.js as a Service on Ubuntu.
Forever will do the trick.
#Kevin: You should be able to kill processes fine. I would double check the documentation a bit. If you can reproduce the error it would be great to post it as an issue on GitHub.
Try this: http://www.technology-ebay.de/the-teams/mobile-de/blog/deploying-node-applications-with-capistrano-github-nginx-and-upstart.html
A great and detailed guide for deploying Node.js apps with Capistrano, Upstart and Nginx
As Box9 said, Forever is a good choice for production code. But it is also possible to keep a process going even if the SSH connection is closed from the client.
While not necessarily a good idea for production, this is very handy when in the middle of long debug sessions, or to follow the console output of lengthy processes, or whenever is useful to disconnect your SSH connection, but keep the terminal alive in the server to reconnect later (like starting the Node.js application at home and reconnecting to the console later at work to check how things are going).
Assuming that your server is a *nix box, you can use the screen command from the shell to do keep the process running even if the client SSH is closed. You can download/install screen from the web if not already installed (look for a package for your distribution if Linux, or use MacPorts if OS X).
It works as following:
When you first open the SSH connection, type 'screen' - this will start your screen session.
Start working as normal (i.e. start your Node.js application)
When you are done, close your terminal. Your server process(es) will continue running.
To reconnect to your console, ssh back to the server, login, and enter 'screen -r' to reconnect. Your old console context will pop back ready for you to resume using it.
To exit screen, while connected to the server, type 'exit' on the console prompt - that will drop you onto the regular shell.
You can have multiple screen sessions running concurrently like this if you need, and you can connect to any of it from any client. Read the documentation online for all the options.
Forever is a good option for keeping apps running (and it's npm installable as a module which is nice).
But for more serious 'deployment' -- things like remote management of deploying, restarting, running commands etc -- I would use capistrano with the node extension.
https://github.com/loopj/capistrano-node-deploy
https://paastor.com is a relatively new service that does the deploy for you, to a VPS or other server. There is a CLI to push code. Paastor has a free tier, at least it did at the time of posting this.
In your case you may use the upstart daemon. For a complete deployment solution, I may suggest capistrano. Two useful guides are How to setup Node.js env and How to deploy via capistrano + upstart.
Try node-deploy-server. It is a complex toolset for deploying an application onto your private servers. It is written in Node.js and uses npm for installation.

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