I've completed this tutorial and successfully deployed a 3 node replica set. I can connect to it from other hosts and all is good. The question I have is that in the tutorial it states
Start MongoDB
Once the configuration files have been edited, start the database process manual:mongod on each instance by:
Log on onto the instance
Run the following command to start the process:
mongod --config /etc/mongod.conf
This should start the manual:mongod process
To me this seems as though the replica set is running as a user process and not as a system service as in the command
sudo service mongodb start
So what happens if one of the machines reboots? Is that process dead? How can I configure the whole replica set to run as a service?
On machine reboots, the mongod process will stop and you have to restart it.
In system scripts, I am not sure if on box restarts, mongod restart is automatically taken care of or not. But you can have service scripts for mongod process, which you get automatically, when you install using mongodb apt-get/yum packages.
Related
I am trying to configure a replica set on windows as a service, means that even the PC will restart the mongod will run again automatically.
problem is that I run the mongod like this:
mongod --dbpath "C:\Program Files\MongoDB\Server\4.2\data" --logpath "C:\Program Files\MongoDB\Server\4.2\log\mongod.log" --port 27017 --storageEngine=wiredTiger --journal --replSet test_replica
And once I close the CMD running this command the service is killed. How do I run it correctly then?
Also, currenctly the service is navigating to the default cfg file but I see the replication there is marked with # (so the service is running as standalone). and when I try to add to replication the replSet: test_replica it won't start anymore.
You should put all your parameters into a configuration file. Then you can create the service like this:
mongod.exe --config c:\MongoDB\config\mongod.cfg --install
For a replica set you typically create several services, not just one. It is possible to run a replica set with just one member, however this is quite useless. Of course, when you create several services then each one needs his own config file (and also his own dbPath, port, etc.)
The next time your PC will boot, the mongo service should also start. Or start it manually with command net start <mongo service name>
You should install mongodb as windows service. Read the guide from the official documentation
Setting --replSet from command line or replication:replSetName in configuration file is not enough. Read this guide, in short: after mongodb process is started in replica set mode, you should run rs.initiate() in mongo shell.
I'm using Ubuntu 16.04, and I can't understand what's difference between using
sudo service mongod start
and
mongod
In mongodb official documentation here
said that to start mongodb just use sudo service mongod start, and its log stores in /var/log/mongodb. However, I try to run mongodb using mongod this way, log shows on terminal, and after I turn off the terminal, I can not find the log file.
It is confused.
sudo - Runs the command as root.
service - Manages the following program as a daemon (background process).
mongod - Obviously the MongoDB program in question.
start - A command that tells service what to do with the program in question.
Together, we get "I want to start mongod as a background process, and I want to run it as root so it has permission to do the things it needs to do". Running mongod by itself, however, runs the program in an ordinary fashion, i.e. as a foreground process. Typically you want to run it as a background process so that you're free to do other things, e.g. connecting to the database via shell access.
This is pretty simplified, but it should explain what you actually need to know at this point in time.
I unable to start MonogoDB service after adding users into admin db as well as my db.
I setup MonogoDB and started service using following command i.e.
service mongod start
Using command prompt, I added few users like dbOwner, clusterAdmin, readWrite, read roles base users. Along with that I also changed configuration from /etc/mongod.conf. in that file, I changed port number, IP addresses, dbPath, and security.authorization: enabled.
Then I restarted mongod service using following command.
service mongod restart
After ran this command, mongod service stopped successfully, but failed to start with only 'FAILED' message.
I tried execute following command i.e.
mongod --port 27123 --dbpath /path/to/db --auth
It is working.
Question: How to execute 'service mongod start' using additional parameters in CentOS?
MonogoDB: 3.4
OS: CentOS 7
I got solution i.e.
mongod --config /etc/mongod.conf
Referred: https://docs.mongodb.com/manual/reference/configuration-options/#use-the-configuration-file
It starts child process and also I can stop mongod service using service mongod stop command.
But I don't know whether it is correct or not.
I can't certify exactly where the script that "service" command uses on CentOS 7, but in Ubuntu 18.04 mongod service script file is in
/lib/systemd/system/mongod.service
There you can change the user who executes the process and add any parameters you want, like --auth.
Said that, if you ever executed mongod as root, some files on where you store the db data will have the owner as root, making the database fail to start as another user. The fix I found for that is to manually chown to mongodb:mongodb (or the user you want to use) all the files that are owned by root inside the database.
Hope this helps.
mongod.service file from mongodb github
I have a mongodb cluster up and running. I want to setup a client (mongos) to connect to the config servers from ubuntu. Most instructions just say to run this command:
mongos --configdb cfg0.example.net:27019,cfg1.example.net:27019,cfg2.example.net:27019
Is this command running as a service? Will the process still be running when I exit the shell? What happens if the process goes down? What is the proper way of running this client as a service?
You would use --fork or an init script to make this run as a service post terminal session shut down.
If the process goes down then your application cannot connect to the sharded set. It will be unable to connect at all to your DB. This is (not the only reason) why you should have good redundancy in mongos instances.
I tend to have one mongos per app server personally, however, it is all down to preference. Another option is to have a load balanced set of mongos instances.
I have two Azure virtual machines. On one I have a Mongo server, on the other I just have a service I created which listens to Twitters streaming API and filters tweets.
Neither of these two services work unless I manually activate them and keep my console window open. For example, to run Mongo I need to ssh into my virtual machine and type: mongod --config /etc/mongod.conf. This starts the Mongo server successfully, but if at anytime I close my browser the service stops.
I believe the reason this is occurring is because when I login the system is allocating me a process by which I can navigate around the system and perform commands. When I type mongod --config /etc/mongod.conf I believe I am using that process to run Mongo. I am not sure how to make Mongo run without doing this though.
How do I make it so Mongo runs automatically all the time on my Azure server?
EDIT:
I tried running Mongo as a daemon but I receive an error:
$ mongod --fork --logpath /var/log/mongodb.log
>>>about to fork child process, waiting until server is ready for connections.
>>>forked process: 63470
>>>ERROR: child process failed, exited with error number 1
This issue has nothing to do with Azure; it's all about how you install MongoDB.
If you install mongodb as a service, via apt-get (or whatever other means your version of linux requires), then it will run independent of you being logged in. You shouldn't be running an always-on service through your command shell.
Here are instructions for installing under Ubuntu. You'll see that, once you set up the prerequisite public key and list file, you then run:
sudo apt-get install -y mongodb-org
You can then start and stop the service via
sudo service mongod start
and
sudo service mongod stop
You can enable mongo to autostart on boot by typing this command in your console:
sudo systemctl enable mongod
Then test it by this command:
sudo service mongod status