Stopping and Starting

The following commands are for Linux distributions.

Stopping Docker

Stop docker. This will shutdown all of the containers.
```
$ sudo systemctl stop docker
```

Restarting Docker

To restart docker, first set the docker to start on boot using the enable command.
```
$ sudo systemctl enable docker
```
To start docker, run the start command.
```
$ sudo systemctl start docker
```

Shutting Down Cassandra

On the deployer node, SSH to the target node.

Check Cassandra status.

Datacenter: datacenter1
=======================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
--  Address      Load       Tokens       Owns (effective)  Host ID                               Rack
UN  10.128.0.38  1.17 MiB   256          100.0%            d134e7f6-408e-43e5-bf8a-7adff055637a  rack1

To stop Cassandra, find the process ID and run the kill command.
```
$ pgrep -u autoid -f cassandra | xargs kill -9
```

Check the status again.

nodetool: Failed to connect to '127.0.0.1:7199' - ConnectException: 'Connection refused (Connection refused)'.

Re-Starting Cassandra

On the deployer node, SSH to the target node.

Restart Cassandra. When you see the No gossip backlog; proceeding message, hit Enter to continue.

$ cassandra
...
INFO  [main] 2020-11-10 17:22:49,306 Gossiper.java:1670 - Waiting for gossip to settle...
INFO  [main] 2020-11-10 17:22:57,307 Gossiper.java:1701 - No gossip backlog; proceeding

Check the status of Cassandra. You should see that it is in UN status ("Up" and "Normal").
```
$ nodetool status
```

Shutting Down MongoDB

Check the status of the MongDB
```
$ ps -ef | grep mongod
```

Connect to the Mongo shell.

$ mongo --tls --tlsCAFile /opt/autoid/mongo/certs/rootCA.pem --tlsCertificateKeyFile /opt/autoid/mongo/certs/mongodb.pem
--tlsAllowInvalidHostnames --host <ip-address>
MongoDB shell version v4.2.9
connecting to: mongodb://<ip-address>:27017/?compressors=disabled&gssapiServiceName=mongodb
2020-10-08T18:46:23.285+0000 W  NETWORK  [js] The server certificate does not match the host name. Hostname: <ip-address> does not match CN: mongonode
Implicit session: session { "id" : UUID("22c0123-30e3-4dc9-9d16-5ec310e1ew7b") }
MongoDB server version: 4.2.9

Switch the admin table.
```
> use admin
switched to db admin
```
Authenticate using the password set in vault.yml file.
```
> db.auth("root", "Welcome123")
1
```

Start the shutdown process.

> db.shutdownServer()
2020-10-08T18:47:06.396+0000 I  NETWORK  [js] DBClientConnection failed to receive message from <ip-address>:27017 - SocketException: short read
server should be down...
2020-10-08T18:47:06.399+0000 I  NETWORK  [js] trying reconnect to <ip-address>:27017 failed
2020-10-08T18:47:06.399+0000 I  NETWORK  [js] reconnect <ip-address>:27017 failed

Exit the mongo shell.
```
$ quit() or <Ctrl-C>
```

Check the status of the MongDB

$ ps -ef | grep mongod
no instance of mongod found

Re-Starting MongoDB

Re-start the MongoDB service.

$ /usr/bin/mongod --config /opt/autoid/mongo/mongo.conf
about to fork child process, waiting until server is ready for connections.
forked process: 31227
child process started successfully, parent exiting

Check the status of the MongDB

$ ps -ef | grep mongod
autoid    9245     1  0 18:48 ?        00:00:45 /usr/bin/mongod --config /opt/autoid/mongo/mongo.conf
autoid   22003  6037  0 21:12 pts/1    00:00:00 grep --color=auto mongod

Shutting Down Spark

On the deployer node, SSH to the target node.
Check Spark status. You should see that it is up-and-running.
```
$ elinks http://localhost:8080
```

Stop the Spark Master and workers.

$ /opt/autoid/spark/spark-2.4.4-bin-hadoop2.7/sbin/stop-all.sh
localhost: stopping org.apache.spark.deploy.worker.Worker
stopping org.apache.spark.deploy.master.Master

Check the Spark status again. You should see: Unable to retrieve htp://localhost:8080: Connection refused.

Re-Starting Spark

On the deployer node, SSH to the target node.

Start the Spark Master and workers. Enter the user password on the target node when prompted.

$ /opt/autoid/spark/spark-2.4.4-bin-hadoop2.7/sbin/start-all.sh
starting org.apache.spark.deploy.master.Master, logging to /opt/autoid/spark/spark-2.4.4-bin-hadoop2.7/logs/spark-a
utoid-org.apache.spark.deploy.master.Master-1.out
autoid-2 password:
localhost: starting org.apache.spark.deploy.worker.Worker, logging to /opt/autoid/spark/spark-2.4.4-bin-hadoop2.7/l
ogs/spark-autoid-org.apache.spark.deploy.worker.Worker-1.out

Check the Spark status again. You should see that it is up-and-running.