DolphinScheduler Expansion and Reduction

1. Expansion

This article describes how to add a new master service or worker service to an existing DolphinScheduler cluster.

 Attention: There cannot be more than one master service process or worker service process on a physical machine.
       If the physical machine where the expansion master or worker node is located has already installed the scheduled service, skip to [1.4 Modify configuration] Edit the configuration file `conf/config/install_config.conf` on **all ** nodes, add masters or workers parameter, and restart the scheduling cluster.

1.1 Basic software installation (please install the mandatory items yourself)

[required] JDK (1.8+):Must be installed, please install and configure JAVA_HOME and PATH variables under /etc/profile
[optional] If the expansion is a worker node, you need to consider whether to install an external client, such as Hadoop, Hive, Spark Client.

 Attention: DolphinScheduler itself does not depend on Hadoop, Hive, Spark, but will only call their Client for the corresponding task submission.

1.2 Get installation package

Check which version of DolphinScheduler is used in your existing environment, and get the installation package of the corresponding version, if the versions are different, there may be compatibility problems.
Confirm the unified installation directory of other nodes, this article assumes that DolphinScheduler is installed in /opt/ directory, and the full path is /opt/dolphinscheduler.
Please download the corresponding version of the installation package to the server installation directory, uncompress it and rename it to dolphinscheduler and store it in the /opt directory.
Add database dependency package, this article uses Mysql database, add mysql-connector-java driver package to /opt/dolphinscheduler/lib directory.

# create the installation directory, please do not create the installation directory in /root, /home and other high privilege directories 
mkdir -p /opt
cd /opt
# decompress
tar -zxvf apache-dolphinscheduler-1.3.9-bin.tar.gz -C /opt 
cd /opt
mv apache-dolphinscheduler-1.3.9-bin  dolphinscheduler

 Attention: The installation package can be copied directly from an existing environment to an expanded physical machine for use.

1.3 Create Deployment Users

Create deployment users on all expansion machines, and be sure to configure sudo-free. If we plan to deploy scheduling on four expansion machines, ds1, ds2, ds3, and ds4, we first need to create deployment users on each machine

# to create a user, you need to log in with root and set the deployment user name, please modify it yourself, later take dolphinscheduler as an example
useradd dolphinscheduler;

# set the user password, please change it by yourself, later take dolphinscheduler123 as an example
echo "dolphinscheduler123" | passwd --stdin dolphinscheduler

# configure sudo password-free
echo 'dolphinscheduler  ALL=(ALL)  NOPASSWD: NOPASSWD: ALL' >> /etc/sudoers
sed -i 's/Defaults    requirett/#Defaults    requirett/g' /etc/sudoers

 Attention:
 - Since it is sudo -u {linux-user} to switch between different Linux users to run multi-tenant jobs, the deploying user needs to have sudo privileges and be password free.
 - If you find the line "Default requiretty" in the /etc/sudoers file, please also comment it out.
 - If resource uploads are used, you also need to assign read and write permissions to the deployment user on `HDFS or MinIO`.

1.4 Modify configuration

From an existing node such as Master/Worker, copy the conf directory directly to replace the conf directory in the new node. After copying, check if the configuration items are correct.

Highlights:
datasource.properties: database connection information 
zookeeper.properties: information for connecting zk 
common.properties: Configuration information about the resource store (if hadoop is set up, please check if the core-site.xml and hdfs-site.xml configuration files exist).
env/dolphinscheduler_env.sh: environment Variables

Modify the dolphinscheduler_env.sh environment variable in the conf/env directory according to the machine configuration (take the example that the software used is installed in /opt/soft)

    export HADOOP_HOME=/opt/soft/hadoop
    export HADOOP_CONF_DIR=/opt/soft/hadoop/etc/hadoop
    # export SPARK_HOME1=/opt/soft/spark1
    export SPARK_HOME2=/opt/soft/spark2
    export PYTHON_HOME=/opt/soft/python
    export JAVA_HOME=/opt/soft/jav
    export HIVE_HOME=/opt/soft/hive
    export FLINK_HOME=/opt/soft/flink
    export DATAX_HOME=/opt/soft/datax/bin/datax.py
    export PATH=$HADOOP_HOME/bin:$SPARK_HOME2/bin:$PYTHON_HOME:$JAVA_HOME/bin:$HIVE_HOME/bin:$PATH:$FLINK_HOME/bin:$DATAX_HOME:$PATH

Attention: This step is very important, such as JAVA_HOME and PATH is necessary to configure, not used can be ignored or commented out

Softlink the JDK to /usr/bin/java (still using JAVA_HOME=/opt/soft/java as an example)
```
sudo ln -s /opt/soft/java/bin/java /usr/bin/java
```
Modify the configuration file conf/config/install_config.conf on the all nodes, synchronizing the following configuration.
- To add a new master node, you need to modify the ips and masters parameters.
- To add a new worker node, modify the ips and workers parameters.

# which machines to deploy DS services on, separated by commas between multiple physical machines
ips="ds1,ds2,ds3,ds4"

# ssh port,default 22
sshPort="22"

# which machine the master service is deployed on
masters="existing master01,existing master02,ds1,ds2"

# the worker service is deployed on which machine, and specify the worker belongs to which worker group, the following example of "default" is the group name
workers="existing worker01:default,existing worker02:default,ds3:default,ds4:default"

If the expansion is for worker nodes, you need to set the worker group. Please refer to the user manual 5.7 Worker grouping
On all new nodes, change the directory permissions so that the deployment user has access to the dolphinscheduler directory

sudo chown -R dolphinscheduler:dolphinscheduler dolphinscheduler

1.4. Restart the cluster & verify

restart the cluster

# stop command:

bin/stop-all.sh # stop all services

sh bin/dolphinscheduler-daemon.sh stop master-server  # stop master service
sh bin/dolphinscheduler-daemon.sh stop worker-server  # stop worker service
sh bin/dolphinscheduler-daemon.sh stop logger-server  # stop logger service
sh bin/dolphinscheduler-daemon.sh stop api-server     # stop api    service
sh bin/dolphinscheduler-daemon.sh stop alert-server   # stop alert  service


# start command::
bin/start-all.sh # start all services

sh bin/dolphinscheduler-daemon.sh start master-server  # start master service
sh bin/dolphinscheduler-daemon.sh start worker-server  # start worker service
sh bin/dolphinscheduler-daemon.sh start logger-server  # start logger service
sh bin/dolphinscheduler-daemon.sh start api-server     # start api    service
sh bin/dolphinscheduler-daemon.sh start alert-server   # start alert  service

 Attention: When using stop-all.sh or stop-all.sh, if the physical machine executing the command is not configured to be ssh-free on all machines, it will prompt for the password

After the script is completed, use the jps command to see if each node service is started (jps comes with the Java JDK)

    MasterServer         ----- master service
    WorkerServer         ----- worker service
    LoggerServer         ----- logger service
    ApiApplicationServer ----- api    service
    AlertServer          ----- alert  service

After successful startup, you can view the logs, which are stored in the logs folder.

 logs/
    ├── dolphinscheduler-alert-server.log
    ├── dolphinscheduler-master-server.log
    |—— dolphinscheduler-worker-server.log
    |—— dolphinscheduler-api-server.log
    |—— dolphinscheduler-logger-server.log

If the above services are started normally and the scheduling system page is normal, check whether there is an expanded Master or Worker service in the [Monitor] of the web system. If it exists, the expansion is complete.

2. Reduction

The reduction is to reduce the master or worker services for the existing DolphinScheduler cluster. There are two steps for shrinking. After performing the following two steps, the shrinking operation can be completed.

2.1 Stop the service on the scaled-down node

If you are scaling down the master node, identify the physical machine where the master service is located, and stop the master service on the physical machine.
If the worker node is scaled down, determine the physical machine where the worker service is to be scaled down and stop the worker and logger services on the physical machine.

# stop command:
bin/stop-all.sh # stop all services

sh bin/dolphinscheduler-daemon.sh stop master-server  # stop master service
sh bin/dolphinscheduler-daemon.sh stop worker-server  # stop worker service
sh bin/dolphinscheduler-daemon.sh stop logger-server  # stop logger service
sh bin/dolphinscheduler-daemon.sh stop api-server     # stop api    service
sh bin/dolphinscheduler-daemon.sh stop alert-server   # stop alert  service


# start command:
bin/start-all.sh # start all services

sh bin/dolphinscheduler-daemon.sh start master-server # start master service
sh bin/dolphinscheduler-daemon.sh start worker-server # start worker service
sh bin/dolphinscheduler-daemon.sh start logger-server # start logger service
sh bin/dolphinscheduler-daemon.sh start api-server    # start api    service
sh bin/dolphinscheduler-daemon.sh start alert-server  # start alert  service

 Attention: When using stop-all.sh or stop-all.sh, if the machine without the command is not configured to be ssh-free for all machines, it will prompt for the password.

After the script is completed, use the jps command to see if each node service was successfully shut down (jps comes with the Java JDK)

    MasterServer         ----- master service
    WorkerServer         ----- worker service
    LoggerServer         ----- logger service
    ApiApplicationServer ----- api    service
    AlertServer          ----- alert  service

If the corresponding master service or worker service does not exist, then the master/worker service is successfully shut down.

2.2 Modify the configuration file

modify the configuration file conf/config/install_config.conf on the all nodes, synchronizing the following configuration.
- to scale down the master node, modify the ips and masters parameters.
- to scale down worker nodes, modify the ips and workers parameters.

# which machines to deploy DS services on, "localhost" for this machine
ips="ds1,ds2,ds3,ds4"

# ssh port,default: 22
sshPort="22"

# which machine the master service is deployed on
masters="existing master01,existing master02,ds1,ds2"

# The worker service is deployed on which machine, and specify which worker group this worker belongs to, the following example of "default" is the group name
workers="existing worker01:default,existing worker02:default,ds3:default,ds4:default"