Setting up a 4-node Service Chain

This section covers how to set up a multi-node service chain. To tolerate byzantine faults, at least four nodes are required. We will set up a 4-consensus-node service chain.

Prerequisites

Step 0: Install SCN on all nodes

The installation is the uncompression of the downloaded package. Extract the SCN archive on each server.

$ tar xvf kscn-vX.X.X-XXXXX-amd64.tar.gz
x kscn-XXXXX-amd64/
x kscn-XXXXX-amd64/conf/
x kscn-XXXXX-amd64/conf/kscnd.conf
x kscn-XXXXX-amd64/bin/
x kscn-XXXXX-amd64/bin/kscnd
x kscn-XXXXX-amd64/bin/kscn

For the convenience, we will add the binary path to $PATH. Use the actual path on your node.

$ export PATH=$PATH:~/path/to/kscn-XXXXX-amd64/bin

Step 1: Create genesis.json and nodekeys

We will use homi utility to generate the needful files. You can execute homi from any Linux/Mac PC.

First, extract the homi archive you downloaded.

$ tar xvf homi-vX.X.X-XXXXX-amd64.tar.gz
x homi-XXXXX-amd64/
x homi-XXXXX-amd64/bin/
x homi-XXXXX-amd64/bin/homi

Go to the bin folder and execute homi with following options to generate the files. homi setup local --cn-num 4 --test-num 1 --servicechain --p2p-port 30000 -o homi-output

$ ./homi setup local --cn-num 4 --test-num 1 --servicechain --p2p-port 30000 -o homi-output
Created : homi-output/keys/passwd1
Created : homi-output/keys/passwd2
Created : homi-output/keys/passwd3
Created : homi-output/keys/passwd4
Created : homi-output/scripts/genesis.json
Created : homi-output/keys/nodekey1
Created : homi-output/keys/validator1
Created : homi-output/keys/nodekey2
Created : homi-output/keys/validator2
Created : homi-output/keys/nodekey3
Created : homi-output/keys/validator3
Created : homi-output/keys/nodekey4
Created : homi-output/keys/validator4
Created : homi-output/scripts/static-nodes.json
Created : homi-output/keys_test/testkey1
Created : homi-output/keys_test/keystore1/0xdC7218621513f71d609653d22C39d79d558d9CDC
Created : homi-output/Klaytn.json
Created : homi-output/Klaytn_txpool.json

Among the outputs, we will use nodeky*, genesis.json and static-nodes.json in the subsequent steps.

Step 2: Customize static-nodes.json

Open homi-output/scripts/static-nodes.json in a text editor then update the IP addresses and ports with the actual values of your nodes. Note the port you assigned here, the value will be used later in step 4.

[
"kni://38693ad4b17ff778b3f7bcbe6ee7fbc9a51999c443b3952e3e0838e63792f3582[email protected]192.168.0.1:30000?discport=0\u0026ntype=cn",
"kni://f36d969b16f7337b6f3f13ab9b0b3352ecca987cfaf744fa712b235ea3d9e14ac[email protected]192.168.0.2:30000?discport=0\u0026ntype=cn",
"kni://16e55d8921ab034e9538a1faf9666643b6104480397172ab443d4136208e55f36[email protected]192.168.0.3:30000?discport=0\u0026ntype=cn",
"kni://0973e792a421c1d1bedaccaf873f087ae118d895270f9cb3a81f1a31fcd21d62f[email protected]192.168.0.4:30000?discport=0\u0026ntype=cn"
]

After you update static-nodes.json, upload the output folders to all SCNs.

$ scp -r path/to/homi-output/ [email protected]:~/

Step 3: Node initialization

Now, we will initialize each node using the genesis file. On each node, execute the following command. It will create the data folder storing the chain data and logs on your home directory. You can change the data folder using the --datadir directive.

$ kscn --datadir ~/data init ~/homi-output/scripts/genesis.json
$ ls ~/data
keystore klay kscn

Step 4: Install nodekey and static-nodes.json

On every SCNs, copy static-nodes.json to the data folder.

$ cp ~/homi-output/scripts/static-nodes.json ~/data/

In step 1, we generated 4 nodekeys. Assign each node key to the SCN and copy the matching nodekey to each SCN's data folder. For example, use nodekey1 for 192.168.0.1 node and use nodekey 2, 3 and 4 for 192.168.0.2, 192.168.0.3 and 192.168.0.4 respectively.

$ cp ~/homi-output/keys/nodekey{1..4} ~/data/klay/nodekey

Step 5: Configure nodes

On every SCNs, go to the kscn installation folder and edit conf/kscnd.conf as follows.

...
PORT=30000
...
SC_SUB_BRIDGE=0
...
DATA_DIR=~/data
...

Step 6: Start nodes

Execute the following command on all SCN nodes.

$ kscnd start
Starting kscnd: OK

You can check block generation status by watching klay.blockNumber. If this number is not 0, the node is working fine.

$ kscn attach --datadir ~/data
> klay.blockNumber
10

If you want to stop a node, you can use the command kscnd stop

(Example) Creation and confirmation of a value transfer transaction

Now the 4-node service chain is running up. We will execute a value transfer transaction in the service chain to confirm the installation.

Step 1: Import the test account

testkey1 was automatically generated by homi in step 1. KLAY is allocated to the test account as described in the genesis.json which was also generated by homi

$ kscn account import --datadir ~/data ~/homi-output/keys_test/testkey1
Your new account is locked with a password. Please give a password. Do not forget this password.
Passphrase:
Repeat passphrase:
Address: {80119c31cdae67c42c8296929bb4f89b2a52cec4}

Step 2: Unlock the account

$ kscn attach --datadir ~/data
> personal.unlockAccount("80119c31cdae67c42c8296929bb4f89b2a52cec4")
Unlock account 80119c31cdae67c42c8296929bb4f89b2a52cec4
Passphrase:
true

Step 3: Send a transaction and check the balance

> klay.sendTransaction({from: "80119c31cdae67c42c8296929bb4f89b2a52cec4", to: "305c6cc464d5fe1e624679695a20d641a01688e1", value: 10})
"0xa0e7102e8f14200cec8d964aacc1c9ed7c22271078b2b213170c64333cbca8a3"
> klay.getBalance("305c6cc464d5fe1e624679695a20d641a01688e1")
10