Using the Fabric test network¶

After you have downloaded the Hyperledger Fabric Docker images and samples, you can deploy a test network by using scripts that are provided in the fabric-samples repository. The test network is provided for learning about Fabric by running nodes on your local machine. Developers can use the network to test their smart contracts and applications. The network is meant to be used only as a tool for education and testing and not as a model for how to set up a network. In general, modifications to the scripts are discouraged and could break the network. It is based on a limited configuration that should not be used as a template for deploying a production network:

It includes two peer organizations and an ordering organization.
For simplicity, a single node Raft ordering service is configured.
To reduce complexity, a TLS Certificate Authority (CA) is not deployed. All certificates are issued by the root CAs.
The sample network deploys a Fabric network with Docker Compose. Because the nodes are isolated within a Docker Compose network, the test network is not configured to connect to other running Fabric nodes.

To learn how to use Fabric in production, see Deploying a production network.

Note: These instructions have been verified to work against the latest stable Fabric Docker images and the pre-compiled setup utilities within the supplied tar file. If you run these commands with images or tools from the current master branch, it is possible that you will encounter errors.

Before you begin¶

Before you can run the test network, you need to install Fabric Samples in your environment. Follow the instructions on getting_started to install the required software.

Note: The test network has been successfully verified with Docker Desktop version 2.5.0.1 and is the recommended version at this time. Higher versions may not work.

Bring up the test network¶

You can find the scripts to bring up the network in the test-network directory of the fabric-samples repository. Navigate to the test network directory by using the following command:

cd fabric-samples/test-network

In this directory, you can find an annotated script, network.sh, that stands up a Fabric network using the Docker images on your local machine. You can run ./network.sh -h to print the script help text:

Usage:
  network.sh <Mode> [Flags]
    Modes:
      up - Bring up Fabric orderer and peer nodes. No channel is created
      up createChannel - Bring up fabric network with one channel
      createChannel - Create and join a channel after the network is created
      deployCC - Deploy a chaincode to a channel (defaults to asset-transfer-basic)
      down - Bring down the network

    Flags:
    Used with network.sh up, network.sh createChannel:
    -ca <use CAs> -  Use Certificate Authorities to generate network crypto material
    -c <channel name> - Name of channel to create (defaults to "mychannel")
    -s <dbtype> - Peer state database to deploy: goleveldb (default) or couchdb
    -r <max retry> - CLI times out after certain number of attempts (defaults to 5)
    -d <delay> - CLI delays for a certain number of seconds (defaults to 3)
    -i <imagetag> - Docker image tag of Fabric to deploy (defaults to "latest")
    -cai <ca_imagetag> - Docker image tag of Fabric CA to deploy (defaults to "latest")
    -verbose - Verbose mode

    Used with network.sh deployCC
    -c <channel name> - Name of channel to deploy chaincode to
    -ccn <name> - Chaincode name.
    -ccl <language> - Programming language of the chaincode to deploy: go (default), java, javascript, typescript
    -ccv <version>  - Chaincode version. 1.0 (default), v2, version3.x, etc
    -ccs <sequence>  - Chaincode definition sequence. Must be an integer, 1 (default), 2, 3, etc
    -ccp <path>  - File path to the chaincode.
    -ccep <policy>  - (Optional) Chaincode endorsement policy using signature policy syntax. The default policy requires an endorsement from Org1 and Org2
    -cccg <collection-config>  - (Optional) File path to private data collections configuration file
    -cci <fcn name>  - (Optional) Name of chaincode initialization function. When a function is provided, the execution of init will be requested and the function will be invoked.

    -h - Print this message

 Possible Mode and flag combinations
   up -ca -r -d -s -i -cai -verbose
   up createChannel -ca -c -r -d -s -i -cai -verbose
   createChannel -c -r -d -verbose
   deployCC -ccn -ccl -ccv -ccs -ccp -cci -r -d -verbose

 Examples:
   network.sh up createChannel -ca -c mychannel -s couchdb -i 2.0.0
   network.sh createChannel -c channelName
   network.sh deployCC -ccn basic -ccp ../asset-transfer-basic/chaincode-javascript/ -ccl javascript
   network.sh deployCC -ccn mychaincode -ccp ./user/mychaincode -ccv 1 -ccl javascript

From inside the test-network directory, run the following command to remove any containers or artifacts from any previous runs:

./network.sh down

You can then bring up the network by issuing the following command. You will experience problems if you try to run the script from another directory:

./network.sh up

This command creates a Fabric network that consists of two peer nodes, one ordering node. No channel is created when you run ./network.sh up, though we will get there in a future step. If the command completes successfully, you will see the logs of the nodes being created:

Creating network "fabric_test" with the default driver
Creating volume "net_orderer.example.com" with default driver
Creating volume "net_peer0.org1.example.com" with default driver
Creating volume "net_peer0.org2.example.com" with default driver
Creating peer0.org2.example.com ... done
Creating orderer.example.com    ... done
Creating peer0.org1.example.com ... done
Creating cli                    ... done
CONTAINER ID   IMAGE                               COMMAND             CREATED         STATUS                  PORTS                                            NAMES
1667543b5634   hyperledger/fabric-tools:latest     "/bin/bash"         1 second ago    Up Less than a second                                                    cli
b6b117c81c7f   hyperledger/fabric-peer:latest      "peer node start"   2 seconds ago   Up 1 second             0.0.0.0:7051->7051/tcp                           peer0.org1.example.com
703ead770e05   hyperledger/fabric-orderer:latest   "orderer"           2 seconds ago   Up Less than a second   0.0.0.0:7050->7050/tcp, 0.0.0.0:7053->7053/tcp   orderer.example.com
718d43f5f312   hyperledger/fabric-peer:latest      "peer node start"   2 seconds ago   Up 1 second             7051/tcp, 0.0.0.0:9051->9051/tcp                 peer0.org2.example.com

If you don’t get this result, jump down to Troubleshooting for help on what might have gone wrong. By default, the network uses the cryptogen tool to bring up the network. However, you can also bring up the network with Certificate Authorities.

The components of the test network¶

After your test network is deployed, you can take some time to examine its components. Run the following command to list all of Docker containers that are running on your machine. You should see the three nodes that were created by the network.sh script:

docker ps -a

Each node and user that interacts with a Fabric network needs to belong to an organization in order to participate in the network. The test network includes two peer organizations, Org1 and Org2. It also includes a single orderer organization that maintains the ordering service of the network.

Peers are the fundamental components of any Fabric network. Peers store the blockchain ledger and validate transactions before they are committed to the ledger. Peers run the smart contracts that contain the business logic that is used to manage the assets on the blockchain ledger.

Every peer in the network needs to belong to an organization. In the test network, each organization operates one peer each, peer0.org1.example.com and peer0.org2.example.com.

Every Fabric network also includes an ordering service. While peers validate transactions and add blocks of transactions to the blockchain ledger, they do not decide on the order of transactions or include them into new blocks. On a distributed network, peers may be running far away from each other and not have a common view of when a transaction was created. Coming to consensus on the order of transactions is a costly process that would create overhead for the peers.

An ordering service allows peers to focus on validating transactions and committing them to the ledger. After ordering nodes receive endorsed transactions from clients, they come to consensus on the order of transactions and then add them to blocks. The blocks are then distributed to peer nodes, which add the blocks to the blockchain ledger.

The sample network uses a single node Raft ordering service that is operated by the orderer organization. You can see the ordering node running on your machine as orderer.example.com. While the test network only uses a single node ordering service, a production network would have multiple ordering nodes, operated by one or multiple orderer organizations. The different ordering nodes would use the Raft consensus algorithm to come to agreement on the order of transactions across the network.

Creating a channel¶

Now that we have peer and orderer nodes running on our machine, we can use the script to create a Fabric channel for transactions between Org1 and Org2. Channels are a private layer of communication between specific network members. Channels can be used only by organizations that are invited to the channel, and are invisible to other members of the network. Each channel has a separate blockchain ledger. Organizations that have been invited “join” their peers to the channel to store the channel ledger and validate the transactions on the channel.

You can use the network.sh script to create a channel between Org1 and Org2 and join their peers to the channel. Run the following command to create a channel with the default name of mychannel:

./network.sh createChannel

If the command was successful, you can see the following message printed in your logs:

========= Channel successfully joined ===========

You can also use the channel flag to create a channel with custom name. As an example, the following command would create a channel named channel1:

./network.sh createChannel -c channel1

The channel flag also allows you to create multiple channels by specifying different channel names. After you create mychannel or channel1, you can use the command below to create a second channel named channel2:

./network.sh createChannel -c channel2

NOTE: Make sure the name of the channel applies the following restrictions:

contains only lower case ASCII alphanumerics, dots ‘.’, and dashes ‘-‘
is shorter than 250 characters
starts with a letter

If you want to bring up the network and create a channel in a single step, you can use the up and createChannel modes together:

./network.sh up createChannel

Starting a chaincode on the channel¶

After you have created a channel, you can start using smart contracts to interact with the channel ledger. Smart contracts contain the business logic that governs assets on the blockchain ledger. Applications run by members of the network can invoke smart contracts to create assets on the ledger, as well as change and transfer those assets. Applications also query smart contracts to read data on the ledger.

To ensure that transactions are valid, transactions created using smart contracts typically need to be signed by multiple organizations to be committed to the channel ledger. Multiple signatures are integral to the trust model of Fabric. Requiring multiple endorsements for a transaction prevents one organization on a channel from tampering with the ledger on their peer or using business logic that was not agreed to. To sign a transaction, each organization needs to invoke and execute the smart contract on their peer, which then signs the output of the transaction. If the output is consistent and has been signed by enough organizations, the transaction can be committed to the ledger. The policy that specifies the set organizations on the channel that need to execute the smart contract is referred to as the endorsement policy, which is set for each chaincode as part of the chaincode definition.

In Fabric, smart contracts are deployed on the network in packages referred to as chaincode. A Chaincode is installed on the peers of an organization and then deployed to a channel, where it can then be used to endorse transactions and interact with the blockchain ledger. Before a chaincode can be deployed to a channel, the members of the channel need to agree on a chaincode definition that establishes chaincode governance. When the required number of organizations agree, the chaincode definition can be committed to the channel, and the chaincode is ready to be used.

After you have used the network.sh to create a channel, you can start a chaincode on the channel using the following command:

./network.sh deployCC -ccn basic -ccp ../asset-transfer-basic/chaincode-go -ccl go

The deployCC subcommand will install the asset-transfer (basic) chaincode on peer0.org1.example.com and peer0.org2.example.com and then deploy the chaincode on the channel specified using the channel flag (or mychannel if no channel is specified). If you are deploying a chaincode for the first time, the script will install the chaincode dependencies. You can use the language flag, -l, to install the Go, typescript or javascript versions of the chaincode. You can find the asset-transfer (basic) chaincode in the asset-transfer-basic folder of the fabric-samples directory. This folder contains sample chaincode that are provided as examples and used by tutorials to highlight Fabric features.

Interacting with the network¶

After you bring up the test network, you can use the peer CLI to interact with your network. The peer CLI allows you to invoke deployed smart contracts, update channels, or install and deploy new smart contracts from the CLI.

Make sure that you are operating from the test-network directory. If you followed the instructions to install the Samples, Binaries and Docker Images, You can find the peer binaries in the bin folder of the fabric-samples repository. Use the following command to add those binaries to your CLI Path:

export PATH=${PWD}/../bin:$PATH

You also need to set the FABRIC_CFG_PATH to point to the core.yaml file in the fabric-samples repository:

export FABRIC_CFG_PATH=$PWD/../config/

You can now set the environment variables that allow you to operate the peer CLI as Org1:

# Environment variables for Org1

export CORE_PEER_TLS_ENABLED=true
export CORE_PEER_LOCALMSPID="Org1MSP"
export CORE_PEER_TLS_ROOTCERT_FILE=${PWD}/organizations/peerOrganizations/org1.example.com/peers/peer0.org1.example.com/tls/ca.crt
export CORE_PEER_MSPCONFIGPATH=${PWD}/organizations/peerOrganizations/org1.example.com/users/Admin@org1.example.com/msp
export CORE_PEER_ADDRESS=localhost:7051

The CORE_PEER_TLS_ROOTCERT_FILE and CORE_PEER_MSPCONFIGPATH environment variables point to the Org1 crypto material in the organizations folder.

If you used ./network.sh deployCC -ccl go to install and start the asset-transfer (basic) chaincode, you can invoke the InitLedger function of the (Go) chaincode to put an initial list of assets on the ledger (if using typescript or javascript ./network.sh deployCC -ccl javascript for example, you will invoke the InitLedger function of the respective chaincodes).

Run the following command to initialize the ledger with assets:

peer chaincode invoke -o localhost:7050 --ordererTLSHostnameOverride orderer.example.com --tls --cafile "${PWD}/organizations/ordererOrganizations/example.com/orderers/orderer.example.com/msp/tlscacerts/tlsca.example.com-cert.pem" -C mychannel -n basic --peerAddresses localhost:7051 --tlsRootCertFiles "${PWD}/organizations/peerOrganizations/org1.example.com/peers/peer0.org1.example.com/tls/ca.crt" --peerAddresses localhost:9051 --tlsRootCertFiles "${PWD}/organizations/peerOrganizations/org2.example.com/peers/peer0.org2.example.com/tls/ca.crt" -c '{"function":"InitLedger","Args":[]}'

If successful, you should see similar output to below:

-> INFO 001 Chaincode invoke successful. result: status:200

You can now query the ledger from your CLI. Run the following command to get the list of assets that were added to your channel ledger:

peer chaincode query -C mychannel -n basic -c '{"Args":["GetAllAssets"]}'

If successful, you should see the following output:

[
  {"ID": "asset1", "color": "blue", "size": 5, "owner": "Tomoko", "appraisedValue": 300},
  {"ID": "asset2", "color": "red", "size": 5, "owner": "Brad", "appraisedValue": 400},
  {"ID": "asset3", "color": "green", "size": 10, "owner": "Jin Soo", "appraisedValue": 500},
  {"ID": "asset4", "color": "yellow", "size": 10, "owner": "Max", "appraisedValue": 600},
  {"ID": "asset5", "color": "black", "size": 15, "owner": "Adriana", "appraisedValue": 700},
  {"ID": "asset6", "color": "white", "size": 15, "owner": "Michel", "appraisedValue": 800}
]

Chaincodes are invoked when a network member wants to transfer or change an asset on the ledger. Use the following command to change the owner of an asset on the ledger by invoking the asset-transfer (basic) chaincode:

peer chaincode invoke -o localhost:7050 --ordererTLSHostnameOverride orderer.example.com --tls --cafile "${PWD}/organizations/ordererOrganizations/example.com/orderers/orderer.example.com/msp/tlscacerts/tlsca.example.com-cert.pem" -C mychannel -n basic --peerAddresses localhost:7051 --tlsRootCertFiles "${PWD}/organizations/peerOrganizations/org1.example.com/peers/peer0.org1.example.com/tls/ca.crt" --peerAddresses localhost:9051 --tlsRootCertFiles "${PWD}/organizations/peerOrganizations/org2.example.com/peers/peer0.org2.example.com/tls/ca.crt" -c '{"function":"TransferAsset","Args":["asset6","Christopher"]}'

If the command is successful, you should see the following response:

2019-12-04 17:38:21.048 EST [chaincodeCmd] chaincodeInvokeOrQuery -> INFO 001 Chaincode invoke successful. result: status:200

Because the endorsement policy for the asset-transfer (basic) chaincode requires the transaction to be signed by Org1 and Org2, the chaincode invoke command needs to target both peer0.org1.example.com and peer0.org2.example.com using the --peerAddresses flag. Because TLS is enabled for the network, the command also needs to reference the TLS certificate for each peer using the --tlsRootCertFiles flag.

After we invoke the chaincode, we can use another query to see how the invoke changed the assets on the blockchain ledger. Since we already queried the Org1 peer, we can take this opportunity to query the chaincode running on the Org2 peer. Set the following environment variables to operate as Org2:

# Environment variables for Org2

export CORE_PEER_TLS_ENABLED=true
export CORE_PEER_LOCALMSPID="Org2MSP"
export CORE_PEER_TLS_ROOTCERT_FILE=${PWD}/organizations/peerOrganizations/org2.example.com/peers/peer0.org2.example.com/tls/ca.crt
export CORE_PEER_MSPCONFIGPATH=${PWD}/organizations/peerOrganizations/org2.example.com/users/Admin@org2.example.com/msp
export CORE_PEER_ADDRESS=localhost:9051

You can now query the asset-transfer (basic) chaincode running on peer0.org2.example.com:

peer chaincode query -C mychannel -n basic -c '{"Args":["ReadAsset","asset6"]}'

The result will show that "asset6" was transferred to Christopher:

{"ID":"asset6","color":"white","size":15,"owner":"Christopher","appraisedValue":800}

Bring down the network¶

When you are finished using the test network, you can bring down the network with the following command:

./network.sh down

The command will stop and remove the node and chaincode containers, delete the organization crypto material, and remove the chaincode images from your Docker Registry. The command also removes the channel artifacts and docker volumes from previous runs, allowing you to run ./network.sh up again if you encountered any problems.

Next steps¶

Now that you have used the test network to deploy Hyperledger Fabric on your local machine, you can use the tutorials to start developing your own solution:

Learn how to deploy your own smart contracts to the test network using the Deploying a smart contract to a channel tutorial.
Visit the Running a Fabric Application tutorial to learn how to use the APIs provided by the Fabric SDKs to invoke smart contracts from your client applications.
If you are ready to deploy a more complicated smart contract to the network, follow the commercial paper tutorial to explore a use case in which two organizations use a blockchain network to trade commercial paper.

You can find the complete list of Fabric tutorials on the tutorials page.

Bring up the network with Certificate Authorities¶

Hyperledger Fabric uses public key infrastructure (PKI) to verify the actions of all network participants. Every node, network administrator, and user submitting transactions needs to have a public certificate and private key to verify their identity. These identities need to have a valid root of trust, establishing that the certificates were issued by an organization that is a member of the network. The network.sh script creates all of the cryptographic material that is required to deploy and operate the network before it creates the peer and ordering nodes.

By default, the script uses the cryptogen tool to create the certificates and keys. The tool is provided for development and testing, and can quickly create the required crypto material for Fabric organizations with a valid root of trust. When you run ./network.sh up, you can see the cryptogen tool creating the certificates and keys for Org1, Org2, and the Orderer Org.

creating Org1, Org2, and ordering service organization with crypto from 'cryptogen'

/Usr/fabric-samples/test-network/../bin/cryptogen

##########################################################
##### Generate certificates using cryptogen tool #########
##########################################################

##########################################################
############ Create Org1 Identities ######################
##########################################################
+ cryptogen generate --config=./organizations/cryptogen/crypto-config-org1.yaml --output=organizations
org1.example.com
+ res=0
+ set +x
##########################################################
############ Create Org2 Identities ######################
##########################################################
+ cryptogen generate --config=./organizations/cryptogen/crypto-config-org2.yaml --output=organizations
org2.example.com
+ res=0
+ set +x
##########################################################
############ Create Orderer Org Identities ###############
##########################################################
+ cryptogen generate --config=./organizations/cryptogen/crypto-config-orderer.yaml --output=organizations
+ res=0
+ set +x

However, the test network script also provides the option to bring up the network using Certificate Authorities (CAs). In a production network, each organization operates a CA (or multiple intermediate CAs) that creates the identities that belong to their organization. All of the identities created by a CA run by the organization share the same root of trust. Although it takes more time than using cryptogen, bringing up the test network using CAs provides an introduction to how a network is deployed in production. Deploying CAs also allows you to enroll client identities with the Fabric SDKs and create a certificate and private key for your applications.

If you would like to bring up a network using Fabric CAs, first run the following command to bring down any running networks:

./network.sh down

You can then bring up the network with the CA flag:

./network.sh up -ca

After you issue the command, you can see the script bringing up three CAs, one for each organization in the network.

##########################################################
##### Generate certificates using Fabric CA's ############
##########################################################
Creating network "net_default" with the default driver
Creating ca_org2    ... done
Creating ca_org1    ... done
Creating ca_orderer ... done

It is worth taking time to examine the logs generated by the ./network.sh script after the CAs have been deployed. The test network uses the Fabric CA client to register node and user identities with the CA of each organization. The script then uses the enroll command to generate an MSP folder for each identity. The MSP folder contains the certificate and private key for each identity, and establishes the identity’s role and membership in the organization that operated the CA. You can use the following command to examine the MSP folder of the Org1 admin user:

tree organizations/peerOrganizations/org1.example.com/users/Admin@org1.example.com/

The command will reveal the MSP folder structure and configuration file:

organizations/peerOrganizations/org1.example.com/users/Admin@org1.example.com/
└── msp
    ├── IssuerPublicKey
    ├── IssuerRevocationPublicKey
    ├── cacerts
    │   └── localhost-7054-ca-org1.pem
    ├── config.yaml
    ├── keystore
    │   └── 58e81e6f1ee8930df46841bf88c22a08ae53c1332319854608539ee78ed2fd65_sk
    ├── signcerts
    │   └── cert.pem
    └── user

You can find the certificate of the admin user in the signcerts folder and the private key in the keystore folder. To learn more about MSPs, see the Membership Service Provider concept topic.

Both cryptogen and the Fabric CAs generate the cryptographic material for each organization in the organizations folder. You can find the commands that are used to set up the network in the registerEnroll.sh script in the organizations/fabric-ca directory. To learn more about how you would use the Fabric CA to deploy a Fabric network, visit the Fabric CA operations guide. You can learn more about how Fabric uses PKI by visiting the identity and membership concept topics.

What’s happening behind the scenes?¶

If you are interested in learning more about the sample network, you can investigate the files and scripts in the test-network directory. The steps below provide a guided tour of what happens when you issue the command of ./network.sh up.

./network.sh creates the certificates and keys for two peer organizations and the orderer organization. By default, the script uses the cryptogen tool using the configuration files located in the organizations/cryptogen folder. If you use the -ca flag to create Certificate Authorities, the script uses Fabric CA server configuration files and registerEnroll.sh script located in the organizations/fabric-ca folder. Both cryptogen and the Fabric CAs create the crypto material and MSP folders for all three organizations in the organizations folder.
Once the organization crypto material has been generated, the network.sh can bring up the nodes of the network. The script uses the docker-compose-test-net.yaml file in the docker folder to create the peer and orderer nodes. The docker folder also contains the docker-compose-e2e.yaml file that brings up the nodes of the network alongside three Fabric CAs. This file is meant to be used to run end-to-end tests by the Fabric SDK. Refer to the Node SDK repo for details on running these tests.
If you use the createChannel subcommand, ./network.sh runs the createChannel.sh script in the scripts folder to create a channel using the supplied channel name. The script uses the configtxgen tool to create the channel genesis block based on the TwoOrgsApplicationGenesis channel profile in the configtx/configtx.yaml file. After creating the channel, the script uses the peer cli to join peer0.org1.example.com and peer0.org2.example.com to the channel, and make both of the peers anchor peers.
If you issue the deployCC command, ./network.sh runs the deployCC.sh script to install the asset-transfer (basic) chaincode on both peers and then define then chaincode on the channel. Once the chaincode definition is committed to the channel, the peer cli initializes the chaincode using the Init and invokes the chaincode to put initial data on the ledger.

Troubleshooting¶

If you have any problems with the tutorial, review the following:

You should always start your network fresh. You can use the following command to remove the artifacts, crypto material, containers, volumes, and chaincode images from previous runs:
```
./network.sh down
```
You will see errors if you do not remove old containers, images, and volumes.
If you see Docker errors, first check your Docker version (Prerequisites), and then try restarting your Docker process. Problems with Docker are oftentimes not immediately recognizable. For example, you may see errors that are the result of your node not being able to access the crypto material mounted within a container.

If problems persist, you can remove your images and start from scratch:
```
docker rm -f $(docker ps -aq)
docker rmi -f $(docker images -q)
```

If you are running Docker Desktop on macOS and experience the following error during chaincode installation:

Error: chaincode install failed with status: 500 - failed to invoke backing implementation of 'InstallChaincode': could not build chaincode: docker build failed: docker image inspection failed: Get "http://unix.sock/images/dev-peer0.org1.example.com-basic_1.0-4ec191e793b27e953ff2ede5a8bcc63152cecb1e4c3f301a26e22692c61967ad-42f57faac8360472e47cbbbf3940e81bba83439702d085878d148089a1b213ca/json": dial unix /host/var/run/docker.sock: connect: no such file or directory
Chaincode installation on peer0.org1 has failed
Deploying chaincode failed

This problem is caused by a newer version of Docker Desktop for macOS. To resolve this issue, in the Docker Desktop preferences, uncheck the box Use gRPC FUSE for file sharing to use the legacy osxfs file sharing instead and click Apply & Restart.

If you see errors on your create, approve, commit, invoke or query commands, make sure you have properly updated the channel name and chaincode name. There are placeholder values in the supplied sample commands.

If you see the error below:

Error: Error endorsing chaincode: rpc error: code = 2 desc = Error installing chaincode code mycc:1.0(chaincode /var/hyperledger/production/chaincodes/mycc.1.0 exits)

You likely have chaincode images (e.g. dev-peer1.org2.example.com-asset-transfer-1.0 or dev-peer0.org1.example.com-asset-transfer-1.0) from prior runs. Remove them and try again.

docker rmi -f $(docker images | grep dev-peer[0-9] | awk '{print $3}')

If you see the below error:
```
[configtx/tool/localconfig] Load -> CRIT 002 Error reading configuration: Unsupported Config Type ""
panic: Error reading configuration: Unsupported Config Type ""
```
Then you did not set the FABRIC_CFG_PATH environment variable properly. The configtxgen tool needs this variable in order to locate the configtx.yaml. Go back and execute an export FABRIC_CFG_PATH=$PWD/configtx/configtx.yaml, then recreate your channel artifacts.
If you see an error stating that you still have “active endpoints”, then prune your Docker networks. This will wipe your previous networks and start you with a fresh environment:
```
docker network prune
```
You will see the following message:
```
WARNING! This will remove all networks not used by at least one container.
Are you sure you want to continue? [y/N]
```
Select y.

If you try to create a channel with the command ./network.sh createChannel, and it fails with the following error:

[comm.tls] ClientHandshake -> ERRO 003 Client TLS handshake failed after 1.908956ms with error: EOF remoteaddress=127.0.0.1:7051
Error: error getting endorser client for channel: endorser client failed to connect to localhost:7051: failed to create new connection: context deadline exceeded
After 5 attempts, peer0.org1 has failed to join channel 'mychannel'

You need to uninstall Docker Desktop and reinstall the recommended version 2.5.0.1. Then, reclone the fabric-samples repository before reattempting the commands.

If you see an error similar to the following:
```
/bin/bash: ./scripts/createChannel.sh: /bin/bash^M: bad interpreter: No such file or directory
```
Ensure that the file in question (createChannel.sh in this example) is encoded in the Unix format. This was most likely caused by not setting core.autocrlf to false in your Git configuration (see Windows). There are several ways of fixing this. If you have access to the vim editor for instance, open the file:
```
vim ./fabric-samples/test-network/scripts/createChannel.sh
```
Then change its format by executing the following vim command:
```
:set ff=unix
```

If you continue to see errors, share your logs on the fabric-questions channel on Hyperledger Rocket Chat or on StackOverflow.