fabric-builder-k8s

Proof of concept Fabric builder for Kubernetes

Status: the k8s builder should just about work now for basic scenarios but there are a few issues to iron out (and tests to write) before it's fully functional and stable!

Advantages:

• prepublished chaincode images avoids compile issues at deploy time
• standard CI/CD pipelines can be used to publish chaincode images
• traceability of installed chaincode's implementation (demo uses Git commit hash as image tag)

The aim is for the builder to work as closely as possible with the Fabric chaincode lifecycle first, and then make sensible choices for deploying chaincode workloads using Kubernetes within those Fabric constraints. (The assumption being that there are more people with Kubernetes skills than are familiar with the inner workings of Fabric!)

For example:

• The contents of the chaincode package must uniquely identify the chaincode that will eventually run.

  In the case of the k8s builder the chaincode is not actually inside the package so, in order not to break the Fabric chaincode lifecycle, the chaincode image must be specified using a digest, which is immutable, not a tag which can be moved.

  See Pull an image by digest (immutable identifier) for more details.

• The Fabric peer manages the chaincode process, not Kubernetes.

  Running the chaincode in server mode, i.e. allowing the peer to initiate the gRPC connection, would make it possible to leave Kubernetes to manage the chaincode process by creating a chaincode deployment.

  Unfortunetly due to limitations in Fabric's builder and launcher implementation, that is not possible and the peer expects to control the chaincode process.

Usage

The k8s builder can be run in cluster using the KUBERNETES_SERVICE_HOST and KUBERNETES_SERVICE_PORT environment variables, or it can connect using a KUBECONFIG_PATH environment variable.

An optional FABRIC_K8S_BUILDER_NAMESPACE can be used to specify the namespace to deploy chaincode to.

A CORE_PEER_ID environment variable is also currently required.

External builders are configured in the core.yaml file, for example:

  externalBuilders:
    - name: k8s_builder
      path: /opt/hyperledger/k8s_builder
      propagateEnvironment:
        - CORE_PEER_ID
        - FABRIC_K8S_BUILDER_DEBUG
        - FABRIC_K8S_BUILDER_NAMESPACE
        - KUBERNETES_SERVICE_HOST
        - KUBERNETES_SERVICE_PORT

See External Builders and Launchers for details of Hyperledger Fabric builders.

There are addition docs with more detailed usage instructions for specific Fabric network deployments:

• Kubernetes Test Network
• Nano Test Network
• Fabric Operator
• HLF Operator

Chaincode Docker image

Unlike the traditional chaincode language support for Go, Java, and Node.js, the k8s builder does not build a chaincode Docker image using Docker-in-Docker. Instead, a chaincode Docker image must be built and published before it can be used with the k8s builder.

The chaincode will have access to the following environment variables:

• CORE_CHAINCODE_ID_NAME
• CORE_PEER_ADDRESS
• CORE_PEER_TLS_ENABLED
• CORE_PEER_TLS_ROOTCERT_FILE
• CORE_TLS_CLIENT_KEY_PATH
• CORE_TLS_CLIENT_CERT_PATH
• CORE_TLS_CLIENT_KEY_FILE
• CORE_TLS_CLIENT_CERT_FILE
• CORE_PEER_LOCALMSPID

See conga-nft-contract for an example project which publishes a chaincode image using GitHub Actions.

Chaincode package

The k8s chaincode package file, which is installed by the peer lifecycle chaincode install command, must contain the Docker image name and digest of the chaincode being deployed.

Fabric chaincode packages are .tgz files which contain two files:

• metadata.json - the chaincode label and type
• code.tar.gz - source artifacts for the chaincode

To create a k8s chaincode package file, start by creating an image.json file. For example,

cat << IMAGEJSON-EOF > image.json
{
  "name": "ghcr.io/hyperledgendary/conga-nft-contract",
  "digest": "sha256:b35962f000d26ad046d4102f22d70a1351692fc69a9ddead89dfa13aefb942a7"
}
IMAGEJSON-EOF

Note: the k8s chaincode package file uses digests because these are immutable, unlike tags. The docker inspect command can be used to find the digest if required.

docker inspect --format='{{index .RepoDigests 0}}' ghcr.io/hyperledgendary/conga-nft-contract:0bee560018ea932ec4c7ec252134e2506ec6e797 | cut -d'@' -f2

Create a code.tar.gz archive containing the image.json file.

tar -czf code.tar.gz image.json

Create a metadata.json file for the chaincode package. For example,

cat << METADATAJSON-EOF > metadata.json
{
    "type": "k8s",
    "label": "conga-nft-contract"
}
METADATAJSON-EOF

Create the final chaincode package archive.

tar -czf conga-nft-contract.tgz metadata.json code.tar.gz

Ideally the chaincode package should be created in the same CI/CD pipeline which builds the docker image. There is an example package-k8s-chaincode-action GitHub Action which can create the required k8s chaincode package.

The GitHub Action repository includes a basic shell script which can also be used for automating the process above outside GitHub workflows. For example, to create a basic k8s chaincode package using the pkgk8scc.sh helper script.

curl -fsSL https://raw.githubusercontent.com/hyperledgendary/package-k8s-chaincode-action/main/pkgk8scc.sh -o pkgk8scc.sh && chmod u+x pkgk8scc.sh
./pkgk8scc.sh -l conga-nft-contract -n ghcr.io/hyperledgendary/conga-nft-contract -d sha256:b39eb624e9cc7ed3fa70bf7ea27721e266ae56b48992a916165af3a6b2a4f6eb

Chaincode deploy

Deploy the chaincode package as usual, starting by installing the k8s chaincode package.

peer lifecycle chaincode install conga-nft-contract.tgz

You can also user the peer command to get the chaincode package ID.

export PACKAGE_ID=$(peer lifecycle chaincode calculatepackageid conga-nft-contract.tgz) && echo $PACKAGE_ID