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The Bitcoin Operator

The Bitcoin Operator is powered by Ansible. Ansible is a simple IT automation language that allows for idempotent runs of a set of tasks to ensure that the application is healthy and performing as expected. It allows us to put the logic for installation, deployment, and lifecycle management all inside of an operator. An Operator allows us to package, deploy, and manage a Kubernetes application (Bitcoin).

Clone the Bitcoin Operator source

I have created the Bitcoin Operator using Operator-SDK. This provides us with all of the needed resource files already created so that deploying the operator is simple. To get started, clone the repo:

$ git clone
$ cd bitcoin-operator

Deploying Bitcoin Operator

To deploy the operator, we need to create the relevant RBAC resources along with the Custom Resource Definition (CRD) of our Bitcoin application.

Create the RBAC resources:

$ kubectl create -f deploy/service_account.yaml
$ kubectl create -f deploy/role.yaml
$ kubectl create -f deploy/role_binding.yaml

Create the CRD:

$ kubectl create -f deploy/crds/bitcoin_v1_bitd_crd.yaml

Next, create the Bitcoin Operator deployment:

$ kubectl create -f deploy/operator.yaml

Creating RPC Credentials

Bitcoin exposes a JSON-RPC API that uses Basic Authentication for communication. To hide the credentials, a Kubernetes user can create a secret with the user/password combination that the Bitcoin Operator can read from when starting up the node.

In the namespace where the operator will live, create a secret with the fields user and password:

$ kubectl create secret generic --from-literal=user=<user> --from-literal=password=<password> bitcoin-rpc-credentials

Deploying a Bitcoin instance

Now that the operator is up and running:

$ kubectl get pods
NAME                                  READY   STATUS    RESTARTS   AGE
bitcoinsv-operator-79cb6bdb87-sm97z   1/1     Running   0          4m

and we have our secret:

$ kubectl get secret bitcoin-rpc-credentials
NAME                      TYPE     DATA   AGE
bitcoin-rpc-credentials   Opaque   2      25m

We can create our Bitcoin instance by creating a Kubernetes Custom Resource. This is included in our repository with some sane defaults:

$ cat deploy/crds/bitcoin_v1_bitd_cr.yaml
kind: Bitd
  name: example-bitd
  # Add fields here
  rpc_secret_name: bitcoin-rpc-credentials
  pvc_size: 200Gi

Note: pvc_size is set to 200Gi since Bitcoin stores all of the blockchain data inside of the persistent volume. If you are interested in just testing this out and don't have enough space, feel free to decrease this.

Since the secret name is correct, we can simply create this CR as is:

$ kubectl create -f deploy/crds/bitcoin_v1_bitd_cr.yaml

In a few seconds, you should have a Bitcoin instance running in a pod:

$ kubectl get pods
NAME                                  READY   STATUS              RESTARTS   AGE
bitcoinsv-operator-79cb6bdb87-sm97z   1/1     Running             0          17m
example-bitd-bitd-674bf9fb4f-czmsz    0/1     ContainerCreating   0          1s

Once the pod is running, the operator will update the status of the Bitd CR we created where we can monitor it's syncing status:

$ kubectl get bitd example-bitd -o yaml
kind: Bitd
  creationTimestamp: "2018-12-11T17:32:11Z"
  generation: 1
  name: example-bitd
  namespace: default
  resourceVersion: "2351"
  selfLink: /apis/
  uid: b12cdc2e-fd6a-11e8-8d6b-525400c036d2
  pvc_size: 200Gi
  rpc_secret_name: bitcoin-rpc-credentials
  address: bitcoincash:qp4zfxj230h9dvq48ndmwnwrv79pc29gcvwc89uwuz
  balance: "0.0"
  blockCount: "76181"
  - ansibleResult:
      changed: 1
      completion: 2018-12-11T17:33:04.212035
      failures: 0
      ok: 17
      skipped: 4
    lastTransitionTime: "2018-12-11T17:32:52Z"
    message: Awaiting next reconciliation
    reason: Successful
    status: "True"
    type: Running
  headers: "560381"
  synced: false
  unconfirmedBalance: "0.0"

Note that the status of the CR provides us with the syncing status of the node with the field synced and also gives us an address we can use to fund the node if needed. This is useful because an application can monitor our Bitd resource to detect chain splits.

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