Prometheus Instrumentation

[shorsher]

While the http metrics and manager are going to be instrumented in FFTM in hyperledger/firefly-transaction-manager#38, it will still be useful for evmconnect to create its own custom metrics.

See https://github.com/hyperledger/firefly/blob/0b6c289ffee87330f578796d5ece8268216e133f/internal/metrics/prometheus.go for the firefly implementation of http and custom metrics.

• One metric that could be useful, is a counter for each submitted transaction.

• Another metric that will be useful would be block indexing progress metrics to capture issues such as adding warning logs for rebuiding in memory chain #157

[vishalrajofficial]

Adding this in function initMetricsCollectors() may resolve the issue:

submittedTransactionsCounter = prometheus.NewCounter(
prometheus.CounterOpts{
Namespace: "evmconnect",
Name: "submitted_transactions_total",
Help: "Total number of submitted transactions in EVMConnect.",
},
)
registry.MustRegister(submittedTransactionsCounter)