Added firewall.rules.hash metric

[britcey]

Added a FNV-1 hash of the firewall rules as a Prometheus value.

[salesforce-cla]

Thanks for the contribution! Before we can merge this, we need @britcey to sign the Salesforce Inc. Contributor License Agreement.

[britcey]

Closes issue #1005

[nbrownus]

Thanks for the PR! My primary concern is that there is no direct correlation back to the log line. I think this could be resolved in two ways.

1. Include the FNV hash in the log lines
2. Include the sha256 hash as a label

Ideally we would do both here but option 2 is more difficult so lets add the FNV hash to the log lines.

[britcey]

Thanks for the PR! My primary concern is that there is no direct correlation back to the log line. I think this could be resolved in two ways.

1. Include the FNV hash in the log lines
2. Include the sha256 hash as a label

Ideally we would do both here but option 2 is more difficult so lets add the FNV hash to the log lines.

Option 2 would also increase cardinality, creating a new timeseries every time that label changed, so including the FNV hash in the log is the way to go, for sure. I'll make that happen.

[britcey]

This work for the logs?

Startup:

level=info msg="Firewall started" firewallHashes="SHA:8cdd862ba57eca683ac4fb32fcd8f727743df3ba0c92b267c3e9ca128e43be8d,FNV:-4874977699962996863"

after a reload:

level=info msg="New firewall has been installed" firewallHashes="SHA:3775881c4dfa7c63e3d343e747ad66b0ddf6a72fde1ce3b2eea43436175f101f,FNV:7449190936218615427" oldFirewallHashes="SHA:8cdd862ba57eca683ac4fb32fcd8f727743df3ba0c92b267c3e9ca128e43be8d,FNV:-4874977699962996863" rulesVersion=1

[britcey]

Anything needed here?

[johnmaguire]

@britcey Thanks for your contribution!