Add TLS encryption

[mahdi-orbitalize]

What I did:

• consensus.go was updated to enable client-side (handled by rafthttp if we provide a transport.TLSInfo when constructing a rafthttp.transport) and server-side (handled by extracting a tls.Config from the transport.TLSInfo and passing it to the server at construction plus using ListenAndServeTLS instead of ListenAndServe)
• gen-cert.sh was introduced to make certificates (with the number of nodes as a parameter). Note that it's made to work for local setups (i.e. address is localhost or 127.0.0.1). I also provided example certificates to save the trouble of generating them.
• params.go was updated to support passing the paths to the TLS certificates as a parameter. It also enforces the use of HTTPS instead of HTTP for the peers' URLs. Also, more tests were added to params_test.go to test the new features.
• start_cluster.sh was created to quickly test a 3-node setup with TLS and easily inspect logs.

How I tested it:

• Verified that logs where similar when trying with/without encryption (and that it fails when it's supposed to fail)

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: MariemBaccari / name: Mariem Baccari (ea5f499)
• ✅ login: mahdi-orbitalize / name: Mahdi Atallah (049e28c, 05ed116, 40208fb, 4e4da08, 7e92677, e20c325)

[the-glu]

Could you squash your changes in one commit, leaving only the one from the base PR and the one from your PR ? That would avoid mixing changes

[the-glu]

Can you make it optional, with a

raft_insecure

flag, default to false?

If set to true, don't require https + log a warning about beeing run in an insecure mode. If there are certificate, don't verify them (no CA check / trust blindly client certificates) . If there is no certificate, don't enable https at all.

It will be useful for local deployments and testing (to validate that test fail if mis configured).

Thanks

[mahdi-orbitalize]

Can you make it optional, with a

raft_insecure

flag, default to false?

If set to true, don't require https + log a warning about beeing run in an insecure mode. If there are certificate, don't verify them (no CA check / trust blindly client certificates) . If there is no certificate, don't enable https at all.

It will be useful for local deployments and testing (to validate that test fail if mis configured).

Thanks

Adressed in 64f3f9a