[CAD-779] Add a database backend.

[ksaric]

https://jira.iohk.io/browse/CAD-779

[KtorZ]

I get from this line that poolHash is actually not the pool id but the hash of the metadata? This feels rather confusing with the name "poolHash"?

[ksaric]

A lot of things in this PR are confusing, will address that.

[KtorZ]

As a result, this returns a string which encodes a JSON object, and not a JSON object.

[ksaric]

Yes. Encoding it into a JSON object can change the JSON contents, and accordingly, the hash.

[KtorZ]

Some additional notes:

• When a "unknown" hash is provided, the server doesn't reply at all (simply closes the connection) and this shows in the logs:

FatalError {fatalErrorMessage = "Tx metadata hash cbdfc4f21feb0a414b2b9471fa56b0ebd312825e63db776d68cc3fa0ca1f5aaa"}

[ksaric]

Now returning the original JSON content on the correct hash (as agreed):

{"name": "test", "description": "This is a test pool", "ticker": "testy", "homepage": "https://github.com/input-output-hk/cardano-db-sync/tree/master/cardano-db/src/Cardano/Db"}

Returning the error structure (as agreed):

{"code":"DbLookupTxMetadataHash","description":"The hash cbdfc4f21feb0a414b2b9471fa56b0ebd312825e63db776d68cc3fa0ca1f5a2b is missing from the DB."}

[ksaric]

A note that might be of use - the argument name was changed from filepath to metadata when inserting the pool metadata:

PGPASSFILE=config/pgpass stack run smash-exe -- insert-pool --metadata test_pool.json --poolhash "cbdfc4f21feb0a414b2b9471fa56b0ebd312825e63db776d68cc3fa0ca1f5a2f"

[ksaric]

@jbgi This was merged so you can base deployment commit from master if you want. New PR with some new changes should be going up today.