Initial GraphQL interface implementation

[SLoeuillet]

That's an initial PR mostly for code review, not ready for production use

Got basic GraphQL working when querying a single block

[SLoeuillet]

GraphQL actually enabled if using --graphql but could be changed to use --http.api=graphql

To test it, go to
http://localhost:8545/graphql for request, /graphql/ui for user-friendly UI

A sample block query is bundled in the graphql/ subdirectory

[AskAlexSharov]

looks good. need port geth's tests also

[SLoeuillet]

@AskAlexSharov : I'll try to add unit tests this week-end

Any preference for protocol activation ? (--graphql to mimic Geth) or via the "erigon standard" --http.api=graphql ?

[AskAlexSharov]

@AskAlexSharov : I'll try to add unit tests this week-end

Any preference for protocol activation ? (--graphql to mimic Geth) or via the "erigon standard" --http.api=graphql ?

Geth-compatible

[SLoeuillet]

Unit tests from geth imported and improved (tests via regexps, also tests chainID query)

[SLoeuillet]

For Graphq tests to work, rpcdaemon have to be run with --graphql

--- FAIL: TestGraphQLQueryBlock (0.00s)
graph_test.go:106: could not post: Post "http://localhost:8545/graphql": dial tcp [::1]:8545: connect: connection refused
FAIL
FAIL github.com/ledgerwatch/erigon/cmd/rpcdaemon/graphql 0.216s
? github.com/ledgerwatch/erigon/cmd/rpcdaemon/graphql/graph [no test files]

[SLoeuillet]

Thanks @AskAlexSharov

[AskAlexSharov]

@SLoeuillet

--- FAIL: TestGraphQLQueryBlock (0.00s)
graph_test.go:106: could not post: Post "http://localhost:8545/graphql": dial tcp [::1]:8545: connect: connection refused
FAIL

Let's turn this test to UnitTest. I don't see why we can't start graphql server inside test.
For example we have:
rpc/server_test.go
rpc/http_test.go

[s1na]

Hey I see you guys added basic support for GraphQL. I made a PR to change the schema slightly, basically enforcing every number (Int, Long or BigInt) to be formatted as hex. Feel free to chime in: ethereum/execution-apis#389

[SLoeuillet]

Thanks @s1na. Would take a look