Parse configs from toml file - #223

[nodech]

Implements: #223

Integrated codebase from go-ethereum for parsing toml files.

Now we can remove configs flag and expect it in the home and remove flags.
Where should I put example toml file ?

[codecov]

Codecov Report

Merging #224 into unstable will decrease coverage by 6.23%.
The diff coverage is 10.95%.

@@             Coverage Diff              @@
##           unstable     #224      +/-   ##
============================================
- Coverage     40.42%   34.18%   -6.24%     
============================================
  Files             5        5              
  Lines           282      351      +69     
============================================
+ Hits            114      120       +6     
- Misses          149      208      +59     
- Partials         19       23       +4

Impacted Files	Coverage Δ
cmd/utils/config.go	35.93% <10.95%> (-31.86%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 9c6c201...9d8e69f. Read the comment docs.

[odeke-em]

Am not familiar with toml, but toml:",omitempty" for all the struct fields seems a little off to me.

[odeke-em]

Could we make this:
LoadConfig reads a configuration from disk and saves it into cfg

Minor not: also perhaps for easier parameter reading, make cfg something like
saveCfg or so and if that change applies, apply it to the comment above, please.

[odeke-em]

The signature http://godoc.org/github.com/naoina/toml#Config.NewDecoder is:

func (*toml.Config).NewDecoder(io.Reader)

so I don't think we need the bufio.NewReader(f) since *os.File is already an io.Reader, unless there is something special about that decoder that it needs buffered io.

[odeke-em]

Nice!

[odeke-em]

Might be a lot easier to read if for a non channel we didn't use i := range lines
so

for i := 0; i < len(lines); i++

[odeke-em]

Double indirection here, cfg is already a pointer i.e *GethConfig

[odeke-em]

This is a nice helper but we could perhaps make it more configurable like this

// FdumpTomlConfig serializes cfg to the output writer
func FdumpTomlConfig(f io.Writer, cfg *GethConfig) error {
   comment := ""
   if cfg.Eth.Genesis != nil {
      cfg.Eth.Genesis = nil
      comment += "# Note: this config doesn't contain the genesis block.\n\n"
   }

   out, err := tomlSettings.Marshal(cfg)
   if err != nil {
      return err
   }
   io.WriteString(w, comment)
   _, err = w.Write(out)
   return err
}

and then

// DumpTomlConfig is a helper that serializes cfg to stdout
func DumpTomlConfig(cfg *GethConfig) error {
   return FdumpTomlConfig(os.Stdout, cfg)
}

and then we can also make unit tests to test that FdumpTomlConfig works well and matches our expectations.

[odeke-em]

Hello @nodar-chkuaselidze, thank you for the PR! I am getting familiar with Ethermint, so please pardon me if I suggested the wrong thing, but I've left some comments that perhaps could be applied to the code.

[nodech]

Well, DumpConfig and config parsing stuff is directly taken from geth. I was more concentrated on moving flags to config file and making them work than improving go-ethereum's implementation.

[odeke-em]

@nodar-chkuaselidze oh I see, my bad. In that case, please feel free to get your changes in for parity with geth, and then I'll submit a follow up PR adding the changes and tag you as a review if you are free. Am new around here so just learning how things work :)

[odeke-em]

To avoid blocking you as mentioned in my last comment, I'll remove my requested changes :)

[adrianbrink]

This PR will not be merged in this form. I would like to thank everyone that contributed, but the new proposed structure in #295 will tackle this separately.