Poll bitcoind at startup instead of trying only once

[t-bast]

When we start, bitcoind may not be ready to handle requests if we restarted it around the same time. We thus poll it for 30 seconds before giving up. This is especially useful for tests (e.g. on regtest).

@tee8z this should fix the start-up issue you're seeing for https://github.com/tee8z/doppler

[codecov-commenter]

Codecov Report

Merging #2739 (14caaba) into master (37f3fbe) will increase coverage by 0.00%.
Report is 1 commits behind head on master.
The diff coverage is 100.00%.

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@@           Coverage Diff           @@
##           master    #2739   +/-   ##
=======================================
  Coverage   85.87%   85.87%           
=======================================
  Files         216      216           
  Lines       18077    18070    -7     
  Branches      772      732   -40     
=======================================
- Hits        15523    15517    -6     
+ Misses       2554     2553    -1     

Files	Coverage Δ
...ir-core/src/main/scala/fr/acinq/eclair/Setup.scala	75.14% <100.00%> (ø)

... and 12 files with indirect coverage changes

[sstone]

LGTM, I would just not change our current behaviour, and there should be a test to verify that we do wait for bitcoind to be ready (maybe a simple tests like restarting bitcoind inside a Future instantiating an eclair node would be enough?)

[t-bast]

there should be a test to verify that we do wait for bitcoind to be ready (maybe a simple tests like restarting bitcoind inside a Future instantiating an eclair node would be enough?)

This is quite hard to do in a reliable way, isn't it? I'll think about it, but that sounds quite hard to do without introducing a lot of new code...

[sstone]

This is quite hard to do in a reliable way, isn't it? I'll think about it, but that sounds quite hard to do without introducing a lot of new code...

What about something like:

  test("wait for bitcoind") {
    import scala.concurrent.ExecutionContext.Implicits.global
    val sender = TestProbe()
    stopBitcoind()
    Future {
      startBitcoind()
      waitForBitcoindUp(sender)
      sender.send(bitcoincli, BitcoinReq("loadwallet", defaultWallet))
      sender.expectMsgType[JValue]
    }
    val config = ConfigFactory.parseMap(Map("eclair.bitcoind.wait-for-bitcoind-up" -> "true").asJava).withFallback(createConfig(wallet_opt = Some(defaultWallet)))
    instantiateEclairNode("A", config)
  }

[t-bast]

I added a test in 14caaba, but it's annoying because it takes 30 seconds to run (there seems to be a timeout somewhere on bitcoind restart, when calling bitcoind.exitValue()), I'm trying to figure out why and if we can improve this.

[sstone]

Yes it's annoying, and it is the bitcoin core process that takes an extra 30s to shutdown, I could not figure out why either.