dev(regtest): prepare 'wait-for-bitcoind' feature

[theborakompanioni]

This is the test branch for joinmarket-webui/jam-docker#76.

Once joinmarket-webui/jam-docker#76 is merged and a new jam-dev-standalone:master image has been created, the last commit of this PR will be reverted and this PR can be undrafted.

Please do not merge it without reverting the image base for the additional contains from jam-dev-standalone:wait-for-bitcoind back to jam-dev-standalone:master!

This PR removes the need for the READY_FILE in the secondary JM instance (jm_regtest_joinmarket2) and relies on the WAIT_FOR_BITCOIND env var to default to true. The tertiary instance (jm_regtest_joinmarket3) verifies that WAIT_FOR_BITCOIND can be disabled and the READY_FILE feature continues to work as expected. Please keep in mind that the primary test instance (jm_regtest_joinmarket) does not use the official "dev"-base image at all!

How to test

Build your env environment with npm run regtest:build (makes sure new images are pulled) and run npm run regtest:up.
The environment should start normally as usual. npm run regtest:init should be able to create wallets on all instances.

You should see the following in the logs:

For jm_regtest_joinmarket2 (enabling WAIT_FOR_BITCOIND and not using READY_FILE):

jm_regtest_joinmarket2          | Waiting for bitcoind to accept RPC requests...
jm_regtest_bitcoind             | 2022-11-02T10:36:08.423004Z ThreadRPCServer method=getblockchaininfo user=joinmarket2
jm_regtest_joinmarket2          | Successfully waited for bitcoind to accept RPC requests.

For jm_regtest_joinmarket3 (disabling WAIT_FOR_BITCOIND and using READY_FILE):

jm_regtest_joinmarket3          | Waiting for file /root/.regtest-initializer/btc_fully_synched to be created...
jm_regtest_joinmarket3          | Successfully waited for file /root/.regtest-initializer/btc_fully_synched to be created.

You should NOT see Waiting for bitcoind to accept RPC requests... for jm_regtest_joinmarket3.

---

Also, see what happens when jm_regtest_bitcoind_initializer mines 99 instead of 101 blocks.
Then you should see getblockchaininfo calls from jm_regtest_joinmarket2 every 5 seconds:

jm_regtest_bitcoind             | 2022-11-02T10:36:42.020179Z ThreadRPCServer method=getblockchaininfo user=joinmarket2
jm_regtest_bitcoind             | 2022-11-02T10:36:47.130406Z ThreadRPCServer method=getblockchaininfo user=joinmarket2
jm_regtest_bitcoind             | 2022-11-02T10:36:52.210399Z ThreadRPCServer method=getblockchaininfo user=joinmarket2
[...]

---

In case bitcoind is not available at all, jm_regtest_joinmarket2 should be "stuck" and wait for it to come up indefinitely:

jm_regtest_joinmarket2          | Waiting for bitcoind to accept RPC requests...
[...]

[theborakompanioni]

joinmarket-webui/jam-docker#76 is merged. Waiting for https://github.com/joinmarket-webui/jam-docker/actions/runs/3427611995 to finish before reverting the last commit and undrafting this PR. 🙌

[dergigi]

Looks good to me ✅