depends: Multiple `FALLBACK_DOWNLOAD_PATH`s #17234

Right now we can only have a single FALLBACK_DOWNLOAD_PATH, but ideally we should be able to have many of them and try them sequentially.

https://github.com/bitcoin/bitcoin/blob/bc7e721d97dc5b9f46df2a46e8101f3b6ce278fe/depends/Makefile#L17

The page does not exist, is the variable no longer needed ?

I won't object this, but I think the source should be reliable in the first place. If it is randomly down, a highly reliable mirror should jump in. Allowing for a second mirror might just lead to having three unreliable download sources for depends instead of two highly reliable ones. Thus, decreasing overall reliability.

The page does not exist, is the variable no longer needed ?

There's no page as such, but the individual files should be under there.

The page does not exist, is the variable no longer needed ?

There's no page as such, but the individual files should be under there.

I'm sorry for being a noob, but I didn't understand.. Can i view these files? Is that endpoint just for the API and there is no front end, or has it been removed, I'm really grateful ; if someone could delete my confusion

Is that endpoint just for the API

Yes, it is only a fallback URL for curl. Not for browsers or human users.

Is that endpoint just for the API

Yes, it is only a fallback URL for curl. Not for browsers or human users.

Thank you very much, I understand now, so to get around this, we just have to host it at one more location, to give the fallback a fallback? Just like commits c897b1e fe740f1 by theuni when the fallback was added

OR we just change it to a more reliable mirror as you said, that might be better

Since the issue with missing dependencies on the https://bitcoincore.org/depends-sources as well as the blocking issue preventing updates on the fallback has been fixed, this fallback is a "highly reliable mirror" and this can be closed.

Otherwise, @MarcoFalke you started https://drahtbot.space/depends_download_fallback. If we still want to add a second mirror, then this should be the choice.

Since the issue with missing dependencies on the https://bitcoincore.org/depends-sources as well as the blocking issue preventing updates on the fallback has been fixed, this fallback is a "highly reliable mirror" and this can be closed.

Open issue #22556 mentions that for example capnproto-c++-0.7.0.tar.gz is missing from the fallback, I see you commented on that issue too (a few months after this one).

I can see at least some of the dependencies mentioned in that issue are still missing from the fallback url (I didn't check all of them).

This issue is unlikely to be fixed in Bitcoin Core. We'll close for now, but feel free to open another issue or pull request with a fix.

For reference, for now I am using this diff locally to get the depends from a ipv6 (cloudflare):

diff --git a/depends/Makefile b/depends/Makefile
index 27bf804..768db6b 100644
--- a/depends/Makefile
+++ b/depends/Makefile
@@ -45,7 +45,7 @@ NO_USDT ?=
 NO_NATPMP ?=
 MULTIPROCESS ?=
 LTO ?=
-FALLBACK_DOWNLOAD_PATH ?= https://bitcoincore.org/depends-sources
+FALLBACK_DOWNLOAD_PATH ?= https://drahtbot.space/depends_download_fallback
 
 C_STANDARD ?= c11
 CXX_STANDARD ?= c++17

Same as https://github.com/bitcoin/bitcoin/pull/17704