Added ability to set config parameters through environment variables #3476

jmcorgan commented at 8:01 AM on December 30, 2013: contributor

The environment is parsed for variables starting with BITCOIN_, and the remaining portion of the name becomes the argument name, with the value set to the portion after the = sign, e.g.,

BITCOIN_DATADIR=FOO is equivalent to -datadir=FOO

The environment is parsed before the command line, allowing the command line to take precedence over the environment.

There is a whitelist in util.cpp that only allows specified environment variables to be used this way; currently, this is set to just -datadir and -conf.

Signed-off-by: Johnathan Corgan johnathan@corganlabs.com

Added ability to set config parameters through environment variables

The environment is parsed for variables starting with BITCOIN_, and
the remaining portion of the name becomes the argument name, with
the value set to the portion after the = sign, e.g.,

BITCOIN_DATADIR=FOO is equivalent to -datadir=FOO

The environment is parsed before the command line, allowing the
command line to take precedence over the environment.

There is a whitelist in util.cpp that only allows specified environment
variables to be used this way; currently, this is set to just -datadir
and -conf.

Signed-off-by: Johnathan Corgan <johnathan@corganlabs.com>

ba935ec954

in src/util.cpp:None in ba935ec954 outdated

 548 | +static const set<string> envWhitelist(envNames, envNames+sizeof(envNames)/sizeof(envNames[0]));
 549 | +
 550 | +void ParseEnvironment()
 551 | +{
 552 | +    int i = 0;
 553 | +    while (environ[i] != NULL && strlen(environ[i]) > 0) {

laanwj commented at 8:20 AM on December 30, 2013:

Indentation looks a bit strange here. Are you mixing tabs and spaces? Please use four spaces for indentation.

in src/bitcoin-cli.cpp:None in ba935ec954 outdated

  19 | @@ -20,6 +20,8 @@ static bool AppInitRPC(int argc, char* argv[])
  20 |      //
  21 |      // Parameters
  22 |      //
  23 | +    ClearArgs();

laanwj commented at 8:23 AM on December 30, 2013:

This ClearArgs() shouldn't be needed as the args start out empty (same for bitcoind and bitcoin-qt)

jmcorgan commented at 8:35 AM on December 30, 2013: contributor

I'm using emacs C++ mode, which defaults to two spaces, then trying to make things match up with what is already there. It didn't work out so well.

Regarding the ClearArgs, I'm just replicating what was already there at the start of ParseParameters(). It's true they start out empty, but in the test code it calls ParseParameters multiple times and assumes that the args get cleared in between.

I'm happy to make whatever changes you feel are necessary, of course.

jmcorgan commented at 8:37 AM on December 30, 2013: contributor

Also, there is a backport to 0.8.6 on my branch envconfig-0.8.6.

Removed unneeded ClearArgs() calls.

Signed-off-by: Johnathan Corgan <johnathan@corganlabs.com>

41d56c87f8

Remove one additional unneeded ClearArgs(). d2ea3a3bdd

Fixed whitespace issues with tab/space 0729a596da

jmcorgan commented at 4:55 PM on December 30, 2013: contributor

All of Iaanwj's comments should be addressed now.

BitcoinPullTester commented at 5:27 PM on December 30, 2013: none

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emmix commented at 3:27 AM on December 31, 2013: none

It seems that do not have the strong requirement for this extended feature, since we already have configure file(bitcoin.conf) to do it. Also it make the bitcoin to tangle the OSs environments. Different OS may have some quirks.

jmcorgan commented at 3:44 AM on December 31, 2013: contributor

This serves several needs that I personally have, to run bitcoind with different conf files and not have to always specify them with -conf=foo on the command line. Instead I set the BITCOIN_CONF=foo environment variable and I can type bitcoind (or bitcoin-cli) repeatedly and it will use that value. Being able to specify alternate datadir locations works the same way.

It also allows running common scripts whose parameters can be changed via the environment they are passed, instead of having to point at different conf files.

In any case, I'll keep using this locally, and the pull request is offered up to the devs to integrate or not as they see fit.

laanwj commented at 8:11 AM on December 31, 2013: member

@emmix How does this "tangle" the OS environment? It reads it only, uses clearly identifiable variable names that you'd never use by accident, and currently only allows two settings (-datadir and -conf) to be set through the environment.

I can see how this can be useful. Though, to be fair, you can accomplish the same with something like:

alias bitcoin-cli='bitcoin-cli -datadir=${BITCOIN_DATADIR}'

(sure, an alias won't nest into scripts, but the scripts could pass the environment variable to bitcoin-cli)

emmix commented at 3:51 AM on January 1, 2014: none

'Tangle" which I mean couple with the OS environment. Sorry for my unclarity. My concerns are: [1] Windows, Mac, Linux, etc have the same style to deal with environment? Do we need to consider the OS's quirks? I do not look into it. [2] The change bring the convenience as the global variables in programming language. Sure, it is useful if we have clearly identifiable names. But the convenience can obtain only by scripts without need to introduce the environment variables into source code.

Anyway the change takes convenience actually. But type the whole commands and options let you know what you are dong clearly.

laanwj commented at 1:19 PM on April 1, 2014: member

This adds more testing work. Especially in the case of the GUI, there are already many sources of configuration options that interact in non-trivial ways and this has resulted in bugs in the past.

And as said this can be easily handled from outside the code; either by defining an alias or function for bitcoin-cli with arguments, or by using a script.

In general we don't add extra code to the core for what can be handled easily from outside. So - I'm closing this.

laanwj closed this on Apr 1, 2014

jmcorgan deleted the branch on Jun 7, 2014

bitcoin locked this on Sep 8, 2021

jmcorgan restored the branch on Dec 23, 2025