The local config file is `$HOME/.bigchaindb` by default (a file which might not even exist), but you can tell BigchainDB to use a different file by using the `-c` command-line option, e.g. `bigchaindb -c path/to/config_file.json start`
or using the `BIGCHAINDB_CONFIG_PATH` environment variable, e.g. `BIGHAINDB_CONFIG_PATH=.my_bigchaindb_config bigchaindb start`.
You can read the current default values in the file [bigchaindb/\_\_init\_\_.py](https://github.com/bigchaindb/bigchaindb/blob/master/bigchaindb/__init__.py). (The link is to the latest version.)
Running `bigchaindb -y configure rethinkdb` will generate a local config file in `$HOME/.bigchaindb` with all the default values, with two exceptions: It will generate a valid private/public keypair, rather than using the default keypair (`None` and `None`).
The [cryptographic keypair](../appendices/cryptography.html) used by the node. The public key is how the node idenifies itself to the world. The private key is used to generate cryptographic signatures. Anyone with the public key can verify that the signature was generated by whoever had the corresponding private key.
Internally (i.e. in the Python code), both keys have a default value of `None`, but that's not a valid key. Therefore you can't rely on the defaults for the keypair. If you want to run BigchainDB, you must provide a valid keypair, either in the environment variables or in the local config file. You can generate a local config file with a valid keypair (and default everything else) using `bigchaindb -y configure rethinkdb`.
*`database.connection_timeout` is the maximum number of milliseconds that BigchainDB will wait before giving up on one attempt to connect to the database backend. Note: At the time of writing, this setting was only used by MongoDB; there was an open [issue to make RethinkDB use it as well](https://github.com/bigchaindb/bigchaindb/issues/1337).
*`database.max_tries` is the maximum number of times that BigchainDB will try to establish a connection with the database backend. If 0, then it will try forever.
If (no environment variables were set and there's no local config file), or you used `bigchaindb -y configure rethinkdb` to create a default local config file for a RethinkDB backend, then the defaults will be:
These settings are for the [Gunicorn HTTP server](http://gunicorn.org/), which is used to serve the [HTTP client-server API](../http-client-server-api.html).
`server.bind` is where to bind the Gunicorn HTTP server socket. It's a string. It can be any valid value for [Gunicorn's bind setting](http://docs.gunicorn.org/en/stable/settings.html#bind). If you want to allow IPv4 connections from anyone, on port 9984, use '0.0.0.0:9984'. In a production setting, we recommend you use Gunicorn behind a reverse proxy server. If Gunicorn and the reverse proxy are running on the same machine, then use 'localhost:PORT' where PORT is _not_ 9984 (because the reverse proxy needs to listen on port 9984). Maybe use PORT=9983 in that case because we know 9983 isn't used. If Gunicorn and the reverse proxy are running on different machines, then use 'A.B.C.D:9984' where A.B.C.D is the IP address of the reverse proxy. There's [more information about deploying behind a reverse proxy in the Gunicorn documentation](http://docs.gunicorn.org/en/stable/deploy.html). (They call it a proxy.)
`server.workers` is [the number of worker processes](http://docs.gunicorn.org/en/stable/settings.html#workers) for handling requests. If `None` (the default), the value will be (cpu_count * 2 + 1). `server.threads` is [the number of threads-per-worker](http://docs.gunicorn.org/en/stable/settings.html#threads) for handling requests. If `None` (the default), the value will be (cpu_count * 2 + 1). The HTTP server will be able to handle `server.workers` * `server.threads` requests simultaneously.
Specifies how long, in seconds, transactions can remain in the backlog before being reassigned. Long-waiting transactions must be reassigned because the assigned node may no longer be responsive. The default duration is 120 seconds.
