# 3.1. Introduction Into Configuring

## 3.1.1. Configuration files

By default, CouchDB reads configuration files from the following locations, in the following order:

1. `etc/default.ini`
2. `etc/default.d/*.ini`
3. `etc/local.ini`
4. `etc/local.d/*.ini`

All paths are specified relative to the CouchDB installation directory: `/opt/couchdb` recommended on UNIX-like systems, `C:\CouchDB` recommended on Windows systems, and a combination of two directories on macOS: `Applications/Apache CouchDB.app/Contents/Resources/couchdbx-core/etc` for the `default.ini` and `default.d` directories, and `/Users/youruser/Library/Application Support/CouchDB2/etc/couchdb` for the `local.ini` and `local.d` directories.

Settings in successive documents override the settings in earlier entries. For example, setting the `httpd/bind_address` parameter in `local.ini` would override any setting in `default.ini`.

Warning

The `default.ini` file may be overwritten during an upgrade or re-installation, so localised changes should be made to the `local.ini` file or files within the `local.d` directory.

The configuration file chain may be changed by setting the ERL_FLAGS environment variable:

    export ERL_FLAGS="-couch_ini /path/to/my/default.ini /path/to/my/local.ini"

or by placing the `-couch_ini ..` flag directly in the `etc/vm.args` file. Passing `-couch_ini ..` as a command-line argument when launching `couchdb` is the same as setting the `ERL_FLAGS` environment variable.

Warning

The environment variable/command-line flag overrides any `-couch_ini` option specified in the `etc/vm.args` file. And, BOTH of these options completely override CouchDB from searching in the default locations. Use these options only when necessary, and be sure to track the contents of `etc/default.ini`, which may change in future releases.

## 3.1.2. Parameter names and values

All parameter names are case-sensitive. Every parameter takes a value of one of five types: boolean, integer, string, tuple and proplist. Boolean values can be written as `true` or `false`.

Parameters with value type of tuple or proplist are following the Erlang requirement for style and naming.

## 3.1.3. Setting parameters via the configuration file

The common way to set some parameters is to edit the `local.ini` file (location explained above).

For example:

    ; This is a comment
    [section]
    param = value ; inline comments are allowed

Each configuration file line may contains section definition, parameter specification, empty (space and newline characters only) or commented line. You can set up inline commentaries for sections or parameters.

The section defines group of parameters that are belongs to some specific CouchDB subsystem. For instance, `httpd` section holds not only HTTP server parameters, but also others that directly interacts with it.

The parameter specification contains two parts divided by the equal sign (`=`): the parameter name on the left side and the parameter value on the right one. The leading and following whitespace for `=` is an optional to improve configuration readability.

Note

In case when you’d like to remove some parameter from the default.ini without modifying that file, you may override in local.ini, but without any value:

    [httpd_global_handlers]
    _all_dbs =

This could be read as: “remove the _all_dbs parameter from the httpd_global_handlers section if it was ever set before”.

The semicolon (`;`) signals the start of a comment. Everything after this character is ignored by CouchDB.

After editing the configuration file, CouchDB should be restarted to apply any changes.

## 3.1.4. Setting parameters via the HTTP API

Alternatively, configuration parameters could be set via the HTTP API. This API allows to change CouchDB configuration on-the-fly without requiring a server restart:

    curl -X PUT http://localhost:5984/_node/<name@host>/_config/uuids/algorithm -d '"random"'

In the response the old parameter’s value returns:

    "sequential"

You should be careful with changing configuration via the HTTP API since it’s easy to make CouchDB unavailable. For instance, if you’d like to change the `httpd/bind_address` for a new one:

    curl -X PUT http://localhost:5984/_node/<name@host>/_config/httpd/bind_address -d '"10.10.0.128"'

However, if you make a typo, or the specified IP address is not available from your network, CouchDB will be unavailable for you in both cases and the only way to resolve this will be by remoting into the server, correcting the errant file, and restarting CouchDB. To protect yourself against such accidents you may set the `httpd/config_whitelist` of permitted configuration parameters for updates via the HTTP API. Once this option is set, further changes to non-whitelisted parameters must take place via the configuration file, and in most cases, also requires a server restart before hand-edited options take effect.