# 3.1. Introduction To 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 one of `/Users/<your-user>/Library/Application Support/CouchDB2/etc/couchdb` or `/Users/<your-user>/Library/Preferences/couchdb2-local.ini` for the `local.ini` and `local.d` directories.

Settings in successive documents override the settings in earlier entries. For example, setting the `chttpd/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.

If there is a need to use different `vm.args` or `sys.config` files, for example, in different locations to the ones provided by CouchDB, or you don’t want to edit the original files, the default locations may be changed by setting the COUCHDB_ARGS_FILE or COUCHDB_SYSCONFIG_FILE environment variables:

    export COUCHDB_ARGS_FILE="/path/to/my/vm.args"
    export COUCHDB_SYSCONFIG_FILE="/path/to/my/sys.config"

## 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:

    [compactions]
    _default =

This could be read as: “remove the _default parameter from the compactions 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 can be set via the HTTP API. This API allows changing CouchDB configuration on-the-fly without requiring a server restart:

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

The old parameter’s value is returned in the response:

    "sequential"

You should be careful changing configuration via the HTTP API since it’s possible to make CouchDB unreachable, for example, by changing the `chttpd/bind_address`:

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

If you make a typo or the specified IP address is not available from your network, CouchDB will be unreachable. The only way to resolve this will be to remote into the server, correct the config file, and restart CouchDB. To protect yourself against such accidents you may set the `chttpd/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, will also require a server restart before taking effect.

## 3.1.5. Configuring the local node

While the HTTP API allows configuring all nodes in the cluster, as a convenience, you can use the literal string `_local` in place of the node name, to interact with the local node’s configuration. For example:

    curl -X PUT http://localhost:5984/_node/_local/_config/uuids/algorithm -d '"random"'