# 4.7. Reverse Proxies

## 4.7.1. Reverse proxying with HAProxy

CouchDB recommends the use of HAProxy as a load balancer and reverse proxy. The team’s experience with using it in production has shown it to be superior for configuration and monitoring capabilities, as well as overall performance.

CouchDB’s sample haproxy configuration is present in the code repository and release tarball as `rel/haproxy.cfg`. It is included below. This example is for a 3 node CouchDB cluster:

    global
        maxconn 512
        spread-checks 5

    defaults
        mode http
        log global
        monitor-uri /_haproxy_health_check
        option log-health-checks
        option httplog
        balance roundrobin
        option forwardfor
        option redispatch
        retries 4
        option http-server-close
        timeout client 150000
        timeout server 3600000
        timeout connect 500

        stats enable
        stats uri /_haproxy_stats
        # stats auth admin:admin # Uncomment for basic auth

    frontend http-in
         # This requires HAProxy 1.5.x
         # bind *:$HAPROXY_PORT
         bind *:5984
         default_backend couchdbs

    backend couchdbs
        option httpchk GET /_up
        http-check disable-on-404
        server couchdb1 x.x.x.x:5984 check inter 5s
        server couchdb2 x.x.x.x:5984 check inter 5s
        server couchdb3 x.x.x.x:5984 check inter 5s

## 4.7.2. Reverse proxying with nginx

### 4.7.2.1. Basic Configuration

Here’s a basic excerpt from an nginx config file in `<nginx config directory>/sites-available/default`. This will proxy all requests from `http://domain.com/...` to `http://localhost:5984/...`

    location / {
        proxy_pass http://localhost:5984;
        proxy_redirect off;
        proxy_buffering off;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }

Proxy buffering must be disabled, or continuous replication will not function correctly behind nginx.

### 4.7.2.2. Reverse proxying CouchDB in a subdirectory with nginx

It can be useful to provide CouchDB as a subdirectory of your overall domain, especially to avoid CORS concerns. Here’s an excerpt of a basic nginx configuration that proxies the URL `http://domain.com/couchdb` to `http://localhost:5984` so that requests appended to the subdirectory, such as `http://domain.com/couchdb/db1/doc1` are proxied to `http://localhost:5984/db1/doc1`.

    location /couchdb {
        rewrite ^ $request_uri;
        rewrite ^/couchdb/(.*) /$1 break;
        proxy_pass http://localhost:5984$uri;
        proxy_redirect off;
        proxy_buffering off;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }

Session based replication is default functionality since CouchDB 2.3.0. To enable session based replication with reverse proxied CouchDB in a subdirectory.

    location /_session {
        proxy_pass http://localhost:5984/_session;
        proxy_redirect off;
        proxy_buffering off;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }

### 4.7.2.3. Authentication with nginx as a reverse proxy

Here’s a sample config setting with basic authentication enabled, placing CouchDB in the `/couchdb` subdirectory:

    location /couchdb {
        auth_basic "Restricted";
        auth_basic_user_file htpasswd;
        rewrite /couchdb/(.*) /$1 break;
        proxy_pass http://localhost:5984;
        proxy_redirect off;
        proxy_buffering off;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Authorization "";
    }

This setup leans entirely on nginx performing authorization, and forwarding requests to CouchDB with no authentication (with CouchDB in Admin Party mode), which isn’t sufficient in CouchDB 3.0 anymore as Admin Party has been removed. You’d need to at the very least hard-code user credentials into this version with headers.

For a better solution, see Proxy Authentication.

### 4.7.2.4. SSL with nginx

In order to enable SSL, just enable the nginx SSL module, and add another proxy header:

    ssl on;
    ssl_certificate PATH_TO_YOUR_PUBLIC_KEY.pem;
    ssl_certificate_key PATH_TO_YOUR_PRIVATE_KEY.key;
    ssl_protocols SSLv3;
    ssl_session_cache shared:SSL:1m;

    location / {
        proxy_pass http://localhost:5984;
        proxy_redirect off;
        proxy_set_header Host $host;
        proxy_buffering off;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Ssl on;
    }

The `X-Forwarded-Ssl` header tells CouchDB that it should use the `https` scheme instead of the `http` scheme. Otherwise, all CouchDB-generated redirects will fail.

## 4.7.3. Reverse Proxying with Caddy 2

Caddy is `https-by-default`, and will automatically acquire, install, activate and, when necessary, renew a trusted SSL certificate for you - all in the background. Certificates are issued by the Let’s Encrypt certificate authority.

### 4.7.3.1. Basic configuration

Here’s a basic excerpt from a Caddyfile in `/etc/caddy/Caddyfile`. This will proxy all requests from `http(s)://domain.com/...` to `http://localhost:5984/...`

    domain.com {

       reverse_proxy localhost:5984

    }

### 4.7.3.2. Reverse proxying CouchDB in a subdirectory with Caddy 2

It can be useful to provide CouchDB as a subdirectory of your overall domain, especially to avoid CORS concerns. Here’s an excerpt of a basic Caddy configuration that proxies the URL `http(s)://domain.com/couchdb` to `http://localhost:5984` so that requests appended to the subdirectory, such as `http(s)://domain.com/couchdb/db1/doc1` are proxied to `http://localhost:5984/db1/doc1`.

    domain.com {

        reverse_proxy /couchdb/* localhost:5984

    }

### 4.7.3.3. Reverse proxying + load balancing for CouchDB clusters

Here’s a basic excerpt from a Caddyfile in `/<path>/<to>/<site>/Caddyfile`. This will proxy and evenly distribute all requests from `http(s)://domain.com/...` among 3 CouchDB cluster nodes at `localhost:15984`, `localhost:25984` and `localhost:35984`.

Caddy will check the status, i.e. health, of each node every 5 seconds; if a node goes down, Caddy will avoid proxying requests to that node until it comes back online.

    domain.com {

        reverse_proxy http://localhost:15984 http://localhost:25984 http://localhost:35984 {
        lb_policy round_robin
        lb_try_interval 500ms

        health_interval 5s
        }

    }

### 4.7.3.4. Authentication with Caddy 2 as a reverse proxy

Here’s a sample config setting with basic authentication enabled, placing CouchDB in the `/couchdb` subdirectory:

    domain.com {

        basicauth /couchdb/* {
            couch_username couchdb_hashed_password_base64
        }

        reverse_proxy /couchdb/* localhost:5984

    }

This setup leans entirely on nginx performing authorization, and forwarding requests to CouchDB with no authentication (with CouchDB in Admin Party mode), which isn’t sufficient in CouchDB 3.0 anymore as Admin Party has been removed. You’d need to at the very least hard-code user credentials into this version with headers.

For a better solution, see Proxy Authentication.

## 4.7.4. Reverse Proxying with Apache HTTP Server

Warning

As of this writing, there is no way to fully disable the buffering between Apache HTTPD Server and CouchDB. This may present problems with continuous replication. The Apache CouchDB team strongly recommend the use of an alternative reverse proxy such as `haproxy` or `nginx`, as described earlier in this section.

### 4.7.4.1. Basic Configuration

Here’s a basic excerpt for using a `VirtualHost` block config to use Apache as a reverse proxy for CouchDB. You need at least to configure Apache with the `--enable-proxy --enable-proxy-http` options and use a version equal to or higher than Apache 2.2.7 in order to use the `nocanon` option in the `ProxyPass` directive. The `ProxyPass` directive adds the `X-Forwarded-For` header needed by CouchDB, and the `ProxyPreserveHost` directive ensures the original client `Host` header is preserved.

    <VirtualHost *:80>
       ServerAdmin webmaster@dummy-host.example.com
       DocumentRoot "/opt/websites/web/www/dummy"
       ServerName couchdb.localhost
       AllowEncodedSlashes On
       ProxyRequests Off
       KeepAlive Off
       <Proxy *>
          Order deny,allow
          Deny from all
          Allow from 127.0.0.1
       </Proxy>
       ProxyPass / http://localhost:5984 nocanon
       ProxyPassReverse / http://localhost:5984
       ProxyPreserveHost On
       ErrorLog "logs/couchdb.localhost-error_log"
       CustomLog "logs/couchdb.localhost-access_log" common
    </VirtualHost>