4.6. Reverse Proxies

4.6.1. 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 montioring 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 couchdb2 x.x.x.x:5984 check inter 5s

4.6.2. Reverse proxying with nginx

4.6.2.1. 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.

4.6.2.2. 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 /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;
}

4.6.2.3. 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). For a better solution, see Proxy Authentication.

4.6.2.4. 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.

4.6.3. Reverse Proxying with Caddy

4.6.3.1. Basic configuration

Here’s a basic excerpt from a Caddyfile in /<path>/<to>/<site>/Caddyfile. This will proxy all requests from http(s)://domain.com/... to http://localhost:5984/...

domain.com {

    import /path/to/other/config.caddy # logging, error handling etc.

    proxy / localhost:5984 {
        transparent
    }

}

Note

The transparent preset in the proxy directive is shorthand for:

header_upstream Host {host}
header_upstream X-Real-IP {remote}
header_upstream X-Forwarded-For {remote}
header_upstream X-Forwarded-Proto {scheme}

Note that, because Caddy is https-by-default, you must explicitly include the http:// protocol in the site address if you do NOT want Caddy to automatically acquire and install an SSL certificate and begin accepting https connections on port 443.

4.6.3.2. Reverse proxying CouchDB in a subdirectory with Caddy

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 {

    import /path/to/other/config.caddy # logging, error handling etc.

    proxy /couchdb localhost:5984 {
        transparent
        without /couchdb
    }

}

4.6.3.3. 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 {

    import /path/to/other/config.caddy # logging, error handling etc.

    proxy / http://localhost:15984 http://localhost:25984 http://localhost:35984 {
        policy round_robin
        health_check /_up
        health_check_duration 5s
        try_interval 500ms
        keepalive 0
        transparent
    }

}

4.6.3.4. Authentication with Caddy as a reverse proxy

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

domain.com {

    import /path/to/other/config.caddy # logging, error handling etc.

    basicauth /couchdb couch_username couchdb_password

    proxy /couchdb localhost:5984 {
        transparent
        header_upstream -Authorization
        without /couchdb
    }

}

For security reasons, using a plaintext password in the Caddyfile is not advisable. One solution is to define Caddy-process environment variables e.g. COUCH_PW=couchdb_password and using placeholders in the Caddyfile instead, e.g. {$COUCH_PW}.

This setup leans entirely on Caddy performing authorization, and forwarding requests to CouchDB with no authentication (with CouchDB in Admin Party mode). For a better solution, see Proxy Authentication.

4.6.3.5. SSL/TLS with Caddy

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 LetsEncrypt certificate authority.

domain.com {

    import /path/to/other/config.caddy # logging, error handling etc.

    proxy / localhost:5984 {
        transparent
        header_upstream 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.

4.6.4. 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.

4.6.4.1. 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 [email protected]
   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>