Running Cells behind an Apache reverse proxy

Created on 2021/11/12, apache, cells, configuration, reverse-proxy, ssl

In this tutorial, we explain how to use an Apache HTTP Server as reverse proxy in front of a Pydio Cells instance.
We present a basic vanilla setup and give a few tips to address most common issues.

Adapt Cells' internal webserver configuration

By default, Cells start on port 8080 with a self-signed certificate. To adapt your configuration, you have 3 options:

  • open a shell on the same machine where the service is running and call the cells configure sites command
  • define (at least) the CELLS_BIND and CELLS_EXTERNAL environment variables or the corresponding flags (see the help for other flags, typically to choose http or https between Apache and Cells)
  • add a proxyconfig section in your YAML installation file (or ProxyConfig if you use JSON format)

Doing so, you can define:

  • Bind Address: interface and port on which Cells server is bound. It MUST contain a server name (or IP) and a port.
  • External URL: the public URL that you communicate to your end users. Note that the external URL must contain the protocol (http or https) depending on wether you do TLS termination at the Apache layer or not.

A typical example if Apache and Cells run on the same machine:

| # |        BIND(S)         |     TLS     |                EXTERNAL URL                 |
| 0 | https://localhost:8080 | Self-signed |                   |

Configure Apache

You must enable the following mods with Apache:

To enable a module with apache use sudo a2enmod <mod_name>.

A simple example

For this example, we are using a simple setup. The proxy is running on a server under the hostname while Pydio Cells is bound on localhost with port 8080 with TLS enabled.

Create or Edit your apache virtual host configuration with :

<VirtualHost *:80>

    RewriteEngine On
    RewriteCond %{HTTPS} off
    RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}

    RewriteCond %{SERVER_NAME}
    RewriteRule ^ https://%{SERVER_NAME}%{REQUEST_URI} [END,NE,R=permanent]

<VirtualHost *:443>
    AllowEncodedSlashes On
    RewriteEngine On
    SSLProxyEngine On

    ## The order of the directives matters.
    # If Cells is not running with https, consider using ws instead of wss
    ProxyPassMatch "/ws/(.*)" wss://localhost:8080/ws/$1 nocanon

    ## This rewrite condition is required if using Cells-Sync
    # RewriteCond %{HTTP:Content-Type} =application/grpc [NC]
    # RewriteRule /(.*) h2://localhost:8080/$1 [P,L]

    ProxyPass "/" "https://localhost:8080/" 
    ProxyPassReverse "/" "https://localhost:8080/"

    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined

    SSLCertificateFile /etc/letsencrypt/live/
    SSLCertificateKeyFile /etc/letsencrypt/live/
    Include /etc/letsencrypt/options-ssl-apache.conf

This was tested with Apache/2.4.51 on Debian

Important points

Please note:

  • The AllowEncodedSlashes On directive is necessary if it is not globally activated in Apache. It enables API calls like /a/meta/bulk/path%2F%to%2Ffolder.
  • When configuring Cells, even on another port, make sure to bind it directly to the as well (like Apache). This is necessary for the presigned URL used with S3 API for uploads and downloads (they used signed headers and a mismatch between received Host headers may break the signature). Another option is to still bind Cells using a local IP, then in the Admin Settings, under Configs Backend, use the field “Replace Host Header for S3 Signature” and use the internal IP here.
  • nocanon is required after the ProxyPass to be able to download files which names contain special characters such as commas or quotes.
  • websocket: make sure to also proxy the websocket depending on your protocol (ws, or wss) and enable the module.
  • RewriteEngine is required to enable rewriting requests.

Cells Sync

For Cells-Sync to work it is required to proxy the grpc requests using the http2 module, for that 2 prerequisites need to be met:

  • Enable apache module http2 & proxy_http2.
  • http2 does not work with the module mpm_prefork therefore it is required to use mpm_event instead (see apache official documentation).

Once you have met the prerequisites, enable the http2 proxy with the following directive (h2 for TLS or h2c for clear text), for more information please refer to Apache's official documentation.

## The order of the directive is important please see the full example above.
    # RewriteCond %{HTTP:Content-Type} =application/grpc [NC]
    # RewriteRule /(.*) h2://localhost:8080/$1 [P,L]

All requests done from Cells-Sync have the header Content-Type set to application/grpc.

See Also

Running Cells Behind a reverse proxy