Skip to content

Nextcloud in Docker with Letsencrypt and TLS Client Certificates


Notifications You must be signed in to change notification settings


Repository files navigation

section x-masysma-name title date lang author keywords x-masysma-version x-masysma-website x-masysma-repository x-masysma-owned x-masysma-copyright
Nextcloud in Docker with Letsencrypt and TLS Client Certificates
2022/04/24 15:08:29
Linux-Fan, (
Copyright (c) 2022 For further info send an e-mail to


So you want to setup your own Nextcloud ( server? It should be easy as well as productively useful so why not do it the modern way with Docker and Let's Encrypt? Surely there are countless good tutorials about this so it should be quickly done and straight-forward. Turns out it isn't.

In fact there are multiple good tutorials out there, none of which combine all the things I wanted, hence I thought it might be worthwhile to document my approach, too. I thus present the 1001st guide about how to setup Nextcloud in Docker with Let's Encrypt here.

In case you rather want to trust some other tutorial, I found the following resources to be helpful in creating my setup:

None of them seem to combine all of the nice things i.e. Nextcloud, Let's Encrypt and TLS Client Certificates, but maybe you have different use case where some of these are not needed anyways.


This document describes how to setup a Nextcloud instance on your own server. It provides details about how to configure Let's Encrypt and TLS Client Certificates such that the advantages of an automatically trusted Let's Encrypt certificate are combined with the enhanced security of TLS Client Certificates.

Unlike many other tutorials, this one focuses on how to spin-up the entire stack with as much automation as possible.

Please note: While this is intended to yield a secure setup please do not expose services to the Internet without at least some understanding of what you are doing. In this spirit, this document will not explain and assume basic familiarity with all of the following: Docker, Docker-Compose, TLS, Linux, Networking.

Use Case: Why Nextcloud?

Nextcloud can be used for a variety of purposes. My setup focuses on using it as a backup storage server that I can share with some friends. The idea is that each of us runs their own Nextcloud instance and provides access to the other friends. Then we can send backups to friends in order to have them stored offsite.

Compared to a public cloud solution this gives us full control about our data and keeps costs low especially since some of us are already running one or the other machine 24/7.

All of the users are expected to be tech-savvy enough to instruct their clients to use TLS client certificates. In case you want to setup Nextcloud for less experienced users consider dropping client certificates because they can be a PITA for some people to set up.

Compared to other options like running an SSH server for storage, Nextcloud has a major advantage: It can do server-side encryption. If configured correctly, this allows administrators to remain oblivious of what content the users upload. Thus there is no need to worry about license violations if anyone uploads their game installer backup copy or anything.

Setup Principles

The setup principles in this guide are as follows:

  • Set it up with Docker.
  • Use Let's Encrypt.
  • Set up TLS client certificates.
  • Automate as many maintenance tasks as possible.
  • Keep it as simple as possible under the circumstances.

Set it up with Docker

My main argument for a setup with Docker is that I have experience with the technology and use it for some other serivces on the same server already. Hence it plays well in terms of regularity to attempt having all of the services in Containers. It also works pretty well for developing on one machine and deploying to another machine later. Using docker-compose.yml files and scripts it is also possible to easily reproduce the setup later if needed.

Use Let's Encrypt

Actually I am still not sure if this is the best way to go. Let's Encrypt allows you to obtain free TLS Server Certificates that will be accepted by all major clients by default. It thus makes sense to use this for Nextcloud in general. It also gives a good sense of confidence if browsers do not regularly greet you with This page is insecure.

In the setup presented here, an own CA is still needed for the TLS Client Certificates, though. Also, Let's Encrypt does not actually lend itself well to being automated (see Installation Details). Let's Encrypt locks you into certain choices like providing your services through port 443 which may collide with other applications that you might possibly be running there already. While Reverse Proxies solve this issue in theory, their configuration becomes a snowflake as soon as you start mixing multiple services together in a single configuration just to satisfy this Let's Encrypt port requirement.

If you want to deploy a setup similar to mine's, do not take the complexity of Let's Encrypt lightly.

Set up TLS Client Certificates

Use TLS Client Certificates because they are much more secure than passwords or any application-enforced 2FA. Its a hard layer of security that walls-off the Nextcloud directly on the HTTP server level. Being webserver-based, TLS Client Certificate protection endures even in the presence of security holes in Nextcloud.

TLS Client Certificates are one of the three ways to do anything over the Internet securely. The other two options are SSH and VPN.

Compared to the alternatives, most clients support TLS Client Certificates enough such that you do not need to setup any tunnel (as with SSH or VPN based access to a website). TLS Client Certificates are thus well-suited for the purpose.

Keep in mind that other scenarios like mobile devices, less tech-savvy users or access through proprietary programs may require you to give up on TLS Client Certificates. Be aware that despite the complexity, it is the strongest layer of security in the entire setup.

Automate as many Maintenance Tasks as possible

It is remarkable in a negative sense that many tutorials are based on Docker, but still require multiple manual steps to be performed in-sequence rather than allowing for the idiomatic docker-compose up.

Also, in some tutorials, maintenance like renewing Let's Encrypt certificates and handling upgrades comes as an afterhtought. Given that the services are exposed to the Internet and expected to remain online for prolonged amounts of time (we are talking about storage after all!) this seems pretty short-sighted an approach.

This guide attempts to address some of the issues although it does not solve them in their entirety. This is partially due to Nextcloud being a stateful application with a database. This limits the possibilites for fully-automatic upgrades.

As a design decision, a minimum number of Docker images is used. Also, all modifications to the images are done by mounting files into the containers rather than deriving custom images. This should provision for easy upgrading even by automated scripts that just pull the images and re-create the containers.

Keep it as simple as possible under the Circumstances

There are images like e.g. nginx-proxy that attempt to make components like the nginx web server more docker-friendly by automating and scripting configuration file creation. The resulting source codes are rather complex, though, e.g.

Some of this complexity cannot be avoided in automation, but at least for nginx there is an easier way by creating an alsmost-static configuration file and substituting only a limited set of environment variables. As this is already supported by the official nginx container, there is no need to introduce yet another image here.

Installation Details

As promsied under Automate as many Maintenance Tasks as possible, the setup presented here aims at a single docker-compose up to get started.


The following preconditions need to be given:

Ports 80 and 443 need to be available through a public domain and forwareded to your server. If there are firewalls, they should let these ports pass on their way into your server.

Also, you should edit the environment file .env. A sample file _env_sample.txt supplied as part of the repository contains the following lines:


Environment Configuration

POSTGRES_PASSWORD : Set this to a good randomly generated password. You do not normally need to enter it anywhere else. VIRTUAL_HOST : Set this to your public domain name. In this article, I will use as an example value that you need to replace with your own domain. LETSENCRYPT_EMAIL : Configure an e-mail address to register with Let's Encrypt. NEXTCLOUD_ADMIN_USER : Specify an username for the Nextcloud Administrator account. Use this account only to create other accounts that will then hold the actual data. Do not use admin as the username here. Use a name that reminds you that this is the admin but that is not in any of the common names (not root, not admin, not administrator, ...). Also, avoid dashes (-, nextcloud/server#13318) in the username. Underscores are fine, though. NEXTCLOUD_ADMIN_PASSWORD : Specify a password for the Nextcloud Administartor account. The usual rules for passwords apply.

Quickstart with docker-compose.yml

Checkout the repository and fire it up with docker-compose after editing the environment to match your setup.

git clone

mv lo-nextcloud-docker nextcloud
cd nextcloud

cp _env_sample.txt .env
sensible-editor .env # edit .env as described above

docker-compose up -d # optionally leave out -d for testing purposes

Dissecting the docker-compose.yml

While it is nice to quickly spin everything up with a single command, this does not aid as much in understanding what all the components actually do. The following subsections each consider individual parts of the docker-compose.yml and related files. Find all the files together in the repository.

Database Postgresql

The beginning of the docker-compose.yml is as follows:

version: '3'

    image: postgres:13-bullseye
    restart: unless-stopped
      - ./database:/var/lib/postgresql/data
      - POSTGRES_DB=nextcloud
      - POSTGRES_USER=nextcloud

Here, a PostgreSQL database is configured with database and user name nextcloud. Use image postgres:13-bullseye because that's a version from the same series as also available in Debian stable. Automatic restart after machine reboot is implemented by the restart: unless-stopped line. Persistent data is stored in local directory ./database. In case you want to manage your data in a directory outside of the docker-compose.yml configuration, feel free to reconfigure the paths accordingly.

Environment POSTGRES_PASSWORD is passed but not given a value. The value configured in .env takes effect.

The choice of PostgreSQL over Mariadb is only a matter of preference. If you have more/better experience with Mariadb, feel free to reconfigure the services to use that DBMS instead.


    image: redis:6.2-bullseye
    restart: unless-stopped
      - ./redis:/var/lib/redis

This service is optional but improves performance significantly. Given the generally abysmal performance of Nextcloud (see further down), it seems best to enable this all the time!


    image: nextcloud:22-fpm
    restart: unless-stopped
      - ./storage:/var/www/html
      - ./nextcloud_entrypoint.php:/usr/local/bin/nextcloud_entrypoint.php:ro
      - POSTGRES_DB=nextcloud
      - POSTGRES_HOST=postgres
      - POSTGRES_USER=nextcloud
      - REDIS_HOST=redis
      - postgres
      - redis
      - /usr/local/bin/php
      - "-f"
      - /usr/local/bin/nextcloud_entrypoint.php

This is the main service and hence called nextcloud (rather than a generic app from some other tutorials). It passes environment variables to configure Nextcloud correctly out of the box. The NEXTCLOUD_TRUSTED_DOMAINS is noteworthy as it specifies a list of host names that are valid to point a webbrowser to. For some reasons it is necessary to list the internal name (innerweb) as well as the external name (provided by variable VIRTUAL_HOST) here.

The entrypoint is overridden because while in theory, Nextcloud automatically restarts if it cannot reach the database, in practice this yields a corrupted installation. See

The nextcloud_entrypoint.php is thus a simple wrapper that ensures that the database is reachable before executing the Nextcloud-provided entrypoint. It is implemented as follows:


error_reporting(E_ALL | E_NOTICE);

while(TRUE) {
	try {
		$db = new PDO("pgsql:host=postgres;port=5432;dbname=nextcloud",
				"nextcloud", getenv("POSTGRES_PASSWORD"),
		$db->query("SELECT 1");
	} catch(Exception $e) {

pcntl_exec("/", ["php-fpm"]);


This script just tries to connect to the postgres server in a loop and execs to / as soon as connectivity is detected. It makes sense to code it in PHP because that is what Nextcloud will be using in the end, too.

Nextcloud Cron PHP

    image: nextcloud:22-fpm
    restart: unless-stopped
      - ./storage:/var/www/html
    entrypoint: /
      - POSTGRES_DB=nextcloud
      - POSTGRES_HOST=postgres
      - POSTGRES_USER=nextcloud
      - REDIS_HOST=redis
      - postgres
      - redis

This service is using a different entrypoint to automatically perform regularly scheduled Nextcloud tasks. Here, I have just relied on the official example; better implementations might be possible, but this one has the advantage that it works without pulling another image.

Innerweb NGINX Server

    image: nginx:1.21
    restart: unless-stopped
      - ./storage:/var/www/html:ro
      - ./nginx_inner.conf:/etc/nginx/nginx.conf:ro
      - nextcloud
      - proxy-tier
      - default

This is an inner nginx instance that serves the PHP as suggested by Nextcloud. It is separated from the reverse-proxy nginx that terminates TLS as per the official Nextcloud example docker-compose.yml. I am not sure if it is really beneficial to separate them like this here, but one advantage of doing it is the ability to specify Nextcloud-specific webserver configuration in nginx_inner.conf (copied from and TLS-specific webserver configuration in nginx_outer.conf.template.

Proxy NGINX Server exposed to the Internet

    image: nginx:1.21
    restart: unless-stopped
      - 80:80
      - 443:443
      - ./nginx_outer.conf.template:/etc/nginx/templates/default.conf.template:ro
      - ./letsencrypt:/etc/letsencrypt:ro
      - ./
      - ./
      - certbot-www:/var/www/certbot:ro
      - innerweb
      - proxy-tier
        - CMD
        - /bin/sh
        - "-euc"
        - " || sleep 5; || kill -s TERM 1"
      interval: 1min
      retries: 1

This is the nginx instance that will be exposed to the Internet as per the ports specification. It takes a lot of special files and has a pecuilar healthcheck to automate restarting the server in case a renewed Let's Encrypt certificate is going to be used.


server {
	listen 80;
	server_name ${VIRTUAL_HOST};

	location /.well-known/acme-challenge/ {
		root /var/www/certbot;

	location / {
		return 301 https://$host$request_uri;

server {
	listen 443 ssl;
	server_name ${VIRTUAL_HOST};
	server_tokens off;

	ssl_certificate /etc/letsencrypt/live/${VIRTUAL_HOST}/fullchain.pem;
	ssl_certificate_key /etc/letsencrypt/live/${VIRTUAL_HOST}/privkey.pem;

	# include /etc/letsencrypt/options-ssl-nginx.conf;
	# -- begin options-ssl-nginx.conf --
	ssl_session_cache shared:le_nginx_SSL:10m;
	ssl_session_timeout 1440m;
	ssl_session_tickets off;
	ssl_protocols TLSv1.2 TLSv1.3;
	ssl_prefer_server_ciphers off;
	# -- end options-ssl-nginx.conf --

	ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem;

	ssl_client_certificate /etc/letsencrypt/client-ca.crt;
	ssl_verify_client on;
	# new
	ssl_verify_depth 2;

	# avoid request entity too large error
	client_max_body_size 2048M;

	location / {
		proxy_pass http://innerweb;
		proxy_set_header  X-Real-IP  $remote_addr;

This is the production server configuration. It includes all the gory details to use only secure ciphers, TLSv1.2 and TLSv1.3 and the client certificates. The only Nextcloud-specific thing in here is line client_max_body_size 2048M which permits large file uploads to Nextcloud.

In order for Let's Encrypt to work, it needs to recognize a challenge either in form of a DNS record or a file served through HTTP. While the DNS record has the advantage of not needing to expose a web server on port 80 it is also very rarely configurable automatically with free dyndns providers. Hence the variant over HTTP is implemented here. The only path available through HTTP is /.well-known/acme-challenge whereas all other HTTP queries are redirected to HTTPS causing the client certificate to become required.

This script checks the server's reported fingerprint against the on-disk representation of the certificate. If they match, the server is already running the most recent version of the certificate. If they do not match, the server should be restarted as to pick up the new certificate.

Note that you do not strictly need to restart the server, a reload might be sufficient. If have not tried that out, though.

#!/bin/sh -eu
expected_fingerprint="$(openssl x509 -fingerprint -sha256 -noout \
		-in "/etc/letsencrypt/live/$VIRTUAL_HOST/fullchain.pem")"
server_fingerprint="$(openssl s_client -connect "$1:443" \
		< /dev/null 2>/dev/null | openssl x509 -fingerprint \
		-sha256 -noout -in /dev/stdin 2> /dev/null || echo "RV=$?")"
[ "$server_fingerprint" = "$expected_fingerprint" ]

It is not necessary to supply a valid client-side certificate for picking up the fingerprint.

This is another script that waits in a loop. It waits until script has generated a preliminary certificate before the nginx server can continue to start up. Without this wait, the server might come up with some files mentioned in the configuration file being missing which would cause the server startup to fail.

#!/bin/sh -eu

while { ! [ -f /etc/letsencrypt/stage ]; } || \
		[ "$(cat /etc/letsencrypt/stage)" = 1_before_first_startup ]; do
	printf .
	sleep 1
	numt=$((numt - 1))
	if [ "$numt" = 0 ]; then
		echo ERROR: Number of tries exceeded. Operation cancelled. 1>&2
		exit 1

Certbot Automatic Certificate Acquisition and Renewal

As already mentioned, Let's Encrypt does not lend itself well to automation. That is mostly because of the problem mentioned in the preceding paragraphs: In order for Let's Encrypt to work it requires access to the challenge through port 80. As this port is served by the same webserver that is also binding port 443 for TLS, the server needs some certificates already to start up.

Hence usually, this part of the setup is hand-crafted by first starting the server with either a dummy certificate or on port 80 only. Then, the Let's Encrypt Challenge is answered to receive the production certificates after which the Nginx server is restarted to pick up the new certificates.

Additionally, after having performed this procedure once, a part of it has to be re-run in order to renew certificates after a few months.

In this repository, a custom script is used to automate all of these tasks. It works by passing through multiple stages some of which are synchronized by the other parts of the automation ( and

The main part of the script is a large cases statement that is described in the following:

case "$stage" in
	if [ -d "$path" ]; then
		find "$path" -mindepth 1 -delete
		mkdir -p "$path"
	cp /opt/certbot/src/certbot/certbot/ssl-dhparams.pem /etc/letsencrypt
	openssl req -x509 -nodes -newkey rsa:4096 -days 10 \
			-keyout "$path/privkey.pem" -out "$path/fullchain.pem" \
			-subj "/CN=$VIRTUAL_HOST"
	uuid="$(cat /proc/sys/kernel/random/uuid)"
	echo "uuid=$uuid"
	mkdir -p /var/www/certbot/.well-known/acme-challenge
	echo "$uuid" \
		> /var/www/certbot/.well-known/acme-challenge/server_online.txt
	echo 2_await_server_online > /etc/letsencrypt/stage
	exec "$0"

The first stage is concerned with generating a self-signed certificate such that nginx will come up despite there not being a Let's Encrypt certificate yet. It also writes an UUID to a text file that will be served by nginx which allows the subsequent stage to detect if the server is online yet.

	uuid="$(cat \
	while sleep 1; do
		printf .
		if wget -qO- http://proxy/.well-known/acme-challenge/server_online.txt 2> /dev/null | grep -qF "$uuid"; then
	echo 3_get_first_letsencrypt > /etc/letsencrypt/stage
	exec "$0"

This stage awaits the nginx (proxy service) to come online. This is a required precondition such that Let's Encrypt can download the challenge response in the next step.

	rm -r "/etc/letsencrypt/live/${VIRTUAL_HOST}"
	certbot certonly --webroot -w /var/www/certbot \
				--email "${LETSENCRYPT_EMAIL}" $test_cert_arg \
				-d "$VIRTUAL_HOST" --rsa-key-size 4096 \
				--agree-tos --force-renewal
	echo 4_await_server_restart > /etc/letsencrypt/stage
	exec "$0"

This stage directs certbot to trigger Let's Encrypt certificate generation. As soon as it is completed, it proceeds to the next stage.

	expected_fingerprint="$(openssl x509 -fingerprint -sha256 -noout \
		-in "/etc/letsencrypt/live/$VIRTUAL_HOST/fullchain.pem")"
	while sleep 10 && ! proxy; do
		printf .
	echo 5_update_letsencrypt_periodic > /etc/letsencrypt/stage
	exec "$0"

This stage synchronizes to the restart triggered by the healthcheck of the proxy service. In theory this would be optional (the delay in stage 5 is long enough that it should have restarted by then) but it better signals the completion of the process to have this stage pass through.

	sleep 86400 || echo 5_update_letsencrypt_periodic: ignoring \
							interrupted start delay
	echo 6_update_letsencrypt_now > /etc/letsencrypt/stage
	exec "$0"

This stage passes to 6 once a day in order to have certbot check if it makes sense to renew the certificate.

	echo 5_update_letsencrypt_periodic > /etc/letsencrypt/stage
	certbot renew --webroot -w /var/www/certbot --email \
		"${LETSENCRYPT_EMAIL}" $test_cert_arg \
		--rsa-key-size 4096 --agree-tos --deploy-hook \
		"echo 4_await_server_restart > /etc/letsencrypt/stage"
	exec "$0"

This is the actual invocation of the certificate renewal. After this stage, we go back to stage 5 if the process did not yield a new certificate and to stage 4 if a new certificate was obtained (note the --deploy-hook argument).

Handling Updates

There seem to be two images widely used to address automatic upgrades of docker containers. Both of them work by watching the base images for changes and applying them by re-creating the container using the new image on the fly.

  1. watchtower
  2. ouroboros

Both are setup very similarly. Use e.g. the following command for setting up watchtower (copied from documentation, works):

docker run -d --name ma-d-watchtower -v /var/run/docker.sock:/var/run/docker.sock containrrr/watchtower

Doing it this way is not strictly correct given that with this setup, watchtower could interrupt the containers at any time including during critical transactions. Doing it correctly will only affect a small minority of cases but require much more effort in form of suitable hook scripts. Feel free to extend the setup in that regard and share the results :)

It makes sense to run watchtower outside of docker-compose because it is expected that only a single instance runs per machine. I.e. if there are multiple services deployed through multiple docker-compose.yml in different directories then all should share the same (single) watchtower instance. It would also be possible to configure watchtower to monitor only a limited set of containers explicitly, but in such setups difficulty arises from ensuring that no two services are unexpectedly handled by multiple watchtowers. Here, the single-instance approach is preferred.

Post Installation

After installation, continue configuration by the means presented by Nextcloud. To enable server-side encryption with a per-user key that cannot be recovered by admins, the following settings seem to be needed. Run these inside the nextcloud container -- not all of these features are available through the GUI.

occ app:enable encryption
occ encryption:enable
occ encryption:encrypt-all
occ encryption:disable-master-key

Documentation wrt. encryption seems to be outdated, see nextcloud/server#8283 (comment)

It might also be required to fix some issues in config.php -- it remains a little unclear which of them can will be set correctly by environment variables and which of them need to be set explicitly. In my case, the following settings had to be hand-checked (path storage/config/config.php, notation slightly amended for brevity):

	'memcache.local'       => '\\OC\\Memcache\\APCu',
	'memcache.distributed' => '\\OC\\Memcache\\Redis',
	'memcache.locking'     => '\\OC\\Memcache\\Redis',
	'redis'                => ['host'=>'redis','password'=>'','port'=>6379],
	'trusted_domains'      => [0 => 'innerweb', 1 => ''],
	'overwrite.cli.url'    => '',
	'overwritehost'        => '',
	'overwriteprotocol'    => 'https',
	// ...

Benchmarks and Clients

One of the big drawbacks of a solution like Nextcloud compared to other, less web-centric variants such as exposing an SSH server for file storage or hosting an own AWS S3 compatible storage with minio is the difficulty of integrating Nextcloud as a real file store rather than only a web interface for file upload and download.

One way is the official Nextcloud Desktop client which I will hereafter refer to as GUI client. Additionally, multiple non-Nextcloud tools were researched and tried for comparision. Only two of these tools could be instantiated and run successfully in the setup at hand: rclone and davfs2. Both of them make use of the WebDAV backend for Nextcloud which is available under davs:// where is your domain name and masysma your username.

While there is also an official Nextcloud commandline client (nextcloudcmd), it does not seem to support TLS Client Certificates yet.

The following test data was used to check upload performance:

Testset du -sh/G find | wc -l

JMBB 30 1737 Bupstash 31 68529

The following tools were considered:

Tool In Debian? Worked? Version Tested Programming Language Links

davfs2 Y Y 1.6.0-1 C GUI Y Y 3.5.0 AppImage C++ rclone Y Y 1.53.3-1+b6 Go lftp Y N 4.8.4-2+b1 C++ webdav_sync N N 1.1.9 Java syncany N N 5a90af9c3f3d66 Java

The server runs on an Intel NUC with the following characteristics (syssheet -g output, IP address redacted):

┌─────── System Sheet Script 1.2.7, Copyright (c) 2012-2021 ─────────┐
│ linux-fan (id 1000) on rxvt-unicode-256color  Debian GNU/Linux 11 (bullseye) │
│ Linux 5.10.0-13-amd64                                                 x86_64 │
│ 15.05.2022 15:07:17                                               masysma-16 │
│ up 36 days, 25 min,  4 users,  load avg: 0.24, 0.20, 0.64      1254/7834 MiB │
│ 4 Intel(R) Celeron(R) CPU J3455 @ 1.50GHz                                    │
├────────────────────────────────── Network ───────────────────────────────────┤
│ Interface                      Sent/MiB  Received/MiB                Address │
│ enp2s0                            91337        397894                        │
├─────────────────────────────── File systems ─────────────────────────────────┤
│ Mountpoint                     Used/GiB        Of/GiB             Percentage │
│ /                                   335          1817                    19% │
├─────────────────────────────────── Users ────────────────────────────────────┤
│ Username     MEM/MiB            Top/MEM      CPU          Top/CPU   Time/min │
│ systemd-cor+     454           postgres     2.4%     redis-server         36 │
│ systemd-tim+      58              nginx       1%            nginx         21 │
│ dnsmasq            1            dnsmasq       0%          dnsmasq          0 │

Setup davfs2

  • Add clientcert /etc/davfs2/certs/client01.full.pfx in /etc/davfs2/davfs2.conf
  • chown root:root /etc/davfs2/certs/client01.full.pfx
  • mount -t davfs -o username=masysma,uid=1000,gid=1000 /media/davfs2
  • Enter password

Setup GUI

  • Prepare client01.full.pfx and import it into your default web browser.
  • Start the GUI
  • Give Domain name, username and password.
  • Then select that you want to use a TLS client certificate
  • Provide client01.full.pfx to the GUI
  • Let it open the web browser and login there, presenting the TLS certificate, too.
  • Then the GUI should become accessible. If not, it is most likely that any of the config.php parameters mentioned above is configured wrongly.

Setup rclone

  • Copy client01.crt and client01.key to /media/disk2zfs/wd
  • rclone config create nextcloud webdav url user masysma pass <password>

Benchmark davfs2

$ time rsync -a /media/disk2zfs/wd/testset_jmbb/ /media/davfs2/testset_jmbb/ && time umount /media/davfs2
real    224m23.520s
user    0m32.776s
sys     1m20.936s
/sbin/umount.davfs: waiting for mount.davfs (pid 2810) to terminate gracefully ......................................................................................................................................................................................................................................................................................................................................... OK

real    16m32.194s
user    0m2.828s
sys     0m5.319s

Benchmarks with the Bupstash test set were cancelled for very slow and partial progress after long times. Multiple tries were attempted and cancelled at the following times:

  • rsync test cancelled after 4035m4.004s (IOW after about three days)
  • cp -Rv test cancelled after 1370m25.744s (IOW after about one day)

Benchmark GUI

The GUI benchmark was performed by rsync-ing data between two VMs: One which held the source data and one which held the directory that is being synchronized by the GUI tool. Measurement starts when the copying is initiated and finishes as soon as the GUI displays the green checkmark for completion. The time of this was captured by repeatedly doing screenshots with scrot in intervals of 30 seconds. Due to the large data sizes and times under consideration, this should not account for a large inaccurracy.

$ time rsync -a testset_jmbb/ linux-fan@
linux-fan@'s password: 

real    2m15.060s
user    1m44.812s
sys     1m12.587s
$ date
Sat 14 May 2022 04:54:21 PM CEST
$ date # from screenshots
Sat 14 May 2022 06:42:58 PM CEST
$ maxima

(%i1) (2*60+15.060) + (06-04)*3600+(42-54)*60+58-21;
(%o1)                               6652.06
$ date; time rsync -a testset_bupstash/ linux-fan@; date
Sat 14 May 2022 09:29:30 PM CEST
linux-fan@'s password:

real    4m54.974s
user    3m18.544s
sys     1m52.748s
Sat 14 May 2022 09:34:25 PM CEST
$ date # from screenshots
Sun 15 May 2022 02:44:33 PM CEST

Traffic reported on the Nextcloud machine during GUI uploads

In the figure, one can see two green areas: The large one on the left is the traffic that was monitored during the upload of the JMBB test set with the GUI client. The smaller and wider one on the right is the traffic monitored during the upload of the Bupstash test set.

Benchmark rclone

$ time rclone --fast-list --progress --client-cert /media/disk2zfs/wd/client01.crt --client-key /media/disk2zfs/wd/client01.key sync /media/disk2zfs/wd/testset_jmbb/ nextcloud:testset_jmbb --create-empty-src-dirs
real    84m10.653s
user    1m18.506s
sys     1m26.575s

JMBB rclone Traffic is on the very right

For the JMBB benchmark, a graphical representation of the network traffic on the target (Nextcloud) machine can be seen in the figure above.

$ time rclone --fast-list --client-cert /media/disk2zfs/wd/client01.crt --client-key /media/disk2zfs/wd/client01.key sync /media/disk2zfs/wd/testset_bupstash/ nextcloud:testset_bupstash --create-empty-src-dirs
real    2330m55.025s
user    9m29.465s
sys     6m47.965s


Tool JMBB [MiB/s] Bupstash [MiB/s]

davfs2 2.11 (see text) GUI 4.67 0.51 rclone 6.03 0.22

Conclusion and Future Directions

It is surprising how difficult it is to setup a Nextcloud securely today. Also, Nextcloud's performance on low-end servers like the one used here is rather bad.

The recommended tool to access Nextcloud is definitely rclone given that it shows good performance and is automation-friendly. In case a synchronization running in background is preferred, the GUI client works well, too. davfs2 can only be recommended for cases where a small number of files is processed given that operations grinded to halt with the bupstash testset.

Missing TLS Client Certificate support in the official Nextcloud CLI should be fixed. lftp should be made to run on Nextcloud's WebDAV.

Finally, it also seems important to not foreget about the “easier” means of exposing a secure file storage online: SSH and Minio/S3 come into mind as notable alternatives.


Content of this document and relevant scripts are available under GPLv3 or later. Feel free to contact me if you would like to use them under a different license.

Nextcloud in Docker with Letsencrypt and TLS Client Certificates,
Copyright (c) 2022
For further info send an e-mail to

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <>.

Notes from Failed Benchmarks

This section collects data about programs that couldn't be convinced to run. It serves as a list of “open ends” that could be pursued further if time permits.

Setup lftp

$ lftp
lftp> set ssl:cert-file client01.crt
lftp> set ssl:key-file client01.key
lftp> set ssl:ca-file /etc/ssl/certs/ca-certificates.crt
lftp> set ssl:verify-certificate false
lftp> set http:use-propfind yes
lftp> set http:use-allprop yes
lftp> connect -u masysma,<password> https://<url>/remote.php/dav/files/masysma/
lftp> ls

Displays an empty directory where the remote contents would have been expected!

Setup Webdav_Sync

Setup Syncany

git clone
cd syncany
./gradlew installDist
cd ./build/install/syncany/lib
ls *.jar | tr '\n' ':'
java -cp animal-sniffer-annotations-1.17.jar:bcpkix-jdk15on... org.syncany.Syncany

Here, it only shows local plugin which seems to mean it will not do WebDav? The command series to chose (if it worked) is init, connect, up.


Nextcloud in Docker with Letsencrypt and TLS Client Certificates







No releases published