selfhostblocks/demo/nextcloud

Nextcloud Demo

This whole demo is highly insecure as all the private keys are available publicly. This is only done for convenience as it is just a demo. Do not expose the VM to the internet.

The flake.nix file sets up a Nextcloud server with Self Host Blocks. There are actually 3 demos:

• The basic demo sets up a lone Nextcloud server accessible through http with the Preview Generator app enabled.
• The ldap demo builds on top of the basic demo integrating Nextcloud with a LDAP provider.
• The sso demo builds on top of the lsap demo integrating Nextcloud with a SSO provider.

They were set up by following the manual. This guide will show how to deploy these demos to a Virtual Machine, like showed here.

Deploy to the VM

The demos are setup to either deploy to a VM through nixos-rebuild or through Colmena.

Using nixos-rebuild is very fast and requires less steps because it reuses your nix store.

Using colmena is more authentic because you are deploying to a stock VM, like you would with a real machine but it needs to copy over all required store derivations so it takes a few minutes the first time.

Deploy with nixos-rebuild

Assuming your current working directory is the one where this Readme file is located, the one-liner command which builds and starts the VM configured to run Self Host Blocks' Nextcloud is:

rm nixos.qcow2; \
  nixos-rebuild build-vm --flake .#basic \
  && QEMU_NET_OPTS="hostfwd=tcp::2222-:2222,hostfwd=tcp::8080-:80" \
     ./result/bin/run-nixos-vm

This will deploy the basic demo. If you want to deploy the ldap or sso demos, use respectively the .#ldap or .#sso flake uris.

You can even test the demos from any directory without cloning this repository by using the GitHub uri like github:ibizaman/selfhostblocks?path=demo/nextcloud

It is very important to remove leftover nixos.qcow2 files, if any.

You can ssh into the VM like this, but this is not required for the demo:

ssh -F ssh_config example

But before that works, you will need to change the permission of the ssh key like so:

chmod 600 sshkey

This is only needed because git mangles with the permissions. You will not even see this change in git status.

Deploy with Colmena

If you deploy with Colmena, you must first build the VM and start it:

rm nixos.qcow2; \
  nixos-rebuild build-vm-with-bootloader --fast -I nixos-config=./configuration.nix -I nixpkgs=. ; \
  QEMU_NET_OPTS="hostfwd=tcp::2222-:2222,hostfwd=tcp::8080-:80" ./result/bin/run-nixos-vm

It is very important to remove leftover nixos.qcow2 files, if any.

This last call is blocking, so I advice adding a & at the end of the command otherwise you will need to run the rest of the commands in another terminal.

With the VM started, make the secrets in secrets.yaml decryptable in the VM. This change will appear in git status but you don't need to commit this.

SOPS_AGE_KEY_FILE=keys.txt \
  nix run --impure nixpkgs#sops -- --config sops.yaml -r -i \
  --add-age $(nix shell nixpkgs#ssh-to-age --command sh -c 'ssh-keyscan -p 2222 -t ed25519 -4 localhost 2>/dev/null | ssh-to-age') \
  secrets.yaml

The nested command, the one in between the parenthesis $(...), is used to print the VM's public age key, which is then added to the secrets.yaml file in order to make the secrets decryptable by the VM.

If you forget this step, the deploy will seem to go fine but the secrets won't be populated and Nextcloud will not start.

Make the ssh key private:

chmod 600 sshkey

This is only needed because git mangles with the permissions. You will not even see this change in git status.

You can ssh into the VM like this, but this is not required for the demo:

ssh -F ssh_config example

Nextcloud through HTTP

:::: {.note} This section corresponds to the basic section of the Nextcloud manual. ::::

Assuming you already deployed the basic demo, now you must add the following entry to the /etc/hosts file on the host machine (not the VM):

networking.hosts = {
  "127.0.0.1" = [ "n.example.com" ];
};

Which produces:

$ cat /etc/hosts
127.0.0.1 n.example.com

Go to http://n.example.com:8080 and login with:

• username: root
• password: the value of the field nextcloud.adminpass in the secrets.yaml file which is 43bb4b8f82fc645ce3260b5db803c5a8.

This is the admin user of Nextcloud and that's the end of the basic demo.

Nextcloud with LDAP through HTTP

:::: {.note} This section corresponds to the ldap section of the Nextcloud manual. ::::

Assuming you already deployed the ldap demo, now you must add the following entry to the /etc/hosts file on the host machine (not the VM):

networking.hosts = {
  "127.0.0.1" = [ "n.example.com" "ldap.example.com" ];
};

Which produces:

$ cat /etc/hosts
127.0.0.1 n.example.com ldap.example.com

Go first to http://ldap.example.com:8080 and login with:

• username: admin
• password: the value of the field lldap.user_password in the secrets.yaml file which is c2e32e54ea3e0053eb30841f818a3d9a.

Create the group nextcloud_user and a create a user and assign them to that group.

Finally, go to http://n.example.com/login:8080 and login with the user and password you just created above.

Nextcloud doesn't like being run without SSL protection, which this demo does not setup, so you might see errors loading scripts. See the sso demo for SSL.

This is the end of the ldap demo.

Nextcloud with LDAP and SSO through self-signed HTTPS

:::: {.note} This section corresponds to the sso section of the Nextcloud manual. ::::

At this point, it is assumed you already deployed the sso demo. There is no host to add to /etc/hosts here. Instead, there is a dnsmasq server running in the VM and you must create a SOCKS proxy to connect to it like so:

ssh -F ssh_config -D 1080 -N example

This is a blocking call but it is not necessary to fork this process in the background by appending & because we will not need to use the terminal for the rest of the demo.

Now, configure your browser to use that SOCKS proxy. When that's done go to https://ldap.example.com and login with:

• username: admin
• password: the value of the field lldap.user_password in the secrets.yaml file which is c2e32e54ea3e0053eb30841f818a3d9a.

Create the group nextcloud_user and a create a user and assign them to that group.

Visit https://auth.example.com and make your browserauthorize the certificate.

Finally, go to https://n.example.com and login with the user and password you just created above. You will see that the login page is actually the one from the SSO provider.

This is the end of the sso demo.

In More Details

Files

• flake.nix: nix entry point, defines the target hosts for colmena to deploy to as well as the selfhostblock's config for setting up Nextcloud and the auxiliary services.
• configuration.nix: defines all configuration required for colmena to deploy to the VM. The file has comments if you're interested.
• hardware-configuration.nix: defines VM specific layout. This was generated with nixos-generate-config on the VM.
• Secrets related files:
  • keys.txt: your private key for sops-nix, allows you to edit the secrets.yaml file. This file should never be published but here I did it for convenience, to be able to deploy to the VM in less steps.
  • secrets.yaml: encrypted file containing required secrets for Nextcloud. This file can be publicly accessible.
  • sops.yaml: describes how to create the secrets.yaml file. Can be publicly accessible.
• SSH related files:
  • sshkey(.pub): your private and public ssh keys. Again, the private key should usually not be published as it is here but this makes it possible to deploy to the VM in less steps.
  • ssh_config: the ssh config allowing you to ssh into the VM by just using the hostname example. Usually you would store this info in your ~/.ssh/config file but it's provided here to avoid making you do that.

Virtual Machine

More info about the VM.

We use build-vm-with-bootloader instead of just build-vm as that's the only way to deploy to the VM.

The VM's User and password are both nixos, as setup in the configuration.nix file under user.users.nixos.initialPassword.

You can login with ssh -F ssh_config example. You just need to accept the fingerprint.

The VM's hard drive is a file name nixos.qcow2 in this directory. It is created when you first create the VM and re-used since. You can just remove it when you're done.

That being said, the VM uses tmpfs to create the writable nix store so if you stumble in a disk space issue, you must increase the virtualisation.vmVariantWithBootLoader.virtualisation.memorySize setting.

Secrets

More info about the secrets can be found in the Usage manual

To open the secrets.yaml file and optionnally edit it, run:

SOPS_AGE_KEY_FILE=keys.txt nix run --impure nixpkgs#sops -- \
  --config sops.yaml \
  secrets.yaml

You can generate random secrets with:

nix run nixpkgs#openssl -- rand -hex 64

If you choose secrets too small, some services could refuse to start.

Why do we need the VM's public key

The sops.yaml file describes what private keys can decrypt and encrypt the secrets.yaml file containing the application secrets. Usually, you will create and add secrets to that file and when deploying, it will be decrypted and the secrets will be copied in the /run/secrets folder on the VM. We thus need one private key for you to edit the secrets.yaml file and one in the VM for it to decrypt the secrets.

Your private key is already pre-generated in this repo, it's the sshkey file. But when creating the VM for Colmena, a new private key and its accompanying public key were automatically generated under /etc/ssh/ssh_host_ed25519_key in the VM. We just need to get the public key and add it to the secrets.yaml which we did in the Deploy section.

SSH

The private and public ssh keys were created with:

ssh-keygen -t ed25519 -f sshkey

You don't need to copy over the ssh public key over to the VM as we set the keyFiles option which copies the public key when the VM gets created. This allows us also to disable ssh password authentication.

For reference, if instead you didn't copy the key over on VM creating and enabled ssh authentication, here is what you would need to do to copy over the key:

$ nix shell nixpkgs#openssh --command ssh-copy-id -i sshkey -F ssh_config example

Deploy

If you get a NAR hash mismatch error like hereunder, you need to run nix flake lock --update-input selfhostblocks.

error: NAR hash mismatch in input ...

Update Demo

If you update the Self Host Blocks configuration in flake.nix file, you can just re-deploy.

If you update the configuration.nix file, you will need to rebuild the VM from scratch.

If you update a module in the Self Host Blocks repository, you will need to update the lock file with:

nix flake lock --override-input selfhostblocks ../.. --update-input selfhostblocks