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@@ -17,6 +17,142 @@ The following scripts are available here:
 - `tlsproxy.sh`, a script that allows non-TLS access to the TLS-secured Consul and Nomad, by running a simple local proxy with socat
 - `tlsenv.sh`, a script to be sourced (`source tlsenv.sh`) that configures the correct environment variables to use the Nomad and Consul CLI tools with TLS
 
+## Configuring the OS
+
+This repo contains a bunch of scripts to configure NixOS on all cluster nodes.
+Most scripts are invoked with the following syntax:
+
+- for scripts that generate secrets: `./gen_<something> <cluster_name>` to generate the secrets to be used on cluster `<cluster_name>`
+- for deployment scripts:
+  - `./deploy_<something> <cluster_name>` to run the deployment script on all nodes of the cluster `<cluster_name>`
+  - `./deploy_<something> <cluster_name> <node1> <node2> ...` to run the deployment script only on nodes `node1, node2, ...` of cluster `<cluster_name>`.
+
+
+### Assumptions (how to setup your environment)
+
+- you have an SSH access to all of your cluster nodes (listed in `cluster/<cluster_name>/ssh_config`)
+
+- your account is in group `wheel` and you know its password (you need it to become root using `sudo`)
+
+- you have a clone of the secrets repository in your `pass` password store, for instance at `~/.password-store/deuxfleurs`
+  (scripts in this repo will read and write all secrets in `pass` under `deuxfleurs/cluster/<cluster_name>/`)
+
+### Deploying the NixOS configuration
+
+The NixOS configuration makes use of a certain number of files:
+
+- files in `nix/` that are the same for all deployments on all clusters
+- the file `cluster/<cluster_name>/cluster.nix`, a Nix configuration file that is specific to the cluster but is copied the same on all cluster nodes
+- files in `cluster/<cluster_name>/site/`, which are specific to the various sites on which Nix nodes are deployed
+- files in `cluster/<cluster_name>/node/` which are specific to each node
+
+To deploy the NixOS configuration on the cluster, simply do:
+
+```
+./deploy_nixos <cluster_name>
+```
+
+or to deploy only on a single node:
+
+```
+./deploy_nixos <cluster_name> <node_name>
+```
+
+To upgrade NixOS, use the `./upgrade_nixos` script instead (it has the same syntax).
+
+**When adding a node to the cluster:** just do `./deploy_nixos <cluster_name> <name_of_new_node>`
+
+### Deploying Wesher
+
+We use Wesher to provide an encrypted overlay network between nodes in the cluster.
+This is usefull in particular for securing services that are not able to do mTLS,
+but as a security-in-depth measure, we make all traffic go through Wesher even when
+TLS is done correctly. It is thus mandatory to have a working Wesher installation
+in the cluster for it to run correctly.
+
+First, if no Wesher shared secret key has been generated for this cluster yet,
+generate it with:
+
+```
+./gen_wesher_key <cluster_name>
+```
+
+This key will be stored in `pass`, so you must have a working `pass` installation
+for this script to run correctly.
+
+Then, deploy the key on all nodes with:
+
+```
+./deploy_wesher_key <cluster_name>
+```
+
+This should be done after `./deploy_nixos` has run successfully on all nodes.
+You should now have a working Wesher network between all your nodes!
+
+**When adding a node to the cluster:** just do `./deploy_wesher_key <cluster_name> <name_of_new_node>`
+
+### Generating and deploying a PKI for Consul and Nomad
+
+This is very similar to how we do for Wesher.
+
+First, if the PKI has not yet been created, create it with:
+
+```
+./gen_pki <cluster_name>
+```
+
+Then, deploy the PKI on all nodes with:
+
+```
+./deploy_pki <cluster_name>
+```
+
+**When adding a node to the cluster:** just do `./deploy_pki <cluster_name> <name_of_new_node>`
+
+### Adding administrators
+
+Adminstrators are defined in the `cluster.nix` file for each cluster (they could also be defined in the site-specific Nix files if necessary).
+This is where their public SSH keys for remote access are put.
+
+Administrators will also need passwords to administrate the cluster, as we are not using passwordless sudo.
+To set the password for a new administrator, they must have a working `pass` installation as specified above.
+They must then run:
+
+```
+./passwd <cluster_name> <user_name>
+```
+
+to set their password in the `pass` database (the password is hashed, so other administrators cannot learn their password even if they have access to the `pass` db).
+
+Then, an administrator that already has root access must run the following (after syncing the `pass` db) to set the password correctly on all cluster nodes:
+
+```
+./deploy_passwords <cluster_name>
+```
+
+## Deploying stuff on Nomad
+
+### Connecting to Nomad
+
+Connect using SSH to one of the cluster nodes, forwarding port 14646 to port 4646 on localhost, and port 8501 to port 8501 on localhost.
+
+You can for instance use an entry in your `~/.ssh/config` that looks like this:
+
+```
+Host caribou
+	HostName 2a01:e0a:c:a720::23
+	LocalForward 14646 127.0.0.1:4646
+	LocalForward 8501 127.0.0.1:8501
+```
+
+Then, in a separate window, launch `./tlsproxy <cluster_name>`: this will
+launch `socat` proxies that strip the TLS layer and allow you to simply access
+Nomad and Consul on the regular, unencrypted URLs: `http://localhost:4646` for
+Nomad and `http://localhost:8500` for Consul.  Keep this terminal window for as
+long as you need to access Nomad and Consul on the cluster.
+
+### Launching services
+
 Stuff should be started in this order:
 
 - `app/core`