doc(use): add configuration with environment variables

doc/use/conf_env_var.md

+Title: Configure Duniter server variant with environment variables
+Order: 9
+Date: 2021-05-07
+Slug: configurer
+Authors: elois
+
+# Configure Duniter (server variant) with environment variables
+
+This tutorial shows how to configure duniter by setting **environment variables**.
+It is also possible to [configure duniter on command line](./configure.md).
+
+## Configuring the cryptographic keypair
+
+All duniter nodes have a cryptographic keypair, which they use to sign the information they transmit over the network. There are two types of duniter nodes:
+
+**1. member nodes:** If the node's keypair corresponds to a member identity, then the node is a "member" node, and
+will automatically take part in the calculation of the blocks.
+
+**2. Mirror nodes:** If the node's keypair does not match a member identity, then the node is "mirror" type, it will not be able to write a block, but will still be useful for network resilience and for responding to client requests.
+
+By default this keypair is random, so the duniter node is a mirror node.
+
+To modify the keypair of the node, you must create a keypair in a file and indicate the path to this file with the environment variable `DUNITER_KEYFILE`.
+
+## Configuring the network
+
+### The APIs
+
+  In version `2.0.x` there are two APIs (Application Programming Interface) allowing your node to communicate with other programs.
+
+1. WS2P (WebSocketToPeer): this API is dedicated to inter-node communication, i.e. between your duniter node and other nodes of the same currency. **WS2P is enabled by default** on your duniter node.
+2. GVA (Graphql Verification Api): this API is dedicated to the communication with client software (Ğecko, Tikka, ğcli, etc), it can also be used by any external program wishing to request the network (a website that would like to check the presence of a blockchain transaction for example). **GVA is disabled by default** on your duniter node.
+
+### Configuring WS2P Public
+
+This mode is disabled by default, in order for it to work you must configure a WS2P endpoint that other duniter nodes will be able to use to reach you.
+
+First enable the public WS2P mode:
+
+```bash
+DUNITER_WS2_PUBLIC="true"
+```
+
+#### Configure a WS2P endpoint
+
+For WS2P Public to work you must configure a WS2P endpoint that other duniter nodes will be able to use to reach you.
+
+If you use a reverse proxy, you must define "remote" host and port:
+
+```bash
+DUNITER_WS2_REMOTE_HOST="mydomaine.tld"
+DUNITER_WS2_REMOTE_PORT="443"
+```
+
+You can define a remote path:
+
+```bash
+DUNITER_WS2_REMOTE_PATH="/ws2p"
+```
+
+If you not use a reverse proxy, you can expose duniter directly
+
+```bash
+DUNITER_WS2_HOST="<your public IP>"
+DUNITER_WS2_PORT="your opened port"
+```
+
+#### WS2P preferred and privileged nodes
+
+See [dedicated page](./ws2p_preferred_privileged.md)
+
+### Configuring GVA
+
+GVA is still disabled by default, to enable it:
+
+```bash
+DUNITER_GVA_ENABLED="true"
+```
+
+Each parameter value can be defined by the environment variable of the parameter name in uppercase prefixed by `DUNITER_GVA_`.
+
+| parameter | env var name | type | default value |
+|:-:|:-:|:-:|:-:|
+| enabled | `DUNITER_GVA_ENABLED` | boolean | `false` |
+| ip4 | `DUNITER_GVA_IP4` | IPv4 | `0.0.0.0` |
+| ip6 | `DUNITER_GVA_IP6` | IPv6 | `::` |
+| port | `DUNITER_GVA_PORT` | number | `30901` |
+| path | `DUNITER_GVA_PATH` | string | `"gva"` |
+| remoteHost | `DUNITER_GVA_REMOTE_HOST` | string | - |
+| remotePath | `DUNITER_GVA_REMOTE_PATH` | string | `"gva"` |
+| subscriptionsPath | `DUNITER_GVA_SUBSCRIPTIONS_PATH` | string |  `"gva-sub"` |
+| remoteSubscriptionsPath | `DUNITER_GVA_REMOTE_SUBSCRIPTIONS_PATH` | string | `"gva-sub"` |
+| remoteTls | `DUNITER_GVA_REMOTE_TLS` | boolean |  `false` |
+| whitelist | `DUNITER_GVA_WHITELIST` | IP[] |  `["127.0.0.1", "::1"]` |

doc/use/ws2p_preferred_privileged.md

@@ -28,6 +28,12 @@ To consult the list of your preferred keys:
 duniter ws2p list-prefered
 ```
 
+Or use environment variable `DUNITER_WS2_PREFERED_KEYS`:
+
+```bash
+DUNITER_WS2_PREFERED_KEYS=PUBKEY1,PUBKEY2,PUBKEY3
+```
+
 ## Privileged nodes
 
 Just as you can set preferred keys for your outgoing WS2P connections, you can set privileged keys for your incoming WS2P connections. That is, if you receive more connection requests than the maximum number you have configured, connections initiated by nodes whose public key is part of your privileged keys will be given priority.
@@ -49,3 +55,9 @@ To consult the list of your privileged keys:
 ```bash
 duniter ws2p list-privileged
 ```
+
+Or use environment variable `DUNITER_WS2_PRIVILEGED_KEYS`:
+
+```bash
+DUNITER_WS2_PRIVILEGED_KEYS=PUBKEY1,PUBKEY2,PUBKEY3
+```