Reorganize documentation for new website (#213)

This PR should be merged after the new website is deployed.

- [x] Rename files
- [x] Add front matter section to all `.md` files in the book (necessary for Zola)
- [x] Change all internal links to use Zola's linking system that checks broken links
- [x] Some updates to documentation contents and organization

Co-authored-by: Alex Auvolat <alex@adnab.me>
Reviewed-on: https://git.deuxfleurs.fr/Deuxfleurs/garage/pulls/213
Co-authored-by: Alex <alex@adnab.me>
Co-committed-by: Alex <alex@adnab.me>

1 files changed, 240 insertions, 0 deletions

diff --git a/doc/book/reference-manual/configuration.md b/doc/book/reference-manual/configuration.md
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+title = "Configuration file format"
+weight = 5
++++
+
+Here is an example `garage.toml` configuration file that illustrates all of the possible options:
+
+```toml
+metadata_dir = "/var/lib/garage/meta"
+data_dir = "/var/lib/garage/data"
+
+block_size = 1048576
+
+replication_mode = "3"
+
+compression_level = 1
+
+rpc_secret = "4425f5c26c5e11581d3223904324dcb5b5d5dfb14e5e7f35e38c595424f5f1e6"
+rpc_bind_addr = "[::]:3901"
+rpc_public_addr = "[fc00:1::1]:3901"
+
+bootstrap_peers = [
+    "563e1ac825ee3323aa441e72c26d1030d6d4414aeb3dd25287c531e7fc2bc95d@[fc00:1::1]:3901",
+    "86f0f26ae4afbd59aaf9cfb059eefac844951efd5b8caeec0d53f4ed6c85f332[fc00:1::2]:3901",
+    "681456ab91350f92242e80a531a3ec9392cb7c974f72640112f90a600d7921a4@[fc00:B::1]:3901",
+    "212fd62eeaca72c122b45a7f4fa0f55e012aa5e24ac384a72a3016413fa724ff@[fc00:F::1]:3901",
+]
+
+consul_host = "consul.service"
+consul_service_name = "garage-daemon"
+
+sled_cache_capacity = 134217728
+sled_flush_every_ms = 2000
+
+[s3_api]
+api_bind_addr = "[::]:3900"
+s3_region = "garage"
+root_domain = ".s3.garage"
+
+[s3_web]
+bind_addr = "[::]:3902"
+root_domain = ".web.garage"
+index = "index.html"
+```
+
+The following gives details about each available configuration option.
+
+## Available configuration options
+
+### `metadata_dir`
+
+The directory in which Garage will store its metadata. This contains the node identifier,
+the network configuration and the peer list, the list of buckets and keys as well
+as the index of all objects, object version and object blocks.
+
+Store this folder on a fast SSD drive if possible to maximize Garage's performance.
+
+### `data_dir`
+
+The directory in which Garage will store the data blocks of objects.
+This folder can be placed on an HDD. The space available for `data_dir`
+should be counted to determine a node's capacity
+when [configuring it](@/documentation/cookbook/real-world.md).
+
+### `block_size`
+
+Garage splits stored objects in consecutive chunks of size `block_size`
+(except the last one which might be smaller). The default size is 1MB and
+should work in most cases.  If you are interested in tuning this, feel free
+to do so (and remember to report your findings to us!). If this value is
+changed for a running Garage installation, only files newly uploaded will be
+affected. Previously uploaded files will remain available. This however
+means that chunks from existing files will not be deduplicated with chunks
+from newly uploaded files, meaning you might use more storage space that is
+optimally possible.
+
+### `replication_mode`
+
+Garage supports the following replication modes:
+
+- `none` or `1`: data stored on Garage is stored on a single node. There is no redundancy,
+  and data will be unavailable as soon as one node fails or its network is disconnected.
+  Do not use this for anything else than test deployments.
+
+- `2`: data stored on Garage will be stored on two different nodes, if possible in different
+  zones. Garage tolerates one node failure before losing data. Data should be available
+  read-only when one node is down, but write operations will fail.
+  Use this only if you really have to.
+
+- `3`: data stored on Garage will be stored on three different nodes, if possible each in
+  a different zones.
+  Garage tolerates two node failure before losing data. Data should be available
+  read-only when two nodes are down, and writes should be possible if only a single node
+  is down.
+
+Note that in modes `2` and `3`,
+if at least the same number of zones are available, an arbitrary number of failures in 
+any given zone is tolerated as copies of data will be spread over several zones.
+
+**Make sure `replication_mode` is the same in the configuration files of all nodes.
+Never run a Garage cluster where that is not the case.**
+
+Changing the `replication_mode` of a cluster might work (make sure to shut down all nodes
+and changing it everywhere at the time), but is not officially supported.
+
+### `compression_level`
+
+Zstd compression level to use for storing blocks.
+
+Values between `1` (faster compression) and `19` (smaller file) are standard compression
+levels for zstd. From `20` to `22`, compression levels are referred as "ultra" and must be
+used with extra care as it will use lot of memory. A value of `0` will let zstd choose a
+default value (currently `3`). Finally, zstd has also compression designed to be faster
+than default compression levels, they range from `-1` (smaller file) to `-99` (faster 
+compression).
+
+If you do not specify a `compression_level` entry, garage will set it to `1` for you. With
+this parameters, zstd consumes low amount of cpu and should work faster than line speed in
+most situations, while saving some space and intra-cluster
+bandwidth.
+
+If you want to totally deactivate zstd in garage, you can pass the special value `'none'`. No
+zstd related code will be called, your chunks will be stored on disk without any processing.
+
+Compression is done synchronously, setting a value too high will add latency to write queries.
+
+This value can be different between nodes, compression is done by the node which receive the
+API call.
+
+### `rpc_secret`
+
+Garage uses a secret key that is shared between all nodes of the cluster
+in order to identify these nodes and allow them to communicate together.
+This key should be specified here in the form of a 32-byte hex-encoded
+random string. Such a string can be generated with a command
+such as `openssl rand -hex 32`.
+
+### `rpc_bind_addr`
+
+The address and port on which to bind for inter-cluster communcations
+(reffered to as RPC for remote procedure calls).
+The port specified here should be the same one that other nodes will used to contact
+the node, even in the case of a NAT: the NAT should be configured to forward the external
+port number to the same internal port nubmer. This means that if you have several nodes running
+behind a NAT, they should each use a different RPC port number.
+
+### `rpc_public_addr`
+
+The address and port that other nodes need to use to contact this node for
+RPC calls.  **This parameter is optional but recommended.** In case you have
+a NAT that binds the RPC port to a port that is different on your public IP,
+this field might help making it work.
+
+### `bootstrap_peers`
+
+A list of peer identifiers on which to contact other Garage peers of this cluster.
+These peer identifiers have the following syntax:
+
+```
+<node public key>@<node public IP or hostname>:<port>
+```
+
+In the case where `rpc_public_addr` is correctly specified in the
+configuration file, the full identifier of a node including IP and port can
+be obtained by running `garage node id` and then included directly in the
+`bootstrap_peers` list of other nodes.  Otherwise, only the node's public
+key will be returned by `garage node id` and you will have to add the IP
+yourself.
+
+### `consul_host` and `consul_service_name`
+
+Garage supports discovering other nodes of the cluster using Consul.
+This works only when nodes are announced in Consul by an orchestrator such as Nomad,
+as Garage is not able to announce itself.
+
+The `consul_host` parameter should be set to the hostname of the Consul server,
+and `consul_service_name` should be set to the service name under which Garage's
+RPC ports are announced.
+
+### `sled_cache_capacity`
+
+This parameter can be used to tune the capacity of the cache used by
+[sled](https://sled.rs), the database Garage uses internally to store metadata.
+Tune this to fit the RAM you wish to make available to your Garage instance.
+More cache means faster Garage, but the default value (128MB) should be plenty
+for most use cases.
+
+### `sled_flush_every_ms`
+
+This parameters can be used to tune the flushing interval of sled.
+Increase this if sled is thrashing your SSD, at the risk of losing more data in case
+of a power outage (though this should not matter much as data is replicated on other
+nodes). The default value, 2000ms, should be appropriate for most use cases.
+
+
+
+## The `[s3_api]` section
+
+### `api_bind_addr`
+
+The IP and port on which to bind for accepting S3 API calls.
+This endpoint does not suport TLS: a reverse proxy should be used to provide it.
+
+### `s3_region`
+
+Garage will accept S3 API calls that are targetted to the S3 region defined here.
+API calls targetted to other regions will fail with a AuthorizationHeaderMalformed error
+message that redirects the client to the correct region.
+
+### `root_domain` {#root_domain}
+
+The optionnal suffix to access bucket using vhost-style in addition to path-style request.
+Note path-style requests are always enabled, whether or not vhost-style is configured.
+Configuring vhost-style S3 required a wildcard DNS entry, and possibly a wildcard TLS certificate,
+but might be required by softwares not supporting path-style requests.
+
+If `root_domain` is `s3.garage.eu`, a bucket called `my-bucket` can be interacted with
+using the hostname `my-bucket.s3.garage.eu`.
+
+
+
+## The `[s3_web]` section
+
+Garage allows to publish content of buckets as websites. This section configures the
+behaviour of this module.
+
+### `bind_addr`
+
+The IP and port on which to bind for accepting HTTP requests to buckets configured
+for website access.
+This endpoint does not suport TLS: a reverse proxy should be used to provide it.
+
+### `root_domain`
+
+The optionnal suffix appended to bucket names for the corresponding HTTP Host.
+
+For instance, if `root_domain` is `web.garage.eu`, a bucket called `deuxfleurs.fr`
+will be accessible either with hostname `deuxfleurs.fr.web.garage.eu`
+or with hostname `deuxfleurs.fr`.
+