Write documentation on configuration file and other improvements

3 files changed, 203 insertions, 3 deletions

diff --git a/doc/book/src/reference_manual/cli.md b/doc/book/src/reference_manual/cli.md
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@@ -0,0 +1,4 @@
+# Garage CLI
+
+The Garage CLI is mostly self-documented. Make use of the `help` subcommand
+and the `--help` flag to discover all available options.
diff --git a/doc/book/src/reference_manual/configuration.md b/doc/book/src/reference_manual/configuration.md
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+# Garage configuration file format reference
+
+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"
+
+rpc_bind_addr = "[::]:3901"
+
+bootstrap_peers = [
+  "[fc00:1::1]:3901",
+  "[fc00:1::2]:3901",
+  "[fc00:B::1]:3901",
+  "[fc00:F::1]:3901",
+]
+
+consul_host = "consul.service"
+consul_service_name = "garage-daemon"
+
+max_concurrent_rpc_requests = 12
+
+sled_cache_capacity = 134217728
+sled_flush_every_ms = 2000
+
+[rpc_tls]
+ca_cert = "/etc/garage/pki/garage-ca.crt"
+node_cert = "/etc/garage/pki/garage.crt"
+node_key = "/etc/garage/pki/garage.key"
+
+[s3_api]
+s3_region = "garage"
+api_bind_addr = "[::]:3900"
+
+[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](../getting_started/05_cluster.md).
+
+#### `block_size`
+
+Garage splits stored objects in consecutive chunks of size `block_size` (except the last
+one which might be standard). 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!)
+
+#### `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.
+
+#### `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.
+
+#### `bootstrap_peers`
+
+A list of IPs and ports on which to contact other Garage peers of this cluster.
+This should correspond to the RPC ports set up with `rpc_bind_addr`.
+
+#### `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.
+
+#### `max_concurrent_rpc_requests`
+
+Garage implements rate limiting for RPC requests: no more than
+`max_concurrent_rpc_requests` concurrent outbound RPC requests will be made
+by a Garage node (additionnal requests will be put in a waiting queue).
+
+#### `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 `[rpc_tls]` section
+
+This section should be used to configure the TLS certificates used to encrypt
+intra-cluster traffic (RPC traffic). The following parameters should be set:
+
+- `ca_cert`: the certificate of the CA that is allowed to sign individual node certificates
+- `node_cert`: the node certificate for the current node
+- `node_key`: the key associated with the node certificate
+
+Note tha several nodes may use the same node certificate, as long as it is signed
+by the CA.
+
+If this section is absent, TLS is not used to encrypt intra-cluster traffic.
+
+
+## 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.
+
+
+## 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`.
+
+#### `index`
+
+The name of the index file to return for requests ending with `/` (usually `index.html`).
diff --git a/doc/book/src/reference_manual/s3_compatibility.md b/doc/book/src/reference_manual/s3_compatibility.md
index c0fc2863..5f9f527a 100644
--- a/doc/book/src/reference_manual/s3_compatibility.md
+++ b/doc/book/src/reference_manual/s3_compatibility.md
@@ -1,6 +1,6 @@
-## S3 Compatibility status
+# S3 Compatibility status
 
-### Global S3 features
+## Global S3 features
 
 Implemented:
 
@@ -18,7 +18,7 @@ Not implemented:
 - most `x-amz-` headers
 
 
-### Endpoint implementation
+## Endpoint implementation
 
 All APIs that are not mentionned are not implemented and will return a 400 bad request.