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diff --git a/nixos/modules/services/databases/foundationdb.xml b/nixos/modules/services/databases/foundationdb.xml deleted file mode 100644 index 611535a9eb8a..000000000000 --- a/nixos/modules/services/databases/foundationdb.xml +++ /dev/null @@ -1,425 +0,0 @@ -<!-- Do not edit this file directly, edit its companion .md instead - and regenerate this file using nixos/doc/manual/md-to-db.sh --> -<chapter xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xml:id="module-services-foundationdb"> - <title>FoundationDB</title> - <para> - <emphasis>Source:</emphasis> - <filename>modules/services/databases/foundationdb.nix</filename> - </para> - <para> - <emphasis>Upstream documentation:</emphasis> - <link xlink:href="https://apple.github.io/foundationdb/">https://apple.github.io/foundationdb/</link> - </para> - <para> - <emphasis>Maintainer:</emphasis> Austin Seipp - </para> - <para> - <emphasis>Available version(s):</emphasis> 5.1.x, 5.2.x, 6.0.x - </para> - <para> - FoundationDB (or <quote>FDB</quote>) is an open source, distributed, - transactional key-value store. - </para> - <section xml:id="module-services-foundationdb-configuring"> - <title>Configuring and basic setup</title> - <para> - To enable FoundationDB, add the following to your - <filename>configuration.nix</filename>: - </para> - <programlisting> -services.foundationdb.enable = true; -services.foundationdb.package = pkgs.foundationdb52; # FoundationDB 5.2.x -</programlisting> - <para> - The <option>services.foundationdb.package</option> option is - required, and must always be specified. Due to the fact - FoundationDB network protocols and on-disk storage formats may - change between (major) versions, and upgrades must be explicitly - handled by the user, you must always manually specify this - yourself so that the NixOS module will use the proper version. - Note that minor, bugfix releases are always compatible. - </para> - <para> - After running <command>nixos-rebuild</command>, you can verify - whether FoundationDB is running by executing - <command>fdbcli</command> (which is added to - <option>environment.systemPackages</option>): - </para> - <programlisting> -$ sudo -u foundationdb fdbcli -Using cluster file `/etc/foundationdb/fdb.cluster'. - -The database is available. - -Welcome to the fdbcli. For help, type `help'. -fdb> status - -Using cluster file `/etc/foundationdb/fdb.cluster'. - -Configuration: - Redundancy mode - single - Storage engine - memory - Coordinators - 1 - -Cluster: - FoundationDB processes - 1 - Machines - 1 - Memory availability - 5.4 GB per process on machine with least available - Fault Tolerance - 0 machines - Server time - 04/20/18 15:21:14 - -... - -fdb> -</programlisting> - <para> - You can also write programs using the available client libraries. - For example, the following Python program can be run in order to - grab the cluster status, as a quick example. (This example uses - <command>nix-shell</command> shebang support to automatically - supply the necessary Python modules). - </para> - <programlisting> -a@link> cat fdb-status.py -#! /usr/bin/env nix-shell -#! nix-shell -i python -p python pythonPackages.foundationdb52 - -import fdb -import json - -def main(): - fdb.api_version(520) - db = fdb.open() - - @fdb.transactional - def get_status(tr): - return str(tr['\xff\xff/status/json']) - - obj = json.loads(get_status(db)) - print('FoundationDB available: %s' % obj['client']['database_status']['available']) - -if __name__ == "__main__": - main() -a@link> chmod +x fdb-status.py -a@link> ./fdb-status.py -FoundationDB available: True -a@link> -</programlisting> - <para> - FoundationDB is run under the <command>foundationdb</command> user - and group by default, but this may be changed in the NixOS - configuration. The systemd unit - <command>foundationdb.service</command> controls the - <command>fdbmonitor</command> process. - </para> - <para> - By default, the NixOS module for FoundationDB creates a single - SSD-storage based database for development and basic usage. This - storage engine is designed for SSDs and will perform poorly on - HDDs; however it can handle far more data than the alternative - <quote>memory</quote> engine and is a better default choice for - most deployments. (Note that you can change the storage backend - on-the-fly for a given FoundationDB cluster using - <command>fdbcli</command>.) - </para> - <para> - Furthermore, only 1 server process and 1 backup agent are started - in the default configuration. See below for more on scaling to - increase this. - </para> - <para> - FoundationDB stores all data for all server processes under - <filename>/var/lib/foundationdb</filename>. You can override this - using <option>services.foundationdb.dataDir</option>, e.g. - </para> - <programlisting> -services.foundationdb.dataDir = "/data/fdb"; -</programlisting> - <para> - Similarly, logs are stored under - <filename>/var/log/foundationdb</filename> by default, and there - is a corresponding <option>services.foundationdb.logDir</option> - as well. - </para> - </section> - <section xml:id="module-services-foundationdb-scaling"> - <title>Scaling processes and backup agents</title> - <para> - Scaling the number of server processes is quite easy; simply - specify <option>services.foundationdb.serverProcesses</option> to - be the number of FoundationDB worker processes that should be - started on the machine. - </para> - <para> - FoundationDB worker processes typically require 4GB of RAM - per-process at minimum for good performance, so this option is set - to 1 by default since the maximum amount of RAM is unknown. You’re - advised to abide by this restriction, so pick a number of - processes so that each has 4GB or more. - </para> - <para> - A similar option exists in order to scale backup agent processes, - <option>services.foundationdb.backupProcesses</option>. Backup - agents are not as performance/RAM sensitive, so feel free to - experiment with the number of available backup processes. - </para> - </section> - <section xml:id="module-services-foundationdb-clustering"> - <title>Clustering</title> - <para> - FoundationDB on NixOS works similarly to other Linux systems, so - this section will be brief. Please refer to the full FoundationDB - documentation for more on clustering. - </para> - <para> - FoundationDB organizes clusters using a set of - <emphasis>coordinators</emphasis>, which are just - specially-designated worker processes. By default, every - installation of FoundationDB on NixOS will start as its own - individual cluster, with a single coordinator: the first worker - process on <command>localhost</command>. - </para> - <para> - Coordinators are specified globally using the - <command>/etc/foundationdb/fdb.cluster</command> file, which all - servers and client applications will use to find and join - coordinators. Note that this file <emphasis>can not</emphasis> be - managed by NixOS so easily: FoundationDB is designed so that it - will rewrite the file at runtime for all clients and nodes when - cluster coordinators change, with clients transparently handling - this without intervention. It is fundamentally a mutable file, and - you should not try to manage it in any way in NixOS. - </para> - <para> - When dealing with a cluster, there are two main things you want to - do: - </para> - <itemizedlist spacing="compact"> - <listitem> - <para> - Add a node to the cluster for storage/compute. - </para> - </listitem> - <listitem> - <para> - Promote an ordinary worker to a coordinator. - </para> - </listitem> - </itemizedlist> - <para> - A node must already be a member of the cluster in order to - properly be promoted to a coordinator, so you must always add it - first if you wish to promote it. - </para> - <para> - To add a machine to a FoundationDB cluster: - </para> - <itemizedlist spacing="compact"> - <listitem> - <para> - Choose one of the servers to start as the initial coordinator. - </para> - </listitem> - <listitem> - <para> - Copy the <command>/etc/foundationdb/fdb.cluster</command> file - from this server to all the other servers. Restart - FoundationDB on all of these other servers, so they join the - cluster. - </para> - </listitem> - <listitem> - <para> - All of these servers are now connected and working together in - the cluster, under the chosen coordinator. - </para> - </listitem> - </itemizedlist> - <para> - At this point, you can add as many nodes as you want by just - repeating the above steps. By default there will still be a single - coordinator: you can use <command>fdbcli</command> to change this - and add new coordinators. - </para> - <para> - As a convenience, FoundationDB can automatically assign - coordinators based on the redundancy mode you wish to achieve for - the cluster. Once all the nodes have been joined, simply set the - replication policy, and then issue the - <command>coordinators auto</command> command - </para> - <para> - For example, assuming we have 3 nodes available, we can enable - double redundancy mode, then auto-select coordinators. For double - redundancy, 3 coordinators is ideal: therefore FoundationDB will - make <emphasis>every</emphasis> node a coordinator automatically: - </para> - <programlisting> -fdbcli> configure double ssd -fdbcli> coordinators auto -</programlisting> - <para> - This will transparently update all the servers within seconds, and - appropriately rewrite the <command>fdb.cluster</command> file, as - well as informing all client processes to do the same. - </para> - </section> - <section xml:id="module-services-foundationdb-connectivity"> - <title>Client connectivity</title> - <para> - By default, all clients must use the current - <command>fdb.cluster</command> file to access a given FoundationDB - cluster. This file is located by default in - <command>/etc/foundationdb/fdb.cluster</command> on all machines - with the FoundationDB service enabled, so you may copy the active - one from your cluster to a new node in order to connect, if it is - not part of the cluster. - </para> - </section> - <section xml:id="module-services-foundationdb-authorization"> - <title>Client authorization and TLS</title> - <para> - By default, any user who can connect to a FoundationDB process - with the correct cluster configuration can access anything. - FoundationDB uses a pluggable design to transport security, and - out of the box it supports a LibreSSL-based plugin for TLS - support. This plugin not only does in-flight encryption, but also - performs client authorization based on the given endpoint’s - certificate chain. For example, a FoundationDB server may be - configured to only accept client connections over TLS, where the - client TLS certificate is from organization <emphasis>Acme - Co</emphasis> in the <emphasis>Research and Development</emphasis> - unit. - </para> - <para> - Configuring TLS with FoundationDB is done using the - <option>services.foundationdb.tls</option> options in order to - control the peer verification string, as well as the certificate - and its private key. - </para> - <para> - Note that the certificate and its private key must be accessible - to the FoundationDB user account that the server runs under. These - files are also NOT managed by NixOS, as putting them into the - store may reveal private information. - </para> - <para> - After you have a key and certificate file in place, it is not - enough to simply set the NixOS module options – you must also - configure the <command>fdb.cluster</command> file to specify that - a given set of coordinators use TLS. This is as simple as adding - the suffix <command>:tls</command> to your cluster coordinator - configuration, after the port number. For example, assuming you - have a coordinator on localhost with the default configuration, - simply specifying: - </para> - <programlisting> -XXXXXX:XXXXXX@127.0.0.1:4500:tls -</programlisting> - <para> - will configure all clients and server processes to use TLS from - now on. - </para> - </section> - <section xml:id="module-services-foundationdb-disaster-recovery"> - <title>Backups and Disaster Recovery</title> - <para> - The usual rules for doing FoundationDB backups apply on NixOS as - written in the FoundationDB manual. However, one important - difference is the security profile for NixOS: by default, the - <command>foundationdb</command> systemd unit uses <emphasis>Linux - namespaces</emphasis> to restrict write access to the system, - except for the log directory, data directory, and the - <command>/etc/foundationdb/</command> directory. This is enforced - by default and cannot be disabled. - </para> - <para> - However, a side effect of this is that the - <command>fdbbackup</command> command doesn’t work properly for - local filesystem backups: FoundationDB uses a server process - alongside the database processes to perform backups and copy the - backups to the filesystem. As a result, this process is put under - the restricted namespaces above: the backup process can only write - to a limited number of paths. - </para> - <para> - In order to allow flexible backup locations on local disks, the - FoundationDB NixOS module supports a - <option>services.foundationdb.extraReadWritePaths</option> option. - This option takes a list of paths, and adds them to the systemd - unit, allowing the processes inside the service to write (and - read) the specified directories. - </para> - <para> - For example, to create backups in - <command>/opt/fdb-backups</command>, first set up the paths in the - module options: - </para> - <programlisting> -services.foundationdb.extraReadWritePaths = [ "/opt/fdb-backups" ]; -</programlisting> - <para> - Restart the FoundationDB service, and it will now be able to write - to this directory (even if it does not yet exist.) Note: this path - <emphasis>must</emphasis> exist before restarting the unit. - Otherwise, systemd will not include it in the private FoundationDB - namespace (and it will not add it dynamically at runtime). - </para> - <para> - You can now perform a backup: - </para> - <programlisting> -$ sudo -u foundationdb fdbbackup start -t default -d file:///opt/fdb-backups -$ sudo -u foundationdb fdbbackup status -t default -</programlisting> - </section> - <section xml:id="module-services-foundationdb-limitations"> - <title>Known limitations</title> - <para> - The FoundationDB setup for NixOS should currently be considered - beta. FoundationDB is not new software, but the NixOS compilation - and integration has only undergone fairly basic testing of all the - available functionality. - </para> - <itemizedlist spacing="compact"> - <listitem> - <para> - There is no way to specify individual parameters for - individual <command>fdbserver</command> processes. Currently, - all server processes inherit all the global - <command>fdbmonitor</command> settings. - </para> - </listitem> - <listitem> - <para> - Ruby bindings are not currently installed. - </para> - </listitem> - <listitem> - <para> - Go bindings are not currently installed. - </para> - </listitem> - </itemizedlist> - </section> - <section xml:id="module-services-foundationdb-options"> - <title>Options</title> - <para> - NixOS’s FoundationDB module allows you to configure all of the - most relevant configuration options for - <command>fdbmonitor</command>, matching it quite closely. A - complete list of options for the FoundationDB module may be found - <link linkend="opt-services.foundationdb.enable">here</link>. You - should also read the FoundationDB documentation as well. - </para> - </section> - <section xml:id="module-services-foundationdb-full-docs"> - <title>Full documentation</title> - <para> - FoundationDB is a complex piece of software, and requires careful - administration to properly use. Full documentation for - administration can be found here: - <link xlink:href="https://apple.github.io/foundationdb/">https://apple.github.io/foundationdb/</link>. - </para> - </section> -</chapter> |