diff --git a/doc/manual/advanced-topics/distributed-builds.xml b/doc/manual/advanced-topics/distributed-builds.xml index 1957e1105..20fd6a0cf 100644 --- a/doc/manual/advanced-topics/distributed-builds.xml +++ b/doc/manual/advanced-topics/distributed-builds.xml @@ -4,71 +4,109 @@ version="5.0" xml:id='chap-distributed-builds'> -Distributed Builds +Remote Builds -Nix supports distributed builds, where a local Nix installation can -forward Nix builds to other machines over the network. This allows -multiple builds to be performed in parallel (thus improving -performance) and allows Nix to perform multi-platform builds in a -semi-transparent way. For instance, if you perform a build for a -x86_64-darwin on an i686-linux -machine, Nix can automatically forward the build to a -x86_64-darwin machine, if available. +Nix supports remote builds, where a local Nix installation can +forward Nix builds to other machines. This allows multiple builds to +be performed in parallel and allows Nix to perform multi-platform +builds in a semi-transparent way. For instance, if you perform a +build for a x86_64-darwin on an +i686-linux machine, Nix can automatically forward +the build to a x86_64-darwin machine, if +available. -You can enable distributed builds by setting the environment -variable NIX_BUILD_HOOK to point to a program that Nix -will call whenever it wants to build a derivation. The build hook -(typically a shell or Perl script) can decline the build, in which Nix -will perform it in the usual way if possible, or it can accept it, in -which case it is responsible for somehow getting the inputs of the -build to another machine, doing the build there, and getting the -results back. +To forward a build to a remote machine, it’s required that the +remote machine is accessible via SSH and that it has Nix +installed. You can test whether connecting to the remote Nix instance +works, e.g. -Remote machine configuration: -<filename>remote-systems.conf</filename> - -nix@mcflurry.labs.cs.uu.nl x86_64-darwin /home/nix/.ssh/id_quarterpounder_auto 2 -nix@scratchy.labs.cs.uu.nl i686-linux /home/nix/.ssh/id_scratchy_auto 8 1 kvm -nix@itchy.labs.cs.uu.nl i686-linux /home/nix/.ssh/id_scratchy_auto 8 2 -nix@poochie.labs.cs.uu.nl i686-linux /home/nix/.ssh/id_scratchy_auto 8 2 kvm perf - - + +$ nix ping-store --store ssh://mac + -Nix ships with a build hook that should be suitable for most -purposes. It uses ssh and -nix-copy-closure to copy the build inputs and -outputs and perform the remote build. To use it, you should set -NIX_BUILD_HOOK to -prefix/libexec/nix/build-remote. -You should also define a list of available build machines and point -the environment variable NIX_REMOTE_SYSTEMS to -it. NIX_REMOTE_SYSTEMS must be an absolute path. An -example configuration is shown in . Each line in the file specifies a machine, with the following -bits of information: +will try to connect to the machine named mac. It is +possible to specify an SSH identity file as part of the remote store +URI, e.g. + + +$ nix ping-store --store ssh://mac?ssh-key=/home/alice/my-key + + +Since builds should be non-interactive, the key should not have a +passphrase. Alternatively, you can load identities ahead of time into +ssh-agent or gpg-agent. + +If you get the error + + +bash: nix-store: command not found +error: cannot connect to 'mac' + + +then you need to ensure that the PATH of +non-interactive login shells contains Nix. + +If you are building via the Nix daemon, it is the Nix +daemon user account (that is, root) that should +have SSH access to the remote machine. If you can’t or don’t want to +configure root to be able to access to remote +machine, you can use a private Nix store instead by passing +e.g. --store ~/my-nix. + +The list of remote machines can be specified on the command line +or in the Nix configuration file. The former is convenient for +testing. For example, the following command allows you to build a +derivation for x86_64-darwin on a Linux machine: + + +$ uname +Linux + +$ nix build \ + '(with import <nixpkgs> { system = "x86_64-darwin"; }; runCommand "foo" {} "uname > $out")' \ + --builders 'ssh://mac x86_64-darwin' +[1/0/1 built, 0.0 MiB DL] building foo on ssh://mac + +$ cat ./result +Darwin + + +It is possible to specify multiple builders separated by a semicolon +or a newline, e.g. + + + --builders 'ssh://mac x86_64-darwin ; ssh://beastie x86_64-freebsd' + + + +Each machine specification consists of the following elements, +separated by spaces. Only the first element is required. - The name of the remote machine, with optionally the - user under which the remote build should be performed. This is - actually passed as an argument to ssh, so it can - be an alias defined in your + The URI of the remote store in the format + ssh://[username@]hostname, + e.g. ssh://nix@mac or + ssh://mac. For backward compatibility, + ssh:// may be omitted. The hostname may be an + alias defined in your ~/.ssh/config. A comma-separated list of Nix platform type identifiers, such as x86_64-darwin. It is possible for a machine to support multiple platform types, e.g., - i686-linux,x86_64-linux. + i686-linux,x86_64-linux. If omitted, this + defaults to the local platform type. - The SSH private key to be used to log in to the - remote machine. Since builds should be non-interactive, this key - should not have a passphrase! + The SSH identity file to be used to log in to the + remote machine. If omitted, SSH will use its regular + identities. - The maximum number of builds that - build-remote will execute in parallel on the - machine. Typically this should be equal to the number of CPU cores. - For instance, the machine itchy in the example - will execute up to 8 builds in parallel. + The maximum number of builds that Nix will execute + in parallel on the machine. Typically this should be equal to the + number of CPU cores. For instance, the machine + itchy in the example will execute up to 8 builds + in parallel. The “speed factor”, indicating the relative speed of the machine. If there are multiple machines of the right type, Nix @@ -76,30 +114,69 @@ bits of information: A comma-separated list of supported features. If a derivation has the - requiredSystemFeatures attribute, then - build-remote will only perform the - derivation on a machine that has the specified features. For - instance, the attribute + requiredSystemFeatures attribute, then Nix will + only perform the derivation on a machine that has the specified + features. For instance, the attribute requiredSystemFeatures = [ "kvm" ]; will cause the build to be performed on a machine that has the - kvm feature (i.e., scratchy in - the example above). + kvm feature. A comma-separated list of mandatory features. A machine will only be used to build a derivation if all of the machine’s mandatory features appear in the - derivation’s requiredSystemFeatures attribute. - Thus, in the example, the machine poochie will - only do derivations that have - requiredSystemFeatures set to ["kvm" - "perf"] or ["perf"]. + derivation’s requiredSystemFeatures + attribute.. - +For example, the machine specification + + +nix@scratchy.labs.cs.uu.nl i686-linux /home/nix/.ssh/id_scratchy_auto 8 1 kvm +nix@itchy.labs.cs.uu.nl i686-linux /home/nix/.ssh/id_scratchy_auto 8 2 +nix@poochie.labs.cs.uu.nl i686-linux /home/nix/.ssh/id_scratchy_auto 1 2 kvm benchmark + + +specifies several machines that can perform +i686-linux builds. However, +poochie will only do builds that have the attribute + + +requiredSystemFeatures = [ "benchmark" ]; + + +or + + +requiredSystemFeatures = [ "benchmark" "kvm" ]; + + +itchy cannot do builds that require +kvm, but scratchy does support +such builds. For regular builds, itchy will be +preferred over scratchy because it has a higher +speed factor. + +Remote builders can also be configured in +nix.conf, e.g. + + +builders = ssh://mac x86_64-darwin ; ssh://beastie x86_64-freebsd + + +Finally, remote builders can be configured in a separate configuration +file included in via the syntax +@file. For example, + + +builders = @/etc/nix/machines + + +causes the list of machines in /etc/nix/machines +to be included. (This is the default.) diff --git a/doc/manual/command-ref/conf-file.xml b/doc/manual/command-ref/conf-file.xml index c14a4d206..f65805899 100644 --- a/doc/manual/command-ref/conf-file.xml +++ b/doc/manual/command-ref/conf-file.xml @@ -763,7 +763,7 @@ builtins.fetchurl { more details. - Since these files are loaded into the same address space as + Since these files are loaded into the same address space as Nix itself, they must be DSOs compatible with the instance of Nix running at the time (i.e. compiled against the same headers, not linked to any incompatible libraries). They @@ -771,14 +771,23 @@ builtins.fetchurl { be available already at load time. - If an entry in the list is a directory, all files in the - directory are loaded as plugins (non-recursively). + If an entry in the list is a directory, all files in the + directory are loaded as plugins (non-recursively). + + builders + + A list of machines on which to perform builds. See for details. + + + diff --git a/src/nix/ping-store.cc b/src/nix/ping-store.cc new file mode 100644 index 000000000..310942574 --- /dev/null +++ b/src/nix/ping-store.cc @@ -0,0 +1,35 @@ +#include "command.hh" +#include "shared.hh" +#include "store-api.hh" + +using namespace nix; + +struct CmdPingStore : StoreCommand +{ + std::string name() override + { + return "ping-store"; + } + + std::string description() override + { + return "test whether a store can be opened"; + } + + Examples examples() override + { + return { + Example{ + "To test whether connecting to a remote Nix store via SSH works:", + "nix ping-store --store ssh://mac1" + }, + }; + } + + void run(ref store) override + { + store->connect(); + } +}; + +static RegisterCommand r1(make_ref());