tvl-depot/ops/pipelines/depot.nix
Vincent Ambo e4231c9816 refactor(ops/pipelines): Move 🦆 logic into static pipeline
This simplifies the fallback logic used in case of Nix evaluation
failure and makes it so that the evaluation step itself is the one
that is marked as failed in Buildkite.

This is possible because the pipeline upload command will insert new
steps at the point where it runs in the pipeline, and not later.

Change-Id: I870534c004ebc457a1602623c4e5f9c0c68e28fc
2021-12-10 07:55:34 +00:00

100 lines
3.9 KiB
Nix

# This file configures the primary build pipeline used for the
# top-level list of depot targets.
#
# It outputs a "YAML" (actually JSON) file which is evaluated and
# submitted to Buildkite at the start of each build. This means we can
# dynamically configure the pipeline execution here.
{ depot, lib, pkgs, ... }:
let
inherit (builtins) concatStringsSep foldl' map toJSON;
inherit (pkgs) symlinkJoin writeText;
# Create an expression that builds the target at the specified
# location.
mkBuildExpr = target:
let
descend = expr: attr: "builtins.getAttr \"${attr}\" (${expr})";
targetExpr = foldl' descend "import ./. {}" target.__readTree;
subtargetExpr = descend targetExpr target.__subtarget;
in if target ? __subtarget then subtargetExpr else targetExpr;
# Create a pipeline label from the targets tree location.
mkLabel = target:
let label = concatStringsSep "/" target.__readTree;
in if target ? __subtarget
then "${label}:${target.__subtarget}"
else label;
# Create a pipeline step from a single target.
mkStep = target: {
command = let
drvPath = builtins.unsafeDiscardStringContext target.drvPath;
in lib.concatStringsSep " " [
# First try to realise the drvPath of the target so we don't evaluate twice.
# Nix has no concept of depending on a derivation file without depending on
# at least one of its `outPath`s, so we need to discard the string context
# if we don't want to build everything during pipeline construction.
"nix-store --realise '${drvPath}'"
# However, Nix doesn't track references of store paths to derivations, so
# there's no guarantee that the derivation file is not garbage collected.
# To handle this case we fall back to an ordinary build if the derivation
# file is missing.
"|| (test ! -f '${drvPath}' && nix-build -E '${mkBuildExpr target}' --show-trace)"
];
label = ":nix: ${mkLabel target}";
# Skip build steps if their out path has already been built.
skip = let
shouldSkip = with builtins;
# Only skip in real Buildkite builds
(getEnv "BUILDKITE_BUILD_ID" != "") &&
# Always build everything for the canon branch.
(getEnv "BUILDKITE_BRANCH" != "refs/heads/canon") &&
# Discard string context to avoid realising the store path during
# pipeline construction.
(pathExists (unsafeDiscardStringContext target.outPath));
in if shouldSkip then "Target was already built." else false;
};
# Protobuf check step which validates that changes to .proto files
# between revisions don't cause backwards-incompatible or otherwise
# flawed changes.
protoCheck = {
command = "${depot.nix.bufCheck}/bin/ci-buf-check";
label = ":water_buffalo:";
};
# This defines the build pipeline, using the pipeline format
# documented on https://buildkite.com/docs/pipelines/defining-steps
#
# Pipeline steps need to stay in order.
pipeline.steps =
# Create build steps for each CI target
(map mkStep depot.ci.targets)
++ [
# Simultaneously run protobuf checks
protoCheck
# After duck, on success, create a gcroot if the build branch is
# canon.
#
# We care that this anchors *most* of the depot, in practice
# it's unimportant if there is a build race and we get +-1 of
# the targets.
#
# Unfortunately this requires a third evaluation of the graph,
# but since it happens after :duck: it should not affect the
# timing of status reporting back to Gerrit.
({
command = "nix-instantiate -A ci.gcroot --add-root /nix/var/nix/gcroots/depot/canon";
label = ":anchor:";
"if" = ''build.branch == "refs/heads/canon"'';
depends_on = [{
step = ":duck:";
allow_failure = false;
}];
})
];
in (writeText "depot.yaml" (toJSON pipeline))