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# 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.
#
# If the build fails, Buildkite metadata is updated to mark the
# pipeline as failed. Buildkite has a concept of a failed pipeline
# regardless, but this data is not accessible.
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)"
"|| (buildkite-agent meta-data set 'failure' '1'; exit 1)"
];
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
# Wait for all previous checks to complete
({
wait = null;
continue_on_failure = true;
})
# Wait for all steps to complete, then exit with success or
# failure depending on whether any failure status was written.
# This step must be :duck:! (yes, really!)
({
command = "exit $(buildkite-agent meta-data get 'failure')";
label = ":duck:";
key = ":duck:";
})
# 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))
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