508d67ad49
At least terraform wants all parameters passed via JSON to be strings. It can't accept maps. This means, allowing to pass a `argstr` JSON dict isn't really possible. However, terraform is perfectly able to JSON-encode a map. So accept a `argstr_json` argument instead, which `jq` will JSON-decode before further processing it. I dropped `argstr` support again so the jq expression still fits on my screen, if anyone else (started) using this, I'm happy to review a CL adding this. We should probably move the jq expression to some multiline format then, though. Change-Id: I5ab7a1169ab7305d3ab02db31c27732d9d1ab4e8 Reviewed-on: https://cl.tvl.fyi/c/depot/+/11228 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI
47 lines
1.9 KiB
Bash
Executable file
47 lines
1.9 KiB
Bash
Executable file
#!/usr/bin/env bash
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# SPDX-FileCopyrightText: 2023 The TVL Authors
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#
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# SPDX-License-Identifier: MIT
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set -ueo pipefail
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# Evaluates a Nix expression.
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#
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# Receives input parameters as JSON from stdin.
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# It expects a dict with the following keys:
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#
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# - `attrpath`: the attribute.path pointing to the expression to instantiate.
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# Required.
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# - `entrypoint`: the path to the Nix file to invoke.
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# Optional. If omitted, will shell out to git to determine the repo root,
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# and Nix will use `default.nix` in there.
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# - `argstr_json`: A string JSON-encoding a map containing string keys and
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# values which should be passed to Nix as `--argstr $key $value`.
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# command line args. Optional.
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# - `build`: A boolean (or string being "true" or "false") stating whether the
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# expression should also be built/substituted on the machine executing this script.
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#
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# jq's @sh format takes care of escaping.
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eval "$(jq -r '@sh "attrpath=\(.attrpath) && entrypoint=\(.entrypoint) && argstr=\((.argstr_json // "{}"|fromjson) | to_entries | map ("--argstr", .key, .value) | join(" ")) build=\(.build)"')"
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# Evaluate the expression.
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[[ -z "$entrypoint" ]] && entrypoint=$(git rev-parse --show-toplevel)
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# shellcheck disable=SC2086,SC2154
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drv=$(nix-instantiate -A "${attrpath}" "${entrypoint}" ${argstr})
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# If `build` is set to true, invoke nix-build on the .drv.
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# We need to swallow all stdout, to not garble the JSON printed later.
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# shellcheck disable=SC2154
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if [ "${build}" == "true" ]; then
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nix-build --no-out-link "${drv}" > /dev/null
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fi
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# Determine the output path.
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outPath=$(nix show-derivation "${drv}" | jq -r ".\"${drv}\".outputs.out.path")
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# Return a JSON back to stdout.
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# It contains the following keys:
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#
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# - `drv`: the store path of the Derivation that has been instantiated.
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# - `outPath`: the output store path.
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jq -n --arg drv "$drv" --arg outPath "$outPath" '{"drv":$drv, "outPath":$outPath}'
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