49 lines
2.2 KiB
Markdown
49 lines
2.2 KiB
Markdown
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# Custom Jsonnet Compiler
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This directory contains a custom Jsonnet compiler built with Go. It wraps the standard `go-jsonnet` library and adds a native function `helmTemplate` to support rendering Helm charts directly within Jsonnet.
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## `helmTemplate` Native Function
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The `helmTemplate` function allows you to render a Helm chart located on the filesystem.
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### Signature
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```jsonnet
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native("helmTemplate")(name, chartPath, opts)
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```
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- `name`: The release name.
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- `chartPath`: The path to the Helm chart directory (containing `Chart.yaml`). **Crucial:** This path must be relative to the directory containing the file that calls `helmTemplate`. When using Bazel external repositories, this often means navigating up to the execution root (e.g., `../../external/repo_name`).
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- `opts`: A configuration object.
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- `calledFrom`: (Required) The path of the file calling the function. Usually `std.thisFile`. The compiler uses this to resolve relative paths.
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- `nameFormat`: (Optional) Format string for resource names.
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- `values`: (Optional) Values to pass to the Helm chart.
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- `includeCRDs`: (Optional) Boolean, default `true`.
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- `namespace`: (Optional) Namespace for the release.
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### Usage Example
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```jsonnet
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local helm = std.native("helmTemplate");
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helm("my-release", "../../external/my_chart_repo", {
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calledFrom: std.thisFile,
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namespace: "default",
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values: {
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replicaCount: 2,
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},
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})
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```
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## Bazel Integration
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This compiler is registered as a custom toolchain in `//tools/jsonnet_compiler:helm_jsonnet_toolchain` and used by `rules_jsonnet`.
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### Imports and JPaths
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When using `rules_jsonnet`, the `imports` attribute adds directories to the Jsonnet search path (`-J`).
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- `imports = ["."]` adds the package directory.
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- `deps` on `jsonnet_library` targets adds their roots to the search path.
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When importing files from external repositories (like `tanka-util`), ensure the import path matches the structure within that repository. For example, if `tanka-util` library is at the root of the `@github_com_grafana_jsonnet_libs_tanka_util` repo, you can import it as `import "tanka-util/main.libsonnet"` provided the repo root is in the search path (which `deps` handles).
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