forked from lix-project/lix
fetchClosure: Interleave the examples in the docs
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@ -211,52 +211,42 @@ static RegisterPrimOp primop_fetchClosure({
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.name = "__fetchClosure",
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.args = {"args"},
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.doc = R"(
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Fetch a store path [closure](@docroot@/glossary.md#gloss-closure) from a binary cache.
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Fetch a store path [closure](@docroot@/glossary.md#gloss-closure) from a binary cache, and return the store path as a string with context.
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This function can be used in three ways:
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This function can be invoked in three ways, that we will discuss in order of preference.
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- Fetch any store path and rewrite it to a fully content-addressed store path.
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Example:
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```nix
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builtins.fetchClosure {
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fromStore = "https://cache.nixos.org";
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fromPath = /nix/store/r2jd6ygnmirm2g803mksqqjm4y39yi6i-git-2.33.1;
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toPath = /nix/store/ldbhlwhh39wha58rm61bkiiwm6j7211j-git-2.33.1;
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}
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```
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- Fetch a content-addressed store path.
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**Fetch a content-addressed store path**
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Example:
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```nix
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builtins.fetchClosure {
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fromStore = "https://cache.nixos.org";
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fromPath = /nix/store/ldbhlwhh39wha58rm61bkiiwm6j7211j-git-2.33.1;
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}
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```
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```nix
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builtins.fetchClosure {
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fromStore = "https://cache.nixos.org";
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fromPath = /nix/store/ldbhlwhh39wha58rm61bkiiwm6j7211j-git-2.33.1;
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}
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```
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- Fetch an [input-addressed store path](@docroot@/glossary.md#gloss-input-addressed-store-object) as is. This depends on user configuration, which is less preferable.
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This is the simplest invocation, and it does not require the user of the expression to configure [`trusted-public-keys`](@docroot@/command-ref/conf-file.md#conf-trusted-public-keys) to ensure their authenticity.
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Example:
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If your store path is [input addressed](@docroot@/glossary.md#gloss-input-addressed-store-object) instead of content addressed, consider the other two invocations.
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```nix
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builtins.fetchClosure {
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fromStore = "https://cache.nixos.org";
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fromPath = /nix/store/r2jd6ygnmirm2g803mksqqjm4y39yi6i-git-2.33.1;
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inputAddressed = true;
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}
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```
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**Fetch any store path and rewrite it to a fully content-addressed store path**
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**Rewriting a store path**
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Example:
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This first example fetches `/nix/store/r2jd...` from the specified binary cache,
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```nix
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builtins.fetchClosure {
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fromStore = "https://cache.nixos.org";
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fromPath = /nix/store/r2jd6ygnmirm2g803mksqqjm4y39yi6i-git-2.33.1;
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toPath = /nix/store/ldbhlwhh39wha58rm61bkiiwm6j7211j-git-2.33.1;
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}
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```
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This example fetches `/nix/store/r2jd...` from the specified binary cache,
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and rewrites it into the content-addressed store path
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`/nix/store/ldbh...`.
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By rewriting the store paths, you can add the contents to any store without requiring that you or perhaps your users configure any extra trust.
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Like the previous example, no extra configuration or privileges are required.
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To find out the correct value for `toPath` given a `fromPath`,
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use [`nix store make-content-addressed`](@docroot@/command-ref/new-cli/nix3-store-make-content-addressed.md):
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@ -268,20 +258,25 @@ static RegisterPrimOp primop_fetchClosure({
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Alternatively, set `toPath = ""` and find the correct `toPath` in the error message.
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**Not rewriting**
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**Fetch an input-addressed store path as is**
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`toPath` may be omitted when either
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- `fromPath` is already content-addressed, or
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- `inputAddressed = true;` is set.
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Example:
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Fetching an [input addressed path](@docroot@/glossary.md#gloss-input-addressed-store-object) is not recommended because it requires that the source be trusted by the Nix configuration.
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```nix
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builtins.fetchClosure {
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fromStore = "https://cache.nixos.org";
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fromPath = /nix/store/r2jd6ygnmirm2g803mksqqjm4y39yi6i-git-2.33.1;
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inputAddressed = true;
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}
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```
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It is possible to fetch an [input-addressed store path](@docroot@/glossary.md#gloss-input-addressed-store-object) and return it as is.
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However, this is the least preferred way of invoking `fetchClosure`, because it requires that the input-addressed paths are trusted by the Nix configuration.
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**`builtins.storePath`**
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This function is similar to [`builtins.storePath`](#builtins-storePath) in that it
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allows you to use a previously built store path in a Nix
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expression. However, it is more reproducible because it requires
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specifying a binary cache from which the path can be fetched.
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`fetchClosure` is similar to [`builtins.storePath`](#builtins-storePath) in that it allows you to use a previously built store path in a Nix expression.
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However, `fetchClosure` is more reproducible because it specifies a binary cache from which the path can be fetched.
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Also, using content-addressed store paths does not require users to configure [`trusted-public-keys`](@docroot@/command-ref/conf-file.md#conf-trusted-public-keys) to ensure their authenticity.
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)",
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.fun = prim_fetchClosure,
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