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Diffstat (limited to 'doc/builders/special/invalidateFetcherByDrvHash.section.md')
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diff --git a/doc/builders/special/invalidateFetcherByDrvHash.section.md b/doc/builders/special/invalidateFetcherByDrvHash.section.md deleted file mode 100644 index 7c2f03a64b7..00000000000 --- a/doc/builders/special/invalidateFetcherByDrvHash.section.md +++ /dev/null @@ -1,31 +0,0 @@ - -## `invalidateFetcherByDrvHash` {#sec-pkgs-invalidateFetcherByDrvHash} - -Use the derivation hash to invalidate the output via name, for testing. - -Type: `(a@{ name, ... } -> Derivation) -> a -> Derivation` - -Normally, fixed output derivations can and should be cached by their output -hash only, but for testing we want to re-fetch everytime the fetcher changes. - -Changes to the fetcher become apparent in the drvPath, which is a hash of -how to fetch, rather than a fixed store path. -By inserting this hash into the name, we can make sure to re-run the fetcher -every time the fetcher changes. - -This relies on the assumption that Nix isn't clever enough to reuse its -database of local store contents to optimize fetching. - -You might notice that the "salted" name derives from the normal invocation, -not the final derivation. `invalidateFetcherByDrvHash` has to invoke the fetcher -function twice: once to get a derivation hash, and again to produce the final -fixed output derivation. - -Example: - - tests.fetchgit = invalidateFetcherByDrvHash fetchgit { - name = "nix-source"; - url = "https://github.com/NixOS/nix"; - rev = "9d9dbe6ed05854e03811c361a3380e09183f4f4a"; - sha256 = "sha256-7DszvbCNTjpzGRmpIVAWXk20P0/XTrWZ79KSOGLrUWY="; - }; |