nix-tree

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I was trying to find why a derivation was taking up so much space. The best way I could figure out how to do it, with any tools, was to use nix-tree --derivation (without derivation I got basically no information). Unfortunately, when I use --derivation, the sizes nix-tree displays are the size of the .drv files, not the size of the outputs they correspond to, so I had to go through the tree and manually check each one with nix path-info -sh. I would really like it if there was a feature where I could see all derivations needed by a particular derivations, and how big their closures were.

I agree that this would be great. But with a quick glance at the output of nix path-info I don't know how to get it (all nix-tree does it to present the output from nix path-info):

Here's what we get from a .drv file:

[
  {
    "ca": "text:sha256:09032k2k62hs2rdci4d73m0700x8lg3y5akjsmfm1vwisqaja0yx",
    "narHash": "sha256-fRoQmEOYFdaO1RUirIIRyPvYr4DgtGjkwhmxIlwA6QQ=",
    "narSize": 10976,
    "path": "/nix/store/78vq5lqc8zc293p5l1pi8mclpdc7srjl-nix-tree-0.3.2.drv",
    "references": [
      "/nix/store/0f5651q4ad0f8kmnw7wnjzvjvar1xx1k-hedgehog-1.2.drv",
      "/nix/store/0yj0vb9cgz12qfh44748aq8igpr680ih-brick-1.9.drv",
      "/nix/store/23iz5hzg1k3zz6hg1s3vv0l6a4jr1f35-microlens-0.4.13.1.drv",
      "/nix/store/23rvqfz487pldw8g9l47j1smzvxirssp-relude-1.2.1.0.drv",
      "/nix/store/4mdp8nhyfddh7bllbi7xszz7k9955n79-Setup.hs",
      "/nix/store/6fy2r0i30qib0kh45mlkkjd1rkr9bqkv-aeson-2.1.2.1.drv",
      "/nix/store/7vanskz0pcjzl8733fl5n8lj6lc9mlip-stdenv-darwin.drv",
      "/nix/store/7w61llva61mlaq62dgz6420cv7898nhg-bash-5.2-p15.drv",
      "/nix/store/907d7wf2d113vlv8dlhi1i3d683gc1rs-unpretty-cabal-conf.awk",
      "/nix/store/a6jp2zh4970kxnzhnwq5pkk5jak6qfp8-gnugrep-3.11.drv",
      "/nix/store/h6m1z7vvi4jfw6pj9b5ijvp05p24flfg-optparse-applicative-0.17.1.0.drv",
      "/nix/store/n91kmq7mqdgrrpfzygrwkiff3vczdan8-coreutils-9.3.drv",
      "/nix/store/q102qffb637kr06lsjn1zrybs01gydl9-typed-process-0.2.11.1.drv",
      "/nix/store/r5r46wvv329iqilmsprx9d09c7awk6xz-hrfsize-0.0.2.drv",
      "/nix/store/rg6s4mzlfaynf7lndn4naxasdlp51aak-source",
      "/nix/store/s32q0nbjnm1nzwy5lfa7dbg7gv0gw8fh-unordered-containers-0.2.19.1.drv",
      "/nix/store/sflf2z2a8rbi2yq87df7pjapxfpbda6x-clock-0.8.4.drv",
      "/nix/store/svrj9sll3sfdmpwn8rz8rayyvm1z9s3d-ghc-9.4.8.drv",
      "/nix/store/v5vzabhax400n50n366qkqgkyfp0br2p-vty-5.38.drv",
      "/nix/store/v6x3cs394jgqfbi0a42pam708flxaphh-default-builder.sh",
      "/nix/store/wakr8bwj5ghyhl26vz866gy14bc2m6cs-remove-references-to.drv",
      "/nix/store/xw62q6v31bkl0l1p8qpbyn6fhva0hz51-terminal-progress-bar-0.4.2.drv",
      "/nix/store/zy871mjac4979r4nzfhgni5ksqamwh9a-async-2.2.4.drv"
    ],
    "registrationTime": 1702251131,
    "valid": true
  }
]

And here's one from the output:

[
  {
    "deriver": "/nix/store/78vq5lqc8zc293p5l1pi8mclpdc7srjl-nix-tree-0.3.2.drv",
    "narHash": "sha256-J9NGSgfPk2kXiuP53jGlWyRW69utXjMRo1L4+7fR+X0=",
    "narSize": 51749224,
    "path": "/nix/store/ii16nz4gvdmxal722ngd99qgjgkdfrq2-nix-tree-0.3.2",
    "references": [
      "/nix/store/f9m8fq8d8cfx8dw4y5p6p34gqpgli96w-gmp-with-cxx-6.3.0",
      "/nix/store/g5r20rs0qhcjcbf9dhbnbd9ksg0h0jmx-libiconv-50",
      "/nix/store/knf3077k6fhm0g5qw2z51m22afzhz279-ncurses-6.4",
      "/nix/store/lb9b1yj8l0zqgj5f28m4k1lw9wcj8d1m-libffi-3.4.4"
    ],
    "registrationTime": 1702507999,
    "ultimate": true,
    "valid": true
  }
]

As you can see, the output points out to the derivation file (through the deriver field), but the derivation doesn't point to output. So when you pass nix-tree a derivation, it doesn't even know whether that derivation is built or not, let alone the output it produced.

Unless someone can find a way to get the output path from a deriver, unfortunately I do not know of a (straightforward) way to get this info.