Document each store type on its own page

This makes for more useful manual table of contents, that displays the information at a glance. The `nix help-stores` command is kept as-is, even though it will show up in the manual with the same information as these pages due to the way it is written as a "`--help`-style" command. Deciding what to do with that command is left for a later PR. This change also lists all store types at the top of the respective overview page. Co-authored-by: John Ericson <[email protected]
NixOS · Dec 1, 2023 · 4781e7f · 4781e7f
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diff --git a/.gitignore b/.gitignore
@@ -22,6 +22,8 @@ perl/Makefile.config
 /doc/manual/xp-features.json
 /doc/manual/src/SUMMARY.md
 /doc/manual/src/SUMMARY-rl-next.md
+/doc/manual/src/store/types/*
+!/doc/manual/src/store/types/index.md.in
 /doc/manual/src/command-ref/new-cli
 /doc/manual/src/command-ref/conf-file.md
 /doc/manual/src/command-ref/experimental-features-shortlist.md

diff --git a/doc/manual/generate-manpage.nix b/doc/manual/generate-manpage.nix
@@ -51,7 +51,7 @@ let
 
         ${maybeSubcommands}
 
-        ${maybeStoreDocs}
+        ${maybeProse}
 
         ${maybeOptions}
       '';
@@ -91,25 +91,55 @@ let
         * [`${command} ${name}`](./${appendName filename name}.md) - ${subcmd.description}
       '';
 
-      # FIXME: this is a hack.
-      # store parameters should not be part of command documentation to begin
-      # with, but instead be rendered on separate pages.
-      maybeStoreDocs = optionalString (details ? doc)
-        (replaceStrings [ "@stores@" ] [ (showStoreDocs inlineHTML commandInfo.stores) ] details.doc);
-
-      maybeOptions = let
-        allVisibleOptions = filterAttrs
-          (_: o: ! o.hiddenCategory)
-          (details.flags // toplevel.flags);
-      in optionalString (allVisibleOptions != {}) ''
-        # Options
-
-        ${showOptions inlineHTML allVisibleOptions}
+      maybeProse =
+        # FIXME: this is a horrible hack to keep `nix help-stores` working.
+        # the correct answer to this is to remove that command and replace it
+        # by statically generated manpages or the output of something like `nix
+        # store info <store type>`.
+        let
+          help-stores = ''
+            ${index}
 
-        > **Note**
-        >
-        > See [`man nix.conf`](@docroot@/command-ref/conf-file.md#command-line-flags) for overriding configuration settings with command line flags.
-      '';
+            ${allStores}
+          '';
+          index = replaceStrings
+            [ "@store-types@" ] [ storesOverview ]
+            details.doc;
+          storesOverview =
+            let
+              showEntry = store:
+                "- [${store.name}](#${store.slug})";
+            in
+            concatStringsSep "\n" (map showEntry storesList) + "\n";
+          allStores = concatStringsSep "\n" (attrValues storePages);
+          storePages = listToAttrs
+            (map (s: { name = s.filename; value = s.page; }) storesList);
+          storesList = showStoreDocs {
+            storeInfo = commandInfo.stores;
+            inherit inlineHTML;
+          };
+        in
+        optionalString (details ? doc) (
+          if match "@store-types@" details.doc != [ ]
+          then help-stores
+          else details.doc
+        );
+
+      maybeOptions =
+        let
+          allVisibleOptions = filterAttrs
+            (_: o: ! o.hiddenCategory)
+            (details.flags // toplevel.flags);
+        in
+        optionalString (allVisibleOptions != { }) ''
+          # Options
+
+          ${showOptions inlineHTML allVisibleOptions}
+
+          > **Note**
+          >
+          > See [`man nix.conf`](@docroot@/command-ref/conf-file.md#command-line-flags) for overriding configuration settings with command line flags.
+        '';
 
       showOptions = inlineHTML: allOptions:
         let

diff --git a/doc/manual/generate-store-info.nix b/doc/manual/generate-store-info.nix
@@ -1,14 +1,20 @@
 let
-  inherit (builtins) attrValues mapAttrs;
-  inherit (import <nix/utils.nix>) concatStrings optionalString squash;
+  inherit (builtins) attrNames listToAttrs concatStringsSep readFile replaceStrings;
+  inherit (import <nix/utils.nix>) optionalString filterAttrs trim squash toLower unique indent;
   showSettings = import <nix/generate-settings.nix>;
 in
 
-inlineHTML: storesInfo:
+{
+  # data structure describing all stores and their parameters
+  storeInfo,
+  # whether to add inline HTML tags
+  # `lowdown` does not eat those for one of the output modes
+  inlineHTML,
+}:
 
 let
 
-  showStore = name: { settings, doc, experimentalFeature }:
+  showStore = { name, slug }: { settings, doc, experimentalFeature }:
     let
       result = squash ''
         # ${name}
@@ -22,9 +28,6 @@ let
         ${showSettings { prefix = "store-${slug}"; inherit inlineHTML; } settings}
       '';
 
-      # markdown doesn't like spaces in URLs
-      slug = builtins.replaceStrings [ " " ] [ "-" ] name;
-
       experimentalFeatureNote = optionalString (experimentalFeature != null) ''
         > **Warning**
         >
@@ -42,4 +45,13 @@ let
       '';
     in result;
 
-in concatStrings (attrValues (mapAttrs showStore storesInfo))
+  storesList = map
+    (name: rec {
+      inherit name;
+      slug = replaceStrings [ " " ] [ "-" ] (toLower name);
+      filename = "${slug}.md";
+      page = showStore { inherit name slug; } storeInfo.${name};
+    })
+    (attrNames storeInfo);
+
+in storesList
diff --git a/doc/manual/generate-store-types.nix b/doc/manual/generate-store-types.nix
@@ -0,0 +1,39 @@
+let
+  inherit (builtins) attrNames listToAttrs concatStringsSep readFile replaceStrings;
+  showSettings = import <nix/generate-settings.nix>;
+  showStoreDocs = import <nix/generate-store-info.nix>;
+in
+
+storeInfo:
+
+let
+  storesList = showStoreDocs {
+    inherit storeInfo;
+    inlineHTML = true;
+  };
+
+  index =
+    let
+      showEntry = store:
+        "- [${store.name}](./${store.filename})";
+    in
+    concatStringsSep "\n" (map showEntry storesList);
+
+  "index.md" = replaceStrings
+    [ "@store-types@" ] [ index ]
+    (readFile ./src/store/types/index.md.in);
+
+  tableOfContents =
+    let
+      showEntry = store:
+        "    - [${store.name}](store/types/${store.filename})";
+    in
+    concatStringsSep "\n" (map showEntry storesList) + "\n";
+
+  "SUMMARY.md" = tableOfContents;
+
+  storePages = listToAttrs
+    (map (s: { name = s.filename; value = s.page; }) storesList);
+
+in
+storePages // { inherit "index.md" "SUMMARY.md"; }
diff --git a/doc/manual/generate-xp-features.nix b/doc/manual/generate-xp-features.nix
@@ -8,4 +8,6 @@ let
 
       ${doc}
     '';
-in xps: (concatStringsSep "\n" (attrValues (mapAttrs showExperimentalFeature xps)))
+in
+
+xps: (concatStringsSep "\n" (attrValues (mapAttrs showExperimentalFeature xps)))
diff --git a/doc/manual/local.mk b/doc/manual/local.mk
@@ -97,10 +97,17 @@ $(d)/nix-profiles.5: $(d)/src/command-ref/files/profiles.md
 	$(trace-gen) lowdown -sT man --nroff-nolinks -M section=5 $^.tmp -o $@
 	@rm $^.tmp
 
-$(d)/src/SUMMARY.md: $(d)/src/SUMMARY.md.in $(d)/src/SUMMARY-rl-next.md $(d)/src/command-ref/new-cli $(d)/src/contributing/experimental-feature-descriptions.md
+$(d)/src/SUMMARY.md: $(d)/src/SUMMARY.md.in $(d)/src/SUMMARY-rl-next.md $(d)/src/store/types $(d)/src/command-ref/new-cli $(d)/src/contributing/experimental-feature-descriptions.md
 	@cp $< $@
 	@$(call process-includes,$@,$@)
 
+$(d)/src/store/types: $(d)/nix.json $(d)/utils.nix $(d)/generate-store-info.nix  $(d)/generate-store-types.nix $(d)/src/store/types/index.md.in $(doc_nix)
+	@# FIXME: build out of tree!
+	@rm -rf $@.tmp
+	$(trace-gen) $(nix-eval) --write-to $@.tmp --expr 'import doc/manual/generate-store-types.nix (builtins.fromJSON (builtins.readFile $<)).stores'
+	@# do not destroy existing contents
+	@mv $@.tmp/* $@/
+
 $(d)/src/command-ref/new-cli: $(d)/nix.json $(d)/utils.nix $(d)/generate-manpage.nix $(d)/generate-settings.nix $(d)/generate-store-info.nix $(doc_nix)
 	@rm -rf $@ $@.tmp
 	$(trace-gen) $(nix-eval) --write-to $@.tmp --expr 'import doc/manual/generate-manpage.nix true (builtins.readFile $<)'
@@ -200,7 +207,7 @@ doc/manual/generated/man1/nix3-manpages: $(d)/src/command-ref/new-cli
 # `@docroot@` is to be preserved for documenting the mechanism
 # FIXME: maybe contributing guides should live right next to the code
 # instead of in the manual
-$(docdir)/manual/index.html: $(MANUAL_SRCS) $(d)/book.toml $(d)/anchors.jq $(d)/custom.css $(d)/src/SUMMARY.md $(d)/src/command-ref/new-cli $(d)/src/contributing/experimental-feature-descriptions.md $(d)/src/command-ref/conf-file.md $(d)/src/language/builtins.md $(d)/src/language/builtin-constants.md $(d)/src/release-notes/rl-next.md
+$(docdir)/manual/index.html: $(MANUAL_SRCS) $(d)/book.toml $(d)/anchors.jq $(d)/custom.css $(d)/src/SUMMARY.md $(d)/src/store/types $(d)/src/command-ref/new-cli $(d)/src/contributing/experimental-feature-descriptions.md $(d)/src/command-ref/conf-file.md $(d)/src/language/builtins.md $(d)/src/language/builtin-constants.md $(d)/src/release-notes/rl-next.md
 	$(trace-gen) \
 		tmp="$$(mktemp -d)"; \
 		cp -r doc/manual "$$tmp"; \

diff --git a/doc/manual/src/SUMMARY.md.in b/doc/manual/src/SUMMARY.md.in
@@ -20,6 +20,8 @@
   - [File System Object](store/file-system-object.md)
   - [Store Object](store/store-object.md)
   - [Store Path](store/store-path.md)
+  - [Store Types](store/types/index.md)
+{{#include ./store/types/SUMMARY.md}}
 - [Nix Language](language/index.md)
   - [Data Types](language/values.md)
   - [Language Constructs](language/constructs.md)

diff --git a/doc/manual/src/contributing/cli-guideline.md b/doc/manual/src/contributing/cli-guideline.md
@@ -426,7 +426,7 @@ This leads to the following guidelines:
 ### Examples
 
 
-This is bad, because all keys must be assumed to be store implementations:
+This is bad, because all keys must be assumed to be store types:
 
 ```json
 {

diff --git a/doc/manual/src/store/index.md b/doc/manual/src/store/index.md
@@ -2,4 +2,4 @@
 
 The *Nix store* is an abstraction to store immutable file system data (such as software packages) that can have dependencies on other such data.
 
-There are multiple implementations of Nix stores with different capabilities, such as the actual filesystem (`/nix/store`) or binary caches.
+There are [multiple types of Nix stores](./types/index.md) with different capabilities, such as the default one on the [local filesystem](./types/local-store.md) (`/nix/store`) or [binary caches](./types/http-binary-cache-store.md).
diff --git a/doc/manual/src/store/types/index.md.in b/doc/manual/src/store/types/index.md.in
@@ -1,4 +1,6 @@
-Nix supports different types of stores. These are described below.
+Nix supports different types of stores:
+
+@store-types@
 
 ## Store URL format
 
@@ -39,4 +41,3 @@ store as follows:
 
 * Otherwise, use the [local store](#local-store) `/nix/store`.
 
-@stores@
diff --git a/doc/manual/utils.nix b/doc/manual/utils.nix
@@ -1,5 +1,11 @@
 with builtins;
 
+let
+  lowerChars = stringToCharacters "abcdefghijklmnopqrstuvwxyz";
+  upperChars = stringToCharacters "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+  stringToCharacters = s: genList (p: substring p 1 s) (stringLength s);
+in
+
 rec {
   splitLines = s: filter (x: !isList x) (split "\n" s);
 
@@ -18,6 +24,8 @@ rec {
     in
       if replaced == string then string else replaceStringsRec from to replaced;
 
+  toLower = replaceStrings upperChars lowerChars;
+
   squash = replaceStringsRec "\n\n\n" "\n\n";
 
   trim = string:

diff --git a/src/libcmd/common-eval-args.cc b/src/libcmd/common-eval-args.cc
@@ -141,7 +141,7 @@ MixEvalArgs::MixEvalArgs()
         .longName = "eval-store",
         .description =
           R"(
-            The [URL of the Nix store](@docroot@/command-ref/new-cli/nix3-help-stores.md#store-url-format)
+            The [URL of the Nix store](@docroot@/store/types/index.md#store-url-format)
             to use for evaluation, i.e. to store derivations (`.drv` files) and inputs referenced by them.
           )",
         .category = category,

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
@@ -4460,7 +4460,7 @@ void EvalState::createBaseEnv()
         .doc = R"(
           Logical file system location of the [Nix store](@docroot@/glossary.md#gloss-store) currently in use.
 
-          This value is determined by the `store` parameter in [Store URLs](@docroot@/command-ref/new-cli/nix3-help-stores.md):
+          This value is determined by the `store` parameter in [Store URLs](@docroot@/store/types/index.md#store-url-format):
 
           ```shell-session
           $ nix-instantiate --store 'dummy://?store=/blah' --eval --expr builtins.storeDir

diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
@@ -117,10 +117,11 @@ public:
 
     Setting<std::string> storeUri{this, getEnv("NIX_REMOTE").value_or("auto"), "store",
         R"(
-          The [URL of the Nix store](@docroot@/command-ref/new-cli/nix3-help-stores.md#store-url-format)
+          The [URL of the Nix store](@docroot@/store/types/index.md#store-url-format)
           to use for most operations.
-          See [`nix help-stores`](@docroot@/command-ref/new-cli/nix3-help-stores.md)
-          for supported store types and settings.
+          See the
+          [Store Types](@docroot@/store/types/index.md)
+          section of the manual for supported store types and settings.
         )"};
 
     Setting<bool> keepFailed{this, false, "keep-failed",
@@ -759,7 +760,7 @@ public:
         Strings{"https://cache.nixos.org/"},
         "substituters",
         R"(
-          A list of [URLs of Nix stores](@docroot@/command-ref/new-cli/nix3-help-stores.md#store-url-format) to be used as substituters, separated by whitespace.
+          A list of [URLs of Nix stores](@docroot@/store/types/index.md#store-url-format) to be used as substituters, separated by whitespace.
           A substituter is an additional [store]{@docroot@/glossary.md##gloss-store} from which Nix can obtain [store objects](@docroot@/glossary.md#gloss-store-object) instead of building them.
 
           Substituters are tried based on their priority value, which each substituter can set independently.
@@ -778,7 +779,7 @@ public:
     Setting<StringSet> trustedSubstituters{
         this, {}, "trusted-substituters",
         R"(
-          A list of [Nix store URLs](@docroot@/command-ref/new-cli/nix3-help-stores.md#store-url-format), separated by whitespace.
+          A list of [Nix store URLs](@docroot@/store/types/index.md#store-url-format), separated by whitespace.
           These are not used by default, but users of the Nix daemon can enable them by specifying [`substituters`](#conf-substituters).
 
           Unprivileged users (those set in only [`allowed-users`](#conf-allowed-users) but not [`trusted-users`](#conf-trusted-users)) can pass as `substituters` only those URLs listed in `trusted-substituters`.

diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
@@ -20,7 +20,7 @@
 
 namespace nix {
 
-/* TODO: Separate these store impls into different files, give them better names */
+/* TODO: Separate these store types into different files, give them better names */
 RemoteStore::RemoteStore(const Params & params)
     : RemoteStoreConfig(params)
     , Store(params)

diff --git a/src/libstore/ssh-store-config.hh b/src/libstore/ssh-store-config.hh
@@ -20,7 +20,7 @@ struct CommonSSHStoreConfig : virtual StoreConfig
 
     const Setting<std::string> remoteStore{this, "", "remote-store",
         R"(
-          [Store URL](@docroot@/command-ref/new-cli/nix3-help-stores.md#store-url-format)
+          [Store URL](@docroot@/store/types/index.md#store-url-format)
           to be used on the remote machine. The default is `auto`
           (i.e. use the Nix daemon or `/nix/store` directly).
         )"};

diff --git a/src/libstore/store-api.hh b/src/libstore/store-api.hh
@@ -30,7 +30,7 @@
 namespace nix {
 
 /**
- * About the class hierarchy of the store implementations:
+ * About the class hierarchy of the store types:
  *
  * Each store type `Foo` consists of two classes:
  *
@@ -962,7 +962,7 @@ OutputPathMap resolveDerivedPath(Store &, const DerivedPath::Built &, Store * ev
  * - ‘ssh://[user@]<host>’: A remote Nix store accessed by running
  *   ‘nix-store --serve’ via SSH.
  *
- * You can pass parameters to the store implementation by appending
+ * You can pass parameters to the store type by appending
  * ‘?key=value&key=value&...’ to the URI.
  */
 ref<Store> openStore(const std::string & uri = settings.storeUri.get(),

diff --git a/src/libutil/experimental-features.cc b/src/libutil/experimental-features.cc
@@ -252,7 +252,7 @@ constexpr std::array<ExperimentalFeatureDetails, numXpFeatures> xpFeatureDetails
         .tag = Xp::ReadOnlyLocalStore,
         .name = "read-only-local-store",
         .description = R"(
-            Allow the use of the `read-only` parameter in [local store](@docroot@/command-ref/new-cli/nix3-help-stores.md#local-store) URIs.
+            Allow the use of the `read-only` parameter in [local store](@docroot@/store/types/local-store.md) URIs.
         )",
     },
     {

diff --git a/src/nix/nix.md b/src/nix/nix.md
@@ -235,10 +235,14 @@ operate are determined as follows:
 
 # Nix stores
 
-Most `nix` subcommands operate on a *Nix store*. These are documented
-in [`nix help-stores`](./nix3-help-stores.md).
+Most `nix` subcommands operate on a *Nix store*.
+The various store types are documented in the
+[Store Types](@docroot@/store/types/index.md)
+section of the manual.
 
-# Shebang interpreter 
+The same information is also available from the [`nix help-stores`](./nix3-help-stores.md) command.
+
+# Shebang interpreter
 
 The `nix` command can be used as a `#!` interpreter.
 Arguments to Nix can be passed on subsequent lines in the script.
-Original file line number
+Diff line change
@@ Expand Up / @@ -8,4 +8,6 @@ let @@
           ${doc}
         '';
-    in xps: (concatStringsSep "\n" (attrValues (mapAttrs showExperimentalFeature xps)))
+    in
+    xps: (concatStringsSep "\n" (attrValues (mapAttrs showExperimentalFeature xps)))
Original file line number	Diff line number	Diff line change
Expand Up		@@ -2,4 +2,4 @@

		The Nix store is an abstraction to store immutable file system data (such as software packages) that can have dependencies on other such data.

		There are multiple implementations of Nix stores with different capabilities, such as the actual filesystem (`/nix/store`) or binary caches.
		There are [multiple types of Nix stores](./types/index.md) with different capabilities, such as the default one on the [local filesystem](./types/local-store.md) (`/nix/store`) or [binary caches](./types/http-binary-cache-store.md).