Merge pull request #7887 from obsidiansystems/add-derivation

`nix derivation add`, `show-derivation` -> `derivation show`

doc/manual/src/glossary.md

@@ -15,7 +15,7 @@
 
     Example: `/nix/store/g946hcz4c8mdvq2g8vxx42z51qb71rvp-git-2.38.1.drv`
 
-    See [`nix show-derivation`](./command-ref/new-cli/nix3-show-derivation.md) (experimental) for displaying the contents of store derivations.
+    See [`nix derivation show`](./command-ref/new-cli/nix3-derivation-show.md) (experimental) for displaying the contents of store derivations.
 
     [store derivation]: #gloss-store-derivation
 

doc/manual/src/release-notes/rl-next.md

@@ -45,3 +45,14 @@
   This is useful for scripting interactions with (non-legacy-ssh) remote Nix stores.
 
   `nix store ping` and `nix doctor` now display this information.
+
+* A new command `nix derivation add` is created, to allow adding derivations to the store without involving the Nix language.
+  It exists to round out our collection of basic utility/plumbing commands, and allow for a low barrier-to-entry way of experimenting with alternative front-ends to the Nix Store.
+  It uses the same JSON layout as `nix show-derivation`, and is its inverse.
+
+* `nix show-derivation` has been renamed to `nix derivation show`.
+  This matches `nix derivation add`, and avoids bloating the top-level namespace.
+  The old name is still kept as an alias for compatibility, however.
+
+* The `nix derivation {add,show}` JSON format now includes the derivation name as a top-level field.
+  This is useful in general, but especially necessary for the `add` direction, as otherwise we would need to pass in the name out of band for certain cases.

src/libstore/content-address.hh

@@ -3,6 +3,7 @@
 
 #include <variant>
 #include "hash.hh"
+#include "comparator.hh"
 
 namespace nix {
 
@@ -30,6 +31,8 @@ struct TextHash {
      * Hash of the contents of the text/file.
      */
     Hash hash;
+
+    GENERATE_CMP(TextHash, me->hash);
 };
 
 /**
@@ -46,6 +49,8 @@ struct FixedOutputHash {
     Hash hash;
 
     std::string printMethodAlgo() const;
+
+    GENERATE_CMP(FixedOutputHash, me->method, me->hash);
 };
 
 /**

src/libstore/derivations.cc

@@ -889,6 +889,67 @@ std::optional<BasicDerivation> Derivation::tryResolve(
     return resolved;
 }
 
+
+void Derivation::checkInvariants(Store & store, const StorePath & drvPath) const
+{
+    assert(drvPath.isDerivation());
+    std::string drvName(drvPath.name());
+    drvName = drvName.substr(0, drvName.size() - drvExtension.size());
+
+    if (drvName != name) {
+        throw Error("Derivation '%s' has name '%s' which does not match its path", store.printStorePath(drvPath), name);
+    }
+
+    auto envHasRightPath = [&](const StorePath & actual, const std::string & varName)
+    {
+        auto j = env.find(varName);
+        if (j == env.end() || store.parseStorePath(j->second) != actual)
+            throw Error("derivation '%s' has incorrect environment variable '%s', should be '%s'",
+                store.printStorePath(drvPath), varName, store.printStorePath(actual));
+    };
+
+
+    // Don't need the answer, but do this anyways to assert is proper
+    // combination. The code below is more general and naturally allows
+    // combinations that are currently prohibited.
+    type();
+
+    std::optional<DrvHash> hashesModulo;
+    for (auto & i : outputs) {
+        std::visit(overloaded {
+            [&](const DerivationOutput::InputAddressed & doia) {
+                if (!hashesModulo) {
+                    // somewhat expensive so we do lazily
+                    hashesModulo = hashDerivationModulo(store, *this, true);
+                }
+                auto currentOutputHash = get(hashesModulo->hashes, i.first);
+                if (!currentOutputHash)
+                    throw Error("derivation '%s' has unexpected output '%s' (local-store / hashesModulo) named '%s'",
+                        store.printStorePath(drvPath), store.printStorePath(doia.path), i.first);
+                StorePath recomputed = store.makeOutputPath(i.first, *currentOutputHash, drvName);
+                if (doia.path != recomputed)
+                    throw Error("derivation '%s' has incorrect output '%s', should be '%s'",
+                        store.printStorePath(drvPath), store.printStorePath(doia.path), store.printStorePath(recomputed));
+                envHasRightPath(doia.path, i.first);
+            },
+            [&](const DerivationOutput::CAFixed & dof) {
+                StorePath path = store.makeFixedOutputPath(dof.hash.method, dof.hash.hash, drvName);
+                envHasRightPath(path, i.first);
+            },
+            [&](const DerivationOutput::CAFloating &) {
+                /* Nothing to check */
+            },
+            [&](const DerivationOutput::Deferred &) {
+                /* Nothing to check */
+            },
+            [&](const DerivationOutput::Impure &) {
+                /* Nothing to check */
+            },
+        }, i.second.raw());
+    }
+}
+
+
 const Hash impureOutputHash = hashString(htSHA256, "impure");
 
 nlohmann::json DerivationOutput::toJSON(
@@ -916,10 +977,79 @@ nlohmann::json DerivationOutput::toJSON(
     return res;
 }
 
+
+DerivationOutput DerivationOutput::fromJSON(
+    const Store & store, std::string_view drvName, std::string_view outputName,
+    const nlohmann::json & _json)
+{
+    std::set<std::string_view> keys;
+    auto json = (std::map<std::string, nlohmann::json>) _json;
+
+    for (const auto & [key, _] : json)
+        keys.insert(key);
+
+    auto methodAlgo = [&]() -> std::pair<FileIngestionMethod, HashType> {
+        std::string hashAlgo = json["hashAlgo"];
+        auto method = FileIngestionMethod::Flat;
+        if (hashAlgo.substr(0, 2) == "r:") {
+            method = FileIngestionMethod::Recursive;
+            hashAlgo = hashAlgo.substr(2);
+        }
+        auto hashType = parseHashType(hashAlgo);
+        return { method, hashType };
+    };
+
+    if (keys == (std::set<std::string_view> { "path" })) {
+        return DerivationOutput::InputAddressed {
+            .path = store.parseStorePath((std::string) json["path"]),
+        };
+    }
+
+    else if (keys == (std::set<std::string_view> { "path", "hashAlgo", "hash" })) {
+        auto [method, hashType] = methodAlgo();
+        auto dof = DerivationOutput::CAFixed {
+            .hash = {
+                .method = method,
+                .hash = Hash::parseNonSRIUnprefixed((std::string) json["hash"], hashType),
+            },
+        };
+        if (dof.path(store, drvName, outputName) != store.parseStorePath((std::string) json["path"]))
+            throw Error("Path doesn't match derivation output");
+        return dof;
+    }
+
+    else if (keys == (std::set<std::string_view> { "hashAlgo" })) {
+        auto [method, hashType] = methodAlgo();
+        return DerivationOutput::CAFloating {
+            .method = method,
+            .hashType = hashType,
+        };
+    }
+
+    else if (keys == (std::set<std::string_view> { })) {
+        return DerivationOutput::Deferred {};
+    }
+
+    else if (keys == (std::set<std::string_view> { "hashAlgo", "impure" })) {
+        auto [method, hashType] = methodAlgo();
+        return DerivationOutput::Impure {
+            .method = method,
+            .hashType = hashType,
+        };
+    }
+
+    else {
+        throw Error("invalid JSON for derivation output");
+    }
+}
+
+
 nlohmann::json Derivation::toJSON(const Store & store) const
 {
     nlohmann::json res = nlohmann::json::object();
 
+    res["name"] = name;
+
     {
         nlohmann::json & outputsObj = res["outputs"];
         outputsObj = nlohmann::json::object();
@@ -950,4 +1080,43 @@ nlohmann::json Derivation::toJSON(const Store & store) const
     return res;
 }
 
+
+Derivation Derivation::fromJSON(
+    const Store & store,
+    const nlohmann::json & json)
+{
+    Derivation res;
+
+    res.name = json["name"];
+
+    {
+        auto & outputsObj = json["outputs"];
+        for (auto & [outputName, output] : outputsObj.items()) {
+            res.outputs.insert_or_assign(
+                outputName,
+                DerivationOutput::fromJSON(store, res.name, outputName, output));
+        }
+    }
+
+    {
+        auto & inputsList = json["inputSrcs"];
+        for (auto & input : inputsList)
+            res.inputSrcs.insert(store.parseStorePath(static_cast<const std::string &>(input)));
+    }
+
+    {
+        auto & inputDrvsObj = json["inputDrvs"];
+        for (auto & [inputDrvPath, inputOutputs] : inputDrvsObj.items())
+            res.inputDrvs[store.parseStorePath(inputDrvPath)] =
+                static_cast<const StringSet &>(inputOutputs);
+    }
+
+    res.platform = json["system"];
+    res.builder = json["builder"];
+    res.args = json["args"];
+    res.env = json["env"];
+
+    return res;
+}
+
 }

src/libstore/derivations.hh

@@ -7,6 +7,7 @@
 #include "content-address.hh"
 #include "repair-flag.hh"
 #include "sync.hh"
+#include "comparator.hh"
 
 #include <map>
 #include <variant>
@@ -24,6 +25,8 @@ class Store;
 struct DerivationOutputInputAddressed
 {
     StorePath path;
+
+    GENERATE_CMP(DerivationOutputInputAddressed, me->path);
 };
 
 /**
@@ -44,6 +47,8 @@ struct DerivationOutputCAFixed
      * @param outputName The name of this output.
      */
     StorePath path(const Store & store, std::string_view drvName, std::string_view outputName) const;
+
+    GENERATE_CMP(DerivationOutputCAFixed, me->hash);
 };
 
 /**
@@ -62,13 +67,17 @@ struct DerivationOutputCAFloating
      * How the serialization will be hashed
      */
     HashType hashType;
+
+    GENERATE_CMP(DerivationOutputCAFloating, me->method, me->hashType);
 };
 
 /**
  * Input-addressed output which depends on a (CA) derivation whose hash
  * isn't known yet.
  */
-struct DerivationOutputDeferred {};
+struct DerivationOutputDeferred {
+    GENERATE_CMP(DerivationOutputDeferred);
+};
 
 /**
  * Impure output which is moved to a content-addressed location (like
@@ -85,6 +94,8 @@ struct DerivationOutputImpure
      * How the serialization will be hashed
      */
     HashType hashType;
+
+    GENERATE_CMP(DerivationOutputImpure, me->method, me->hashType);
 };
 
 typedef std::variant<
@@ -125,6 +136,11 @@ struct DerivationOutput : _DerivationOutputRaw
         const Store & store,
         std::string_view drvName,
         std::string_view outputName) const;
+    static DerivationOutput fromJSON(
+        const Store & store,
+        std::string_view drvName,
+        std::string_view outputName,
+        const nlohmann::json & json);
 };
 
 typedef std::map<std::string, DerivationOutput> DerivationOutputs;
@@ -273,6 +289,15 @@ struct BasicDerivation
     DerivationOutputsAndOptPaths outputsAndOptPaths(const Store & store) const;
 
     static std::string_view nameFromPath(const StorePath & storePath);
+
+    GENERATE_CMP(BasicDerivation,
+        me->outputs,
+        me->inputSrcs,
+        me->platform,
+        me->builder,
+        me->args,
+        me->env,
+        me->name);
 };
 
 struct Derivation : BasicDerivation
@@ -308,11 +333,26 @@ struct Derivation : BasicDerivation
         Store & store,
         const std::map<std::pair<StorePath, std::string>, StorePath> & inputDrvOutputs) const;
 
+    /* Check that the derivation is valid and does not present any
+       illegal states.
+
+       This is mainly a matter of checking the outputs, where our C++
+       representation supports all sorts of combinations we do not yet
+       allow. */
+    void checkInvariants(Store & store, const StorePath & drvPath) const;
+
     Derivation() = default;
     Derivation(const BasicDerivation & bd) : BasicDerivation(bd) { }
     Derivation(BasicDerivation && bd) : BasicDerivation(std::move(bd)) { }
 
     nlohmann::json toJSON(const Store & store) const;
+    static Derivation fromJSON(
+        const Store & store,
+        const nlohmann::json & json);
+
+    GENERATE_CMP(Derivation,
+        static_cast<const BasicDerivation &>(*me),
+        me->inputDrvs);
 };