Add Nix-based build environment, update CI pipeline to use it, add contribution guide

.devcontainer.json

@@ -0,0 +1,35 @@
+{
+  "containerEnv": {
+    "HOME": "/home/vscode"
+  },
+  "containerUser": "vscode",
+  "customizations": {
+    "jetbrains": {
+      "plugins": [
+        "com.jetbrains.rust",
+        "systems.fehn.intellijdirenv"
+      ]
+    },
+    "vscode": {
+      "extensions": [
+        "rust-lang.rust-analyzer",
+        "ms-vscode.cpptools",
+        "mkhl.direnv",
+        "vadimcn.vscode-lldb",
+        "tamasfe.even-better-toml"
+      ],
+      "settings": {
+        "rust-analyzer.cargo.features": [
+          "vendored"
+        ]
+      }
+    }
+  },
+  "image": "ghcr.io/cachix/devenv/devcontainer:latest",
+  "overrideCommand": false,
+  "runArgs": [
+    "--userns=keep-id:uid=1000,gid=1000"
+  ],
+  "updateContentCommand": "devenv test",
+  "updateRemoteUserUID": true
+}

.envrc

@@ -0,0 +1,10 @@
+export DIRENV_WARN_TIMEOUT=20s
+
+eval "$(devenv direnvrc)"
+
+# `use devenv` supports the same options as the `devenv shell` command.
+#
+# To silence the output, use `--quiet`.
+#
+# Example usage: use devenv --quiet --impure --option services.postgres.enable:bool true
+use devenv

.github/pull_request_template.md

@@ -0,0 +1,26 @@
+
+## Description
+
+Please describe the changes made in the Pull Request here.
+
+## How to Test
+
+If there are any specific test procedures that pertain to this change in
+particular, you may describe them here.
+
+## Related Issues
+
+If this pull request resolves an issue that can be found in the repository's
+issue tracker, you [may reference the issue here using a keyword](https://docs.github.com/en/issues/tracking-your-work-with-issues/using-issues/linking-a-pull-request-to-an-issue#linking-a-pull-request-to-an-issue-using-a-keyword).
+Example: This pull request closes [TODO].
+
+## Checklist
+
+- [ ] I have read, understood, and acknowledged the [NOTICE](https://github.com/namib-project/libcoap-rs/blob/main/NOTICE.md) file and the [Contribution Guide](https://github.com/namib-project/libcoap-rs/blob/main/CONTRIBUTING.md)
+- [ ] I affirm that I have the right to submit the changes made by this pull
+      request under the BSD-2-Clause license as indicated in the NOTICE file.
+- [ ] This PR is either a) free of any LLM-generated code, or b) I have
+      disclosed all uses of LLM-generated code in this pull request and
+      indicated the models that were used.
+      Any submitted LLM-generated code may verifiably be licensed under the
+      BSD-2-Clause license.

.github/workflows/test.yml

@@ -28,50 +28,44 @@ jobs:
       LLVM_PROFILE_FILE: "${{ github.workspace }}/coverage-data/coverage/libcoap-rs-%p-%m.profraw"
       RUSTFLAGS: "${{ matrix.rust_version == 'nightly' && '-Cinstrument-coverage -Cpanic=abort -Zpanic_abort_tests' || ' ' }}"
       RUSTDOCFLAGS: "${{ matrix.rust_version == 'nightly' && '-C instrument-coverage -Cpanic=abort -Zpanic_abort_tests -Z unstable-options --persist-doctests target/debug/doctests' || ' ' }}"
-      LIBRARY_FEATURES: |
-        ${{ (matrix.crate == 'libcoap-rs' && 'tcp,vendored,rand')
-            || (matrix.crate == 'libcoap-sys' && 'default,vendored')
-            || 'vendored'
-        }}
-      LIBCOAP_RS_DTLS_BACKEND: ${{ matrix.dtls_backend }}
       LIBCOAP_RS_BUILD_SYSTEM: "vendored"
-      DTLS_LIBRARY_FEATURES: |
-        ${{ (matrix.crate == 'libcoap-rs' && matrix.dtls_backend == 'tinydtls' && 'tcp,dtls-psk,dtls-rpk,dtls-tinydtls-sys-vendored')
-            || (matrix.crate == 'libcoap-rs' && matrix.dtls_backend == 'mbedtls' && 'tcp,dtls-psk,dtls-pki')
-            || (matrix.crate == 'libcoap-rs' && matrix.dtls_backend == 'openssl' && 'tcp,dtls-psk,dtls-pki,dtls-openssl-sys-vendored')
-            || (matrix.crate == 'libcoap-rs' && matrix.dtls_backend == 'gnutls' && 'tcp,dtls-psk,dtls-pki,dtls-rpk')
-            || (matrix.crate == 'libcoap-sys' && matrix.dtls_backend == 'tinydtls' && 'dtls,dtls-tinydtls-sys-vendored')
-            || (matrix.crate == 'libcoap-sys' && matrix.dtls_backend == 'mbedtls' && 'dtls')
-            || (matrix.crate == 'libcoap-sys' && matrix.dtls_backend == 'openssl' && 'dtls,dtls-openssl-sys-vendored')
-            || (matrix.crate == 'libcoap-sys' && matrix.dtls_backend == 'gnutls' && 'dtls')
-            || 'vendored'
-        }}
     steps:
       - uses: actions/checkout@v4
         with:
           submodules: true
-      - uses: dtolnay/rust-toolchain@stable
+      - uses: nixbuild/nix-quick-install-action@v33
+      - name: Restore and save Nix store in GitHub cache
+        uses: nix-community/cache-nix-action@v6
         with:
-          components: rust-src, rustc, rust-std, cargo, llvm-tools, llvm-tools-preview
-          toolchain: ${{ matrix.rust_version == 'msrv' && '1.82' || matrix.rust_version }}
-      - if: matrix.dtls_backend == 'gnutls'
-        uses: awalsh128/[email protected]
-        with:
-          packages: libgnutls28-dev libgnutls30
-          version: 1.0
-      - if: matrix.dtls_backend == 'mbedtls'
-        uses: awalsh128/[email protected]
-        with:
-          packages: libmbedtls-dev
-          version: 1.0
-      - run: cargo test -p ${{ matrix.crate }} --no-default-features --features "$LIBRARY_FEATURES" --features "$DTLS_LIBRARY_FEATURES" --no-fail-fast
+          # restore and save a cache using this key
+          primary-key: nix-${{ runner.os }}-${{ hashFiles('**/*.nix', '**/devenv.lock') }}
+          # if there's no cache hit, restore a cache by this prefix
+          restore-prefixes-first-match: nix-${{ runner.os }}-
+          # collect garbage until the Nix store size (in bytes) is at most this number
+          # before trying to save a new cache
+          # 1G = 1073741824
+          gc-max-store-size: 3G
+          # do purge caches
+          purge: true
+          # purge all versions of the cache
+          purge-prefixes: nix-${{ runner.os }}-
+          # last accessed more than this number of seconds ago
+          # relative to the start of the `Post Restore and save Nix store` phase
+          purge-last-accessed: 86400
+          # except any version with the key that is the same as the `primary-key`
+          purge-primary-key: never
+      - name: Install devenv.sh using Nix
+        run: nix profile install 'nixpkgs#devenv'
+      - name: Run tests
+        run: devenv shell --option rust-version:string ${{ matrix.rust_version }} ${{ matrix.crate }}:test_${{ matrix.dtls_backend }}
       - if: matrix.rust_version == 'nightly'
+        name: Generate coverage data
         run: |
           mkdir -p coverage-data/test-binaries
           mkdir -p target/debug/doctests
-          cp $(cargo test -p ${{ matrix.crate }} --no-run --message-format=json --no-default-features --features "$LIBRARY_FEATURES" --features "$DTLS_LIBRARY_FEATURES" --no-fail-fast  \
+          devenv shell --option rust-version:string ${{ matrix.rust_version }} 'cp $(${{ matrix.crate }}:test_${{ matrix.dtls_backend }} --no-run --message-format=json --no-fail-fast \
               | jq -r "select(.profile.test == true) | .filenames[]" \
-              | grep -v dSYM -) coverage-data/test-binaries/
+              | grep -v dSYM -) coverage-data/test-binaries/'
           cp -r target/debug/doctests coverage-data/test-binaries/
       - if: matrix.rust_version == 'nightly'
         uses: actions/upload-artifact@v4
@@ -80,6 +74,8 @@ jobs:
           name: test-coverage-data-${{ matrix.crate }}-${{ matrix.dtls_backend }}
           path: |
             coverage-data/
+      - name: devenv.sh garbage collection
+        run: devenv gc
 
   lint:
     name: lint
@@ -88,21 +84,40 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: true
+      - uses: nixbuild/nix-quick-install-action@v33
+      - name: Restore and save Nix store in GitHub cache
+        uses: nix-community/cache-nix-action@v6
+        with:
+          # restore and save a cache using this key
+          primary-key: nix-${{ runner.os }}-${{ hashFiles('**/*.nix', '**/devenv.lock') }}
+          # if there's no cache hit, restore a cache by this prefix
+          restore-prefixes-first-match: nix-${{ runner.os }}-
+          # collect garbage until the Nix store size (in bytes) is at most this number
+          # before trying to save a new cache
+          # 1G = 1073741824
+          gc-max-store-size: 3G
+          # do purge caches
+          purge: true
+          # purge all versions of the cache
+          purge-prefixes: nix-${{ runner.os }}-
+          # last accessed more than this number of seconds ago
+          # relative to the start of the `Post Restore and save Nix store` phase
+          purge-last-accessed: 86400
+          # except any version with the key that is the same as the `primary-key`
+          purge-primary-key: never
+      - name: Install devenv.sh using Nix
+        run: nix profile install 'nixpkgs#devenv'
       - uses: reviewdog/action-setup@v1
         with:
           reviewdog_version: latest
-      # Nightly required for rustfmt's --emit=checkstyle argument
-      - uses: dtolnay/rust-toolchain@nightly
-        with:
-          components: clippy, rustfmt
       - uses: baptiste0928/cargo-install@v3
         with:
           crate: clippy-reviewdog-filter
       - name: Run Linter
         env:
           REVIEWDOG_GITHUB_API_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
-          reviewdog -reporter=github-pr-check -fail-level=any
+          devenv shell --option rust-version:string nightly reviewdog -reporter=github-pr-check -fail-level=any
 
   docs:
     runs-on: ubuntu-latest
@@ -113,16 +128,31 @@ jobs:
         with:
           submodules: true
           ref: ${{ env.HEAD_REF }}
-      # --all-features uses GNUTLS as backend, must provide it.
-      - uses: awalsh128/[email protected]
-        with:
-          packages: libgnutls28-dev libgnutls30
-          version: 1.0
-      - uses: dtolnay/rust-toolchain@nightly
+      - uses: nixbuild/nix-quick-install-action@v33
+      - name: Restore and save Nix store in GitHub cache
+        uses: nix-community/cache-nix-action@v6
         with:
-          components: rustc
+          # restore and save a cache using this key
+          primary-key: nix-${{ runner.os }}-${{ hashFiles('**/*.nix', '**/devenv.lock') }}
+          # if there's no cache hit, restore a cache by this prefix
+          restore-prefixes-first-match: nix-${{ runner.os }}-
+          # collect garbage until the Nix store size (in bytes) is at most this number
+          # before trying to save a new cache
+          # 1G = 1073741824
+          gc-max-store-size: 3G
+          # do purge caches
+          purge: true
+          # purge all versions of the cache
+          purge-prefixes: nix-${{ runner.os }}-
+          # last accessed more than this number of seconds ago
+          # relative to the start of the `Post Restore and save Nix store` phase
+          purge-last-accessed: 86400
+          # except any version with the key that is the same as the `primary-key`
+          purge-primary-key: never
+      - name: Install devenv.sh using Nix
+        run: nix profile install 'nixpkgs#devenv'
       - name: Build documentation
-        run: cargo doc --all-features --no-deps --workspace
+        run: devenv shell docs
       - uses: actions/upload-artifact@v4
         id: upload-docs
         with:

.gitignore

@@ -87,3 +87,28 @@ fabric.properties
 
 # Android studio 3.1+ serialized cache file
 .idea/caches/build_file_checksums.ser
+
+# Devenv
+.devenv*
+devenv.local.nix
+
+# direnv
+.direnv
+
+# pre-commit
+.pre-commit-config.yaml
+
+# VSCode, see https://github.com/github/gitignore/blob/main/VisualStudio.gitignore
+# VS Code files for those working on multiple tools
+.vscode/*
+!.vscode/settings.json
+!.vscode/tasks.json
+!.vscode/launch.json
+!.vscode/extensions.json
+!.vscode/*.code-snippets
+
+# Local History for Visual Studio Code
+.history/
+
+# Built Visual Studio Code Extensions
+*.vsix