Fix examples manifest version detection (#3863)

### What

Continued from #3859

- `ref` is no longer set to `github.sha` by default, because that checks
out a commit. Instead it's left empty, which checks out the branch +
uses the merge commit on PRs and head commit on `push`.
- Also fix how we detect branch name in `re_build_tools`, it defaults to
`GITHUB_REF` if it exists, otherwise it runs the command as it did
before. `GITHUB_REF` is set when a workflow starts, and contains the
fully-formed ref of the branch that the workflow was started on, e.g.
`refs/heads/jan/fix-exmaples/manifest-version` - we can parse the branch
name from that.

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested [demo.rerun.io](https://demo.rerun.io/pr/3863) (if
applicable)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG

- [PR Build Summary](https://build.rerun.io/pr/3863)
- [Docs
preview](https://rerun.io/preview/a0f00e401d830d472b7df6f0144a22e4b1ff4139/docs)
<!--DOCS-PREVIEW-->
- [Examples
preview](https://rerun.io/preview/a0f00e401d830d472b7df6f0144a22e4b1ff4139/examples)
<!--EXAMPLES-PREVIEW-->
- [Recent benchmark results](https://ref.rerun.io/dev/bench/)
- [Wasm size tracking](https://ref.rerun.io/dev/sizes/)

---------

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

.github/workflows/checkboxes.yml

@@ -26,7 +26,7 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Set up Python
         uses: actions/setup-python@v2

.github/workflows/reusable_bench.yml

@@ -61,7 +61,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Set up Rust
         uses: ./.github/actions/setup-rust

.github/workflows/reusable_build_and_test_wheels.yml

@@ -126,7 +126,7 @@ jobs:
 
       - uses: actions/checkout@v4
         with:
-          ref: ${{ inputs.RELEASE_COMMIT || ((github.event_name == 'pull_request' && github.event.pull_request.head.ref) || github.sha) }}
+          ref: ${{ inputs.RELEASE_COMMIT || ((github.event_name == 'pull_request' && github.event.pull_request.head.ref) || '') }}
 
       - name: Set up Rust
         uses: ./.github/actions/setup-rust

.github/workflows/reusable_build_and_upload_rerun_c.yml

@@ -149,7 +149,7 @@ jobs:
 
       - uses: actions/checkout@v4
         with:
-          ref: ${{ (github.event_name == 'pull_request' && github.event.pull_request.head.ref) || github.sha }}
+          ref: ${{ (github.event_name == 'pull_request' && github.event.pull_request.head.ref) || '' }}
 
       - name: Set up Rust
         uses: ./.github/actions/setup-rust

.github/workflows/reusable_build_web.yml

@@ -43,7 +43,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Set up Rust
         uses: ./.github/actions/setup-rust

.github/workflows/reusable_build_web_demo.yml

@@ -45,7 +45,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ (github.event_name == 'pull_request' && github.event.pull_request.head.ref) || github.sha }}
+          ref: ${{ (github.event_name == 'pull_request' && github.event.pull_request.head.ref) || '' }}
 
       - name: Download Web Viewer
         uses: actions/download-artifact@v3

.github/workflows/reusable_checks.yml

@@ -53,7 +53,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - uses: extractions/setup-just@v1
         env:
@@ -89,7 +89,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Set up Python
         uses: actions/setup-python@v4
@@ -149,7 +149,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Set up Rust
         uses: ./.github/actions/setup-rust
@@ -234,7 +234,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Set up Rust
         uses: ./.github/actions/setup-rust
@@ -267,7 +267,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Install taplo-cli
         uses: taiki-e/install-action@v2
@@ -286,7 +286,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Set up Python
         uses: actions/setup-python@v4
@@ -329,7 +329,7 @@ jobs:
       - name: Checkout Actions Repository
         uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Check spelling of entire workspace
         uses: crate-ci/typos@master
@@ -344,7 +344,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Cargo Deny
         shell: bash
@@ -359,7 +359,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Run clang format on all relevant files
         uses: jidicula/clang-format-action@v4.11.0
@@ -378,7 +378,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Set up Rust
         uses: ./.github/actions/setup-rust
@@ -400,3 +400,4 @@ jobs:
       - name: Build doc-code examples
         shell: bash
         run: ./docs/code-examples/cpp_build_all.sh --werror
+

.github/workflows/reusable_deploy_docs.yml

@@ -52,7 +52,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0 # Don't do a shallow clone
-          ref: ${{ inputs.RELEASE_COMMIT || (github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha) }}
+          ref: ${{ inputs.RELEASE_COMMIT || (github.event_name == 'pull_request' && github.event.pull_request.head.ref || '') }}
 
       - name: Set up Python
         uses: actions/setup-python@v4
@@ -123,7 +123,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0 # Don't do a shallow clone since we need to push gh-pages
-          ref: ${{ inputs.RELEASE_COMMIT || (github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha) }}
+          ref: ${{ inputs.RELEASE_COMMIT || (github.event_name == 'pull_request' && github.event.pull_request.head.ref || '') }}
 
       - name: Set up Rust
         uses: ./.github/actions/setup-rust
@@ -171,7 +171,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ inputs.RELEASE_COMMIT || (github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha) }}
+          ref: ${{ inputs.RELEASE_COMMIT || (github.event_name == 'pull_request' && github.event.pull_request.head.ref || '') }}
 
       - name: Re-deploy rerun.io
         uses: ./.github/actions/deploy-vercel

.github/workflows/reusable_pip_index.yml

@@ -29,7 +29,7 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
         with:
-          ref: ${{ inputs.COMMIT || (github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha) }}
+          ref: ${{ inputs.COMMIT || (github.event_name == 'pull_request' && github.event.pull_request.head.ref || '') }}
 
       - name: Set up Python
         uses: actions/setup-python@v2

.github/workflows/reusable_pr_summary.yml

@@ -29,7 +29,7 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Set up Python
         uses: actions/setup-python@v2

.github/workflows/reusable_release_crates.yml

@@ -22,7 +22,7 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
         with:
-          ref: ${{ inputs.RELEASE_COMMIT || (github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha) }}
+          ref: ${{ inputs.RELEASE_COMMIT || (github.event_name == 'pull_request' && github.event.pull_request.head.ref || '') }}
 
       - name: Install dependencies
         run: |

.github/workflows/reusable_run_notebook.yml

@@ -37,7 +37,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Download Wheel Artifact
         uses: actions/download-artifact@v3

.github/workflows/reusable_track_size.yml

@@ -23,7 +23,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Get context
         id: context

.github/workflows/reusable_update_pr_body.yml

@@ -29,7 +29,7 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Set up Python
         uses: actions/setup-python@v2

.github/workflows/reusable_upload_web.yml

@@ -49,7 +49,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Download RRD
         uses: actions/download-artifact@v3

.github/workflows/reusable_upload_web_demo.yml

@@ -48,7 +48,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
         with:
-          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha }}
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.ref || '' }}
 
       - name: Download web demo assets
         uses: actions/download-artifact@v3

.github/workflows/reusable_upload_wheels.yml

@@ -52,7 +52,7 @@ jobs:
 
       - uses: actions/checkout@v4
         with:
-          ref: ${{ inputs.RELEASE_COMMIT || (github.event_name == 'pull_request' && github.event.pull_request.head.ref || github.sha) }}
+          ref: ${{ inputs.RELEASE_COMMIT || (github.event_name == 'pull_request' && github.event.pull_request.head.ref || '') }}
 
       - name: Download RRD
         uses: actions/download-artifact@v3

crates/re_build_tools/src/git.rs

@@ -43,16 +43,42 @@ pub fn rebuild_if_branch_or_commit_changes() {
     }
 }
 
-pub fn commit_hash() -> anyhow::Result<String> {
+/// Get the full commit hash
+pub fn git_commit_hash() -> anyhow::Result<String> {
     let git_hash = run_command("git", &["rev-parse", "HEAD"])?;
     if git_hash.is_empty() {
         anyhow::bail!("empty commit hash");
     }
     Ok(git_hash)
 }
 
-pub fn branch() -> anyhow::Result<String> {
-    run_command("git", &["symbolic-ref", "--short", "HEAD"])
+/// Get the first 7 characters of the commit hash
+pub fn git_commit_short_hash() -> anyhow::Result<String> {
+    Ok(git_commit_hash()?[0..7].to_string())
+}
+
+fn parse_branch_from_github_ref() -> Option<String> {
+    // The ref given is fully-formed, meaning that for branches the format is refs/heads/<branch_name>,
+    // for pull requests it is refs/pull/<pr_number>/merge, and for tags it is refs/tags/<tag_name>.
+    // For example, refs/heads/feature-branch-1.
+    // https://docs.github.com/en/actions/learn-github-actions/variables#default-environment-variables
+
+    let github_ref = std::env::var("GITHUB_REF").ok()?;
+    let branch = github_ref
+        .strip_prefix("refs/")?
+        .split_once('/')?
+        .1
+        .to_owned();
+    Some(branch)
+}
+
+/// Get the current git branch name
+pub fn git_branch() -> anyhow::Result<String> {
+    if let Some(branch) = parse_branch_from_github_ref() {
+        Ok(branch)
+    } else {
+        run_command("git", &["symbolic-ref", "--short", "HEAD"])
+    }
 }
 
 /// From <https://git-scm.com/docs/git-rev-parse>:

crates/re_build_tools/src/lib.rs

@@ -14,6 +14,7 @@ mod rebuild_detector;
 
 pub(crate) use self::rebuild_detector::Packages;
 
+pub use self::git::{git_branch, git_commit_hash, git_commit_short_hash};
 pub use self::hashing::{
     compute_crate_hash, compute_dir_filtered_hash, compute_dir_hash, compute_file_hash,
     compute_strings_hash, iter_dir, read_versioning_hash, write_versioning_hash,
@@ -142,8 +143,14 @@ pub fn export_build_info_vars_for_crate(crate_name: &str) {
     }
 
     if export_git_info {
-        set_env("RE_BUILD_GIT_HASH", &git::commit_hash().unwrap_or_default());
-        set_env("RE_BUILD_GIT_BRANCH", &git::branch().unwrap_or_default());
+        set_env(
+            "RE_BUILD_GIT_HASH",
+            &git::git_commit_hash().unwrap_or_default(),
+        );
+        set_env(
+            "RE_BUILD_GIT_BRANCH",
+            &git::git_branch().unwrap_or_default(),
+        );
 
         // Make sure the above are up-to-date
         git::rebuild_if_branch_or_commit_changes();
@@ -249,3 +256,8 @@ fn rust_llvm_versions() -> anyhow::Result<(String, String)> {
         llvm_version.unwrap_or_else(|| "unknown".to_owned()),
     ))
 }
+
+/// Returns info parsed from an invocation of the `cargo metadata` command
+pub fn cargo_metadata() -> anyhow::Result<cargo_metadata::Metadata> {
+    Ok(cargo_metadata::MetadataCommand::new().exec()?)
+}

crates/re_viewer/Cargo.toml

@@ -106,7 +106,7 @@ web-sys = { workspace = true, features = ["Window"] }
 re_build_tools.workspace = true
 
 # External
+anyhow.workspace = true
 serde = { workspace = true, features = ["derive"] }
 serde_json.workspace = true
 serde_yaml.workspace = true
-xshell.workspace = true