.devcontainer

Dev Container

The recommended way to develop on tableauio/loader. One container, all four target languages (C++17, Go, .NET, Node) plus protobuf via vcpkg, pinned to the same toolchain CI uses. Version pins live in ./versions.env, consumed by the Dockerfile, make.py, and the CI workflows.

For native dev (no Docker, no WSL2), use make.py directly.

Prerequisites

• Docker Desktop (Windows / macOS) or Docker Engine (Linux)
• VS Code with the Dev Containers extension

Open the container

code .

Then Dev Containers: Reopen in Container from the command palette. First build is one-time ~25 min (vcpkg compiles protobuf); reopens are near-instant.

Inside the container, python3 make.py setup is a no-op. Use python3 make.py test --lang <X> for any language.

Pin a different protobuf version

LOADER_PROTOBUF_VERSION=3.21.12 code .

Then Rebuild Container. Only the vcpkg layer rebuilds.

Host-OS caveats

• Windows. WSL2 backend required. Check the workspace out under WSL2 (\\wsl.localhost\Ubuntu\home\<user>\loader) — not /mnt/c/... — for good bind-mount performance.
• Apple Silicon. Docker builds the image natively as arm64. Confirm with docker info | grep Architecture.
• Linux (native Docker Engine). No special configuration.

Architecture

Single-stage Dockerfile on mcr.microsoft.com/devcontainers/cpp:1-ubuntu-24.04:

1. Architecture detection (TARGETARCH → Go arch, buf arch, vcpkg triplet)
2. Go — version from versions.env
3. buf — version from versions.env
4. vcpkg pinned to VCPKG_BASELINE_COMMIT, protobuf installed via manifest mode (asserts version)
5. .NET SDK — version from versions.env
6. Node.js LTS — version from versions.env
7. ENV CMAKE_PREFIX_PATH=/opt/vcpkg/active so find_package(Protobuf CONFIG) resolves automatically

Build context is .devcontainer/, so COPY versions.env … resolves directly.

versions.env format

• One KEY=VALUE per line.
• No quotes, no spaces around =, no inline comments.
• Comments at column 0 with #. Blank lines ignored. No shell expansion.

Consumers: Dockerfile (sourced as a shell file), make.py (Versions.load()), and .github/actions/load-versions (exports to $GITHUB_ENV).

Use python3 make.py env for a JSON dump of resolved values.

Troubleshooting

Stale-codegen errors after buf generate

Symptoms:

• C++: fatal error: google/protobuf/generated_message_table_driven.h: No such file or directory
• C#: hundreds of error CS0101: The namespace already contains a definition for ...

The host workspace has gitignored *.pb.* from a previous protobuf version that git pull didn't remove. Wipe with python3 make.py clean --lang cpp (or --lang csharp), then rerun the test.

Falling back

No Docker? Use make.py directly: python3 make.py setup --lang all then python3 make.py test --lang <X>. Works on macOS / Linux / Windows native.