Remove docker and devcontainer as unused (#5500)

As far as I'm aware, the the devcontainers aren't in frequent use, which
is why they fall out of date. Comparing with
https://github.com/llvm/llvm-project/, I don't see devcontainer configs
maintained as part of llvm
(https://github.com/llvm/llvm-project/issues?q=devcontainer doesn't have
much either) so I think we should trim these instead of investing in
maintenance.

These configs aren't being maintained. In the docker configs, note `RUN
bazel build //explorer` is broken. Also, #5496 noted the clang version
is out of date.

Closes #5496

.devcontainer/devcontainer.json

@@ -1,36 +0,0 @@
-// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
-// Exceptions. See /LICENSE for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-
-{
-  "name": "carbon-lang",
-  "build": {
-    "dockerfile": "../docker/ubuntu2404/base/Dockerfile"
-  },
-  "mounts": [
-    {
-      "source": "carbon-cache",
-      "target": "/home/ubuntu/.cache",
-      "type": "volume"
-    }
-  ],
-  "containerUser": "ubuntu",
-  "remoteUser": "ubuntu",
-  // When using devcontainer with podman, you may see /workspace being owned
-  // by root. To work around this, uncomment the following lines
-  // "runArgs": [
-  //   "--userns=keep-id"
-  // ],
-  "customizations": {
-    "vscode": {
-      "extensions": [
-        "bazelbuild.vscode-bazel",
-        "bierner.github-markdown-preview",
-        "daohong-emilio.yash",
-        "esbenp.prettier-vscode",
-        "llvm-vs-code-extensions.vscode-clangd",
-        "ms-python.python"
-      ]
-    }
-  }
-}

docker/README.md

@@ -1,55 +0,0 @@
-# Docker
-
-<!--
-Part of the Carbon Language project, under the Apache License v2.0 with LLVM
-Exceptions. See /LICENSE for license information.
-SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
--->
-
-ubuntu:22.04
-
-## Build and run image
-
-### Build
-
-Building the base image is required.
-
-```
-docker build -t carbon-ubuntu2404-base ./ubuntu2404/base
-```
-
-Build image using git repository
-
-```bash
-docker build -t carbon-ubuntu2404 ./ubuntu2404/github
-```
-
-Build image using copy instruction
-
-```bash
-docker build -f ./ubuntu2404/Dockerfile -t carbon-ubuntu2404 ..
-```
-
-Run image
-
-```bash
-docker run carbon-ubuntu2404
-```
-
-Run image using specific file
-
-```bash
-docker run carbon-ubuntu2404 bazel run //explorer -- ./explorer/testdata/print/format_only.carbon
-```
-
-### Using a mounted volume
-
-Run from the repository root for PWD.
-
-```
-cd ..
-```
-
-```bash
-docker run -w "/carbon-lang" -v "${PWD}:/carbon-lang" "carbon-ubuntu2404-base" bazel run "//explorer" -- "./explorer/testdata/print/format_only.carbon"
-```

docker/ubuntu2404/Dockerfile

@@ -1,15 +0,0 @@
-# Part of the Carbon Language project, under the Apache License v2.0 with LLVM
-# Exceptions. See /LICENSE for license information.
-# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-
-FROM carbon-ubuntu2404-base as carbon-ubuntu2404-build
-
-COPY . /carbon-lang
-WORKDIR /carbon-lang
-
-# Build
-RUN bazel build //explorer
-
-FROM carbon-ubuntu2404-build
-
-CMD ["bazel", "run", "//explorer", "--", "./explorer/testdata/print/format_only.carbon"]

docker/ubuntu2404/base/Dockerfile

@@ -1,49 +0,0 @@
-# Part of the Carbon Language project, under the Apache License v2.0 with LLVM
-# Exceptions. See /LICENSE for license information.
-# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-
-FROM ubuntu:24.04 as carbon-ubuntu2404-base
-
-# Install apt tools:
-#   git: Used by VS Code.
-#   golang: Used for Bazelisk and Buildifier.
-#   python3: For Carbon tools.
-#   gnupg, software-properties-common, wget: For llvm.sh.
-# apt-get update and install together per Docker best practice.
-RUN apt-get update && \
-  apt-get install -y \
-  git \
-  gnupg \
-  golang \
-  python3-pip \
-  python3 \
-  software-properties-common \
-  wget \
-  nodejs \
-  npm
-
-ENV PATH="/root/go/bin:${PATH}"
-
-# Bazelisk is used for Carbon builds.
-RUN go install github.com/bazelbuild/bazelisk@v1.14.0
-RUN ln -s /root/go/bin/bazelisk /root/go/bin/bazel
-
-# Buildifier is used by the Bazel VS Code extension.
-RUN go install github.com/bazelbuild/buildtools/buildifier@5.1.0
-
-# Install LLVM from apt.llvm.org.
-RUN wget https://apt.llvm.org/llvm.sh
-RUN chmod +x llvm.sh
-RUN ./llvm.sh 18 all
-RUN rm llvm.sh
-
-# Add the lib dir to the PATH. This helps Bazel find clang and VS Code find
-# clangd, without version suffixes.
-ENV PATH="/usr/lib/llvm-18/bin:${PATH}"
-
-# Update pip and install black and pre-commit.
-RUN pip3 install black pre-commit --break-system-packages
-
-# Create .cache directory with proper ownership. We will mount a named volume
-# at this location to allow caching of bazel build files.
-RUN mkdir /home/ubuntu/.cache && chown -R ubuntu:ubuntu /home/ubuntu/.cache

docker/ubuntu2404/github/Dockerfile

@@ -1,20 +0,0 @@
-# Part of the Carbon Language project, under the Apache License v2.0 with LLVM
-# Exceptions. See /LICENSE for license information.
-# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-
-FROM carbon-ubuntu2404-base as carbon-ubuntu2404-github-build
-
-# Clone git repository
-RUN git clone https://github.com/carbon-language/carbon-lang
-
-WORKDIR /carbon-lang
-
-# Setup pre-commit
-RUN pre-commit install
-
-# Build
-RUN bazel build //explorer
-
-FROM carbon-ubuntu2404-github-build
-
-CMD ["bazel", "run", "//explorer", "--", "./explorer/testdata/print/format_only.carbon"]

docs/project/contribution_tools.md

@@ -227,13 +227,6 @@ considering if they fit your workflow.
         **either** normal terminals **or** Visual Studio Code to run `bazel`,
         not both in combination. Visual Studio Code can still be used for other
         purposes, such as editing files, without interfering with `bazel`.
-    -   [DevContainers](https://code.visualstudio.com/docs/remote/containers): A
-        way to use Docker for build environments.
-        -   After following the
-            [installation instructions](https://code.visualstudio.com/docs/remote/containers#_installation),
-            you should be prompted to use Carbon's
-            [devcontainer](/.devcontainer/devcontainer.json) with "Reopen in
-            container".
 -   [clangd](https://clangd.llvm.org/installation): An LSP server implementation
     for C/C++.
     -   To ensure that `clangd` reports accurate diagnostics. It needs a