### Dockerfile Example with Multiple Installations

Source: https://github.com/milkclouds/devcontainer-feature-installer/blob/main/README.md

A comprehensive Dockerfile example demonstrating the installation of the feature-cli script followed by installing two different devcontainer features with options.

```Dockerfile
RUN curl -fsSL https://raw.githubusercontent.com/milkclouds/devcontainer-feature-installer/main/install-feature-cli.sh \
    | FEATURE_CLI_BIN_DIR=/bin bash \
    && feature-install ghcr.io/milkclouds/devcontainer-features/system-tools:0.1.4 \
    && feature-install --features '{"ghcr.io/milkclouds/devcontainer-features/python-tools:0.1.4":{"tools":"ruff"}}'
```

--------------------------------

### Install Single Feature

Source: https://github.com/milkclouds/devcontainer-feature-installer/blob/main/README.md

Quick start example to install a single devcontainer feature from a specified OCI registry and tag.

```bash
RUN feature-install ghcr.io/milkclouds/devcontainer-features/system-tools:0.1.4
```

--------------------------------

### Run Feature Installer Test Suite

Source: https://context7.com/milkclouds/devcontainer-feature-installer/llms.txt

Installs dependencies and runs the full test suite for the feature-installer using bats. Tests cover version consistency, dependency ordering, option conflicts, and install execution.

```bash
# Install dependencies (Debian/Ubuntu)
sudo apt-get install -y bats jq curl tar

# Run the full suite
bats test/feature-install.bats
# Output (passing):
#  ✓ version matches VERSION
#  ✓ dependsOn order
#  ✓ installsAfter order
#  ✓ conflicting options fail
#  ✓ install order when running features
#
# 5 tests, 0 failures
```

--------------------------------

### Install Features Using a Features File

Source: https://context7.com/milkclouds/devcontainer-feature-installer/llms.txt

Install features by referencing a JSON file containing the features and their options. This can be a standard devcontainer.json with a `.features` key or a plain JSON file.

```bash
feature-install --features-file /tmp/devcontainer.json
```

```json
// devcontainer.json (the .features object is extracted automatically)
{
  "name": "My Dev Container",
  "features": {
    "ghcr.io/milkclouds/devcontainer-features/system-tools:0.1.4": {},
    "ghcr.io/milkclouds/devcontainer-features/python-tools:0.1.4": { "tools": "ruff" }
  }
}
```

```bash
# Plain JSON file (no .features wrapper)
# features.json:
# {
#   "ghcr.io/milkclouds/devcontainer-features/system-tools:0.1.4": {}
# }
feature-install --features-file features.json
```

--------------------------------

### Check Feature Installer Version

Source: https://context7.com/milkclouds/devcontainer-feature-installer/llms.txt

Prints the current version of the feature-install tool and exits. This is useful for verifying the installed version.

```bash
feature-install --version
# Output: 0.1.0
```

--------------------------------

### Install Features from devcontainer.json

Source: https://github.com/milkclouds/devcontainer-feature-installer/blob/main/README.md

Installs devcontainer features by reading their configuration from a specified devcontainer.json file.

```bash
RUN feature-install --features-file devcontainer.json
```

--------------------------------

### Bootstrap feature-install CLI

Source: https://context7.com/milkclouds/devcontainer-feature-installer/llms.txt

Installs the feature-install binary into a container image. Use FEATURE_CLI_BIN_DIR to control the install location. Override FEATURE_CLI_REPO and FEATURE_CLI_REF to specify a custom source repository and git ref.

```dockerfile
FROM ubuntu:24.04

# Bootstrap: installs feature-install to /bin
RUN curl -fsSL \
      https://raw.githubusercontent.com/milkclouds/devcontainer-feature-installer/main/install-feature-cli.sh \
    | FEATURE_CLI_BIN_DIR=/bin bash
# Output: Installed feature-install to /bin/feature-install

# Override repo/ref to pin a specific fork or commit
RUN curl -fsSL \
      https://raw.githubusercontent.com/milkclouds/devcontainer-feature-installer/main/install-feature-cli.sh \
    | FEATURE_CLI_REPO=myorg/feature-installer \
      FEATURE_CLI_REF=v0.1.0 \
      FEATURE_CLI_BIN_DIR=/usr/local/bin bash
```

--------------------------------

### Install Feature with Overridden Options

Source: https://context7.com/milkclouds/devcontainer-feature-installer/llms.txt

Installs a devcontainer feature, overriding specific options. The installer exports merged options as uppercase environment variables to the install script.

```bash
# User overrides "tools"; "pythonVersion" falls back to default "3.12"
feature-install --features '{ 
  "ghcr.io/milkclouds/devcontainer-features/python-tools:0.1.4": {
    "tools": "ruff"
  }
}'
# install.sh receives:
#   TOOLS=ruff
#   PYTHONVERSION=3.12
```

--------------------------------

### Dry-run Feature Installation

Source: https://github.com/milkclouds/devcontainer-feature-installer/blob/main/README.md

Performs a dry run to determine the installation order of specified devcontainer features without actually installing them.

```bash
RUN feature-install --dry-run ghcr.io/milkclouds/devcontainer-features/system-tools:0.1.4
```

--------------------------------

### Install a Single Feature using Positional Argument

Source: https://context7.com/milkclouds/devcontainer-feature-installer/llms.txt

Installs a single remote feature from an OCI registry. The tag is required. `oras` is auto-downloaded if not present. Multiple features can be installed in one invocation by listing them as positional arguments.

```dockerfile
FROM ubuntu:24.04

RUN curl -fsSL \
      https://raw.githubusercontent.com/milkclouds/devcontainer-feature-installer/main/install-feature-cli.sh \
    | FEATURE_CLI_BIN_DIR=/bin bash

# Install a single remote feature — tag is required
RUN feature-install ghcr.io/milkclouds/devcontainer-features/system-tools:0.1.4
# Output:
#   Installing feature: ghcr.io/milkclouds/devcontainer-features/system-tools:0.1.4
#   <output from install.sh>

# Install multiple features in one invocation (positional args)
RUN feature-install \
      ghcr.io/milkclouds/devcontainer-features/system-tools:0.1.4 \
      ghcr.io/milkclouds/devcontainer-features/python-tools:0.1.4
```

--------------------------------

### Pre-install oras for Dockerfile Builds

Source: https://context7.com/milkclouds/devcontainer-feature-installer/llms.txt

Demonstrates pre-installing the 'oras' binary in a Dockerfile to avoid auto-download during feature installation. Sets the ORAS_BIN environment variable to point to the pre-installed binary.

```dockerfile
FROM ubuntu:24.04

# Pre-install oras to avoid auto-download on every build
RUN curl -fsSL https://github.com/oras-project/oras/releases/download/v1.1.0/oras_1.1.0_linux_amd64.tar.gz \
    | tar -xz -C /usr/local/bin oras

RUN curl -fsSL 
      https://raw.githubusercontent.com/milkclouds/devcontainer-feature-installer/main/install-feature-cli.sh 
    | FEATURE_CLI_BIN_DIR=/bin bash

# Point feature-install at the pre-installed binary
ENV ORAS_BIN=/usr/local/bin/oras
RUN feature-install ghcr.io/milkclouds/devcontainer-features/system-tools:0.1.4
```

--------------------------------

### Install feature-cli Script

Source: https://github.com/milkclouds/devcontainer-feature-installer/blob/main/README.md

Installs the feature-cli script into the /bin directory. Run this only inside containers (Dockerfile build or devcontainer image build).

```bash
RUN curl -fsSL https://raw.githubusercontent.com/milkclouds/devcontainer-feature-installer/main/install-feature-cli.sh \
  | FEATURE_CLI_BIN_DIR=/bin bash
```

--------------------------------

### Install Multiple Features with Options

Source: https://github.com/milkclouds/devcontainer-feature-installer/blob/main/README.md

Installs multiple devcontainer features, specifying options for each. Options are provided as a JSON object where keys are feature identifiers and values are their respective option objects.

```bash
RUN feature-install --features '{ \
  "ghcr.io/milkclouds/devcontainer-features/system-tools:0.1.4": {}, \
  "ghcr.io/milkclouds/devcontainer-features/python-tools:0.1.4": {"tools":"ruff"} \
}'
```

--------------------------------

### Install Features Using Local Paths

Source: https://context7.com/milkclouds/devcontainer-feature-installer/llms.txt

Install features by referencing local directories. The tool automatically converts relative or absolute paths to absolute paths. This is useful for testing features in development or monorepos.

```bash
# Absolute path
feature-install /workspace/features/my-feature
```

```bash
# Relative paths
feature-install ./src/system-tools ./src/python-tools
```

```bash
# Mix of local and remote in JSON
feature-install --features '{
  "./src/system-tools": {},
  "ghcr.io/milkclouds/devcontainer-features/python-tools:0.1.4": {}
}'
```

```plaintext
# Local feature devcontainer-feature.json layout expected:
# src/system-tools/
# ←← devcontainer-feature.json
# ←← install.sh
```

--------------------------------

### Soft Ordering Constraint with installsAfter

Source: https://context7.com/milkclouds/devcontainer-feature-installer/llms.txt

Use `installsAfter` to specify that a feature should be installed after another *if* the other feature is already selected. It does not auto-add features. The installer incorporates these constraints into the topological sort.

```json
// test/fixtures/ia-c/devcontainer-feature.json
{
  "id": "ia-c",
  "version": "0.0.1",
  "name": "ia-c",
  "description": "installsAfter dependent",
  "installsAfter": ["../ia-b"],
  "options": {}
}
```

```bash
# ia-c declares installsAfter ia-b; when both are selected ia-b runs first
feature-install --dry-run ./test/fixtures/ia-b ./test/fixtures/ia-c
```

```bash
# If ia-b is NOT in the selected set, ia-c still installs (constraint is ignored)
feature-install --dry-run ./test/fixtures/ia-c
```

--------------------------------

### Install Features from Local Paths

Source: https://github.com/milkclouds/devcontainer-feature-installer/blob/main/README.md

Installs devcontainer features directly from local file paths. This is useful for development or testing custom features.

```bash
RUN feature-install ./src/system-tools ./src/python-tools
```

--------------------------------

### Install Features with Options using --features

Source: https://context7.com/milkclouds/devcontainer-feature-installer/llms.txt

Accepts a JSON object mapping feature references to their option objects. Options override defaults declared in each Feature's `devcontainer-feature.json`. Option keys are sanitized to uppercase environment variable names before being exported to `install.sh`.

```dockerfile
FROM ubuntu:24.04

RUN curl -fsSL \
      https://raw.githubusercontent.com/milkclouds/devcontainer-feature-installer/main/install-feature-cli.sh \
    | FEATURE_CLI_BIN_DIR=/bin bash

# Pass options as inline JSON
RUN feature-install --features '{ 
  "ghcr.io/milkclouds/devcontainer-features/system-tools:0.1.4": {}, 
  "ghcr.io/milkclouds/devcontainer-features/python-tools:0.1.4": {"tools": "ruff"}
}'
# install.sh for python-tools receives: TOOLS=ruff

# Escape quotes when used inside a single RUN string
RUN feature-install --features 
  "{\"ghcr.io/milkclouds/devcontainer-features/python-tools:0.1.4\":{\"tools\":\"ruff\"}}"
```

--------------------------------

### Install Features from a File using --features-file

Source: https://context7.com/milkclouds/devcontainer-feature-installer/llms.txt

Reads feature references and options from a `devcontainer.json` (extracts the `.features` key) or a plain JSON object file. This is useful when reusing an existing devcontainer configuration for standalone image builds.

```dockerfile
FROM ubuntu:24.04

COPY .devcontainer/devcontainer.json /tmp/devcontainer.json

RUN curl -fsSL \
      https://raw.githubusercontent.com/milkclouds/devcontainer-feature-installer/main/install-feature-cli.sh \
    | FEATURE_CLI_BIN_DIR=/bin bash

```

--------------------------------

### Dry-Run Mode for Dependency Resolution

Source: https://context7.com/milkclouds/devcontainer-feature-installer/llms.txt

Use `--dry-run` to resolve the dependency graph and display the install order without executing any installations. This is useful for validating dependencies and detecting conflicts.

```bash
# Dry-run a single remote feature (resolves dependsOn transitively)
feature-install --dry-run ghcr.io/milkclouds/devcontainer-features/system-tools:0.1.4
```

```bash
# Dry-run local fixtures to inspect ordering
feature-install --dry-run ./test/fixtures/dep-a
```

```bash
# Dry-run with --features JSON
feature-install --dry-run --features '{
  "ghcr.io/milkclouds/devcontainer-features/system-tools:0.1.4": {},
  "ghcr.io/milkclouds/devcontainer-features/python-tools:0.1.4": {}
}'
```

--------------------------------

### Define Feature Options in devcontainer-feature.json

Source: https://context7.com/milkclouds/devcontainer-feature-installer/llms.txt

Defines available options for a devcontainer feature, including their type and default values. These options can be overridden during installation.

```json
{
  "id": "python-tools",
  "version": "0.1.4",
  "options": {
    "tools": {
      "type": "string",
      "default": "pip"
    },
    "pythonVersion": {
      "type": "string",
      "default": "3.12"
    }
  }
}
```

--------------------------------

### Automatic Dependency Resolution with dependsOn

Source: https://context7.com/milkclouds/devcontainer-feature-installer/llms.txt

Declare `dependsOn` in `devcontainer-feature.json` for automatic dependency resolution. The installer builds a dependency graph and sorts features topologically. Conflicts in options for the same dependency will cause failure.

```json
// test/fixtures/dep-a/devcontainer-feature.json
{
  "id": "dep-a",
  "version": "0.0.1",
  "name": "dep-a",
  "description": "Dependency A",
  "dependsOn": {
    "../dep-b": {}
  },
  "options": {}
}
```

```bash
# dep-b is installed automatically before dep-a
feature-install ./test/fixtures/dep-a
```

```bash
# Conflict detection: dep-a requires conflict-e with opt=1,
# but the caller also passes opt=2 → hard failure
feature-install --features '{
  "./test/fixtures/conflict-e": {"opt": "2"},
  "./test/fixtures/conflict-a": {}
}'
```

--------------------------------

### Run Bats Tests

Source: https://github.com/milkclouds/devcontainer-feature-installer/blob/main/README.md

Executes the test suite for the feature-install project using the Bats testing framework.

```bash
bats test/feature-install.bats
```

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