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Consolidate duplicated user selection logic into shared helper #1552

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bf357fa
Initial plan
Copilot Jan 29, 2026
8c41a74
Add common-setup.sh helper script with user selection logic and compr…
Copilot Jan 29, 2026
8c1c8dc
Update all feature scripts to use common-setup.sh helper for user sel…
Copilot Jan 29, 2026
79767c0
Update java wrapper.sh to use common-setup.sh helper
Copilot Jan 29, 2026
5c4e356
Add documentation for _common helper scripts
Copilot Jan 29, 2026
964dccf
Fix code review issues: validate _REMOTE_USER, fix common-utils none …
Copilot Jan 29, 2026
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122 changes: 122 additions & 0 deletions src/_common/README.md
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# Common Helper Scripts

This directory contains common helper scripts that can be shared across multiple features to avoid code duplication.

## common-setup.sh

A helper script that provides common setup functions used across multiple features.

### Functions

#### `determine_user_from_input`

Determines the appropriate non-root user based on the input username.

**Usage:**
```bash
# Source the helper script
source "${SCRIPT_DIR}/../_common/common-setup.sh"

# Determine the user
USERNAME=$(determine_user_from_input "${USERNAME}" "root")
```

**Parameters:**
- `$1` (required): Input username from feature configuration (e.g., "automatic", "auto", "none", or a specific username)
- `$2` (optional): Fallback username when no user is found in automatic mode (defaults to "root")

**Behavior:**
- **"auto" or "automatic"**:
- First checks if `_REMOTE_USER` environment variable is set and is not "root"
- If `_REMOTE_USER` is root or not set, searches for an existing user from the priority list:
1. `devcontainer`
2. `vscode`
3. `node`
4. `codespace`
5. User with UID 1000 (from `/etc/passwd`)
- If no user is found, returns the fallback user (default: "root")

- **"none"**: Always returns "root"

- **Specific username**:
- Validates the user exists using `id -u`
- If the user exists, returns that username
- If the user doesn't exist, returns "root"

**Examples:**

```bash
# Basic usage with default fallback (root)
USERNAME=$(determine_user_from_input "automatic")

# With custom fallback
USERNAME=$(determine_user_from_input "automatic" "vscode")

# Explicit user
USERNAME=$(determine_user_from_input "myuser")

# None (always returns root)
USERNAME=$(determine_user_from_input "none")
```

**Return Value:**
Prints the resolved username to stdout, which can be captured using command substitution.

## Testing

Tests for the helper scripts are located in `/test/_common/`. Run the tests with:

```bash
bash test/_common/test-common-setup.sh
```

## Edge Cases

The helper handles several edge cases:

1. **Missing awk**: Some systems (like Mariner) don't have awk by default. Features should install it before sourcing the helper if needed.

2. **UID 1000 lookup**: The user with UID 1000 is included in the search as it's commonly the first non-system user created.

3. **_REMOTE_USER behavior**: When `_REMOTE_USER` is set to a non-root user, it takes priority over all other detection methods in automatic mode.

4. **Empty user list entries**: The helper safely handles empty entries in the user detection loop.

## Migration Guide

To migrate an existing feature to use the common helper:

### Before:
```bash
# Determine the appropriate non-root user
if [ "${USERNAME}" = "auto" ] || [ "${USERNAME}" = "automatic" ]; then
USERNAME=""
POSSIBLE_USERS=("vscode" "node" "codespace" "$(awk -v val=1000 -F ":" '$3==val{print $1}' /etc/passwd)")
for CURRENT_USER in "${POSSIBLE_USERS[@]}"; do
if id -u ${CURRENT_USER} > /dev/null 2>&1; then
USERNAME=${CURRENT_USER}
break
fi
done
if [ "${USERNAME}" = "" ]; then
USERNAME=root
fi
elif [ "${USERNAME}" = "none" ] || ! id -u ${USERNAME} > /dev/null 2>&1; then
USERNAME=root
fi
```

### After:
```bash
# Source common helper functions
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "${SCRIPT_DIR}/../_common/common-setup.sh"

# Determine the appropriate non-root user
USERNAME=$(determine_user_from_input "${USERNAME}" "root")
```

**Note:** For features like `common-utils` that create users and need a different fallback, use:
```bash
USERNAME=$(determine_user_from_input "${USERNAME}" "vscode")
```
87 changes: 87 additions & 0 deletions src/_common/common-setup.sh
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#!/bin/bash
#-------------------------------------------------------------------------------------------------------------------------
# Copyright (c) Microsoft Corporation. All rights reserved.
# Licensed under the MIT License. See https://github.com/devcontainers/features/blob/main/LICENSE for license information.
#-------------------------------------------------------------------------------------------------------------------------
#
# Helper script for common feature setup tasks, including user selection logic.
# Maintainer: The Dev Container spec maintainers

# Determine the appropriate non-root user
# Usage: determine_user_from_input USERNAME [FALLBACK_USER]
#
# This function resolves the USERNAME variable based on the input value:
# - If USERNAME is "auto" or "automatic", it will detect an existing non-root user
# - If USERNAME is "none" or doesn't exist, it will fall back to root
# - Otherwise, it validates the specified USERNAME exists
#
# Arguments:
# USERNAME - The username input (typically from feature configuration)
# FALLBACK_USER - Optional fallback user when no user is found in automatic mode (defaults to "root")
#
# Returns:
# The resolved username is printed to stdout
#
# Examples:
# USERNAME=$(determine_user_from_input "automatic")
# USERNAME=$(determine_user_from_input "vscode")
# USERNAME=$(determine_user_from_input "auto" "vscode")
#
determine_user_from_input() {
local input_username="${1:-automatic}"
local fallback_user="${2:-root}"
local resolved_username=""

if [ "${input_username}" = "auto" ] || [ "${input_username}" = "automatic" ]; then
# Automatic mode: try to detect an existing non-root user

# First, check if _REMOTE_USER is set and is not root
if [ -n "${_REMOTE_USER:-}" ] && [ "${_REMOTE_USER}" != "root" ]; then
# Verify the user exists before using it
if id -u "${_REMOTE_USER}" > /dev/null 2>&1; then
resolved_username="${_REMOTE_USER}"
else
# _REMOTE_USER doesn't exist, fall through to normal detection
resolved_username=""
fi
fi

# If we didn't resolve via _REMOTE_USER, try to find a non-root user
if [ -z "${resolved_username}" ]; then
# Try to find a non-root user from a list of common usernames
# The list includes: devcontainer, vscode, node, codespace, and the user with UID 1000
local possible_users=("devcontainer" "vscode" "node" "codespace" "$(awk -v val=1000 -F ":" '$3==val{print $1}' /etc/passwd 2>/dev/null || echo '')")

for current_user in "${possible_users[@]}"; do
# Skip empty entries
if [ -z "${current_user}" ]; then
continue
fi

# Check if user exists
if id -u "${current_user}" > /dev/null 2>&1; then
resolved_username="${current_user}"
break
fi
done

# If no user found, use the fallback
if [ -z "${resolved_username}" ]; then
resolved_username="${fallback_user}"
fi
fi
elif [ "${input_username}" = "none" ]; then
# Explicit "none" means use root
resolved_username="root"
else
# Specific username provided - validate it exists
if id -u "${input_username}" > /dev/null 2>&1; then
resolved_username="${input_username}"
else
# User doesn't exist, fall back to root
resolved_username="root"
fi
fi

echo "${resolved_username}"
}
20 changes: 5 additions & 15 deletions src/anaconda/install.sh
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Expand Up @@ -81,22 +81,12 @@ rm -f /etc/profile.d/00-restore-env.sh
echo "export PATH=${PATH//$(sh -lc 'echo $PATH')/\$PATH}" > /etc/profile.d/00-restore-env.sh
chmod +x /etc/profile.d/00-restore-env.sh

# Source common helper functions
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "${SCRIPT_DIR}/../_common/common-setup.sh"

# Determine the appropriate non-root user
if [ "${USERNAME}" = "auto" ] || [ "${USERNAME}" = "automatic" ]; then
USERNAME=""
POSSIBLE_USERS=("vscode" "node" "codespace" "$(awk -v val=1000 -F ":" '$3==val{print $1}' /etc/passwd)")
for CURRENT_USER in "${POSSIBLE_USERS[@]}"; do
if id -u "${CURRENT_USER}" > /dev/null 2>&1; then
USERNAME="${CURRENT_USER}"
break
fi
done
if [ "${USERNAME}" = "" ]; then
USERNAME=root
fi
elif [ "${USERNAME}" = "none" ] || ! id -u ${USERNAME} > /dev/null 2>&1; then
USERNAME=root
fi
USERNAME=$(determine_user_from_input "${USERNAME}" "root")

architecture="$(uname -m)"
# Normalize arm64 to aarch64 for consistency
Expand Down
31 changes: 12 additions & 19 deletions src/common-utils/main.sh
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Expand Up @@ -399,27 +399,20 @@ case "${ADJUSTED_ID}" in
;;
esac

# If in automatic mode, determine if a user already exists, if not use vscode
if [ "${USERNAME}" = "auto" ] || [ "${USERNAME}" = "automatic" ]; then
if [ "${_REMOTE_USER}" != "root" ]; then
USERNAME="${_REMOTE_USER}"
else
USERNAME=""
POSSIBLE_USERS=("devcontainer" "vscode" "node" "codespace" "$(awk -v val=1000 -F ":" '$3==val{print $1}' /etc/passwd)")
for CURRENT_USER in "${POSSIBLE_USERS[@]}"; do
if id -u ${CURRENT_USER} > /dev/null 2>&1; then
USERNAME=${CURRENT_USER}
break
fi
done
if [ "${USERNAME}" = "" ]; then
USERNAME=vscode
fi
fi
elif [ "${USERNAME}" = "none" ]; then
USERNAME=root
# Source common helper functions
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "${SCRIPT_DIR}/../_common/common-setup.sh"

# Handle the special "none" case for common-utils before user determination
# The "none" case sets USER_UID and USER_GID to 0
ORIGINAL_USERNAME="${USERNAME}"
if [ "${ORIGINAL_USERNAME}" = "none" ]; then
USERNAME="root"
USER_UID=0
USER_GID=0
else
# If in automatic mode, determine if a user already exists, if not use vscode (which will be created)
USERNAME=$(determine_user_from_input "${USERNAME}" "vscode")
fi
# Create or update a non-root user to match UID/GID.
group_name="${USERNAME}"
Expand Down
20 changes: 5 additions & 15 deletions src/conda/install.sh
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Expand Up @@ -27,22 +27,12 @@ rm -f /etc/profile.d/00-restore-env.sh
echo "export PATH=${PATH//$(sh -lc 'echo $PATH')/\$PATH}" > /etc/profile.d/00-restore-env.sh
chmod +x /etc/profile.d/00-restore-env.sh

# Source common helper functions
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "${SCRIPT_DIR}/../_common/common-setup.sh"

# Determine the appropriate non-root user
if [ "${USERNAME}" = "auto" ] || [ "${USERNAME}" = "automatic" ]; then
USERNAME=""
POSSIBLE_USERS=("vscode" "node" "codespace" "$(awk -v val=1000 -F ":" '$3==val{print $1}' /etc/passwd)")
for CURRENT_USER in "${POSSIBLE_USERS[@]}"; do
if id -u "${CURRENT_USER}" > /dev/null 2>&1; then
USERNAME="${CURRENT_USER}"
break
fi
done
if [ "${USERNAME}" = "" ]; then
USERNAME=root
fi
elif [ "${USERNAME}" = "none" ] || ! id -u ${USERNAME} > /dev/null 2>&1; then
USERNAME=root
fi
USERNAME=$(determine_user_from_input "${USERNAME}" "root")

architecture="$(uname -m)"
if [ "${architecture}" != "x86_64" ]; then
Expand Down
20 changes: 5 additions & 15 deletions src/desktop-lite/install.sh
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Expand Up @@ -71,22 +71,12 @@ if [ "$(id -u)" -ne 0 ]; then
exit 1
fi

# Source common helper functions
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "${SCRIPT_DIR}/../_common/common-setup.sh"

# Determine the appropriate non-root user
if [ "${USERNAME}" = "auto" ] || [ "${USERNAME}" = "automatic" ]; then
USERNAME=""
POSSIBLE_USERS=("vscode" "node" "codespace" "$(awk -v val=1000 -F ":" '$3==val{print $1}' /etc/passwd)")
for CURRENT_USER in "${POSSIBLE_USERS[@]}"; do
if id -u ${CURRENT_USER} > /dev/null 2>&1; then
USERNAME=${CURRENT_USER}
break
fi
done
if [ "${USERNAME}" = "" ]; then
USERNAME=root
fi
elif [ "${USERNAME}" = "none" ] || ! id -u ${USERNAME} > /dev/null 2>&1; then
USERNAME=root
fi
USERNAME=$(determine_user_from_input "${USERNAME}" "root")
# Add default Fluxbox config files if none are already present
fluxbox_apps="$(cat \
<< 'EOF'
Expand Down
20 changes: 5 additions & 15 deletions src/docker-in-docker/install.sh
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Expand Up @@ -44,22 +44,12 @@ fi
# See: https://github.com/microsoft/vscode-dev-containers/blob/main/script-library/shared/utils.sh
###################

# Source common helper functions
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "${SCRIPT_DIR}/../_common/common-setup.sh"

# Determine the appropriate non-root user
if [ "${USERNAME}" = "auto" ] || [ "${USERNAME}" = "automatic" ]; then
USERNAME=""
POSSIBLE_USERS=("vscode" "node" "codespace" "$(awk -v val=1000 -F ":" '$3==val{print $1}' /etc/passwd)")
for CURRENT_USER in "${POSSIBLE_USERS[@]}"; do
if id -u ${CURRENT_USER} > /dev/null 2>&1; then
USERNAME=${CURRENT_USER}
break
fi
done
if [ "${USERNAME}" = "" ]; then
USERNAME=root
fi
elif [ "${USERNAME}" = "none" ] || ! id -u ${USERNAME} > /dev/null 2>&1; then
USERNAME=root
fi
USERNAME=$(determine_user_from_input "${USERNAME}" "root")

# Package manager update function
pkg_mgr_update() {
Expand Down
20 changes: 5 additions & 15 deletions src/docker-outside-of-docker/install.sh
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Expand Up @@ -38,22 +38,12 @@ if [ "$(id -u)" -ne 0 ]; then
exit 1
fi

# Source common helper functions
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "${SCRIPT_DIR}/../_common/common-setup.sh"

# Determine the appropriate non-root user
if [ "${USERNAME}" = "auto" ] || [ "${USERNAME}" = "automatic" ]; then
USERNAME=""
POSSIBLE_USERS=("vscode" "node" "codespace" "$(awk -v val=1000 -F ":" '$3==val{print $1}' /etc/passwd)")
for CURRENT_USER in "${POSSIBLE_USERS[@]}"; do
if id -u ${CURRENT_USER} > /dev/null 2>&1; then
USERNAME=${CURRENT_USER}
break
fi
done
if [ "${USERNAME}" = "" ]; then
USERNAME=root
fi
elif [ "${USERNAME}" = "none" ] || ! id -u ${USERNAME} > /dev/null 2>&1; then
USERNAME=root
fi
USERNAME=$(determine_user_from_input "${USERNAME}" "root")

apt_get_update()
{
Expand Down
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