Compare GFlag Defaults Across Versions Without Starting a Cluster

				
					#!/bin/bash

# Usage:
# ./compare_docker_flags.sh [--cleanup] \
#   <flag_name> <version1> <version2> [master|tserver|both]
#
# Example:
# ./compare_docker_flags.sh --cleanup \
#   webserver_port 2.20.10.0 2024.1.3.0 master

CLEANUP=0

while [[ "$#" -gt 0 ]]; do
    case $1 in
        --cleanup)
            CLEANUP=1
            shift
            ;;
        -*)
            echo -e "\e[31m[!] Unknown option: $1\e[0m"
            exit 1
            ;;
        *)
            break
            ;;
    esac
done

FLAG=$1
V1=$2
V2=$3
COMP=${4:-both}

if [ "$#" -lt 3 ] || [ "$#" -gt 4 ]; then
    echo -e "\e[31m[!] Error: Invalid number of arguments.\e[0m"
    echo "Usage: $0 [--cleanup] <flag_name> <version1> <version2> [master|tserver|both]"
    exit 1
fi

if [[ ! "$FLAG" =~ ^[a-zA-Z_][a-zA-Z0-9_-]*$ ]]; then
    echo -e "\e[31m[!] Error: '$FLAG' does not look like a valid flag name.\e[0m"
    exit 1
fi

for v in "$V1" "$V2"; do
    if [[ ! "$v" =~ ^[0-9] ]]; then
        echo -e "\e[31m[!] Error: Invalid version string '$v'. Versions must start with a number.\e[0m"
        exit 1
    fi
done

if [[ "$COMP" != "master" &&
      "$COMP" != "tserver" &&
      "$COMP" != "both" ]]; then
    echo -e "\e[31m[!] Error: Invalid component parameter '$COMP'. Use master, tserver, or both.\e[0m"
    exit 1
fi

resolve_tag() {
    local base_version=$1

    if [[ "$base_version" == *-b* ]]; then
        echo "$base_version"
        return
    fi

    local resolved_tag

    resolved_tag=$(
        curl -s \
          "https://hub.docker.com/v2/repositories/yugabytedb/yugabyte/tags?page_size=100&name=${base_version}" |
        grep -o '"name":"[^"]*"' |
        cut -d'"' -f4 |
        grep -E "^${base_version}(\.[0-9]+)*-b[0-9]+$" |
        sort -V |
        tail -n 1
    )

    if [ -n "$resolved_tag" ]; then
        echo "$resolved_tag"
    else
        echo "$base_version"
    fi
}

get_flag_from_binary() {
    local image=$1
    local binary=$2

    docker run --rm "$image" \
        "bin/$binary" --helpxml 2>/dev/null |
        sed 's/<flag>/\n<flag>/g' |
        grep "<name>${FLAG}</name>" |
        grep -o "<default>[^<]*</default>" |
        head -n 1 |
        sed 's/<[^>]*>//g' |
        xargs
}

get_docker_default() {
    local image=$1
    local val_tserver=""
    local val_master=""

    if [[ "$COMP" == "tserver" ||
          "$COMP" == "both" ]]; then
        val_tserver=$(get_flag_from_binary "$image" "yb-tserver")
    fi

    if [[ "$COMP" == "master" ||
          "$COMP" == "both" ]]; then
        val_master=$(get_flag_from_binary "$image" "yb-master")
    fi

    local out=""

    if [ -n "$val_tserver" ]; then
        out="${val_tserver} [yb-tserver]"
    fi

    if [ -n "$val_master" ]; then
        if [ -n "$out" ]; then
            out="${out} | ${val_master} [yb-master]"
        else
            out="${val_master} [yb-master]"
        fi
    fi

    if [ -z "$out" ]; then
        echo "(Flag not found in binary)"
    else
        echo "$out"
    fi
}

echo "Querying compiled binaries via Docker ($COMP)..."
echo "Flag: $FLAG"
echo "----------------------------------------"

TAG1=$(resolve_tag "$V1")
TAG2=$(resolve_tag "$V2")

IMG1="yugabytedb/yugabyte:${TAG1}"
IMG2="yugabytedb/yugabyte:${TAG2}"

echo "Resolved $V1 -> $TAG1"

if [ "$V1" != "$V2" ]; then
    echo "Resolved $V2 -> $TAG2"
fi

PULLED_IMAGES=()

for img in "$IMG1" "$IMG2"; do
    if ! docker image inspect "$img" >/dev/null 2>&1; then
        echo "Pulling image $img (this may take a minute)..."
        docker pull -q "$img" >/dev/null

        if [[ ! " ${PULLED_IMAGES[*]} " =~ " ${img} " ]]; then
            PULLED_IMAGES+=("$img")
        fi
    fi
done

VAL1=$(get_docker_default "$IMG1")
VAL2=$(get_docker_default "$IMG2")

printf "Result Env 1 (%-10s) : %s\n" "$V1" "$VAL1"
printf "Result Env 2 (%-10s) : %s\n" "$V2" "$VAL2"

echo "----------------------------------------"

if [ "$VAL1" != "$VAL2" ]; then
    echo -e "\e[31m[!] DIFFERENCE DETECTED\e[0m"
else
    echo -e "\e[32m[✓] IDENTICAL\e[0m"
fi

if [ "$CLEANUP" -eq 1 ] &&
   [ ${#PULLED_IMAGES[@]} -gt 0 ]; then

    echo "----------------------------------------"
    echo "Cleaning up downloaded images..."

    for img in "${PULLED_IMAGES[@]}"; do
        echo "Removing $img..."
        docker rmi "$img" >/dev/null 2>&1
    done

    echo "Cleanup complete."
fi