From 75a2a7e6cb3349844565aeeebd24431f27824ad7 Mon Sep 17 00:00:00 2001
From: Sunday <dhao2001@outlook.com>
Date: Mon, 3 Feb 2025 20:43:25 +0800
Subject: [PATCH] Add main shell script

---
 pull-docker-image.sh | 208 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 208 insertions(+)
 create mode 100644 pull-docker-image.sh

diff --git a/pull-docker-image.sh b/pull-docker-image.sh
new file mode 100644
index 0000000..402e27a
--- /dev/null
+++ b/pull-docker-image.sh
@@ -0,0 +1,208 @@
+#!/bin/bash
+# pull-docker-image.sh
+# 主要功能：
+#   - 根据用户参数拉取指定 Docker 镜像，生成 tar 包，并支持 gzip 或 zstd 压缩。
+#
+# 具体参数与用法请见：pull-docker-image.sh -h
+
+set -euo pipefail
+
+# Default values.
+IMAGE=""
+DEST="."
+NEWNAME=""
+USE_GZIP=false
+USE_ZSTD=false
+FORCE=false
+PROXY=""
+
+usage() {
+    cat <<EOF
+Usage:  $(basename "$0") -t image:tag [-d destination] [-n newname:tag] [-g] [-z] 
+                                      [-f] [-p proxy]
+  -t    (Required) Docker image name and tag to pull.
+  -d    Destination of pulled image file。
+          - If a directory is given, a new file named as image name and tag 
+            (with ':' replaced by '_') under the given directory is created.
+            Suffixes are inferred from compression options if specified.
+          - If a file path is given, the given file path is used directly.
+          - To forcefully overwrite existing file, use '-f' option.
+          - Default: . (Current directory).
+  -n    Image name and tag in output image file. Keep the same as '-t' option
+        if not specified.
+  -g    Compress image file with gzip.
+  -z    Compress image file with zstd.
+  -f    Forcefully overwrite existing destination file。
+  -p    Set up network proxies (through 'HTTP_PROXY' and 'HTTPS_PROXY' variables).
+  -h    Show this help information.
+  
+Example:
+  1. Pulling 'nginx:mainline' image to existed directory '~/nginx-images/'.
+         $(basename "$0") -t nginx:mainline -d ~/nginx-images/
+EOF
+}
+
+# 解析命令行选项
+parse_args() {
+    while getopts "t:d:n:gzfp:h" opt; do
+        case "$opt" in
+            t)
+                IMAGE="$OPTARG"
+                ;;
+            d)
+                DEST="$OPTARG"
+                ;;
+            n)
+                NEWNAME="$OPTARG"
+                ;;
+            g)
+                USE_GZIP=true
+                ;;
+            z)
+                USE_ZSTD=true
+                ;;
+            f)
+                FORCE=true
+                ;;
+            p)
+                PROXY="$OPTARG"
+                ;;
+            h)
+                usage
+                exit 0
+                ;;
+            *)
+                usage
+                exit 1
+                ;;
+        esac
+    done
+
+    if [[ -z "$IMAGE" ]]; then
+        echo "Error: '-t' option (image name and tag to pull) must be specified." >&2
+        usage
+        exit 1
+    fi
+
+    # 如果未指定 -n，则使用 -t 的值
+    if [[ -z "$NEWNAME" ]]; then
+        NEWNAME="$IMAGE"
+    fi
+
+    # 压缩方法 -g 和 -z 不能同时指定
+    if $USE_GZIP && $USE_ZSTD; then
+        echo "Error: '-g' and '-z' cannot be used together." >&2
+        exit 1
+    fi
+}
+
+# 检查是否安装了 skopeo
+check_skopeo() {
+    if ! command -v skopeo >/dev/null 2>&1; then
+        echo "Error: skopeo is not installed, or not in PATH." >&2
+        exit 1
+    fi
+}
+
+# 设置网络代理
+setup_proxy() {
+    if [[ -n "$PROXY" ]]; then
+        export HTTP_PROXY="$PROXY"
+        export HTTPS_PROXY="$PROXY"
+        echo "Use proxy at $PROXY"
+    fi
+}
+
+# 根据目标参数确定最终的目标文件路径
+determine_target_file() {
+    local target=""
+    if [[ -d "$DEST" ]]; then
+        local base_name
+        base_name=$(echo "$IMAGE" | tr ':' '_')
+        target="${DEST%/}/$base_name.tar"
+    else
+        target="$DEST"
+    fi
+    echo "$target"
+}
+
+# 检查目标文件是否存在冲突
+check_conflict() {
+    local file="$1"
+    if [[ -f "$file" ]]; then
+        if ! $FORCE; then
+            echo "Error: destination file '$file' exists, use '-f' option to overwrite." >&2
+            exit 1
+        else
+            echo "Warning：destination file '$file' exists，override as '-f' specified."
+        fi
+    fi
+}
+
+# 使用 skopeo 拉取 Docker 镜像
+pull_image() {
+    local target_file="$1"
+    echo "Start pulling $IMAGE to $target_file with name $NEWNAME in archive..."
+    if ! skopeo copy "docker://$IMAGE" "docker-archive:$target_file:$NEWNAME"; then
+        echo "Error: skopeo failed during pulling image" >&2
+        exit 1
+    fi
+    echo "Image is saved to $target_file successfully."
+}
+
+# 根据压缩选项对镜像文件进行压缩
+compress_image() {
+    local target_file="$1"
+    local final_file=""
+    if $USE_GZIP || $USE_ZSTD; then
+        if $USE_GZIP; then
+            local compressed="${target_file}.gz"
+            check_conflict "$compressed"
+            echo "Compress $target_file with gzip..."
+            if ! gzip -f "$target_file"; then
+                echo "Error: failed to compress image with gzip." >&2
+                exit 1
+            fi
+            final_file="$compressed"
+        elif $USE_ZSTD; then
+            local compressed="${target_file}.zst"
+            check_conflict "$compressed"
+            echo "Compress $target_file with zstd..."
+            if ! zstd -q -o "$compressed" "$target_file"; then
+                echo "Error: failed to compress image with zstd." >&2
+                exit 1
+            fi
+            rm -f "$target_file"
+            final_file="$compressed"
+        fi
+        echo "Compressed image is saved to $final_file."
+    else
+        final_file="$target_file"
+    fi
+}
+
+# 主函数
+main() {
+    parse_args "$@"
+    check_skopeo
+    setup_proxy
+
+    local target_file
+    target_file=$(determine_target_file)
+    check_conflict "$target_file"
+
+    # 同时检查压缩后的文件是否存在冲突（如果有压缩选项）
+    if $USE_GZIP; then
+        check_conflict "${target_file}.gz"
+    elif $USE_ZSTD; then
+        check_conflict "${target_file}.zst"
+    fi
+
+    pull_image "$target_file"
+    compress_image "$target_file"
+    
+    echo "OK."
+}
+
+# 主入口
+main "$@"