fix(tools-image): fall back to BusyBox ionice for minimal user images - #210
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dushulin wants to merge 1 commit into
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fix(tools-image): fall back to BusyBox ionice for minimal user images#210dushulin wants to merge 1 commit into
dushulin wants to merge 1 commit into
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envd's process wrapper hardcodes `/usr/bin/ionice -c 2 -n 4 /usr/bin/nice -n N ...`, so any user image without util-linux (Alpine/musl, distroless, FROM scratch, various slim rootfs) fails every spawn with `/usr/bin/ionice: not found` even though envd itself launches fine. Mirror the existing nice(1) fallback: when the user rootfs has no executable /usr/bin/ionice, symlink it to /agentenv/bin/busybox so the multi-call binary serves the applet. Images that already ship util-linux keep their real ionice(1) thanks to the [ ! -x ] guard. Also assert both nice and ionice applets are compiled into the shipped BusyBox at image build time. BusyBox ionice supports the -c/-n/-p/-t flags envd relies on (both call the same ioprio_set(2) syscall); the util-linux-only -P/-u flags are not used by envd.
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✅ OpenCodeReview: Review complete: 0 finding(s) across 2 selected item(s). |
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Thanks! We'll merge this PR once support for the tools image upgrade has been added. Otherwise, existing templates/snapshots will fail to resume. |
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背景
envd 的进程 wrapper 硬编码调用
/usr/bin/ionice -c 2 -n 4 /usr/bin/nice -n N ...（packages/envd/internal/services/process/handler/handler.go），只要用户 rootfs 里没有/usr/bin/ionice，每一次进程 spawn 都会立刻失败并报/usr/bin/ionice: not found。这在 Alpine/musl、distroless、FROM scratch、以及各类不带 util-linux 的 slim 镜像上都能稳定复现——envd 自身能起来，用户在 sandbox 里跑任何命令都会立刻挂掉。相关上游 issue / PR：
/usr/bin/ionice和/usr/bin/nice方案
复用现有
nice(1)兜底思路（tools-image/pivot-init）：/usr/bin/ionice，就把它软链到/agentenv/bin/busybox。BusyBox 是 multi-call binary，通过argv[0]=ionice直接走ioniceapplet。[ ! -x /usr/bin/ionice ]guard 保证自带 util-linux 的镜像原样保留自己的ionice，不会被覆盖。nice/ionice。nice+ionice），万一以后 upstream BusyBox 改默认配置或有人重编 BusyBox，能在镜像构建阶段就报错，不至于到 guest 里才发现。与 util-linux ionice 的能力对齐
envd 调用的形式是
ionice -c 2 -n 4 <cmd>，用到的是-c/-n以及 exec 新进程的能力。BusyBox 的 ionice applet 覆盖-c/-n/-p/-t与 exec 语义，与 util-linux 落到同一个ioprio_set(2)syscall，语义完全一致。util-linux 独有的-P PGID、-u UIDenvd 用不到；如果 sandbox 内部用户脚本自己在 fallback 镜像里手动调这两个 flag 会拿到 unknown option，这跟现有nicefallback 面临的情况完全对称。兼容性
[ ! -x ]guard 短路，/usr/bin/ionice保留镜像原有实现，零回退。Test plan
docker build tools-image/通过，BusyBox applet 断言不报错ionice -c 2 -n 4 echo ok通过 envd wrapper 能正常输出okreadlink /usr/bin/ionice仍指向镜像原有二进制（不是/agentenv/bin/busybox）echo $?返回 0