didericis
08e932805d
Answers the last open question in #392: DNS from inside a nested container was not a phantom, but it was also not a DNS problem. Public resolution fails there by design — everything egresses through the proxy — and the actual breakage was two missing pieces: - The proxy URL names `bot-bottle-gateway`, which resolves only through the bottle's own /etc/hosts. Containers got their own hosts file, so they failed at "Could not resolve proxy", which reads like broken DNS. base_hosts_file propagates the bottle's entries. - The gateway TLS-intercepts, so a container that does not trust the bottle's CA bundle fails with "unable to get local issuer certificate". The bundle is now mounted read-only and the usual env vars point at it, which covers curl, wget, python, and node without distro-specific trust commands. Verified on the macOS host by reproducing each failure and confirming that these three conditions applied by hand produced HTTP 200 from inside a nested container. podman already forwards the proxy env, so that needed nothing. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
128 lines
4.6 KiB
Bash
Executable File
128 lines
4.6 KiB
Bash
Executable File
#!/bin/sh
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set -eu
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uid="$(id -u)"
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if [ "$uid" -eq 0 ]; then
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echo "refusing to run the guest container engine as root" >&2
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exit 1
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fi
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# Every piece of podman 5's networking stack is checked here, because each
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# one fails at a different and misleading layer if it is absent: no pasta and
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# nothing starts at all; no nft and netavark cannot build the bridge every
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# compose file expects; no aardvark-dns and DNS inside nested containers fails
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# while everything else looks healthy.
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for command in podman docker fuse-overlayfs pasta nft slirp4netns; do
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command -v "$command" >/dev/null 2>&1 || {
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echo "missing nested-container prerequisite: $command" >&2
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exit 1
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}
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done
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# The inverse of the rootless-Docker check, and the whole point of the podman
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# variant: a subordinate range would push podman onto newuidmap, which cannot
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# write a multi-range uid_map without CAP_SYS_ADMIN in this guest. An empty
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# range keeps it on the single-UID self-mapping an unprivileged process may
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# write itself.
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if grep -q "^$(id -un):" /etc/subuid 2>/dev/null; then
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echo "unexpected subordinate UID range for $(id -un): podman would" >&2
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echo "require CAP_SYS_ADMIN via newuidmap in this guest" >&2
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exit 1
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fi
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for device in /dev/fuse /dev/net/tun; do
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[ -r "$device" ] && [ -w "$device" ] || {
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echo "device $device is not readable/writable by $(id -un)" >&2
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exit 1
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}
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done
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# Short by necessity, not by accident: conmon's attach socket lives under
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# this directory and must fit in a 108-byte sun_path. See nested_containers.py.
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# Must stay in step with AGENT_CA_BUNDLE in bot_bottle/backend/util.py; a unit
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# test pins the two together.
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CA_BUNDLE="/etc/ssl/certs/ca-certificates.crt"
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[ -r "$CA_BUNDLE" ] || {
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echo "gateway CA bundle $CA_BUNDLE is missing or unreadable" >&2
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exit 1
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}
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export XDG_RUNTIME_DIR="${XDG_RUNTIME_DIR:-/tmp/bbp}"
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config="$HOME/.config/containers"
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mkdir -p "$XDG_RUNTIME_DIR" "$config"
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chmod 700 "$XDG_RUNTIME_DIR"
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# ignore_chown_errors is required, not incidental: with a single-UID mapping
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# there is no second UID for image layers to be chowned to, so layers that
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# record other owners would otherwise fail to extract.
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cat > "$config/storage.conf" <<'CONF'
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[storage]
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driver="overlay"
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[storage.options.overlay]
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mount_program="/usr/bin/fuse-overlayfs"
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ignore_chown_errors="true"
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CONF
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# No cgroup delegation reaches this guest, so asking podman to manage cgroups
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# fails; events_logger=file avoids the journald socket that is equally absent.
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#
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# The rest of this block is what makes a nested container reach the network at
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# all. podman already forwards the proxy env, but that alone is useless here:
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#
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# base_hosts_file the proxy URL names `bot-bottle-gateway`, which resolves
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# only through the bottle's own /etc/hosts. Without this a
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# container fails at "Could not resolve proxy", which reads
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# like broken DNS but is a missing hosts entry — public DNS
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# is *supposed* to fail, since everything egresses via the
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# proxy.
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# volumes/env the gateway TLS-intercepts, so a container that does not
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# trust the bottle's CA bundle gets "unable to get local
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# issuer certificate". Mounting the bundle read-only and
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# pointing the usual env vars at it covers curl, wget,
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# python, and node without distro-specific trust commands.
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cat > "$config/containers.conf" <<CONF
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[containers]
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cgroups="disabled"
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base_hosts_file="/etc/hosts"
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volumes=["${CA_BUNDLE}:${CA_BUNDLE}:ro"]
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env=[
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"SSL_CERT_FILE=${CA_BUNDLE}",
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"CURL_CA_BUNDLE=${CA_BUNDLE}",
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"REQUESTS_CA_BUNDLE=${CA_BUNDLE}",
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"NODE_EXTRA_CA_CERTS=${CA_BUNDLE}",
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]
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[engine]
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cgroup_manager="cgroupfs"
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events_logger="file"
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CONF
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# Registry pulls egress through the bottle's proxy like everything else. The
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# token-bearing proxy URL is already in the agent's environment; persisting it
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# inside this disposable VM does not broaden its authority.
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python3 - <<'PY'
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import json
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import os
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from pathlib import Path
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proxy = os.environ.get("HTTPS_PROXY") or os.environ.get("https_proxy", "")
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no_proxy = os.environ.get("NO_PROXY") or os.environ.get("no_proxy", "")
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config = {"proxies": {"default": {
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"httpProxy": proxy,
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"httpsProxy": proxy,
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"noProxy": no_proxy,
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}}}
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path = Path.home() / ".docker" / "config.json"
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path.parent.mkdir(parents=True, exist_ok=True)
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path.write_text(json.dumps(config), encoding="utf-8")
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path.chmod(0o600)
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PY
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if docker info >/dev/null 2>&1; then
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exit 0
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fi
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log=/tmp/bot-bottle-nested-containers.log
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nohup podman system service --time=0 \
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"unix://$XDG_RUNTIME_DIR/podman.sock" \
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>"$log" 2>&1 </dev/null &
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