flake.lock: update inputs

Co-authored-by: Floweynt <floweydev@gmail.com>
Reviewed-on: #4

.github/workflows/diff-pr.yml

@@ -13,26 +13,29 @@ concurrency:
 
 jobs:
   dix:
-    runs-on: ubuntu-latest
+    runs-on: nix
     steps:
       - uses: actions/checkout@v4
         with:
+          ref: ${{ github.event.pull_request.head.sha }}
           fetch-depth: 0
 
-      - uses: cachix/install-nix-action@v31
+      - name: merge base branch
-        with:
+        run: |
-          extra_nix_config: |
+          git config user.email "ci@localhost"
-            experimental-features = nix-command flakes
+          git config user.name "CI"
+          git fetch origin ${{ github.event.pull_request.base.ref }}
+          git merge --no-edit origin/${{ github.event.pull_request.base.ref }}
 
       - name: worktree base for diff
-        run: git worktree add "$RUNNER_TEMP/base" "${{ github.event.pull_request.base.sha }}"
+        run: git worktree add "$RUNNER_TEMP/base" "origin/${{ github.event.pull_request.base.ref }}"
 
       - name: build closures and render diff
         run: |
-          nix run .#ci -- diff "$RUNNER_TEMP/base" . \
+          nix run -L .#ci -- diff "$RUNNER_TEMP/base" . \
             "### System closure diff vs \`${{ github.event.pull_request.base.ref }}\`" \
             > "$RUNNER_TEMP/comment.md"
-          nix run .#ci -- inspect-diff "$RUNNER_TEMP/base" . \
+          nix run -L .#ci -- inspect-diff "$RUNNER_TEMP/base" . \
             "### Inspection diff vs \`${{ github.event.pull_request.base.ref }}\`" \
             >> "$RUNNER_TEMP/comment.md"
 
@@ -42,4 +45,4 @@ jobs:
           API: ${{ github.api_url }}
           REPO: ${{ github.repository }}
           PR: ${{ github.event.pull_request.number }}
-        run: nix run .#ci -- post-comment "<!-- dix-diff -->" "$RUNNER_TEMP/comment.md"
+        run: nix run -L .#ci -- post-comment "<!-- dix-diff -->" "$RUNNER_TEMP/comment.md"

.github/workflows/diff-tag.yml

@@ -9,17 +9,12 @@ permissions:
 
 jobs:
   dix:
-    runs-on: ubuntu-latest
+    runs-on: nix
     steps:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
 
-      - uses: cachix/install-nix-action@v31
-        with:
-          extra_nix_config: |
-            experimental-features = nix-command flakes
-
       - name: diff latest tag against HEAD
         run: |
           tag=$(git tag --sort=-creatordate | head -n1)
@@ -30,8 +25,8 @@ jobs:
           git worktree add "$RUNNER_TEMP/old" "$tag"
           head=$(git rev-parse --short HEAD)
           {
-            nix run .#ci -- diff "$RUNNER_TEMP/old" . \
+            nix run -L .#ci -- diff "$RUNNER_TEMP/old" . \
               "# System closure diff: \`$tag\` -> \`$head\`"
-            nix run .#ci -- inspect-diff "$RUNNER_TEMP/old" . \
+            nix run -L .#ci -- inspect-diff "$RUNNER_TEMP/old" . \
               "# Inspection diff: \`$tag\` -> \`$head\`"
           } | tee -a "$GITHUB_STEP_SUMMARY"

.github/workflows/flake-check.yml

@@ -14,13 +14,8 @@ concurrency:
 
 jobs:
   flake-check:
-    runs-on: ubuntu-latest
+    runs-on: nix
     steps:
       - uses: actions/checkout@v4
 
-      - uses: cachix/install-nix-action@v31
-        with:
-          extra_nix_config: |
-            experimental-features = nix-command flakes
-
       - run: nix flake check -L

.github/workflows/flake-update.yml

@@ -5,29 +5,22 @@ on:
     - cron: "17 4 * * *"
   workflow_dispatch:
 
-permissions:
-  contents: write
-  pull-requests: write
-
 jobs:
   update:
-    runs-on: ubuntu-latest
+    runs-on: nix
     steps:
       - uses: actions/checkout@v4
-
-      - uses: cachix/install-nix-action@v31
         with:
-          extra_nix_config: |
+          persist-credentials: false
-            experimental-features = nix-command flakes
 
-      - run: nix flake update
+      - run: nix flake update -L
 
       - name: open/update PR
         env:
-          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GH_TOKEN: ${{ secrets.BOT_TOKEN }}
           API: ${{ github.api_url }}
           REPO: ${{ github.repository }}
         run: |
           printf 'Automated `nix flake update`.\n' > "$RUNNER_TEMP/body.md"
-          nix run .#ci -- open-pr \
+          nix run -L .#ci -- open-pr \
             flake-update "$GITHUB_REF_NAME" "flake.lock: update inputs" "$RUNNER_TEMP/body.md" automated

.github/workflows/lint.yml

@@ -15,27 +15,22 @@ concurrency:
 
 jobs:
   lint:
-    runs-on: ubuntu-latest
+    runs-on: nix
     steps:
       - uses: actions/checkout@v4
 
-      - uses: cachix/install-nix-action@v31
-        with:
-          extra_nix_config: |
-            experimental-features = nix-command flakes
-
-      - name: pick reporter
-        run: |
-          if [ "${{ github.event_name }}" = pull_request ]; then
-            echo "REPORTER=github-pr-review" >> "$GITHUB_ENV"
-          else
-            echo "REPORTER=local" >> "$GITHUB_ENV"
-          fi
-
       - name: run linters
-        run: nix run .#ci -- lint . "$RUNNER_TEMP/findings"
+        run: nix run -L .#ci -- lint . "$RUNNER_TEMP/findings"
 
       - name: report findings
+        if: always()
         env:
-          REVIEWDOG_GITHUB_API_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          REVIEWDOG_GITEA_API_TOKEN: ${{ secrets.GITEA_TOKEN }}
-        run: nix run .#ci -- lint-report "$REPORTER" "$RUNNER_TEMP/findings"
+          GITEA_ADDRESS: ${{ github.server_url }}
+        run: |
+          if [ "${{ github.event_name }}" = pull_request ]; then
+            nix run -L .#ci -- lint-report gitea-pr-review "$RUNNER_TEMP/findings"
+          else
+            nix run -L .#ci -- lint-summary "$RUNNER_TEMP/findings" \
+              | tee -a "$GITHUB_STEP_SUMMARY"
+          fi

.github/workflows/vulnix.yml

@@ -5,24 +5,15 @@ on:
     - cron: "0 6 * * 1"
   workflow_dispatch:
 
-permissions:
-  contents: read
-  issues: write
-
 jobs:
   scan:
-    runs-on: ubuntu-latest
+    runs-on: nix
     steps:
       - uses: actions/checkout@v4
 
-      - uses: cachix/install-nix-action@v31
-        with:
-          extra_nix_config: |
-            experimental-features = nix-command flakes
-
       - name: scan host closures
         id: scan
-        run: echo "count=$(nix run .#ci -- vulnix . "$RUNNER_TEMP/issue.md")" >> "$GITHUB_OUTPUT"
+        run: echo "count=$(nix run -L .#ci -- vulnix . "$RUNNER_TEMP/issue.md")" >> "$GITHUB_OUTPUT"
 
       - name: file/update issue
         if: steps.scan.outputs.count != '0'
@@ -30,7 +21,7 @@ jobs:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           API: ${{ github.api_url }}
           REPO: ${{ github.repository }}
-        run: nix run .#ci -- upsert-issue vulnix "vulnix: known vulnerabilities in system closure" "$RUNNER_TEMP/issue.md"
+        run: 'nix run -L .#ci -- upsert-issue vulnix "vulnix: known vulnerabilities in system closure" "$RUNNER_TEMP/issue.md"'
 
       - name: close resolved issue
         if: steps.scan.outputs.count == '0'
@@ -38,4 +29,4 @@ jobs:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           API: ${{ github.api_url }}
           REPO: ${{ github.repository }}
-        run: nix run .#ci -- close-issue vulnix
+        run: nix run -L .#ci -- close-issue vulnix

ci.nix

@@ -1,9 +1,17 @@
 { lib, pkgs }:
+let
+  # vulnix's bundled nix-2.34 broke its own --experimental-features detection
+  nixConf = pkgs.writeText "ci-nix.conf" "experimental-features = nix-command flakes";
+in
 # tools must track ci.py's subprocess calls; nix stays ambient (uses the
 # runner's own nix, not a pinned one).
 pkgs.writers.writePython3Bin "ci" {
   flakeIgnore = [ "E501" ];
+  libraries = [ pkgs.python3Packages.subprocess-tee ];
   makeWrapperArgs = [
+    "--set-default"
+    "NIX_USER_CONF_FILES"
+    (toString nixConf)
     "--prefix"
     "PATH"
     ":"

ci.py

@@ -6,7 +6,9 @@ import json
 import os
 import re
 import subprocess
+import subprocess_tee
 import sys
+import urllib.error
 import urllib.request
 from collections import Counter
 from pathlib import Path
@@ -17,13 +19,18 @@ def run(*args, **kw):
 
 
 def nix(*args):
-    return run("nix", "--extra-experimental-features", "nix-command flakes", *args, check=True, capture_output=True).stdout
+    # tee to stderr - stdout leaks into GITHUB_OUTPUT $() captures
+    return subprocess_tee.run(("nix", "--extra-experimental-features", "nix-command flakes", "-L", *args), check=True, text=True, stdout=sys.stderr).stdout
 
 
 def git(*args, check=True):
     return run("git", *args, check=check, capture_output=True)
 
 
+class GiteaError(Exception):
+    pass
+
+
 def gitea(method, path, body=None):
     url = f'{os.environ["API"]}/repos/{os.environ["REPO"]}{path}'
     data = json.dumps(body).encode() if body is not None else None
@@ -31,13 +38,20 @@ def gitea(method, path, body=None):
     req.add_header("Authorization", f'token {os.environ["GH_TOKEN"]}')
     if data is not None:
         req.add_header("Content-Type", "application/json")
-    with urllib.request.urlopen(req) as resp:
+    try:
-        raw = resp.read()
+        with urllib.request.urlopen(req) as resp:
+            raw = resp.read()
+    except urllib.error.HTTPError as e:
+        try:
+            detail = json.loads(e.read()).get("message", e.reason)
+        except (json.JSONDecodeError, UnicodeDecodeError):
+            detail = e.reason
+        raise GiteaError(f"{method} {path}: {e.code} {detail}") from None
     return json.loads(raw) if raw else None
 
 
 def find_open_issue(label):
-    issues = gitea("GET", f"/issues?state=open&labels={label}")
+    issues = gitea("GET", f"/issues?state=open&type=issues&labels={label}")
     return issues[0] if issues else None
 
 
@@ -234,7 +248,7 @@ def format_vulnix(vulns):
     for v in vulns:
         for cve in v["affected_by"]:
             score = v.get("cvssv3_basescore", {}).get(cve)
-            desc = v.get("description", {}).get(cve, "")
+            desc = v.get("description", {}).get(cve, "").replace("\n", " ").replace("|", "∣")
             if len(desc) > 120:
                 desc = desc[:117] + "..."
             rows.append((v["pname"], v["version"], cve, score, desc))
@@ -362,10 +376,63 @@ def lint_report(args):
 
     codes = [reviewdog(f"{args.dir}/{name}", flags)
              for name, flags in LINTERS
-             if os.path.getsize(f"{args.dir}/{name}") > 0]
+             if os.path.isfile(f"{args.dir}/{name}") and os.path.getsize(f"{args.dir}/{name}") > 0]
     sys.exit(1 if any(codes) else 0)
 
 
+def has_findings(path):
+    return os.path.isfile(path) and os.path.getsize(path) > 0
+
+
+def fmt_rdjsonl(path):
+    lines = []
+    with open(path) as f:
+        for raw in f:
+            rec = json.loads(raw)
+            loc = rec["location"]
+            r = loc.get("range", {}).get("start")
+            pos = f"{loc['path']}:{r['line']}:{r['column']}" if r else loc["path"]
+            lines.append(f"- `{pos}`: {rec['message']}")
+    return "\n".join(lines)
+
+
+def fmt_errfmt(path):
+    lines = []
+    with open(path) as f:
+        for raw in f:
+            parts = raw.strip().split(">", 1)
+            if len(parts) == 2:
+                lines.append(f"- `{parts[0]}:{parts[1].split(':', 3)[-1].strip()}`" if ":" in parts[1] else f"- `{raw.strip()}`")
+            elif raw.strip():
+                lines.append(f"- `{raw.strip()}`")
+    return "\n".join(lines)
+
+
+def lint_summary(args):
+    sections = []
+    d = args.dir
+
+    if has_findings(f"{d}/nixfmt.diff"):
+        with open(f"{d}/nixfmt.diff") as f:
+            sections.append(f"## nixfmt\n\n```diff\n{f.read().rstrip()}\n```")
+
+    if has_findings(f"{d}/statix.errfmt"):
+        sections.append(f"## statix\n\n{fmt_errfmt(f'{d}/statix.errfmt')}")
+
+    if has_findings(f"{d}/deadnix.rdjsonl"):
+        sections.append(f"## deadnix\n\n{fmt_rdjsonl(f'{d}/deadnix.rdjsonl')}")
+
+    if has_findings(f"{d}/cycles.rdjsonl"):
+        sections.append(f"## systemd ordering cycles\n\n{fmt_rdjsonl(f'{d}/cycles.rdjsonl')}")
+
+    if sections:
+        print("\n\n".join(["# Lint findings"] + sections))
+        sys.exit(1)
+    else:
+        print("No lint findings.")
+        sys.exit(0)
+
+
 def post_comment(args):
     body = args.marker + "\n" + Path(args.body_file).read_text()
     pr = os.environ["PR"]
@@ -408,16 +475,24 @@ def open_pr(args):
 
     host = os.environ["API"].removesuffix("/api/v1")
     auth = base64.b64encode(f'token:{os.environ["GH_TOKEN"]}'.encode()).decode()
-    git("-c", f"http.extraHeader=Authorization: Basic {auth}",
+    push = git("-c", f"http.extraHeader=Authorization: Basic {auth}",
-        "push", "-f", f'{host}/{os.environ["REPO"]}.git', f"HEAD:{args.branch}")
+               "push", "-f", f'{host}/{os.environ["REPO"]}.git', f"HEAD:{args.branch}",
+               check=False)
+    if push.returncode != 0:
+        raise RuntimeError(f"git push failed:\n{push.stderr}")
 
-    owner = os.environ["REPO"].split("/")[0]
+    pulls = gitea("GET", f"/pulls?state=open&base_branch={args.base}")
-    if gitea("GET", f"/pulls?state=open&head={owner}:{args.branch}"):
+    existing = next((pr for pr in pulls if pr["head"]["ref"] == args.branch), None)
+    if existing:
+        print(f"PR #{existing['number']} already open, pushed update")
         return
     labels = [label_id(args.label)] if args.label else []
-    gitea("POST", "/pulls",
+    pr = gitea("POST", "/pulls",
-          {"title": args.title, "head": args.branch, "base": args.base,
+               {"title": args.title, "head": args.branch, "base": args.base,
-           "body": Path(args.body_file).read_text(), "labels": labels})
+                "body": Path(args.body_file).read_text(), "labels": labels})
+    if not pr or "number" not in pr:
+        raise GiteaError(f"POST /pulls: unexpected response: {json.dumps(pr)}")
+    print(f"opened PR #{pr['number']}")
 
 
 def main():
@@ -438,6 +513,7 @@ def main():
     command("vulnix", vulnix, "ref", "body_out")
     command("lint", lint, "target", "out")
     command("lint-report", lint_report, "reporter", "dir")
+    command("lint-summary", lint_summary, "dir")
     command("post-comment", post_comment, "marker", "body_file")
     command("upsert-issue", upsert_issue, "label", "title", "body_file")
     command("close-issue", close_issue, "label")

containers/common/overseer.nix

@@ -381,6 +381,6 @@ let
         };
       };
     };
-  hostAddr = c.hostAddr;
+  inherit (c) hostAddr;
 in
 c

containers/server-n0/git.nix

@@ -8,6 +8,9 @@ let
   inherit (dsl) mkContainer mkVm;
   inherit (hostInfo.paths) data secrets;
 
+  pubSshPort = 23;
+  intSshPort = 23 + 8000;
+
   ciRunnerData = "${data}/web/git-ci-runner";
   ciRunnerSecrets = "${secrets}/ci-runner";
 in
@@ -17,8 +20,8 @@ in
     net.access = [ { to = "@internet"; } ];
     net.forward.tcp = [
       {
-        host = 23;
+        host = pubSshPort;
-        container = 8023;
+        container = intSshPort;
       }
     ];
     svc.autoStart = true;
@@ -38,7 +41,8 @@ in
             ROOT_URL = "https://git.floweytf.com/";
             START_SSH_SERVER = true;
             BUILTIN_SSH_SERVER_USER = "git";
-            SSH_PORT = 8023;
+            SSH_PORT = pubSshPort;
+            SSH_LISTEN_PORT = intSshPort;
           };
           service.DISABLE_REGISTRATION = true;
         };
@@ -51,128 +55,179 @@ in
     net.expose.tcp = [ 3000 ];
   };
 
-  ci-runner = mkVm {
+  ci-runner =
-    name = "ci-runner";
+    mkVm {
-    net.access = [
+      name = "ci-runner";
-      {
+      includedInTests = false;
-        to = "git";
+      net.access = [
-        tcp = [ 3000 ];
+        {
-      }
+          to = "git";
-      { to = "@internet"; }
+          tcp = [ 3000 ];
-    ];
+        }
-    svc.autoStart = true;
+        { to = "@internet"; }
-    resources.cpu = 4;
+      ];
-    resources.mem = "8G";
+      svc.autoStart = true;
-    resources.fs = [
+      resources.cpu = 4;
-      {
+      resources.mem = "32G";
-        proto = "virtiofs";
+      resources.fs = [
-        tag = "nix-rw-store";
+        {
-        source = "${ciRunnerData}/nix-rw-store";
+          proto = "virtiofs";
-        mountPoint = "/nix/.rw-store";
+          tag = "nix-rw-store";
-      }
+          source = "${ciRunnerData}/nix-rw-store";
-      {
+          mountPoint = "/nix/.rw-store";
-        proto = "virtiofs";
+        }
-        tag = "docker-data";
+        {
-        source = "${ciRunnerData}/docker";
+          proto = "virtiofs";
-        mountPoint = "/var/lib/docker";
+          tag = "nix-db";
-      }
+          source = "${ciRunnerData}/nix-db";
-      {
+          mountPoint = "/nix/var/nix/db";
-        proto = "virtiofs";
+        }
-        tag = "runner-state";
+        {
-        source = "${ciRunnerData}/runner-state";
+          proto = "virtiofs";
-        mountPoint = "/var/lib/gitea-runner";
+          tag = "docker-data";
-      }
+          source = "${ciRunnerData}/docker";
-      {
+          mountPoint = "/var/lib/docker";
-        proto = "virtiofs";
+        }
-        tag = "runner-token";
+        {
-        source = ciRunnerSecrets;
+          proto = "virtiofs";
-        mountPoint = "/run/ci-runner-secrets";
+          tag = "runner-state";
-        readOnly = true;
+          source = "${ciRunnerData}/runner-state";
-      }
+          mountPoint = "/var/lib/private/gitea-runner";
-    ];
+        }
-    guestConfig =
+        {
-      {
+          proto = "virtiofs";
-        pkgs,
+          tag = "runner-token";
-        utils,
+          source = ciRunnerSecrets;
-        lib,
+          mountPoint = "/run/ci-runner-secrets";
-        ...
+          readOnly = true;
-      }:
+        }
-      let
+        {
-        runnerInstanceName = "ci-runner";
+          proto = "virtiofs";
+          tag = "tmp";
+          source = "/tmp";
+          mountPoint = "/tmp";
+        }
+      ];
+      guestConfig =
+        {
+          pkgs,
+          utils,
+          lib,
+          ...
+        }:
+        let
+          runnerInstanceName = "ci-runner";
 
-        ciJobImage = pkgs.dockerTools.buildLayeredImage {
+          ciJobContents = with pkgs; [
-          name = "ci-job-image";
-          tag = "latest";
-          contents = with pkgs; [
             bashInteractive
             coreutils
             gitMinimal
             nixVersions.latest
             nodejs
             cacert
+            (writeTextDir "etc/nix/nix.conf" "experimental-features = nix-command flakes\n")
           ];
-          config = {
+
-            Cmd = [ "/bin/sh" ];
+          ciJobImage = pkgs.dockerTools.buildLayeredImage {
-            Env = [
+            name = "ci-job-image";
-              "SSL_CERT_FILE=${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt"
+            tag = "latest";
-              "NIX_SSL_CERT_FILE=${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt"
+            contents = ciJobContents;
-              "NIX_REMOTE=daemon"
+            config = {
+              Cmd = [ "/bin/sh" ];
+              Env = [
+                "PATH=${lib.makeBinPath ciJobContents}"
+                "SSL_CERT_FILE=${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt"
+                "NIX_SSL_CERT_FILE=${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt"
+                "NIX_REMOTE=daemon"
+              ];
+            };
+          };
+        in
+        {
+          boot.kernelModules = [ "kvm-intel" ];
+          boot.extraModprobeConfig = "options kvm_intel nested=1";
+
+          # volume-mounted into CI containers; must be in VM's store so
+          # image symlinks (/bin/node etc.) resolve through the mount
+          system.extraDependencies = ciJobContents;
+
+          microvm.writableStoreOverlay = "/nix/.rw-store";
+
+          nix.settings = {
+            experimental-features = [
+              "nix-command"
+              "flakes"
             ];
+            max-jobs = "auto";
+            substituters = [ "https://microvm.cachix.org" ];
+            trusted-public-keys = [ "microvm.cachix.org-1:oXnBc6hRE3eX5rSYdRyMYXnfzcCxC7yKPTbZXALsqys=" ];
           };
-        };
-      in
-      {
-        boot.kernelModules = [ "kvm-intel" ];
-        boot.extraModprobeConfig = "options kvm_intel nested=1";
 
-        microvm.writableStoreOverlay = "/nix/.rw-store";
+          nix.settings = {
-
+            min-free = 5 * 1024 * 1024 * 1024;
-        nix.settings = {
+            max-free = 10 * 1024 * 1024 * 1024;
-          experimental-features = [
-            "nix-command"
-            "flakes"
-          ];
-          max-jobs = "auto";
-        };
-
-        nix.gc = {
-          automatic = true;
-          dates = "daily";
-          options = "--delete-older-than 14d";
-        };
-        # nix.optimise.automatic = true; - doesn't work with microvm.writableStoreOverlay
-
-        virtualisation.docker.enable = true;
-
-        systemd.services.load-ci-job-image = {
-          description = "Load the CI job Docker image";
-          wantedBy = [ "multi-user.target" ];
-          after = [ "docker.service" ];
-          requires = [ "docker.service" ];
-          before = [ "gitea-runner-${utils.escapeSystemdPath runnerInstanceName}.service" ];
-          serviceConfig = {
-            Type = "oneshot";
-            RemainAfterExit = true;
-            ExecStart = "${lib.getExe' pkgs.docker "docker"} load -i ${ciJobImage}";
           };
-        };
+          # nix.optimise.automatic = true; - doesn't work with microvm.writableStoreOverlay
 
-        services.gitea-actions-runner.instances.${runnerInstanceName} = {
+          services.openssh = {
-          enable = true;
+            enable = true;
-          name = runnerInstanceName;
+            settings = {
-          url = "http://git:3000/";
+              PermitRootLogin = "yes";
-          tokenFile = "/run/ci-runner-secrets/token";
+              PermitEmptyPasswords = "yes";
-          labels = [
+            };
-            "nix:docker://ci-job-image:latest"
+          };
-          ];
+          users.users.root.initialHashedPassword = "";
-          settings.container = {
+          services.journald.extraConfig = "ForwardToConsole=yes";
-            options = "--device=/dev/kvm --volume=/nix/store:/nix/store:ro --volume=/nix/var/nix/daemon-socket:/nix/var/nix/daemon-socket";
+
-            valid_volumes = [
+          virtualisation.containerd.enable = true;
-              "/nix/store"
+          virtualisation.containerd.settings.plugins."io.containerd.snapshotter.v1.overlayfs".mount_options =
-              "/nix/var/nix/daemon-socket"
+            [ "userxattr" ];
+
+          virtualisation.docker.enable = true;
+          virtualisation.docker.extraOptions = "--containerd /run/containerd/containerd.sock";
+          virtualisation.docker.daemon.settings.exec-opts = [ "native.cgroupdriver=cgroupfs" ];
+          systemd.services.docker.wants = [ "containerd.service" ];
+          systemd.services.docker.after = [ "containerd.service" ];
+
+          systemd.services.load-ci-job-image = {
+            description = "Load the CI job Docker image";
+            wantedBy = [ "multi-user.target" ];
+            after = [ "docker.service" ];
+            requires = [ "docker.service" ];
+            before = [ "gitea-runner-${utils.escapeSystemdPath runnerInstanceName}.service" ];
+            serviceConfig = {
+              Type = "oneshot";
+              RemainAfterExit = true;
+              ExecStart = "${lib.getExe' pkgs.docker "docker"} load -i ${ciJobImage}";
+            };
+          };
+
+          services.gitea-actions-runner.instances.${runnerInstanceName} = {
+            enable = true;
+            name = runnerInstanceName;
+            url = "http://git:3000/";
+            tokenFile = "/run/ci-runner-secrets/token";
+            labels = [
+              "nix:docker://ci-job-image:latest"
             ];
+            settings.container = {
+              options = "--device=/dev/kvm --volume=/nix/store:/nix/store:ro --volume=/nix/var/nix/daemon-socket:/nix/var/nix/daemon-socket";
+              valid_volumes = [
+                "/nix/store"
+                "/nix/var/nix/daemon-socket"
+              ];
+            };
           };
         };
+    }
+    // {
+      hostConfig = {
+        systemd.tmpfiles.rules = [
+          "d ${ciRunnerData}/nix-rw-store 0755 server server -"
+          "d ${ciRunnerData}/nix-db 0755 server server -"
+          "d ${ciRunnerData}/docker 0755 server server -"
+          "d ${ciRunnerData}/runner-state 0755 server server -"
+        ];
       };
-  };
+    };
 }

containers/server-n0/nginx.nix

@@ -210,6 +210,6 @@ let
     };
     inherit (setup) containerConfig;
   };
-  hostAddr = c.hostAddr;
+  inherit (c) hostAddr;
 in
 c

containers/server-n0/ssh.nix

@@ -61,16 +61,29 @@ let
       net ? { },
       resources ? { },
       traits ? [ ],
+      isolation ? { },
     }:
     mkContainer {
       inherit name;
       inherit net resources;
       svc.autoStart = true;
-      isolation.nixDaemon = nixDaemon;
+      isolation = {
+        inherit nixDaemon;
+      }
+      // isolation;
       traits = [ sshTrait ] ++ traits;
       packages = with pkgs; [ tmux ] ++ packages;
       miscProperties = self._sshpiperRegister routingInfo;
     };
+
+  kvmTrait = {
+    containerConfig =
+      { pkgs, ... }:
+      {
+        users.users.runner.extraGroups = [ "kvm" ];
+        environment.systemPackages = [ pkgs.qemu_kvm ];
+      };
+  };
 in
 {
   ssh-admin = mkSsh {
@@ -121,6 +134,25 @@ in
       mem = "16G";
       cpu = 65;
     };
+    traits = [ kvmTrait ];
+    isolation.allowedDevices = [
+      {
+        node = "/dev/kvm";
+        modifier = "rw";
+      }
+      {
+        node = "/dev/vhost-net";
+        modifier = "rw";
+      }
+      {
+        node = "/dev/net/tun";
+        modifier = "rwm";
+      }
+    ];
+    isolation.additionalCapabilities = [
+      "CAP_NET_ADMIN"
+      "CAP_MKNOD"
+    ];
     routingInfo = [
       {
         username = "autumn";

dsl.nix

@@ -228,6 +228,17 @@ rec {
     : systemd-nspawn user namespacing; see `--private-users=` in
       systemd-nspawn(1). Bind mounts always go through idmapped `--bind`.
 
+    `isolation.allowedDevices`
+    : List of `{ node; modifier; }` host devices to grant the container's
+      cgroup access to; see `containers.<name>.allowedDevices` in the NixOS
+      manual. nspawn bind-mounts a handful of devices (`/dev/kvm`,
+      `/dev/net/tun`, ...) into the container itself once the cgroup allows it -
+      this doesn't need a matching `resources.fs` bind mount.
+
+    `isolation.additionalCapabilities`
+    : Extra Linux capabilities granted to the container; see
+      `containers.<name>.additionalCapabilities` in the NixOS manual.
+
     `miscProperties`
     : Arbitrary data attached to the result. Used for cross-container discovery
       via `collectContainers`.
@@ -272,6 +283,8 @@ rec {
       bindMounts = resources.fs or { };
       allowsNixDaemon = isolation.nixDaemon or false;
       privateUsers = isolation.privateUsers or "pick";
+      allowedDevices = isolation.allowedDevices or [ ];
+      additionalCapabilities = isolation.additionalCapabilities or [ ];
 
       allowInternet = hasInternetAccess access;
       allBindMounts = builtins.foldl' (acc: t: acc // (t.resources.fs or { })) { } traits // bindMounts;
@@ -368,7 +381,12 @@ rec {
       kind = "nspawn";
       miscProperties = flattenMiscProp self miscProperties;
       nixosContainer = {
-        inherit autoStart privateUsers;
+        inherit
+          autoStart
+          privateUsers
+          allowedDevices
+          additionalCapabilities
+          ;
         bindMounts = { };
         extraFlags = bindMountExtraFlags;
         privateNetwork = true;
@@ -553,6 +571,11 @@ rec {
               Destination = "0.0.0.0/0";
               Gateway = hostAddr;
             };
+            networkConfig.DNS = [ hostAddr ];
+            networkConfig.Domains = [
+              "~."
+              "containers"
+            ];
             linkConfig.RequiredForOnline = if allowInternet then "routable" else "degraded";
           };
           networking.enableIPv6 = false;

flake.lock

@@ -26,11 +26,11 @@
         "spectrum": "spectrum"
       },
       "locked": {
-        "lastModified": 1786300091,
+        "lastModified": 1789506833,
-        "narHash": "sha256-4UFJOVGpaYtHW5yasSv80MaJxTBYdk2zyf3jhKtt0wA=",
+        "narHash": "sha256-4L8SOCF84de1irB72Ka9VHcu9wrAJ9Amuey4lU9oh4Y=",
         "owner": "microvm-nix",
         "repo": "microvm.nix",
-        "rev": "71beea0076cd46dafcee97a5a2e7d00cbba5bd2f",
+        "rev": "187b0a390ee054028106a674e7b01b1cb940cbba",
         "type": "github"
       },
       "original": {
@@ -63,11 +63,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1786384358,
+        "lastModified": 1789546076,
-        "narHash": "sha256-RzPPiWeUtuvymnpuEWsdtzli5w4kjZs49FqEs3/1u+I=",
+        "narHash": "sha256-zVxLZiSnmaaPLwnhj7pwmqe3axBg/C6nG5JZsJMh2g4=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "2fcb964de67fcf60b43471c55d5d99e61a9ccb5a",
+        "rev": "b1b875982b17dabde9b4a37f3e229e74913e6db3",
         "type": "github"
       },
       "original": {
@@ -87,11 +87,11 @@
     "spectrum": {
       "flake": false,
       "locked": {
-        "lastModified": 1785761586,
+        "lastModified": 1786032750,
-        "narHash": "sha256-MWOMVqJJERwjQGgRIv8d6rlEBqbLM3VZWxHkNKIIZNw=",
+        "narHash": "sha256-+Ba/kIn5BjvV7PN8bWOo7RoqgTY/Yv2M7qeMf3wS2Ag=",
         "ref": "refs/heads/main",
-        "rev": "a7762d6f54b40560dd5255ce902e6e6a5d980fe9",
+        "rev": "77d2389874bb092b8dbf05ecc5b1030372e80e98",
-        "revCount": 1416,
+        "revCount": 1417,
         "type": "git",
         "url": "https://spectrum-os.org/git/spectrum"
       },

flake.nix

@@ -129,11 +129,10 @@
     {
       nixosConfigurations = lib.mapAttrs (_: host: host.hostCfg) allHosts;
 
-      inspect = lib.mapAttrs
+      inspect = lib.mapAttrs (
-        (name: host:
+        name: host:
-          pkgs.writeText "inspect-${name}.json"
+        pkgs.writeText "inspect-${name}.json" (builtins.toJSON (introspect.hostReport { inherit host; }))
-            (builtins.toJSON (introspect.hostReport { inherit host; })))
+      ) allHosts;
-        allHosts;
 
       packages.${system} = customPkgs // {
         inherit ci;

hosts/example.nix

@@ -1,7 +1,7 @@
 _: {
   # New host: copy this file to hosts/<name>.nix. Replace fileSystems/boot
   # below with the real hardware (see hosts/server-n0.nix for a bigger
-  # example). Add a containers/<name>/ directory for its containers.  
+  # example). Add a containers/<name>/ directory for its containers.
 
   module =
     { lib, hostInfo, ... }:

tests/server-n0/integration.py

@@ -205,12 +205,7 @@ with subtest("(isolation): edges are one-way"):
     server.fail(ct_connect("git", ADDR["nginx"], 443, timeout=2))
 
 with subtest("(isolation): host access allowlist"):
-    server.succeed(
+    server.succeed(ct_connect("overseer", HOST_ADDR["overseer"], HOST_EXPORTER_PORT))
-        net_cmd(
-            "overseer",
-            f"{CURL} -sf --max-time 5 http://{HOST_ADDR['overseer']}:{HOST_EXPORTER_PORT}/metrics >&2",
-        )
-    )
     for port in (HOST_EXPORTER_PORT, HOST_CADVISOR_PORT):
         server.fail(ct_connect("git", HOST_ADDR["git"], port, timeout=2))
         server.fail(ct_connect("git", HOST_ADDR["overseer"], port, timeout=2))