Install the guest agent from a vendor-data script instead of editing the user's cloud-config
Merging the bootstrap into each Proxy's cloud-config was the wrong mechanism twice over. Detection only matched a literal #cloud-config first line, so a jinja template or a MIME archive still fell back to vendor-data, where cloud-init's default mergers drop it — the exact failure the merge existed to prevent. And the YAML round-trip re-typed unquoted scalars: version: 1.10 reached the guest as 1.1, comments were dropped and keys reordered. Neither is worth patching, because vendor-data delivered as a shell script bypasses the merger entirely: cloud-init hands vendor-data to its own handler chain, writes scripts to a separate directory and runs them from cc_scripts_vendor, after the user's packages and before the user's runcmd. The merge could not have been rescued anyway — merge_how in user-data governs only the first source, and merge_how in vendor-data is discarded before the document is stored. The Proxy's cloud-init now reaches the seed byte for byte in any format. installGuestAgent (default true) turns the script off; a configured vendorData travels beside it as a MIME multipart, declared text/plain so cloud-init re-sniffs it and this code never classifies user content. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
This commit is contained in:
Claude Opus 5
+122
-138
@@ -4,12 +4,12 @@ import (
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"bytes"
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"io"
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"maps"
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"reflect"
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"mime"
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"mime/multipart"
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"strings"
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"testing"
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"github.com/kdomanski/iso9660"
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"sigs.k8s.io/yaml"
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)
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func readSeed(t *testing.T, iso []byte) (label string, files map[string]string) {
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@@ -44,7 +44,7 @@ func readSeed(t *testing.T, iso []byte) (label string, files map[string]string)
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func TestBuildSeedISO_contents(t *testing.T) {
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t.Parallel()
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userData := "#cloud-config\npackages: [squid]\n"
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iso, err := buildSeedISO("proxy-abc123def456ghij", userData, guestAgentVendorData)
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iso, err := buildSeedISO("proxy-abc123def456ghij", userData, guestAgentScript)
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if err != nil {
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t.Fatalf("buildSeedISO() error = %v", err)
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}
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@@ -58,7 +58,7 @@ func TestBuildSeedISO_contents(t *testing.T) {
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if files["user-data"] != userData {
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t.Errorf("user-data = %q, want verbatim cloud-init", files["user-data"])
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}
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if files["vendor-data"] != guestAgentVendorData {
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if files["vendor-data"] != guestAgentScript {
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t.Errorf("vendor-data = %q", files["vendor-data"])
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}
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if got, want := files["meta-data"], "instance-id: proxy-abc123def456ghij\nlocal-hostname: proxy-abc123def456ghij\n"; got != want {
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@@ -91,7 +91,7 @@ func TestBuildSeedISO_deterministicContent(t *testing.T) {
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func TestBuildSeedISO_emptyUserData(t *testing.T) {
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t.Parallel()
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iso, err := buildSeedISO("proxy-x", "", guestAgentVendorData)
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iso, err := buildSeedISO("proxy-x", "", guestAgentScript)
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if err != nil {
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t.Fatalf("buildSeedISO() error = %v", err)
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}
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@@ -101,149 +101,133 @@ func TestBuildSeedISO_emptyUserData(t *testing.T) {
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}
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}
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// parseCloudConfig is what cloud-init sees: the document under the header.
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func parseCloudConfig(t *testing.T, doc string) map[string]any {
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t.Helper()
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if first, _, _ := strings.Cut(doc, "\n"); first != cloudConfigHeader {
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t.Fatalf("first line = %q, want %q", first, cloudConfigHeader)
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}
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var cfg map[string]any
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if err := yaml.Unmarshal([]byte(doc), &cfg); err != nil {
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t.Fatalf("merged user-data is not YAML: %v\n%s", err, doc)
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}
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return cfg
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}
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func TestWithGuestAgent_mergesIntoCloudConfig(t *testing.T) {
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t.Parallel()
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agentCmd := []any{"systemctl", "enable", "--now", "qemu-guest-agent"}
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tests := []struct {
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name string
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userData string
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wantPackages []any
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wantRuncmd []any
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}{
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{
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name: "empty document",
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userData: "#cloud-config\n",
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wantPackages: []any{"qemu-guest-agent"},
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wantRuncmd: []any{agentCmd},
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},
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{
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name: "no user-data at all",
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userData: "",
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wantPackages: []any{"qemu-guest-agent"},
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wantRuncmd: []any{agentCmd},
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},
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{
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// The case that motivated this: cloud-init's default merger keeps
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// the user-data's lists and drops vendor-data's, so the agent must
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// be appended to the user's own packages and runcmd.
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name: "user packages and runcmd are kept and extended",
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userData: "#cloud-config\npackages:\n - squid\nruncmd:\n - systemctl restart squid\n" +
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"write_files:\n - path: /etc/squid/conf.d/x.conf\n content: |\n http_port 3128\n via off\n",
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wantPackages: []any{"squid", "qemu-guest-agent"},
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wantRuncmd: []any{"systemctl restart squid", agentCmd},
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},
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{
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name: "agent already present is not duplicated",
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userData: "#cloud-config\npackages: [qemu-guest-agent]\nruncmd:\n - [systemctl, enable, --now, qemu-guest-agent]\n",
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wantPackages: []any{"qemu-guest-agent"},
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wantRuncmd: []any{agentCmd},
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},
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{
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name: "header with trailing whitespace",
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userData: "#cloud-config \r\npackages: [curl]\n",
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wantPackages: []any{"curl", "qemu-guest-agent"},
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wantRuncmd: []any{agentCmd},
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},
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}
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for _, tc := range tests {
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t.Run(tc.name, func(t *testing.T) {
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t.Parallel()
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user, vendor, err := withGuestAgent(tc.userData, "")
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if err != nil {
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t.Fatalf("withGuestAgent() error = %v", err)
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}
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if vendor != "" {
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t.Errorf("vendor-data = %q, want none when the agent is merged into the user-data", vendor)
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}
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cfg := parseCloudConfig(t, user)
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if !reflect.DeepEqual(cfg["packages"], tc.wantPackages) {
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t.Errorf("packages = %#v, want %#v", cfg["packages"], tc.wantPackages)
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}
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if !reflect.DeepEqual(cfg["runcmd"], tc.wantRuncmd) {
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t.Errorf("runcmd = %#v, want %#v", cfg["runcmd"], tc.wantRuncmd)
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}
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})
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}
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}
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func TestWithGuestAgent_keepsOtherKeysAndVendorData(t *testing.T) {
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t.Parallel()
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userData := "#cloud-config\nhostname: px\nwrite_files:\n - path: /etc/x\n content: |\n line one\n line two\n permissions: '0644'\nbootcmd: [echo hi]\n"
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user, vendor, err := withGuestAgent(userData, "#cloud-config\nntp: {enabled: true}\n")
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if err != nil {
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t.Fatalf("withGuestAgent() error = %v", err)
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}
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if vendor != "#cloud-config\nntp: {enabled: true}\n" {
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t.Errorf("vendor-data = %q, want the configured one verbatim", vendor)
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}
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got := parseCloudConfig(t, user)
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delete(got, "packages")
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delete(got, "runcmd")
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want := parseCloudConfig(t, userData)
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if !reflect.DeepEqual(got, want) {
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t.Errorf("merged user-data changed the user's keys:\n got %#v\nwant %#v", got, want)
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}
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}
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func TestWithGuestAgent_nonCloudConfigFallsBackToVendorData(t *testing.T) {
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t.Parallel()
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tests := []struct {
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name string
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userData string
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vendorData string
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wantVendor string
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}{
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{"shell script, no vendor-data", "#!/bin/sh\napt-get install -y squid\n", "", guestAgentVendorData},
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{"include, no vendor-data", "#include\nhttps://example/x\n", "", guestAgentVendorData},
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{"shell script, own vendor-data wins", "#!/bin/sh\n", "#cloud-config\nntp: {}\n", "#cloud-config\nntp: {}\n"},
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}
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for _, tc := range tests {
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t.Run(tc.name, func(t *testing.T) {
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t.Parallel()
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user, vendor, err := withGuestAgent(tc.userData, tc.vendorData)
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if err != nil {
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t.Fatalf("withGuestAgent() error = %v", err)
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}
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if user != tc.userData {
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t.Errorf("user-data = %q, want it untouched", user)
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}
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if vendor != tc.wantVendor {
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t.Errorf("vendor-data = %q, want %q", vendor, tc.wantVendor)
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}
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})
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}
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}
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func TestWithGuestAgent_rejectsBrokenCloudConfig(t *testing.T) {
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// The whole point of shipping the agent as vendor-data: whatever the Proxy
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// wrote reaches the guest untouched, in any of cloud-init's formats. The
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// previous implementation parsed and re-rendered cloud-config user-data,
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// which dropped comments, reordered keys and re-typed unquoted scalars
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// (version: 1.10 arrived as 1.1).
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func TestBuildSeedISO_userDataIsNeverRewritten(t *testing.T) {
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t.Parallel()
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tests := []struct {
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name string
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userData string
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}{
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{"not yaml", "#cloud-config\npackages: [squid\n"},
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{"not a mapping", "#cloud-config\n- squid\n"},
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{"packages is not a list", "#cloud-config\npackages: squid\n"},
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{"runcmd is not a list", "#cloud-config\nruncmd:\n a: b\n"},
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{"cloud-config with its own packages", "#cloud-config\n# keep me\npackages:\n - squid\nversion: 1.10\nchpasswd: {list: 'u:0123456789'}\n"},
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{"jinja template", "## template: jinja\n#cloud-config\nhostname: {{ v1.local_hostname }}\n"},
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{"shell script", "#!/bin/sh\napt-get install -y squid\n"},
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{"include", "#include\nhttps://example.invalid/x\n"},
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{"mime multipart", "MIME-Version: 1.0\r\nContent-Type: multipart/mixed; boundary=\"x\"\r\n\r\n--x\r\nContent-Type: text/cloud-config\r\n\r\n#cloud-config\npackages: [squid]\n\r\n--x--\r\n"},
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{"gzip payload", "\x1f\x8b\x08\x00\x00\x00\x00\x00\x00\x03binary\x00bytes"},
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{"leading blank line", "\n\n#cloud-config\npackages: [squid]\n"},
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}
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for _, tc := range tests {
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t.Run(tc.name, func(t *testing.T) {
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t.Parallel()
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if _, _, err := withGuestAgent(tc.userData, ""); err == nil {
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t.Errorf("withGuestAgent() = nil error, want one for %q", tc.userData)
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vendor, err := buildVendorData("", true)
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if err != nil {
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t.Fatalf("buildVendorData() error = %v", err)
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}
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iso, err := buildSeedISO("proxy-x", tc.userData, vendor)
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if err != nil {
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t.Fatalf("buildSeedISO() error = %v", err)
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}
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_, files := readSeed(t, iso)
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if files["user-data"] != tc.userData {
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t.Errorf("user-data was rewritten:\n got %q\nwant %q", files["user-data"], tc.userData)
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}
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if !strings.Contains(files["vendor-data"], "qemu-guest-agent") {
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t.Errorf("vendor-data = %q, want the agent script", files["vendor-data"])
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}
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})
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}
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}
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func TestBuildVendorData_agentScriptAlone(t *testing.T) {
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t.Parallel()
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got, err := buildVendorData("", true)
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if err != nil {
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t.Fatalf("buildVendorData() error = %v", err)
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}
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if got != guestAgentScript {
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t.Errorf("vendor-data = %q, want the bare script", got)
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}
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if !strings.HasPrefix(got, "#!") {
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t.Error("vendor-data must start with a shebang or cloud-init treats it as something other than a script")
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}
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}
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func TestBuildVendorData_optOutKeepsConfiguredOnly(t *testing.T) {
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t.Parallel()
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configured := "#cloud-config\nntp: {enabled: true}\n"
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tests := []struct {
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name string
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configured string
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want string
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}{
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{"nothing configured", "", ""},
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{"configured document passes through", configured, configured},
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}
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for _, tc := range tests {
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t.Run(tc.name, func(t *testing.T) {
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t.Parallel()
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got, err := buildVendorData(tc.configured, false)
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if err != nil {
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t.Fatalf("buildVendorData() error = %v", err)
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}
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if got != tc.want {
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t.Errorf("vendor-data = %q, want %q", got, tc.want)
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}
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if strings.Contains(got, "qemu-guest-agent") {
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t.Error("agent script present although installGuestAgent is off")
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}
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})
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}
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}
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// Both documents have to survive in one file, and cloud-init only looks for
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// the multipart marker in the first 4096 bytes.
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func TestBuildVendorData_multipartCarriesBoth(t *testing.T) {
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t.Parallel()
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configured := "#cloud-config\nntp:\n enabled: true\n"
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got, err := buildVendorData(configured, true)
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if err != nil {
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t.Fatalf("buildVendorData() error = %v", err)
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}
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head := got
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if len(head) > 4096 {
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head = head[:4096]
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}
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if !strings.Contains(strings.ToLower(head), "mime-version:") {
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t.Fatalf("no mime-version: in the first 4096 bytes; cloud-init would treat this as a single document:\n%s", head)
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}
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_, params, err := mime.ParseMediaType(strings.SplitN(got, "\r\n\r\n", 2)[0][strings.Index(got, "Content-Type:")+len("Content-Type: "):])
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if err != nil {
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t.Fatalf("parsing the multipart content type: %v", err)
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}
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body := strings.SplitN(got, "\r\n\r\n", 2)[1]
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r := multipart.NewReader(strings.NewReader(body), params["boundary"])
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var bodies, types []string
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for {
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part, err := r.NextPart()
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if err == io.EOF {
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break
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}
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if err != nil {
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t.Fatalf("reading part: %v", err)
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}
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content, err := io.ReadAll(part)
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if err != nil {
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t.Fatalf("reading part body: %v", err)
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}
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bodies = append(bodies, string(content))
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types = append(types, part.Header.Get("Content-Type"))
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}
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if len(bodies) != 2 || bodies[0] != configured || bodies[1] != guestAgentScript {
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t.Fatalf("parts = %q, want the configured document then the script", bodies)
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}
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// text/plain makes cloud-init re-sniff the user's document from its own
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// header line, so this code never has to classify it.
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if types[0] != "text/plain" || types[1] != "text/x-shellscript" {
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t.Errorf("part types = %v, want [text/plain text/x-shellscript]", types)
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}
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}
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Reference in New Issue
Block a user