Send container logs to syslog server

hook.yaml

@@ -23,6 +23,8 @@ onboot:
 services:
   - name: getty
     image: linuxkit/getty:v0.8
+    binds.add:
+     - /etc/profile.d/local.sh:/etc/profile.d/local.sh
     env:
      - INSECURE=true
   - name: rngd
@@ -51,7 +53,6 @@ services:
     binds:
      - /etc/resolv.conf:/etc/resolv.conf
      - /lib/modules:/lib/modules
-     - /etc/docker/daemon.json:/etc/docker/daemon.json
      - /var/run/docker:/var/run
      - /var/run/worker:/worker
      - /dev/console:/dev/console
@@ -76,11 +77,10 @@ services:
       mkdir:
         - /var/run/docker
 files:
-  - path: etc/docker/daemon.json
-    contents: '{"debug": true}'
   - path: etc/profile.d/local.sh
     contents: |
-      alias docker='ctr -n services.linuxkit tasks exec --tty --exec-id shell docker docker'
+      alias docker='ctr -n services.linuxkit tasks exec --tty --exec-id cmd docker docker'
+      alias docker-shell='ctr -n services.linuxkit tasks exec --tty --exec-id shell docker sh'
     mode: "0644"
 trust:
   org:

tink-docker/Dockerfile

@@ -1,14 +1,14 @@
 # syntax=docker/dockerfile:experimental
 
-FROM golang:1.15-alpine as dev
+FROM golang:1.18-alpine as dev
 COPY . /src/
 WORKDIR /src
 ENV GO111MODULE=on
 RUN --mount=type=cache,sharing=locked,id=gomod,target=/go/pkg/mod/cache \
     --mount=type=cache,sharing=locked,id=goroot,target=/root/.cache/go-build \
     CGO_ENABLED=0 go build -a -ldflags '-w -extldflags "-static"' -o /tink-docker
 
-FROM docker:19.03.8-dind
+FROM docker:20.10.14-dind
 RUN echo "http://dl-cdn.alpinelinux.org/alpine/edge/testing" >> /etc/apk/repositories
 RUN apk update; apk add kexec-tools
 COPY --from=dev /tink-docker .

tink-docker/go.mod

@@ -1,3 +1,3 @@
 module github.com/tinkerbell/hook/tink-docker
 
-go 1.15
+go 1.18

tink-docker/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"encoding/json"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -15,10 +16,17 @@ type tinkConfig struct {
 	registry   string
 	baseURL    string
 	tinkerbell string
+	syslogHost string
 
 	// TODO add others
 }
 
+type dockerConfig struct {
+	Debug     bool              `json:"debug"`
+	LogDriver string            `json:"log-driver,omitempty"`
+	LogOpts   map[string]string `json:"log-opts,omitempty"`
+}
+
 func main() {
 	fmt.Println("Starting Tink-Docker")
 	go rebootWatch()
@@ -45,6 +53,17 @@ func main() {
 	}
 	fmt.Println("Downloaded the repository certificates, starting the Docker Engine")
 
+	d := dockerConfig{
+		Debug:     true,
+		LogDriver: "syslog",
+		LogOpts: map[string]string{
+			"syslog-address": fmt.Sprintf("udp://%v:514", cfg.syslogHost),
+		},
+	}
+	if err := d.writeToDisk("/etc/docker/daemon.json"); err != nil {
+		fmt.Println("Failed to write docker config:", err)
+	}
+
 	// Build the command, and execute
 	cmd := exec.Command("/usr/local/bin/docker-init", "/usr/local/bin/dockerd")
 	cmd.Stdout = os.Stdout
@@ -55,6 +74,19 @@ func main() {
 	}
 }
 
+// writeToDisk writes the dockerConfig to loc.
+func (d dockerConfig) writeToDisk(loc string) error {
+	b, err := json.Marshal(d)
+	if err != nil {
+		return fmt.Errorf("unable to marshal docker config: %w", err)
+	}
+	if err := ioutil.WriteFile(loc, b, 0600); err != nil {
+		return fmt.Errorf("Error writing daemon.json: %w", err)
+	}
+
+	return nil
+}
+
 // parseCmdLine will parse the command line.
 func parseCmdLine(cmdLines []string) (cfg tinkConfig) {
 	for i := range cmdLines {
@@ -71,6 +103,8 @@ func parseCmdLine(cmdLines []string) (cfg tinkConfig) {
 			cfg.baseURL = cmdLine[1]
 		case "tinkerbell":
 			cfg.tinkerbell = cmdLine[1]
+		case "syslog_host":
+			cfg.syslogHost = cmdLine[1]
 		}
 	}
 	return cfg

tink-docker/main_test.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"bytes"
+	"errors"
+	"io/ioutil"
+	"os"
+	"testing"
+)
+
+func TestWriteToDisk(t *testing.T) {
+	tests := map[string]struct {
+		cfg     dockerConfig
+		want    []byte
+		wantErr error
+	}{
+		"success":                {cfg: dockerConfig{Debug: false, LogDriver: "json-file"}, want: []byte(`{"debug":false,"log-driver":"json-file"}`)},
+		"success - empty struct": {cfg: dockerConfig{}, want: []byte(`{"debug":false}`)},
+	}
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			// Create a temporary directory
+			dir, err := ioutil.TempDir("", "tink-docker")
+			if err != nil {
+				t.Fatal(err)
+			}
+			defer os.RemoveAll(dir)
+			loc := dir + "daemon.json"
+
+			err = tt.cfg.writeToDisk(loc)
+			if !errors.Is(err, tt.wantErr) {
+				t.Fatalf("got err %v, want %v", err, tt.wantErr)
+			}
+
+			if tt.wantErr == nil {
+				got, err := ioutil.ReadFile(loc)
+				if err != nil {
+					t.Fatal(err)
+				}
+
+				if !bytes.Equal(got, tt.want) {
+					t.Fatalf("\ngot:\n %s\nwant:\n %s", got, tt.want)
+				}
+			}
+		})
+	}
+}