Reimplement dnsmasq-entrypoint in go

This allowed for deleting all script utilities and environment variable
logic.

default.nix

@@ -57,9 +57,11 @@ in rec {
 
   entrypoint = pkgs.callPackage ./entrypoint {};
 
-  dnsmasq = (pkgs.callPackage ./dnsmasq {
+  dnsmasq = (pkgs.callPackage ./nix/dnsmasq.nix {
     glibcStatic = pkgs.glibc.static;
-  }).env;
+  });
+
+  nebula = pkgs.callPackage ./nix/nebula.nix {};
 
   garage = (pkgs.callPackage ./nix/garage.nix {}).env;
 
@@ -69,18 +71,10 @@ in rec {
     name = "cryptic-net-AppDir";
     paths = [
 
-      pkgs.pkgsStatic.bash
-      pkgs.pkgsStatic.coreutils
-      pkgs.pkgsStatic.gnutar
-      pkgs.pkgsStatic.gzip
-
-      # custom packages from ./pkgs.nix
-      pkgs.yq-go
-      pkgs.nebula
-
       ./AppDir
       version
       dnsmasq
+      nebula
       garage
       entrypoint
 

dnsmasq/bin/dnsmasq-entrypoint

@@ -1,36 +0,0 @@
-# TODO implement this in go
-
-set -e -o pipefail
-cd "$APPDIR"
-
-conf_path="$_RUNTIME_DIR_PATH"/dnsmasq.conf
-
-cat etc/dnsmasq/base.conf > "$conf_path"
-
-tmp="$(mktemp -d -t cryptic-net-dnsmasq-entrypoint-XXX)"
-
-( trap "rm -rf '$tmp'" EXIT
-
-    tar xzf "$_BOOTSTRAP_PATH" -C "$tmp" ./hosts
-
-    thisHostName=$(tar xzf "$_BOOTSTRAP_PATH" --to-stdout ./hostname)
-    thisHostIP=$(cat "$tmp"/hosts/"$thisHostName".yml | yq '.nebula.ip')
-
-    domain=$(tar xzf "$_BOOTSTRAP_PATH" --to-stdout ./admin/creation-params.yml | yq '.domain')
-
-    echo "listen-address=$thisHostIP" >> "$conf_path"
-
-    ls -1 "$tmp"/hosts | while read hostYml; do
-
-        hostName=$(echo "$hostYml" | cut -d. -f1)
-        hostIP=$(cat "$tmp"/hosts/"$hostYml" | yq '.nebula.ip')
-        echo "address=/${hostName}.hosts.$domain/$hostIP" >> "$conf_path"
-
-    done
-)
-
-cat "$_DAEMON_YML_PATH" | \
-    yq '.dns.resolvers | .[] | "server=" + .' \
-    >> "$conf_path"
-
-exec bin/dnsmasq -d -C "$conf_path"

dnsmasq/default.nix

@@ -1,39 +0,0 @@
-{
-
-  stdenv,
-  buildEnv,
-  glibcStatic,
-  rebase,
-
-}: rec {
-
-  dnsmasq = stdenv.mkDerivation rec {
-    pname = "dnsmasq";
-    version = "2.85";
-
-    src = builtins.fetchurl {
-      url = "https://www.thekelleys.org.uk/dnsmasq/${pname}-${version}.tar.xz";
-      sha256 = "sha256-rZjTgD32h+W5OAgPPSXGKP5ByHh1LQP7xhmXh/7jEvo=";
-    };
-
-    nativeBuildInputs = [ glibcStatic ];
-
-    makeFlags = [
-      "LDFLAGS=-static"
-      "DESTDIR="
-      "BINDIR=$(out)/bin"
-      "MANDIR=$(out)/man"
-      "LOCALEDIR=$(out)/share/locale"
-    ];
-  };
-
-  env = buildEnv {
-    name = "cryptic-net-dnsmasq";
-    paths = [
-      (rebase "cryptic-net-dnsmasq-bin" ./bin "bin")
-      (rebase "cryptic-net-dnsmasq-etc" ./etc "etc/dnsmasq")
-      dnsmasq
-    ];
-  };
-
-}

dnsmasq/etc/base.conf

@@ -1,41 +0,0 @@
-# Configuration file for dnsmasq.
-#
-# Format is one option per line, legal options are the same
-# as the long options legal on the command line. See
-# "/usr/sbin/dnsmasq --help" or "man 8 dnsmasq" for details.
-
-# Listen on this specific port instead of the standard DNS port
-# (53). Setting this to zero completely disables DNS function,
-# leaving only DHCP and/or TFTP.
-port=53
-
-# If you don't want dnsmasq to read /etc/resolv.conf or any other
-# file, getting its servers from this file instead (see below), then
-# uncomment this.
-no-resolv
-
-# On systems which support it, dnsmasq binds the wildcard address,
-# even when it is listening on only some interfaces. It then discards
-# requests that it shouldn't reply to. This has the advantage of
-# working even when interfaces come and go and change address. If you
-# want dnsmasq to really bind only the interfaces it is listening on,
-# uncomment this option. About the only time you may need this is when
-# running another nameserver on the same machine.
-bind-interfaces
-
-# If you don't want dnsmasq to read /etc/hosts, uncomment the
-# following line.
-no-hosts
-
-# Unset user and group so that dnsmasq doesn't drop privileges to another user.
-# If this isn't done then dnsmasq fails to start up, since it fails to access
-# /etc/passwd correctly, probably due to nix.
-user=
-group=
-
-# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-#
-# Everything below is generated dynamically based on runtime configuration
-#
-# !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-

entrypoint/src/cmd/entrypoint/daemon.go

@@ -94,16 +94,14 @@ func runDaemonPmuxOnce(env crypticnet.Env) (crypticnet.Env, error) {
 		return crypticnet.Env{}, fmt.Errorf("generating nebula config: %w", err)
 	}
 
+	dnsmasqPmuxProcConfig, err := dnsmasqPmuxProcConfig(env)
+	if err != nil {
+		return crypticnet.Env{}, fmt.Errorf("generating dnsmasq config: %w", err)
+	}
+
 	pmuxProcConfigs := []pmuxlib.ProcessConfig{
 		nebulaPmuxProcConfig,
-		{
+		dnsmasqPmuxProcConfig,
-			Name: "dnsmasq",
-			Cmd:  "bash",
-			Args: []string{"dnsmasq-entrypoint"},
-			StartAfterFunc: func(ctx context.Context) error {
-				return waitForNebula(ctx, env)
-			},
-		},
 	}
 
 	if len(thisDaemon.Storage.Allocations) > 0 {
@@ -302,15 +300,6 @@ var subCmdDaemon = subCmd{
 			return fmt.Errorf("merging daemon.yml into bootstrap data: %w", err)
 		}
 
-		// TODO once dnsmasq entrypoint is written in go and the config
-		// generation is inlined into this process then this Setenv won't be
-		// necessary.
-		for key, val := range env.ToMap() {
-			if err := os.Setenv(key, val); err != nil {
-				return fmt.Errorf("failed to set %q to %q: %w", key, val, err)
-			}
-		}
-
 		for {
 
 			if env, err = runDaemonPmuxOnce(env); errors.Is(err, context.Canceled) {

entrypoint/src/cmd/entrypoint/dnsmasq_util.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	crypticnet "cryptic-net"
+	"cryptic-net/bootstrap"
+	"cryptic-net/dnsmasq"
+	"fmt"
+	"path/filepath"
+	"sort"
+
+	"code.betamike.com/cryptic-io/pmux/pmuxlib"
+)
+
+func dnsmasqPmuxProcConfig(env crypticnet.Env) (pmuxlib.ProcessConfig, error) {
+
+	thisDaemon := env.ThisDaemon()
+
+	confPath := filepath.Join(env.RuntimeDirPath, "dnsmasq.conf")
+
+	hostsSlice := make([]bootstrap.Host, 0, len(env.Bootstrap.Hosts))
+	for _, host := range env.Bootstrap.Hosts {
+		hostsSlice = append(hostsSlice, host)
+	}
+
+	sort.Slice(hostsSlice, func(i, j int) bool {
+		return hostsSlice[i].Nebula.IP < hostsSlice[j].Nebula.IP
+	})
+
+	confData := dnsmasq.ConfData{
+		Resolvers: thisDaemon.DNS.Resolvers,
+		Domain:    env.Bootstrap.AdminCreationParams.Domain,
+		IP:        env.Bootstrap.ThisHost().Nebula.IP,
+		Hosts:     hostsSlice,
+	}
+
+	if err := dnsmasq.WriteConfFile(confPath, confData); err != nil {
+		return pmuxlib.ProcessConfig{}, fmt.Errorf("writing dnsmasq.conf to %q: %w", confPath, err)
+	}
+
+	return pmuxlib.ProcessConfig{
+		Name: "dnsmasq",
+		Cmd:  "dnsmasq",
+		Args: []string{"-d", "-C", confPath},
+	}, nil
+}

entrypoint/src/dnsmasq/dnsmasq.go

@@ -0,0 +1,3 @@
+// Package dnsmasq contains helper functions and types which are useful for
+// setting up dnsmasq configs, processes, and deployments.
+package dnsmasq

entrypoint/src/dnsmasq/tpl.go

@@ -0,0 +1,58 @@
+package dnsmasq
+
+import (
+	"cryptic-net/bootstrap"
+	"fmt"
+	"os"
+	"text/template"
+)
+
+// ConfData describes all the data needed to populate a dnsmasq.conf file.
+type ConfData struct {
+	Resolvers []string
+	Domain    string
+	IP        string
+	Hosts     []bootstrap.Host
+}
+
+var confTpl = template.Must(template.New("").Parse(`
+port=53
+
+bind-interfaces
+listen-address={{ .IP }}
+
+no-resolv
+no-hosts
+
+user=
+group=
+
+{{- range $host := .Hosts }}
+address=/{{ $host.Name }}.hosts.{{ .Domain }}/{{ $host.Nebula.IP }}
+{{ end -}}
+
+{{- range .Resolvers }}
+server={{ . }}
+{{ end -}}
+`))
+
+// WriteConfFile renders a dnsmasq.conf using the given data to a new
+// file at the given path.
+func WriteConfFile(path string, data ConfData) error {
+
+	file, err := os.OpenFile(
+		path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0640,
+	)
+
+	if err != nil {
+		return fmt.Errorf("creating file: %w", err)
+	}
+
+	defer file.Close()
+
+	if err := confTpl.Execute(file, data); err != nil {
+		return fmt.Errorf("rendering template to file: %w", err)
+	}
+
+	return nil
+}

entrypoint/src/env.go

@@ -19,14 +19,6 @@ import (
 	"github.com/adrg/xdg"
 )
 
-// Names of various environment variables which get set by the entrypoint.
-const (
-	DaemonYmlPathEnvVar  = "_DAEMON_YML_PATH"
-	BootstrapPathEnvVar  = "_BOOTSTRAP_PATH"
-	RuntimeDirPathEnvVar = "_RUNTIME_DIR_PATH"
-	DataDirPathEnvVar    = "_DATA_DIR_PATH"
-)
-
 // Env contains the values of environment variables, as well as other entities
 // which are useful across all processes.
 type Env struct {
@@ -74,40 +66,6 @@ func NewEnv(bootstrapOptional bool) (Env, error) {
 	return env.init(bootstrapOptional)
 }
 
-// ReadEnv reads an Env from the process's environment variables, rather than
-// calculating like NewEnv does.
-func ReadEnv() (Env, error) {
-
-	var err error
-
-	readEnv := func(key string) string {
-		if err != nil {
-			return ""
-		}
-
-		val := os.Getenv(key)
-
-		if val == "" {
-			err = fmt.Errorf("envvar %q not set", key)
-		}
-
-		return val
-	}
-
-	env := Env{
-		AppDirPath:     getAppDirPath(),
-		DaemonYmlPath:  readEnv(DaemonYmlPathEnvVar),
-		RuntimeDirPath: readEnv(RuntimeDirPathEnvVar),
-		DataDirPath:    readEnv(DataDirPathEnvVar),
-	}
-
-	if err != nil {
-		return Env{}, err
-	}
-
-	return env.init(false)
-}
-
 // DataDirBootstrapPath returns the path to the bootstrap file within the user's
 // data dir. If the file does not exist there it will be found in the AppDirPath
 // by ReloadBootstrap.
@@ -197,17 +155,6 @@ func (e Env) init(bootstrapOptional bool) (Env, error) {
 	return e.initBootstrap(bootstrapOptional)
 }
 
-// ToMap returns the Env as a map of key/value strings. If this map is set into
-// a process's environment, then that process can read it back using ReadEnv.
-func (e Env) ToMap() map[string]string {
-	return map[string]string{
-		DaemonYmlPathEnvVar:  e.DaemonYmlPath,
-		BootstrapPathEnvVar:  e.BootstrapPath,
-		RuntimeDirPathEnvVar: e.RuntimeDirPath,
-		DataDirPathEnvVar:    e.DataDirPath,
-	}
-}
-
 // ThisDaemon returns the DaemonYml (loaded from DaemonYmlPath) for the
 // currently running process.
 func (e Env) ThisDaemon() DaemonYml {

entrypoint/src/garage/tpl.go

@@ -67,9 +67,7 @@ func WriteGarageTomlFile(path string, data GarageTomlData) error {
 
 	defer file.Close()
 
-	err = RenderGarageToml(file, data)
+	if err := garageTomlTpl.Execute(file, data); err != nil {
-
-	if err != nil {
 		return fmt.Errorf("rendering template to file: %w", err)
 	}
 

nix/dnsmasq.nix

@@ -0,0 +1,25 @@
+{
+
+  stdenv,
+  glibcStatic,
+
+}: stdenv.mkDerivation rec {
+
+  pname = "dnsmasq";
+  version = "2.85";
+
+  src = builtins.fetchurl {
+    url = "https://www.thekelleys.org.uk/dnsmasq/${pname}-${version}.tar.xz";
+    sha256 = "sha256-rZjTgD32h+W5OAgPPSXGKP5ByHh1LQP7xhmXh/7jEvo=";
+  };
+
+  nativeBuildInputs = [ glibcStatic ];
+
+  makeFlags = [
+    "LDFLAGS=-static"
+    "DESTDIR="
+    "BINDIR=$(out)/bin"
+    "MANDIR=$(out)/man"
+    "LOCALEDIR=$(out)/share/locale"
+  ];
+}

nix/pkgs.nix

@@ -2,7 +2,8 @@ rec {
 
   overlays = [
 
-    # Make both buildGoModules use static compilation by default.
+    # Make buildGoModules use static compilation by default, and use go 1.18
+    # everywhere.
     (final: prev:
 
       let
@@ -17,19 +18,11 @@ rec {
       in {
 
         go = prev.go_1_18;
-        buildGoModule = args: prev.buildGoModule (buildArgs // args);
+        buildGoModule = args: prev.buildGo118Module (buildArgs // args);
         buildGo118Module = args: prev.buildGo118Module (buildArgs // args);
 
       }
     )
-
-    (final: prev: { rebase = prev.callPackage ./rebase.nix {}; })
-    (final: prev: { yq-go = prev.callPackage ./yq-go.nix {}; })
-
-    (final: prev: { nebula = prev.callPackage ./nebula.nix {
-      buildGoModule = prev.buildGo118Module;
-    }; })
-
   ];
 
   version = "22-05";

nix/rebase.nix

@@ -1,18 +0,0 @@
-# rebase is a helper which takes all files/dirs under oldroot, and
-# creates a new derivation with those files/dirs copied under newroot
-# (where newroot is a relative path to the root of the derivation).
-
-{
-
-  stdenv,
-
-}: name: oldroot: newroot: stdenv.mkDerivation {
-
-  inherit name oldroot newroot;
-
-  builder = builtins.toFile "builder.sh" ''
-    source $stdenv/setup
-    mkdir -p "$out"/"$newroot"
-    cp -rL "$oldroot"/* "$out"/"$newroot"
-  '';
-}

nix/yq-go.nix

@@ -1,19 +0,0 @@
-{
-
-  buildGoModule,
-  fetchFromGitHub,
-
-}: buildGoModule rec {
-
-  pname = "yq-go";
-  version = "4.21.1";
-
-  src = fetchFromGitHub {
-    owner = "mikefarah";
-    repo = "yq";
-    rev = "v${version}";
-    sha256 = "sha256-283xe7FVHYSsRl4cZD7WDzIW1gqNAFsNrWYJkthZheU=";
-  };
-
-  vendorSha256 = "sha256-F11FnDYJ59aKrdRXDPpKlhX52yQXdaN1sblSkVI2j9w=";
-}