cli: Add setup and firstboot commands
This adds two new top-level commands: setup and firstboot. Firstboot is pure-golang implementation of a service that runs some commands once when a system first boots. You need to install this service, and put the scripts to run in a special directory. This is inspired by the virt-builder --firstboot mechanism. Setup is a general purpose command that makes it easy to setup certain facilities on a new machine. These include the mgmt package dependencies it might need, a service to run it from, and the necessary service to use the mgmt firstboot service as well. All of this has been built to facilitate handoff between provisioning a new machine and running configuration management on it.
This commit is contained in:
James Shubin
53
firstboot/firstboot.go
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53
firstboot/firstboot.go
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// Mgmt
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// Copyright (C) 2013-2024+ James Shubin and the project contributors
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// Written by James Shubin <james@shubin.ca> and the project contributors
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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//
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// Additional permission under GNU GPL version 3 section 7
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//
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// If you modify this program, or any covered work, by linking or combining it
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// with embedded mcl code and modules (and that the embedded mcl code and
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// modules which link with this program, contain a copy of their source code in
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// the authoritative form) containing parts covered by the terms of any other
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// license, the licensors of this program grant you additional permission to
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// convey the resulting work. Furthermore, the licensors of this program grant
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// the original author, James Shubin, additional permission to update this
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// additional permission if he deems it necessary to achieve the goals of this
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// additional permission.
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// Package firstboot provides a service that runs scripts once on first boot.
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// You can easily test this with:
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//
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// mkdir /tmp/mgmt-firstboot/ ; echo 'echo hello' > /tmp/mgmt-firstboot/foo.sh
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// ./mgmt firstboot start --lock-file-path=/tmp/flock.lock \
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// --scripts-dir=/tmp/mgmt-firstboot/ --logging-dir=/tmp/
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package firstboot
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import (
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"context"
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)
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// API is the simple interface we expect for any setup items.
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type API interface {
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// Main runs everything for this setup item.
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Main(context.Context) error
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}
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// Config is a struct of all the configuration values which are shared by all of
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// the setup utilities. By including this as a separate struct, it can be used
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// as part of the API if we want.
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type Config struct {
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//Foo string `arg:"--foo,env:MGMT_FIRSTBOOT_FOO" help:"Foo..."` // TODO: foo
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}
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290
firstboot/start.go
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290
firstboot/start.go
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@@ -0,0 +1,290 @@
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// Mgmt
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// Copyright (C) 2013-2024+ James Shubin and the project contributors
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// Written by James Shubin <james@shubin.ca> and the project contributors
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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//
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// Additional permission under GNU GPL version 3 section 7
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//
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// If you modify this program, or any covered work, by linking or combining it
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// with embedded mcl code and modules (and that the embedded mcl code and
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// modules which link with this program, contain a copy of their source code in
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// the authoritative form) containing parts covered by the terms of any other
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// license, the licensors of this program grant you additional permission to
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// convey the resulting work. Furthermore, the licensors of this program grant
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// the original author, James Shubin, additional permission to update this
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// additional permission if he deems it necessary to achieve the goals of this
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// additional permission.
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package firstboot
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import (
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"context"
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"fmt"
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"os"
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"path/filepath"
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"strings"
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"time"
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cliUtil "github.com/purpleidea/mgmt/cli/util"
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"github.com/purpleidea/mgmt/util"
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"gopkg.in/yaml.v2"
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)
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const (
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// LockFilePath is where we store a lock file to prevent more than one
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// copy of this service running at the same time.
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// TODO: Is there a better place to put this?
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LockFilePath string = "/var/lib/mgmt/firstboot.lock"
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// ScriptsDir is the directory where firstboot scripts can be found. You
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// can put binaries in here too. Contents must be executable.
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ScriptsDir string = "/var/lib/mgmt/firstboot/"
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// StyleSuffix is what we append to executables to specify a style file.
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StyleSuffix = ".yaml"
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)
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// Start is the standalone entry program for the firstboot start component.
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type Start struct {
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*cliUtil.FirstbootStartArgs // embedded config
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Config // embedded Config
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// Program is the name of this program, usually set at compile time.
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Program string
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// Version is the version of this program, usually set at compile time.
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Version string
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// Debug represents if we're running in debug mode or not.
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Debug bool
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// Logf is a logger which should be used.
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Logf func(format string, v ...interface{})
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}
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// Main runs everything for this setup item.
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func (obj *Start) Main(ctx context.Context) error {
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if err := obj.Validate(); err != nil {
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return err
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}
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if err := obj.Run(ctx); err != nil {
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return err
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}
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return nil
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}
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// Validate verifies that the structure has acceptable data stored within.
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func (obj *Start) Validate() error {
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if obj == nil {
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return fmt.Errorf("data is nil")
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}
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if obj.Program == "" {
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return fmt.Errorf("program is empty")
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}
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if obj.Version == "" {
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return fmt.Errorf("version is empty")
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}
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return nil
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}
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// Run performs the desired actions. This runs a list of scripts and then
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// removes them. This is useful for a "firstboot" service. If there exists a
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// file with the same name as an executable script or binary, but which has a
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// .yaml extension, that will be parsed to look for command modifiers.
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func (obj *Start) Run(ctx context.Context) error {
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lockFile := LockFilePath // default
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if s := obj.FirstbootStartArgs.LockFilePath; s != "" && !strings.HasSuffix(s, "/") {
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lockFile = s
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}
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// Ensure the directory exists.
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d := filepath.Dir(lockFile)
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if err := os.MkdirAll(d, 0750); err != nil {
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return fmt.Errorf("could not make lockfile dir at: %s", d)
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}
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// Make sure only one copy of this service is running at a time.
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unlock, err := util.NewFlock(lockFile).TryLock()
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if err != nil {
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return err // can't get lock
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}
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if unlock == nil {
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return fmt.Errorf("already running")
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}
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// now we're locked!
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defer unlock()
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scriptsDir := ScriptsDir // default
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if s := obj.FirstbootStartArgs.ScriptsDir; s != "" && strings.HasSuffix(s, "/") {
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scriptsDir = s
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}
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obj.Logf("scripts dir: %s", scriptsDir)
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// Loop through all the entries and execute what we can...
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entries, err := os.ReadDir(scriptsDir) // ([]os.DirEntry, error)
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if err != nil {
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return err
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}
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for _, entry := range entries {
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if entry.IsDir() { // skip dirs
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continue
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}
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if !entry.Type().IsRegular() { // skip weird things
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// TODO: We may wish to relax this constraint eventually.
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continue
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}
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// TODO: Why is entry.Type() always empty?
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//fmt.Printf("???: %+v\n", entry.Type())
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//if m := entry.Type(); m&0100 == 0 { // owner bit is not executable
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// continue
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//}
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fi, err := entry.Info()
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if os.IsNotExist(err) {
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continue // we might have deleted a style file
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} else if err != nil {
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return err // TODO: continue instead?
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}
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if m := fi.Mode(); m&0100 == 0 { // owner bit is not executable
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continue
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}
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p := filepath.Clean(scriptsDir + entry.Name())
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obj.Logf("found: %s", p)
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styleFile := p + StyleSuffix // maybe it exists!
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style := &Style{ // set defaults here
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DoneDir: obj.FirstbootStartArgs.DoneDir,
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}
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// TODO: check style file is _not_ executable to avoid chains?
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data, err := os.ReadFile(styleFile)
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if err != nil && !os.IsNotExist(err) {
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return err
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}
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if err == nil {
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if err := yaml.Unmarshal(data, style); err != nil {
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return err
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}
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style.exists = true
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}
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// Found one!
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if err := obj.process(ctx, p, style); err != nil {
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}
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}
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return nil
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}
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// process runs the command, logs, and deletes the script if needed.
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func (obj *Start) process(ctx context.Context, name string, style *Style) error {
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logOutput := ""
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if !style.NoLog {
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loggingDir := "/root/"
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if s := obj.FirstbootStartArgs.LoggingDir; s != "" && strings.HasSuffix(s, "/") {
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loggingDir = s
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}
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logOutput = fmt.Sprintf("%smgmt-firstboot-%v.log", loggingDir, time.Now().UnixNano())
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}
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if err := util.AppendFile(logOutput, []byte(name+"\n"), 0600); err != nil {
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obj.Logf("error: %v", err)
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}
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opts := &util.SimpleCmdOpts{
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Debug: obj.Debug,
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Logf: obj.Logf,
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LogOutput: logOutput,
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}
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args := []string{}
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err := util.SimpleCmd(ctx, name, args, opts)
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errStr := fmt.Sprintf("error: %v\n", err)
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if err := util.AppendFile(logOutput, []byte(errStr), 0600); err != nil {
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obj.Logf("error: %v", err)
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}
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if err != nil && style.KeepOnFail {
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return err
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}
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if style.DoneDir != "" && strings.HasSuffix(style.DoneDir, "/") {
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dest := func(p string) string { // dest path from input full path
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return style.DoneDir + filepath.Base(p)
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}
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if err := os.MkdirAll(style.DoneDir, 0750); err != nil { // convenience
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obj.Logf("error: %v", err)
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//return err // let the real final error be seen...
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}
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// Move files!
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if err := os.Rename(name, dest(name)); err != nil {
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obj.Logf("error: %v", err)
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} else {
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obj.Logf("moved: %s", name)
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}
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if style.exists {
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if err := os.Rename(name+StyleSuffix, dest(name+StyleSuffix)); err != nil {
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obj.Logf("error: %v", err)
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} else {
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obj.Logf("moved: %s", name+StyleSuffix)
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}
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}
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return err
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}
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// Remove files!
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if err := os.Remove(name); err != nil {
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obj.Logf("error: %v", err)
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} else {
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obj.Logf("removed: %s", name)
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}
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if style.exists {
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if err := os.Remove(name + StyleSuffix); err != nil {
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obj.Logf("error: %v", err)
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} else {
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obj.Logf("removed: %s", name+StyleSuffix)
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}
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}
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return err
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}
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// Style are some values that are used to specify how each command runs.
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type Style struct {
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// TODO: Is this easy to implement?
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// DeleteFirst should be true to delete the script before it runs. This
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// is useful to prevent scenarios where a read-only filesystem would
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// cause the script to run again and again.
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//DeleteFirst bool `yaml:"delete-first"`
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// DoneDir specifies the dir to move files to instead of deleting them.
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DoneDir string `yaml:"done-dir"`
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// KeepOnFail should be true to preserve the script if it fails. This
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// means it will likely run again the next time the service runs.
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KeepOnFail bool `yaml:"keep-on-fail"`
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// NoLog should be true to skip logging the output of this command.
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NoLog bool `yaml:"no-log"`
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// exists specifies if the style file exists on disk. (And as a result,
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// should it be removed at the end?)
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exists bool
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}
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