github.com/hugh712/snapd@v0.0.0-20200910133618-1a99902bd583/sysconfig/sysconfig.go (about)

     1  // -*- Mode: Go; indent-tabs-mode: t -*-
     2  
     3  /*
     4   * Copyright (C) 2020 Canonical Ltd
     5   *
     6   * This program is free software: you can redistribute it and/or modify
     7   * it under the terms of the GNU General Public License version 3 as
     8   * published by the Free Software Foundation.
     9   *
    10   * This program is distributed in the hope that it will be useful,
    11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    13   * GNU General Public License for more details.
    14   *
    15   * You should have received a copy of the GNU General Public License
    16   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
    17   *
    18   */
    19  
    20  package sysconfig
    21  
    22  import (
    23  	"path/filepath"
    24  
    25  	"github.com/snapcore/snapd/gadget"
    26  )
    27  
    28  // See https://github.com/snapcore/core20/pull/46
    29  const writableDefaultsDir = "_writable_defaults"
    30  
    31  // Options is the set of options used to configure the run system
    32  type Options struct {
    33  	// CloudInitSrcDir is where to find the cloud-init data when installing it,
    34  	// i.e. in early boot install mode it could be something like
    35  	// filepath.Join(boot.InitramfsUbuntuSeedDir,"data")
    36  	CloudInitSrcDir string
    37  
    38  	// TargetRootDir is the root directory where to install configure
    39  	// data, i.e. for cloud-init during the initramfs it will be something like
    40  	// boot.InstallHostWritableDir
    41  	TargetRootDir string
    42  
    43  	// AllowCloudInit is whether to allow cloud-init to run or not in the
    44  	// TargetRootDir.
    45  	AllowCloudInit bool
    46  
    47  	// GadgetDir is the path of the mounted gadget snap.
    48  	GadgetDir string
    49  }
    50  
    51  // FilesystemOnlyApplyOptions is the set of options for
    52  // ApplyFilesystemOnlyDefaults.
    53  type FilesystemOnlyApplyOptions struct {
    54  	// Classic is true when the system in rootdir is a classic system
    55  	Classic bool
    56  }
    57  
    58  // ApplyFilesystemOnlyDefaultsImpl is initialized by init() of configcore.
    59  var ApplyFilesystemOnlyDefaultsImpl = func(rootDir string, defaults map[string]interface{}, options *FilesystemOnlyApplyOptions) error {
    60  	panic("ApplyFilesystemOnlyDefaultsImpl is unset, import overlord/configstate/configcore")
    61  }
    62  
    63  // ApplyFilesystemOnlyDefaults applies (via configcore.filesystemOnlyApply())
    64  // filesystem modifications under rootDir, according to the defaults.
    65  // This is a subset of core config options that is important
    66  // early during boot, before all the configuration is applied as part of
    67  // normal execution of configure hook.
    68  func ApplyFilesystemOnlyDefaults(rootDir string, defaults map[string]interface{}, options *FilesystemOnlyApplyOptions) error {
    69  	return ApplyFilesystemOnlyDefaultsImpl(rootDir, defaults, options)
    70  }
    71  
    72  // ConfigureRunSystem configures the ubuntu-data partition with any
    73  // configuration needed from e.g. the gadget or for cloud-init (and also for
    74  // cloud-init from the gadget).
    75  func ConfigureRunSystem(opts *Options) error {
    76  	if err := configureCloudInit(opts); err != nil {
    77  		return err
    78  	}
    79  
    80  	if opts.GadgetDir != "" {
    81  		ginf, err := gadget.ReadInfo(opts.GadgetDir, nil)
    82  		if err != nil {
    83  			return err
    84  		}
    85  		defaults := gadget.SystemDefaults(ginf.Defaults)
    86  		if len(defaults) > 0 {
    87  			// options are nil which implies core system
    88  			var options *FilesystemOnlyApplyOptions
    89  			if err := ApplyFilesystemOnlyDefaults(WritableDefaultsDir(opts.TargetRootDir), defaults, options); err != nil {
    90  				return err
    91  			}
    92  		}
    93  	}
    94  
    95  	return nil
    96  }
    97  
    98  // WritableDefaultsDir returns the full path of the joined subdir under the
    99  // subtree for default content for system data living at rootdir,
   100  // i.e. rootdir/_writable_defaults/subdir...
   101  func WritableDefaultsDir(rootdir string, subdir ...string) string {
   102  	return filepath.Join(rootdir, writableDefaultsDir, filepath.Join(subdir...))
   103  }