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add support for writing files to containers from cloud-init config
We are adding the support for "write_files" section in cloud-init config for containers. Also the definition of envs is moved to the section "runcmd" with lines like "- VAR=value", however the old syntax of "VAR=value" is still supported. The rest of cloud-init config is ignored. Signed-off-by: Paul Gaiduk <paulg@zededa.com>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,107 @@ | ||
| package cloudconfig | ||
|
|
||
| import ( | ||
| "encoding/base64" | ||
| "errors" | ||
| "fmt" | ||
| "os" | ||
| "path/filepath" | ||
| "strconv" | ||
| "strings" | ||
|
|
||
| "github.com/lf-edge/eve/pkg/pillar/base" | ||
| fileutils "github.com/lf-edge/eve/pkg/pillar/utils/file" | ||
| "gopkg.in/yaml.v2" | ||
| ) | ||
|
|
||
| // CloudConfig represents the structure of the cloud configuration file. | ||
| // Only supported fields are defined here. The rest is ignored. | ||
| type CloudConfig struct { | ||
| RunCmd []string `yaml:"runcmd"` | ||
| WriteFiles []WritableFile `yaml:"write_files"` // nolint:tagliatelle // cloud-init standard uses snake_case | ||
|
Check failure on line 21 in pkg/pillar/utils/cloudconfig/cloudconfig.go
|
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| } | ||
|
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| // WritableFile represents a file that can be written to disk with the specified content, permissions, encoding and owner. | ||
| type WritableFile struct { | ||
| Path string `yaml:"path"` | ||
| Content string `yaml:"content"` | ||
| Permissions string `yaml:"permissions"` | ||
| Encoding string `yaml:"encoding"` | ||
| Owner string `yaml:"owner"` | ||
| } | ||
|
|
||
| // IsCloudConfig checks if the given string is a cloud-config file by checking if the first line starts with "#cloud-config". | ||
| // It returns true if the first line starts with "#cloud-config", otherwise it returns false. | ||
| func IsCloudConfig(ci string) bool { | ||
| // check if the first line is #cloud-config | ||
| lines := strings.Split(ci, "\n") | ||
| if len(lines) == 0 { | ||
| return false | ||
| } | ||
| return strings.HasPrefix(lines[0], "#cloud-config") | ||
| } | ||
|
|
||
| // ParseCloudConfig parses the given cloud-init configuration and returns a pointer to a CloudConfig struct and an error. | ||
| func ParseCloudConfig(ci string) (*CloudConfig, error) { | ||
| var cc CloudConfig | ||
| err := yaml.Unmarshal([]byte(ci), &cc) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| return &cc, nil | ||
| } | ||
|
|
||
| // WriteFile checks the content of a WritableFile and writes it to the specified rootPath. | ||
| func WriteFile(log *base.LogObject, file WritableFile, rootPath string) error { | ||
| // transform file.Permission to os.FileMode | ||
| perm, err := strconv.ParseUint(file.Permissions, 8, 32) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| mode := os.FileMode(perm) | ||
|
|
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| writePath := filepath.Join(rootPath, file.Path) | ||
| // sanitize path | ||
| if !strings.HasPrefix(filepath.Clean(writePath), rootPath) { | ||
| return fmt.Errorf("detected possible attempt to write file outside of root path. invalid path %s", file.Path) | ||
| } | ||
|
|
||
| var contentBytes []byte | ||
| switch file.Encoding { | ||
| case "b64": | ||
| // decode base64 content | ||
| contentBytes, err = base64.StdEncoding.DecodeString(file.Content) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| case "plain": | ||
| contentBytes = []byte(file.Content) | ||
| default: | ||
| return errors.New("unsupported encoding type. Only base64 and plain are supported") | ||
| } | ||
|
|
||
| // check if the parent directory exists | ||
| parentDir := filepath.Dir(writePath) | ||
| if _, err := os.Stat(parentDir); os.IsNotExist(err) { | ||
| // create parent directory | ||
| err = os.MkdirAll(parentDir, 0755) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| } | ||
|
|
||
| log.Tracef("Creating file %s with mode %s in %s\n", file.Path, mode, rootPath) | ||
| err = fileutils.WriteRename(writePath, contentBytes) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| err = os.Chmod(writePath, mode) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| if file.Owner != "" { | ||
| log.Warn("Changing owner of files written by cloud-init is not supported yet") | ||
| } | ||
|
|
||
| return nil | ||
| } | ||
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