mirror of
https://github.com/edgelesssys/constellation.git
synced 2024-12-27 00:19:36 -05:00
110 lines
2.7 KiB
Go
110 lines
2.7 KiB
Go
/*
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Copyright (c) Edgeless Systems GmbH
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SPDX-License-Identifier: AGPL-3.0-only
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*/
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package deploy
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import (
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"bufio"
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"fmt"
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"regexp"
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"strings"
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"github.com/spf13/afero"
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)
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// ImageInfo retrieves OS image information.
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type ImageInfo struct {
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fs *afero.Afero
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}
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// NewImageInfo creates a new imageInfo.
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func NewImageInfo() *ImageInfo {
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return &ImageInfo{
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fs: &afero.Afero{Fs: afero.NewOsFs()},
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}
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}
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// ImageVersion tries to parse the image version from the host mounted os-release file.
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// If the file is not present or does not contain the version, a fallback lookup is performed.
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func (i *ImageInfo) ImageVersion() (string, error) {
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var version string
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var err error
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for _, path := range osReleasePaths {
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version, err = i.getOSReleaseImageVersion(path)
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if err == nil {
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break
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}
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}
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if err != nil {
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return "", err
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}
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if version == "" {
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return "", fmt.Errorf("IMAGE_VERSION not found in %s", strings.Join(osReleasePaths, ", "))
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}
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return version, nil
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}
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// getOSReleaseImageVersion reads the os-release file and returns the image version (if present).
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func (i *ImageInfo) getOSReleaseImageVersion(path string) (string, error) {
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osRelease, err := i.fs.Open(path)
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if err != nil {
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return "", err
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}
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defer osRelease.Close()
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osReleaseMap, err := parseOSRelease(bufio.NewScanner(osRelease))
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if err != nil {
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return "", err
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}
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version, ok := osReleaseMap[versionKey]
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if !ok {
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return "", fmt.Errorf("IMAGE_VERSION not found in %s", path)
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}
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return version, nil
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}
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// parseOSRelease parses the os-release file and returns a map of key-value pairs.
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// The os-release file is a simple key-value file.
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// The format is specified in https://www.freedesktop.org/software/systemd/man/os-release.html.
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func parseOSRelease(osRelease *bufio.Scanner) (map[string]string, error) {
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osReleaseMap := make(map[string]string)
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for osRelease.Scan() {
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line := osRelease.Text()
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matches := osReleaseLine.FindStringSubmatch(line)
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if len(matches) < 6 {
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continue
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}
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key := matches[1]
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var value string
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// group 3 is the value with double quotes
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// group 4 is the value with single quotes
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// group 5 is the value without quotes
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for i := 3; i < 6; i++ {
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if matches[i] != "" {
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value = matches[i]
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break
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}
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}
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// unescape the following characters: \\, \$, \", \', \`
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value = osReleaseUnescape.ReplaceAllString(value, "$1")
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osReleaseMap[key] = value
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}
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if err := osRelease.Err(); err != nil {
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return nil, err
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}
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return osReleaseMap, nil
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}
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const versionKey = "IMAGE_VERSION"
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var (
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osReleaseLine = regexp.MustCompile(`^(?P<name>[a-zA-Z0-9_]+)=("(?P<v1>.*)"|'(?P<v2>.*)'|(?P<v3>[^\n"']+))$`)
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osReleaseUnescape = regexp.MustCompile(`\\([\\\$\"\'` + "`" + `])`)
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osReleasePaths = []string{
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"/host/etc/os-release",
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"/host/usr/lib/os-release",
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}
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)
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