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3c1a73d370
AWS Lambda uses Docker containers but does not have the string "docker" in its /proc/1/cgroup. Infer AWS Lambda via the environment variables it sets. Signed-off-by: Denton Gentry <dgentry@tailscale.com>
138 lines
3.2 KiB
Go
138 lines
3.2 KiB
Go
// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build linux,!android
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package controlclient
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import (
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"bytes"
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"fmt"
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"io"
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"io/ioutil"
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"os"
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"strings"
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"syscall"
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"go4.org/mem"
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"tailscale.com/util/lineread"
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"tailscale.com/version/distro"
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)
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func init() {
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osVersion = osVersionLinux
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}
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func osVersionLinux() string {
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dist := distro.Get()
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propFile := "/etc/os-release"
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switch dist {
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case distro.Synology:
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propFile = "/etc.defaults/VERSION"
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case distro.OpenWrt:
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propFile = "/etc/openwrt_release"
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}
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m := map[string]string{}
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lineread.File(propFile, func(line []byte) error {
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eq := bytes.IndexByte(line, '=')
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if eq == -1 {
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return nil
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}
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k, v := string(line[:eq]), strings.Trim(string(line[eq+1:]), `"'`)
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m[k] = v
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return nil
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})
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var un syscall.Utsname
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syscall.Uname(&un)
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var attrBuf strings.Builder
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attrBuf.WriteString("; kernel=")
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for _, b := range un.Release {
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if b == 0 {
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break
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}
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attrBuf.WriteByte(byte(b))
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}
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if inContainer() {
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attrBuf.WriteString("; container")
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}
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if inKnative() {
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attrBuf.WriteString("; env=kn")
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}
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if inAwsLambda() {
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attrBuf.WriteString("; env=lm")
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}
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attr := attrBuf.String()
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id := m["ID"]
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switch id {
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case "debian":
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slurp, _ := ioutil.ReadFile("/etc/debian_version")
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return fmt.Sprintf("Debian %s (%s)%s", bytes.TrimSpace(slurp), m["VERSION_CODENAME"], attr)
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case "ubuntu":
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return fmt.Sprintf("Ubuntu %s%s", m["VERSION"], attr)
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case "", "centos": // CentOS 6 has no /etc/os-release, so its id is ""
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if cr, _ := ioutil.ReadFile("/etc/centos-release"); len(cr) > 0 { // "CentOS release 6.10 (Final)
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return fmt.Sprintf("%s%s", bytes.TrimSpace(cr), attr)
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}
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fallthrough
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case "fedora", "rhel", "alpine", "nixos":
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// Their PRETTY_NAME is fine as-is for all versions I tested.
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fallthrough
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default:
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if v := m["PRETTY_NAME"]; v != "" {
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return fmt.Sprintf("%s%s", v, attr)
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}
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}
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switch dist {
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case distro.Synology:
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return fmt.Sprintf("Synology %s%s", m["productversion"], attr)
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case distro.OpenWrt:
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return fmt.Sprintf("OpenWrt %s%s", m["DISTRIB_RELEASE"], attr)
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}
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return fmt.Sprintf("Other%s", attr)
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}
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func inContainer() (ret bool) {
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lineread.File("/proc/1/cgroup", func(line []byte) error {
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if mem.Contains(mem.B(line), mem.S("/docker/")) ||
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mem.Contains(mem.B(line), mem.S("/lxc/")) {
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ret = true
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return io.EOF // arbitrary non-nil error to stop loop
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}
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return nil
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})
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lineread.File("/proc/mounts", func(line []byte) error {
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if mem.Contains(mem.B(line), mem.S("fuse.lxcfs")) {
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ret = true
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return io.EOF
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}
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return nil
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})
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return
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}
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func inKnative() bool {
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// https://cloud.google.com/run/docs/reference/container-contract#env-vars
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if os.Getenv("K_REVISION") != "" && os.Getenv("K_CONFIGURATION") != "" &&
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os.Getenv("K_SERVICE") != "" && os.Getenv("PORT") != "" {
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return true
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}
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return false
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}
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func inAwsLambda() bool {
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// https://docs.aws.amazon.com/lambda/latest/dg/configuration-envvars.html
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if os.Getenv("AWS_LAMBDA_FUNCTION_NAME") != "" &&
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os.Getenv("AWS_LAMBDA_FUNCTION_VERSION") != "" &&
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os.Getenv("AWS_LAMBDA_INITIALIZATION_TYPE") != "" &&
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os.Getenv("AWS_LAMBDA_RUNTIME_API") != "" {
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return true
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}
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return false
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}
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