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https://github.com/maxkratz/postfix_exporter.git
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f1d5d0ad4d
When Postfix is running in a Docker container, it's most useful to use the built-in Docker logging (as with Systemd). Setting `--docker.enable` allows that. The log source is using `client.NewEnvClient`, which reads environment variables to determine which Docker to connect to, and how TLS is handled.
97 lines
2.4 KiB
Go
97 lines
2.4 KiB
Go
// +build !nodocker
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package main
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import (
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"bufio"
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"context"
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"io"
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"log"
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"strings"
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"github.com/alecthomas/kingpin"
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"github.com/docker/docker/api/types"
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"github.com/docker/docker/client"
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)
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// A DockerLogSource reads log records from the given Docker
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// journal.
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type DockerLogSource struct {
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client DockerClient
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containerID string
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reader *bufio.Reader
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}
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// A DockerClient is the client interface that client.Client
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// provides. See https://pkg.go.dev/github.com/docker/docker/client
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type DockerClient interface {
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io.Closer
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ContainerLogs(context.Context, string, types.ContainerLogsOptions) (io.ReadCloser, error)
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}
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// NewDockerLogSource returns a log source for reading Docker logs.
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func NewDockerLogSource(ctx context.Context, c DockerClient, containerID string) (*DockerLogSource, error) {
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r, err := c.ContainerLogs(ctx, containerID, types.ContainerLogsOptions{
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ShowStdout: true,
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ShowStderr: true,
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Follow: true,
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Tail: "0",
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})
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if err != nil {
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return nil, err
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}
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logSrc := &DockerLogSource{
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client: c,
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containerID: containerID,
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reader: bufio.NewReader(r),
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}
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return logSrc, nil
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}
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func (s *DockerLogSource) Close() error {
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return s.client.Close()
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}
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func (s *DockerLogSource) Path() string {
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return "docker:" + s.containerID
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}
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func (s *DockerLogSource) Read(ctx context.Context) (string, error) {
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line, err := s.reader.ReadString('\n')
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if err != nil {
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return "", err
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}
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return strings.TrimSpace(line), nil
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}
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// A dockerLogSourceFactory is a factory that can create
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// DockerLogSources from command line flags.
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type dockerLogSourceFactory struct {
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enable bool
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containerID string
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}
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func (f *dockerLogSourceFactory) Init(app *kingpin.Application) {
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app.Flag("docker.enable", "Read from Docker logs. Environment variable DOCKER_HOST can be used to change the address. See https://pkg.go.dev/github.com/docker/docker/client?tab=doc#NewEnvClient for more information.").Default("false").BoolVar(&f.enable)
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app.Flag("docker.container.id", "ID/name of the Postfix Docker container.").Default("postfix").StringVar(&f.containerID)
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}
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func (f *dockerLogSourceFactory) New(ctx context.Context) (LogSourceCloser, error) {
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if !f.enable {
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return nil, nil
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}
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log.Println("Reading log events from Docker")
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c, err := client.NewEnvClient()
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if err != nil {
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return nil, err
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}
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return NewDockerLogSource(ctx, c, f.containerID)
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}
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func init() {
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RegisterLogSourceFactory(&dockerLogSourceFactory{})
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}
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