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27bd6842f8
Logging plugins use the same HTTP interface as other plugins for basic
command operations meanwhile actual logging operations are handled (on
Unix) via a fifo.
The plugin interface looks like so:
```go
type loggingPlugin interface {
StartLogging(fifoPath string, loggingContext Context) error
StopLogging(fifoPath)
```
This means a plugin must implement `LoggingDriver.StartLogging` and
`LoggingDriver.StopLogging` endpoints and be able to consume the passed
in fifo.
Logs are sent via stream encoder to the fifo encoded with protobuf.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
89 lines
2.2 KiB
Go
89 lines
2.2 KiB
Go
package logger
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import (
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"fmt"
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"io"
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"os"
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"path/filepath"
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"strings"
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"github.com/docker/docker/api/types/plugins/logdriver"
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getter "github.com/docker/docker/pkg/plugingetter"
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"github.com/docker/docker/pkg/stringid"
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"github.com/pkg/errors"
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)
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var pluginGetter getter.PluginGetter
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const extName = "LogDriver"
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// logPlugin defines the available functions that logging plugins must implement.
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type logPlugin interface {
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StartLogging(streamPath string, info Info) (err error)
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StopLogging(streamPath string) (err error)
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Capabilities() (cap Capability, err error)
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ReadLogs(info Info, config ReadConfig) (stream io.ReadCloser, err error)
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}
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// RegisterPluginGetter sets the plugingetter
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func RegisterPluginGetter(plugingetter getter.PluginGetter) {
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pluginGetter = plugingetter
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}
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// GetDriver returns a logging driver by its name.
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// If the driver is empty, it looks for the local driver.
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func getPlugin(name string, mode int) (Creator, error) {
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p, err := pluginGetter.Get(name, extName, mode)
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if err != nil {
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return nil, fmt.Errorf("error looking up logging plugin %s: %v", name, err)
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}
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d := &logPluginProxy{p.Client()}
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return makePluginCreator(name, d, p.BasePath()), nil
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}
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func makePluginCreator(name string, l *logPluginProxy, basePath string) Creator {
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return func(logCtx Info) (logger Logger, err error) {
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defer func() {
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if err != nil {
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pluginGetter.Get(name, extName, getter.Release)
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}
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}()
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root := filepath.Join(basePath, "run", "docker", "logging")
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if err := os.MkdirAll(root, 0700); err != nil {
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return nil, err
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}
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id := stringid.GenerateNonCryptoID()
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a := &pluginAdapter{
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driverName: name,
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id: id,
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plugin: l,
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fifoPath: filepath.Join(root, id),
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logInfo: logCtx,
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}
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cap, err := a.plugin.Capabilities()
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if err == nil {
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a.capabilities = cap
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}
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stream, err := openPluginStream(a)
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if err != nil {
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return nil, err
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}
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a.stream = stream
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a.enc = logdriver.NewLogEntryEncoder(a.stream)
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if err := l.StartLogging(strings.TrimPrefix(a.fifoPath, basePath), logCtx); err != nil {
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return nil, errors.Wrapf(err, "error creating logger")
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}
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if cap.ReadLogs {
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return &pluginAdapterWithRead{a}, nil
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}
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return a, nil
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}
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}
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