358 lines
12 KiB
Go
358 lines
12 KiB
Go
// Package template is responsible for rendering user supplied templates to
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// disk. The Server type accepts configuration to communicate to a Vault server
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// and a Vault token for authentication. Internally, the Server creates a Consul
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// Template Runner which manages reading secrets from Vault and rendering
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// templates to disk at configured locations
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package template
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import (
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"context"
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"errors"
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"fmt"
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"io"
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"strings"
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"go.uber.org/atomic"
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ctconfig "github.com/hashicorp/consul-template/config"
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ctlogging "github.com/hashicorp/consul-template/logging"
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"github.com/hashicorp/consul-template/manager"
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"github.com/hashicorp/go-hclog"
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"github.com/hashicorp/vault/command/agent/config"
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"github.com/hashicorp/vault/sdk/helper/pointerutil"
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)
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// ServerConfig is a config struct for setting up the basic parts of the
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// Server
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type ServerConfig struct {
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Logger hclog.Logger
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// Client *api.Client
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AgentConfig *config.Config
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ExitAfterAuth bool
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Namespace string
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// LogLevel is needed to set the internal Consul Template Runner's log level
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// to match the log level of Vault Agent. The internal Runner creates it's own
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// logger and can't be set externally or copied from the Template Server.
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//
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// LogWriter is needed to initialize Consul Template's internal logger to use
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// the same io.Writer that Vault Agent itself is using.
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LogLevel hclog.Level
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LogWriter io.Writer
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}
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// Server manages the Consul Template Runner which renders templates
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type Server struct {
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// config holds the ServerConfig used to create it. It's passed along in other
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// methods
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config *ServerConfig
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// runner is the consul-template runner
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runner *manager.Runner
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runnerStarted *atomic.Bool
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// Templates holds the parsed Consul Templates
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Templates []*ctconfig.TemplateConfig
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// lookupMap is a list of templates indexed by their consul-template ID. This
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// is used to ensure all Vault templates have been rendered before returning
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// from the runner in the event we're using exit after auth.
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lookupMap map[string][]*ctconfig.TemplateConfig
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DoneCh chan struct{}
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stopped *atomic.Bool
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logger hclog.Logger
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exitAfterAuth bool
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}
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// NewServer returns a new configured server
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func NewServer(conf *ServerConfig) *Server {
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ts := Server{
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DoneCh: make(chan struct{}),
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stopped: atomic.NewBool(false),
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runnerStarted: atomic.NewBool(false),
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logger: conf.Logger,
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config: conf,
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exitAfterAuth: conf.ExitAfterAuth,
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}
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return &ts
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}
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// Run kicks off the internal Consul Template runner, and listens for changes to
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// the token from the AuthHandler. If Done() is called on the context, shut down
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// the Runner and return
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func (ts *Server) Run(ctx context.Context, incoming chan string, templates []*ctconfig.TemplateConfig) error {
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if incoming == nil {
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return errors.New("template server: incoming channel is nil")
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}
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latestToken := new(string)
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ts.logger.Info("starting template server")
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defer func() {
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ts.logger.Info("template server stopped")
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}()
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// If there are no templates, we wait for context cancellation and then return
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if len(templates) == 0 {
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ts.logger.Info("no templates found")
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<-ctx.Done()
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return nil
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}
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// construct a consul template vault config based the agents vault
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// configuration
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var runnerConfig *ctconfig.Config
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var runnerConfigErr error
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if runnerConfig, runnerConfigErr = newRunnerConfig(ts.config, templates); runnerConfigErr != nil {
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return fmt.Errorf("template server failed to runner generate config: %w", runnerConfigErr)
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}
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var err error
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ts.runner, err = manager.NewRunner(runnerConfig, false)
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if err != nil {
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return fmt.Errorf("template server failed to create: %w", err)
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}
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// Build the lookup map using the id mapping from the Template runner. This is
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// used to check the template rendering against the expected templates. This
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// returns a map with a generated ID and a slice of templates for that id. The
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// slice is determined by the source or contents of the template, so if a
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// configuration has multiple templates specified, but are the same source /
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// contents, they will be identified by the same key.
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idMap := ts.runner.TemplateConfigMapping()
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lookupMap := make(map[string][]*ctconfig.TemplateConfig, len(idMap))
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for id, ctmpls := range idMap {
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for _, ctmpl := range ctmpls {
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tl := lookupMap[id]
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tl = append(tl, ctmpl)
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lookupMap[id] = tl
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}
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}
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ts.lookupMap = lookupMap
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for {
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select {
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case <-ctx.Done():
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ts.runner.Stop()
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return nil
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case token := <-incoming:
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if token != *latestToken {
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ts.logger.Info("template server received new token")
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// If the runner was previously started and we intend to exit
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// after auth, do not restart the runner if a new token is
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// received.
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if ts.exitAfterAuth && ts.runnerStarted.Load() {
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ts.logger.Info("template server not restarting with new token with exit_after_auth set to true")
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continue
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}
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ts.runner.Stop()
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*latestToken = token
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ctv := ctconfig.Config{
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Vault: &ctconfig.VaultConfig{
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Token: latestToken,
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},
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}
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runnerConfig = runnerConfig.Merge(&ctv)
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var runnerErr error
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ts.runner, runnerErr = manager.NewRunner(runnerConfig, false)
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if runnerErr != nil {
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ts.logger.Error("template server failed with new Vault token", "error", runnerErr)
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continue
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}
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ts.runnerStarted.CAS(false, true)
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go ts.runner.Start()
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}
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case err := <-ts.runner.ErrCh:
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ts.logger.Error("template server error", "error", err.Error())
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ts.runner.StopImmediately()
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// Return after stopping the runner if exit on retry failure was
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// specified
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if ts.config.AgentConfig.TemplateConfig != nil && ts.config.AgentConfig.TemplateConfig.ExitOnRetryFailure {
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return fmt.Errorf("template server: %w", err)
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}
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ts.runner, err = manager.NewRunner(runnerConfig, false)
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if err != nil {
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return fmt.Errorf("template server failed to create: %w", err)
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}
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go ts.runner.Start()
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case <-ts.runner.TemplateRenderedCh():
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// A template has been rendered, figure out what to do
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events := ts.runner.RenderEvents()
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// events are keyed by template ID, and can be matched up to the id's from
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// the lookupMap
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if len(events) < len(ts.lookupMap) {
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// Not all templates have been rendered yet
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continue
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}
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// assume the renders are finished, until we find otherwise
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doneRendering := true
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for _, event := range events {
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// This template hasn't been rendered
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if event.LastWouldRender.IsZero() {
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doneRendering = false
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}
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}
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if doneRendering && ts.exitAfterAuth {
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// if we want to exit after auth, go ahead and shut down the runner and
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// return. The deferred closing of the DoneCh will allow agent to
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// continue with closing down
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ts.runner.Stop()
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return nil
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}
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}
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}
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}
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func (ts *Server) Stop() {
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if ts.stopped.CAS(false, true) {
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close(ts.DoneCh)
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}
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}
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// newRunnerConfig returns a consul-template runner configuration, setting the
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// Vault and Consul configurations based on the clients configs.
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func newRunnerConfig(sc *ServerConfig, templates ctconfig.TemplateConfigs) (*ctconfig.Config, error) {
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conf := ctconfig.DefaultConfig()
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conf.Templates = templates.Copy()
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// Setup the Vault config
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// Always set these to ensure nothing is picked up from the environment
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conf.Vault.RenewToken = pointerutil.BoolPtr(false)
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conf.Vault.Token = pointerutil.StringPtr("")
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conf.Vault.Address = &sc.AgentConfig.Vault.Address
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if sc.Namespace != "" {
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conf.Vault.Namespace = &sc.Namespace
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}
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if sc.AgentConfig.TemplateConfig != nil && sc.AgentConfig.TemplateConfig.StaticSecretRenderInt != 0 {
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conf.Vault.DefaultLeaseDuration = &sc.AgentConfig.TemplateConfig.StaticSecretRenderInt
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}
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conf.Vault.SSL = &ctconfig.SSLConfig{
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Enabled: pointerutil.BoolPtr(false),
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Verify: pointerutil.BoolPtr(false),
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Cert: pointerutil.StringPtr(""),
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Key: pointerutil.StringPtr(""),
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CaCert: pointerutil.StringPtr(""),
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CaPath: pointerutil.StringPtr(""),
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ServerName: pointerutil.StringPtr(""),
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}
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// The cache does its own retry management based on sc.AgentConfig.Retry,
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// so we only want to set this up for templating if we're not routing
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// templating through the cache. We do need to assign something to Retry
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// though or it will use its default of 12 retries.
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var attempts int
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if sc.AgentConfig.Vault != nil && sc.AgentConfig.Vault.Retry != nil {
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attempts = sc.AgentConfig.Vault.Retry.NumRetries
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}
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// Use the cache if available or fallback to the Vault server values.
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// For now we're only routing templating through the cache when persistence
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// is enabled. The templating engine and the cache have some inconsistencies
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// that need to be fixed for 1.7x/1.8
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if sc.AgentConfig.Cache != nil && sc.AgentConfig.Cache.Persist != nil && len(sc.AgentConfig.Listeners) != 0 {
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attempts = 0
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// If we don't want exit on template retry failure (i.e. unlimited
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// retries), let consul-template handle retry and backoff logic.
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//
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// Note: This is a fixed value (12) that ends up being a multiplier to
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// retry.num_retires (i.e. 12 * N total retries per runner restart).
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// Since we are performing retries indefinitely this base number helps
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// prevent agent from spamming Vault if retry.num_retries is set to a
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// low value by forcing exponential backoff to be high towards the end
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// of retries during the process.
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if sc.AgentConfig.TemplateConfig != nil && !sc.AgentConfig.TemplateConfig.ExitOnRetryFailure {
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attempts = ctconfig.DefaultRetryAttempts
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}
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scheme := "unix://"
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if sc.AgentConfig.Listeners[0].Type == "tcp" {
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scheme = "https://"
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if sc.AgentConfig.Listeners[0].TLSDisable {
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scheme = "http://"
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}
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}
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address := fmt.Sprintf("%s%s", scheme, sc.AgentConfig.Listeners[0].Address)
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conf.Vault.Address = &address
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// Skip verification if its using the cache because they're part of the same agent.
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if scheme == "https://" {
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if sc.AgentConfig.Listeners[0].TLSRequireAndVerifyClientCert {
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return nil, errors.New("template server cannot use local cache when mTLS is enabled")
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}
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conf.Vault.SSL.Verify = pointerutil.BoolPtr(false)
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}
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} else if strings.HasPrefix(sc.AgentConfig.Vault.Address, "https") || sc.AgentConfig.Vault.CACert != "" {
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skipVerify := sc.AgentConfig.Vault.TLSSkipVerify
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verify := !skipVerify
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conf.Vault.SSL = &ctconfig.SSLConfig{
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Enabled: pointerutil.BoolPtr(true),
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Verify: &verify,
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Cert: &sc.AgentConfig.Vault.ClientCert,
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Key: &sc.AgentConfig.Vault.ClientKey,
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CaCert: &sc.AgentConfig.Vault.CACert,
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CaPath: &sc.AgentConfig.Vault.CAPath,
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ServerName: &sc.AgentConfig.Vault.TLSServerName,
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}
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}
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enabled := attempts > 0
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conf.Vault.Retry = &ctconfig.RetryConfig{
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Attempts: &attempts,
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Enabled: &enabled,
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}
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conf.Finalize()
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// setup log level from TemplateServer config
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conf.LogLevel = logLevelToStringPtr(sc.LogLevel)
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if err := ctlogging.Setup(&ctlogging.Config{
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Level: *conf.LogLevel,
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Writer: sc.LogWriter,
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}); err != nil {
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return nil, err
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}
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return conf, nil
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}
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// logLevelToString converts a go-hclog level to a matching, uppercase string
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// value. It's used to convert Vault Agent's hclog level to a string version
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// suitable for use in Consul Template's runner configuration input.
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func logLevelToStringPtr(level hclog.Level) *string {
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// consul template's default level is WARN, but Vault Agent's default is INFO,
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// so we use that for the Runner's default.
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var levelStr string
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switch level {
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case hclog.Trace:
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levelStr = "TRACE"
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case hclog.Debug:
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levelStr = "DEBUG"
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case hclog.Warn:
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levelStr = "WARN"
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case hclog.Error:
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levelStr = "ERROR"
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default:
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levelStr = "INFO"
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}
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return pointerutil.StringPtr(levelStr)
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}
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