Can configure DTail client not to mess with ~/.ssh/known_hosts via env var - this is useful for running unit and integration tests in jenkins

4 files changed, 26 insertions, 3 deletions

diff --git a/internal/config/client.go b/internal/config/client.go
index 9f4df97..86f97f0 100644
--- a/internal/config/client.go
+++ b/internal/config/client.go
@@ -104,6 +104,9 @@ type termColors struct {
 type ClientConfig struct {
 	TermColorsEnable bool       `json:",omitempty"`
 	TermColors       termColors `json:",omitempty"`
+	// When unit testing in Jenkins you don't want to touch files in ~jenkins
+	// during integration tests really.
+	SSHDontAddHostsToKnownHostsFile bool `json:",omitempty"`
 }
 
 // Create a new default client configuration.
diff --git a/internal/config/initializer.go b/internal/config/initializer.go
index 8215891..35105bf 100644
--- a/internal/config/initializer.go
+++ b/internal/config/initializer.go
@@ -65,6 +65,8 @@ func (in *initializer) parseSpecificConfig(configFile string) error {
 func (in *initializer) transformConfig(sourceProcess source.Source, args *Args,
 	additionalArgs []string) error {
 
+	in.readEnvironmentVars()
+
 	switch sourceProcess {
 	case source.Server:
 		return in.optimusPrime(transformServer, args, additionalArgs)
@@ -78,6 +80,14 @@ func (in *initializer) transformConfig(sourceProcess source.Source, args *Args,
 	}
 }
 
+// There are some special options which can be set by environment variable.
+func (in *initializer) readEnvironmentVars() {
+	if len(os.Getenv("DTAIL_SSH_DONT_ADD_HOSTS_TO_KNOWNHOSTS_FILE")) != 0 ||
+		len(os.Getenv("DTAIL_JENKINS")) != 0 {
+		in.Client.SSHDontAddHostsToKnownHostsFile = true
+	}
+}
+
 func (in *initializer) optimusPrime(sourceCb transformCb, args *Args,
 	additionalArgs []string) error {
 
diff --git a/internal/ssh/client/authmethods.go b/internal/ssh/client/authmethods.go
index ced1fb9..089a66a 100644
--- a/internal/ssh/client/authmethods.go
+++ b/internal/ssh/client/authmethods.go
@@ -35,8 +35,7 @@ func initKnownHostsAuthMethods(trustAllHosts bool, throttleCh chan struct{},
 	if err != nil {
 		dlog.Common.FatalPanic(knownHostsPath, err)
 	}
-	dlog.Common.Debug("initKnownHostsAuthMethods", "Added known hosts file path",
-		knownHostsPath)
+	dlog.Common.Debug("initKnownHostsAuthMethods", "Added known hosts file path", knownHostsPath)
 	if config.Common.ExperimentalFeaturesEnable {
 		sshAuthMethods = append(sshAuthMethods, gossh.Password("experimental feature test"))
 		dlog.Common.Debug("initKnownHostsAuthMethods", "Added experimental method to list of auth methods")
@@ -88,7 +87,11 @@ func initKnownHostsAuthMethods(trustAllHosts bool, throttleCh chan struct{},
 	}
 	dlog.Common.Debug("initKnownHostsAuthMethods", "Unable to use private key",
 		privateKeyPath, err)
-	dlog.Common.FatalPanic("Unable to find private SSH key information")
+
+	// This is only a panic when we expect to do something about it.
+	if !config.Client.SSHDontAddHostsToKnownHostsFile {
+		dlog.Common.FatalPanic("Unable to find private SSH key information")
+	}
 
 	// Never reach this point.
 	return sshAuthMethods, knownHostsCallback
diff --git a/internal/ssh/client/knownhostscallback.go b/internal/ssh/client/knownhostscallback.go
index 65a590a..2aa0168 100644
--- a/internal/ssh/client/knownhostscallback.go
+++ b/internal/ssh/client/knownhostscallback.go
@@ -10,6 +10,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/mimecast/dtail/internal/config"
 	"github.com/mimecast/dtail/internal/io/dlog"
 	"github.com/mimecast/dtail/internal/io/prompt"
 
@@ -214,6 +215,12 @@ func (c KnownHostsCallback) promptAddHosts(hosts []unknownHost) {
 
 func (c KnownHostsCallback) trustHosts(hosts []unknownHost) {
 	tmpKnownHostsPath := fmt.Sprintf("%s.tmp", c.knownHostsPath)
+
+	if config.Client.SSHDontAddHostsToKnownHostsFile {
+		dlog.Common.Verbose("Not adding hosts to known hosts file, as disabled by config")
+		return
+	}
+
 	newFd, err := os.OpenFile(tmpKnownHostsPath, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0600)
 	if err != nil {
 		panic(fmt.Sprintf("%s: %s", tmpKnownHostsPath, err.Error()))