test images: Adds version and bind-tools to agnhost

Adds bind-tools to the agnhost image. With this, dig will available
in the agnhost image, which can be used in DNS related tests.

Adds the --version flag to the agnhost binary, which will be useful for
debugging purposes (e.g.: when the image version does not match the binary
version).

Bumps version to 2.5.

test/images/agnhost/Dockerfile

@@ -22,7 +22,7 @@ CROSS_BUILD_COPY qemu-QEMUARCH-static /usr/bin/
 # - iproute2: includes ss used in NodePort tests
 # from iperf image
 # install necessary packages: iperf, bash
-RUN apk --update add curl netcat-openbsd iproute2 iperf bash && rm -rf /var/cache/apk/* \
+RUN apk --update add bind-tools curl netcat-openbsd iproute2 iperf bash && rm -rf /var/cache/apk/* \
   && ln -s /usr/bin/iperf /usr/local/bin/iperf \
   && ls -altrh /usr/local/bin/iperf
 

test/images/agnhost/README.md

@@ -15,6 +15,15 @@ word of the words agnostic and host.
 The image was created for testing purposes, reducing the need for having different test
 cases for the same tested behaviour.
 
+
+## Developer notes
+
+We've introduced versioning into the `agnhost` binary for debugging purposes (e.g.: if the
+image and binary versions do not match, see [here](https://github.com/kubernetes/kubernetes/pull/79667#discussion_r304198370)).
+
+Whenever the image `VERSION` is bumped, the `Version` in `agnhost.go` will also have to be bumped.
+
+
 ## Usage
 
 The `agnhost` binary has several subcommands which are can be used to test different

test/images/agnhost/VERSION

@@ -1 +1 @@
-2.4
+2.5

test/images/agnhost/agnhost.go

@@ -44,7 +44,8 @@ import (
 )
 
 func main() {
-	rootCmd := &cobra.Command{Use: "app"}
+	rootCmd := &cobra.Command{Use: "app", Version: "2.5"}
+
 	rootCmd.AddCommand(auditproxy.CmdAuditProxy)
 	rootCmd.AddCommand(connect.CmdConnect)
 	rootCmd.AddCommand(crdconvwebhook.CmdCrdConversionWebhook)