Add warning when mirrord exec docker is detected, hinting the user towards mirrord container.

changelog.d/2599.added.md

@@ -0,0 +1 @@
+Add warning when user tries to mirrord exec [container], pointing them to use mirrord container instead.

mirrord/cli/Cargo.toml

@@ -66,6 +66,7 @@ rustls-pemfile = "2"
 tokio-rustls = "0.26"
 tokio-stream = { workspace = true, features = ["net"] }
 tokio-retry = "0.3"
+regex.workspace = true
 
 
 [target.'cfg(target_os = "macos")'.dependencies]

mirrord/cli/src/main.rs

@@ -35,9 +35,10 @@ use mirrord_config::{
 };
 use mirrord_kube::api::{container::SKIP_NAMES, kubernetes::create_kube_config};
 use mirrord_operator::client::OperatorApi;
-use mirrord_progress::{Progress, ProgressTracker};
+use mirrord_progress::{messages::EXEC_CONTAINER_BINARY, Progress, ProgressTracker};
 use operator::operator_command;
 use port_forward::PortForwarder;
+use regex::Regex;
 use semver::Version;
 use serde_json::json;
 use tracing::{error, info, warn};
@@ -321,6 +322,12 @@ async fn exec(args: &ExecArgs, watch: drain::Watch) -> Result<()> {
         args.binary, args.binary_args
     );
 
+    let container_detection =
+        Regex::new("docker|podman|nerdctl").expect("Failed building container detection regex!");
+    if container_detection.is_match(&args.binary) {
+        progress.warning(EXEC_CONTAINER_BINARY);
+    }
+
     if !(args.params.no_tcp_outgoing || args.params.no_udp_outgoing) && args.params.no_remote_dns {
         warn!("TCP/UDP outgoing enabled without remote DNS might cause issues when local machine has IPv6 enabled but remote cluster doesn't")
     }

mirrord/progress/src/messages.rs

@@ -11,3 +11,9 @@ pub const MULTIPOD_WARNING: (&str, &str) = (
         You can get started with mirrord for Teams at this link: \
         https://mirrord.dev/docs/overview/teams/",
 );
+
+/// Warning when user tries to run `mirrord exec docker` (for example), instead of the correct
+/// `mirrord container ...`.
+pub const EXEC_CONTAINER_BINARY: &str = "`mirrord exec <docker|podman|nerdctl> ...` detected! \
+    If you try to run a container with mirrord, please use \
+    `mirrord container [options] -- <docker|podman|nerdctl> ...` instead.";