client: container: support CLI with entrypoint addition (#4126)

This will allow running netbird commands (including debugging) against the daemon and provide a flow similar to non-container usages.

It will by default both log to file and stderr so it can be handled more uniformly in container-native environments.

client/Dockerfile-rootless

@@ -1,18 +1,33 @@
-FROM alpine:3.21.0
+# build & run locally with:
+#   cd "$(git rev-parse --show-toplevel)"
+#   CGO_ENABLED=0 go build -o netbird ./client
+#   podman build -t localhost/netbird:latest -f client/Dockerfile --ignorefile .dockerignore-client .
+#   podman run --rm -it --cap-add={BPF,NET_ADMIN,NET_RAW} localhost/netbird:latest
 
-ARG NETBIRD_BINARY=netbird
-COPY ${NETBIRD_BINARY} /usr/local/bin/netbird
+FROM alpine:3.22.0
 
-RUN apk add --no-cache ca-certificates \
+RUN apk add --no-cache \
+      bash \
+      ca-certificates \
     && adduser -D -h /var/lib/netbird netbird
+
 WORKDIR /var/lib/netbird
 USER netbird:netbird
 
-ENV NB_FOREGROUND_MODE=true
-ENV NB_USE_NETSTACK_MODE=true
-ENV NB_ENABLE_NETSTACK_LOCAL_FORWARDING=true
-ENV NB_CONFIG=config.json
-ENV NB_DAEMON_ADDR=unix://netbird.sock
-ENV NB_DISABLE_DNS=true
+ENV \
+    NETBIRD_BIN="/usr/local/bin/netbird" \
+    NB_USE_NETSTACK_MODE="true" \
+    NB_ENABLE_NETSTACK_LOCAL_FORWARDING="true" \
+    NB_CONFIG="/var/lib/netbird/config.json" \
+    NB_STATE_DIR="/var/lib/netbird" \
+    NB_DAEMON_ADDR="unix:///var/lib/netbird/netbird.sock" \
+    NB_LOG_FILE="console,/var/lib/netbird/client.log" \
+    NB_DISABLE_DNS="true" \
+    NB_ENTRYPOINT_SERVICE_TIMEOUT="5" \
+    NB_ENTRYPOINT_LOGIN_TIMEOUT="1"
 
-ENTRYPOINT [ "/usr/local/bin/netbird", "up" ]
+ENTRYPOINT [ "/usr/local/bin/netbird-entrypoint.sh" ]
+
+ARG NETBIRD_BINARY=netbird
+COPY client/netbird-entrypoint.sh /usr/local/bin/netbird-entrypoint.sh
+COPY "${NETBIRD_BINARY}"  /usr/local/bin/netbird