Use DHCP for VM networking (#54)

* Add python pip to buildroot

* Use DHCP for agent

* Use systemd for naming network interfaces

* Removed eth0 dhcp setting

* Add ETH_IFACE variable

* Added explanation for ETH_IFACE name

* Further explain ETH_IFACE value

hal/linux/configs/cocos_defconfig

@@ -4,7 +4,8 @@ BR2_x86_64=y
 # System
 BR2_TARGET_GENERIC_HOSTNAME="cocos"
 BR2_TARGET_GENERIC_ISSUE="Welcome to Cocos"
-BR2_SYSTEM_DHCP="eth0"
+BR2_PACKAGE_DHCP=y
+BR2_PACKAGE_DHCP_CLIENT=y
 BR2_INIT_SYSTEMD=y
 
 # Filesystem

hal/linux/package/agent/agent.mk

@@ -14,11 +14,12 @@ endef
 define AGENT_INSTALL_TARGET_CMDS
 	$(INSTALL) -D -m 0755 $(@D)/build/cocos-agent $(TARGET_DIR)/bin
 	mkdir -p $(TARGET_DIR)/var/log/cocos
+	mkdir -p $(TARGET_DIR)/cocos/
 endef
 
 define AGENT_INSTALL_INIT_SYSTEMD
 	$(INSTALL) -D -m 0644 $(@D)/init/systemd/cocos-agent.service $(TARGET_DIR)/usr/lib/systemd/system/cocos-agent.service
-	$(INSTALL) -D -m 0644 $(@D)/init/systemd/eth0.network $(TARGET_DIR)/etc/systemd/network
+	$(INSTALL) -D -m 0755 $(@D)/init/systemd/agent_start_script.sh $(TARGET_DIR)/cocos/agent_start_script.sh
 	$(INSTALL) -D -m 0644 $(@D)/init/systemd/00-network.link $(TARGET_DIR)/etc/systemd/network
 endef
 

init/systemd/00-network.link

@@ -1,6 +0,0 @@
-[Match]
-OriginalName=*
-
-[Link]
-NamePolicy=kernel
-MACAddressPolicy=persistent

init/systemd/agent_start_script.sh

@@ -0,0 +1,22 @@
+#!/bin/sh
+
+# The variable ETH_IFACE contains the name the systemd gave to the network interface. 
+# The systemd configures the name based on the QEMU parameters. 
+# The parts of the name enp0s2 mean:
+#  et - ethernet card. It means this is the ethernet interface.
+#  p - means that the interface is connected to a PCI bus.
+#  0 - the interface is connected to bus 0.
+#  s2 -the interface is connected to slot 2.
+
+# The variable ETH_IFACE value must match the name configured through QEMU parameters for the network device. 
+# The bus number and slot number are configured through QEMU device parameters, parameters
+# addr (for slot number), and bus (for bus number).
+ETH_IFACE=enp0s2
+
+ip link set dev $ETH_IFACE up
+dhclient $ETH_IFACE
+AGENT_GRPC_HOST=$(ip -4 addr show $ETH_IFACE | grep inet | awk '{print $2}' | cut -d/ -f1)
+
+export AGENT_GRPC_HOST
+
+exec /bin/cocos-agent

init/systemd/cocos-agent.service

@@ -6,11 +6,10 @@ After=network.target
 StandardOutput=file:/var/log/cocos/agent.stdout
 StandardError=file:/var/log/cocos/agent.stderr
 
-Environment=AGENT_GRPC_HOST=10.0.0.1
 Environment=AGENT_GRPC_PORT=7002
 Environment=AGENT_LOG_LEVEL=info
 
-ExecStart=/bin/cocos-agent
+ExecStart=/cocos/agent_start_script.sh
 
 [Install]
 WantedBy=default.target

init/systemd/eth0.network

@@ -1,5 +0,0 @@
-[Match]
-Name=eth0
-
-[Network]
-Address=10.0.0.1/24