Network Utility (app-netutil) is a library that provides API methods for applications running in a container to query network information associated with pod. Network Utility is written in golang and can be built into an application binary. It also has a C language binding allowing it to be built into C applications.
To add virtio based interfaces into a DPDK based application in a container, the DPDK application needs a unix socket file, which is shared with the host through a VolumeMount, and a set of configuration data about how the socketfile should be used. Currently, the Userspace CNI uses annotations or configuration files to share the data between host and container. SR-IOV needs to get the PCI Addresses of the VFs share with the DPDK application. Currently it is using Environmental Variables to do this. Once the above data is in the container, this library has been written to abstract out where to look and how to process all data passed in.
Note: Userspace CNI is not officially supported in OpenShift.
Additional Information:
There are three API methods to collect system and network information:
GetCPUInfo()- This function determines which CPUs are available to the container and returns the list to the caller.
GetHugepages()- This function determines the amount of hugepage memory available to each container and returns the values to the caller.
GetInterfaces()- This function determines the set of interfaces in the container and returns the list, along with the interface type and type specific data.
There is a GO and C version of each of these functions.
There is a GO sample app that provides an example of how to include the app-netutil as a library in a GO program and how to use the existing APIs:
There is a C sample app that provides an example of how to include the app-netutil as a library in a C program and how to use the existing APIs:
The gotcha with the C APIs is that data must be allocated on the C side and passed into the GO library. So the C APIs take data buffers as input. Then the GO library populates the input structures with the collect data. It is then up to the C side to free any allocated data.
GO has a special handling for strings where it still allocates the memory for the string on the C side, but it is hidden in the C.CString() library. So strings passed from the GO library back to the calling C code must also free strings, even though there were not explicitly malloc'd. The sample C code shows examples.
The initial problem app-netutil is trying to solve is to collect initial
configuration data for a DPDK application running in a container. The DPDK
Library is written in C, so there is a sample Docker Image that leverages
the C APIs of app-netutil to collect the initial configuration data an
then use it to start DPDK. See:
app-netutil is a set of library functions that are intended to be pulled into a container workload to collect system and network information. In order to tailor the implementation to match the workload's needs, there are a few settings that can be configured.
For C, there is a single C API method to configure app-netutil configuration fields:
SetConfig()- This function takes an input structure and applies the configured fields. Since this C API is only writing (passing data in), no data is allocated on the GO side. Therefore no special freeing of memory is required other than the C side needs to free any memory it specifically allocates.
Since the base code is written in GO, the GO code can call the configuration APIs directly, so there is not one single GO configuration API.
app-netutil supports four levels of logging:
- "error"
- "warning"
- "info"
- "debug"
The default level is "warning". Other settings that can be configure are whether to write to stderr or not (default is true), and whether or not to write logs to a file (default is not write to a file).
GO Example:
import "github.com/openshift/app-netutil/pkg/logging"
logging.SetLogLevel("info")
logging.SetLogStderr(true)
logging.SetLogFile("/tmp/appnetutil.log")
C Example:
#include "libnetutil_api.h"
struct AppNetutilConfig config;
// Update Log Settings
memset(&config, 0, sizeof(config));
config.log.level = LOG_LEVEL_INFO;
config.log.stderr = true;
config.log.filename = "/tmp/appnetutil.log";
err = SetConfig(&config);
The Kubernetes Downward API is leveraged to pass pod annotations and specific Downward API fields to a pod. This data is written to files in a directory defined by a VolumeMount in the podSpec. By default, app-netutil uses "/etc/podnetinfo", which is the directory Network Resources Injector (or SR-IOV DP Admission Controller in OpenShift) uses when Downward API fields are injected into a pod. app-netutil allows the base directory it should use to look for these files to be configured.
GO Example:
import netlib "github.com/openshift/app-netutil/lib/v1alpha"
netlib.SetDownwardAPIMountPath("/etc/podinfo")
C Example:
#include "libnetutil_api.h"
struct AppNetutilConfig config;
// Update Downward API Settings
memset(&config, 0, sizeof(config));
config.downwardAPI.baseDir = "/etc/podinfo";
err = SetConfig(&config);
This section provides examples of building the sample applications that use the Network Utility Library. This is just quick start guide, more details can be found in the links associated with each section.
- Compile executable:
$ make go_sample
This builds application binary called go_app under bin/ dir.
- Run:
$ PCIDEVICE_INTEL_COM_SRIOV=0000:01:02.5,0000:01:0a.4 ./bin/go_app
|CPU |: 0-63
|HugePage |: MyContainerName=sriov-example
| 0 |: ContainerName=sriov-example Request 1G=0 2M=0 Ukn=1024 Limit 1G=0 2M=0 Ukn=1024
|Iface |:
| 0 |: IfName=eth0 DeviceType=host Network= Default=true
| |: MAC=06:eb:7f:3a:48:85 IPs=[10.244.0.25] DNS={Nameservers:[] Domain: Search:[] Options:[]}
| 1 |: IfName=net1 DeviceType=sr-iov Network=default/sriov-net-a Default=false
| |: MAC= IPs=[] DNS={Nameservers:[] Domain: Search:[] Options:[]}
| |: pci 1.0.0 PCI=0000:01:02.5 PF= Vhostnet= RdmaDevice=
| 2 |: IfName=net2 DeviceType=sr-iov Network=default/sriov-net-b Default=false
| |: MAC= IPs=[] DNS={Nameservers:[] Domain: Search:[] Options:[]}
| |: pci 1.0.0 PCI=0000:01:0a.4 PF= Vhostnet= RdmaDevice=
<CTRL>-C
- Clean up:
$ make clean
This cleans up built binary and softlinks.
For more details, see:
- Compile executable:
$ make c_sample
This builds application binary called c_sample under bin/
directory. The bin/ directory also contains the C header file
libnetutil_api.h and shared library libnetutil_api.so needed
to build the C APP.
- Run:
$ PCIDEVICE_INTEL_COM_SRIOV=0000:01:02.5,0000:01:0a.4 \
LD_LIBRARY_PATH=$PWD/bin:$LD_LIBRARY_PATH \
./bin/c_sample
Starting sample C application.
Call NetUtil GetCPUInfo():
cpuRsp.CPUSet = 0-63
Call NetUtil GetHugepages():
MyContainerName=sriov-example
Hugepages[0]:
ContainerName=sriov-example Request: 1G=0 2M=0 Ukn=1024 Limit: 1G=0 2M=0 Ukn=1024
Call NetUtil GetInterfaces():
Interface[0]:
DeviceType=host Interface="eth0"
MAC="06:eb:7f:3a:48:85" IP="10.244.0.25"
Interface[1]:
DeviceType=SR-IOV Name="default/sriov-net-a" Interface="net1"
Type=PCI PCIAddress=0000:01:02.5
Interface[2]:
DeviceType=SR-IOV Name="default/sriov-net-b" Interface="net2"
Type=PCI PCIAddress=0000:01:0a.4
- Clean up:
$ make clean
This cleans up built binary and softlinks.
For more details, see:
The testpod image is a CentOS base image built the app-netutil
library. It simply creates a container that runs the go_app sample
applicatation described above.
- Build application container image:
$ make testpod
- Create application pod:
$ kubectl create -f samples/testpod/pod.yaml
- Check for pod logs:
$ kubectl logs testpod
I1202 18:47:09.067139 1 app_sample.go:16] starting sample application
I1202 18:47:09.069655 1 app_sample.go:20] CALL netlib.GetCPUInfo:
I1202 18:47:09.070542 1 resource.go:27] getting cpuset from path: /proc/1/root/sys/fs/cgroup/cpuset/cpuset.cpus
| CPU |: 0-63
I1202 18:47:09.071110 1 app_sample.go:26] netlib.GetCPUInfo Response:
I1202 18:47:09.071126 1 app_sample.go:30] CALL netlib.GetHugepages:
I1202 18:47:09.071149 1 hugepages.go:22] GetHugepages: Open /etc/podnetinfo/hugepages_request
I1202 18:47:09.071349 1 hugepages.go:25] Error getting /etc/podnetinfo/hugepages_request info: open /etc/podnetinfo/hugepages_request: no such file or directory
I1202 18:47:09.071363 1 hugepages.go:35] GetHugepages: Open /etc/podnetinfo/hugepages_limit
I1202 18:47:09.071390 1 hugepages.go:38] Error getting /etc/podnetinfo/hugepages_limit info: open /etc/podnetinfo/hugepages_limit: no such file or directory
I1202 18:47:09.071404 1 app_sample.go:33] Error calling netlib.GetHugepages: open /etc/podnetinfo/hugepages_request: no such file or directory
I1202 18:47:09.071418 1 app_sample.go:40] CALL netlib.GetInterfaces:
I1202 18:47:09.071424 1 network.go:39] GetInterfaces: ENTER
I1202 18:47:09.071433 1 network.go:45] GetInterfaces: Open /etc/podnetinfo/annotations
I1202 18:47:09.071821 1 network.go:68] s-k8s.v1.cni.cncf.io/network-status="[{\n \"name\": \"\",\n \"interface\": \"eth0\",\n \"ips\": [\n \"10.244.0.57\"\n ],\n \"mac\": \"82:33:bb:68:3a:3c\",\n \"default\": true,\n \"dns\": {}\n}]"
I1202 18:47:09.071832 1 network.go:72] PartsLen-2
I1202 18:47:09.071843 1 network.go:74] parts[0]-k8s.v1.cni.cncf.io/network-status
I1202 18:47:09.072035 1 network.go:68] s-k8s.v1.cni.cncf.io/networks-status="[{\n \"name\": \"\",\n \"interface\": \"eth0\",\n \"ips\": [\n \"10.244.0.57\"\n ],\n \"mac\": \"82:33:bb:68:3a:3c\",\n \"default\": true,\n \"dns\": {}\n}]"
I1202 18:47:09.072047 1 network.go:72] PartsLen-2
I1202 18:47:09.072054 1 network.go:74] parts[0]-k8s.v1.cni.cncf.io/networks-status
I1202 18:47:09.072067 1 network.go:68] s-kubernetes.io/config.seen="2020-12-02T13:46:08.010504651-05:00"
I1202 18:47:09.072075 1 network.go:72] PartsLen-2
I1202 18:47:09.072082 1 network.go:74] parts[0]-kubernetes.io/config.seen
I1202 18:47:09.072090 1 network.go:68] s-kubernetes.io/config.source="api"
I1202 18:47:09.072097 1 network.go:72] PartsLen-2
I1202 18:47:09.072105 1 network.go:74] parts[0]-kubernetes.io/config.source
I1202 18:47:09.072111 1 networkstatus.go:42] PRINT EACH NetworkStatus - len=1
I1202 18:47:09.072118 1 networkstatus.go:46] status:
I1202 18:47:09.072126 1 networkstatus.go:47] { eth0 [10.244.0.57] 82:33:bb:68:3a:3c true {[] [] []} <nil>}
I1202 18:47:09.072162 1 userspace.go:49] PRINT EACH Userspace MappedDir
I1202 18:47:09.072166 1 userspace.go:50] usrspMappedDir:
I1202 18:47:09.072171 1 userspace.go:51]
I1202 18:47:09.072176 1 userspace.go:53] PRINT EACH Userspace ConfigData
I1202 18:47:09.072183 1 network.go:112] PROCESS ENV:
I1202 18:47:09.072190 1 resource.go:38] getting environment variables from path: /proc/1/environ
I1202 18:47:09.072232 1 network.go:165] eth0 is the "default" interface, mark as "host"
I1202 18:47:09.072246 1 network.go:221] RESPONSE:
I1202 18:47:09.072258 1 network.go:223] &{host { eth0 [10.244.0.57] 82:33:bb:68:3a:3c true {[] [] []} <nil>}}
I1202 18:47:09.072280 1 app_sample.go:46] netlib.GetInterfaces Response:
| 0 |: IfName=eth0 DeviceType=host Network= Default=true
| |: MAC=82:33:bb:68:3a:3c IPs=[10.244.0.57] DNS={Nameservers:[] Domain: Search:[] Options:[]}
...
NOTE: If the hugepage Downward API is not included in the Pod Spec, which is the case for samples/testpod/pod.yaml, then the hugepage annotation files will not exist and hugepage data will not be retrieved. The hugepage Downward API requires Kubernetes 1.20 or greater and the feature gate to be enable.
- Delete application pod:
$ kubectl delete -f deployments/pod.yaml
For more details, see:
The dpdk-app-centos image is a CentOS base image built with DPDK
and includes the app-netutil library. The setup to run the image
is more complicated and depends on if you are using vhost interfaces
from something like a Userspace CNI or SR-IOV VFs from SR-IOV CNI.
Below is the quick command to build the image, but it is recommended
that additional README files are consulted for detailed setup
instructions.
- Build application container image:
$ make dpdk_app
For more details, see:
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