FAQ

## 1. Error: Precompiled module at /opt/.kindling/ is not found

### Problem description and logs

```c
## If the kindling pod is not running normally,
## we can use the following command to view the log
kubectl logs --tail=100 -f kindling-agent-xxxx  -c kindling-probe -n kindling

* Mounting debugfs
* Failure to find a BPF probe, try to load kernel probe
* Unloading kindling-falcolib-probe, if present
* Trying to find precompiled kindling-falcolib-probe for 4.19.1-1.el7.elrepo.x86_64
* Error: Precompiled module at /opt/.kindling/ is not found, and the agent will not work as expected
Start kindling probe...
KINDLING_PROBE_VERSION: v0.1-2021-1221
Unable to load the driver
kindling probe init err: error opening device /host/dev/kindling-falcolib0. Make sure you have root credentials and that the kindling-falcolib
```

### Solution

1. You must install the kernel headers manually first.

**For Debian-style distributions,** run the command:

```bash
apt-get -y install linux-headers-$(uname -r)
```

**For RHEL-style distributions,** run the command:
```bash
yum -y install kernel-devel-$(uname -r)
```
Of course, you can also [download RPM files](http://www.kindling.space:33215/project-1/doc-36/) manually to install the header files.

2. Rebuild the Kindling Agent image.

```bash
bash -c "$(curl -fsSL https://k8s-bpf-probes-public.oss-cn-hangzhou.aliyuncs.com/recompile-module.sh)"
```

The product of this step is an image. Please ensure that the image can be accessed by the k8s cluster node. Maybe you can upload the image to a private harbor, or compress it and distribute it to each node of the k8s cluster. (You should set the imagePullPolicy of kindling-agent to `ifNotPresent` when compress and distribute image.)

3. Finally, modify the image name of Kindling Agent:

```bash
kubectl set image ds/kindling-agent kindling-agent=kindlingproject/kindling-probe:bymyself -n kindling
```

## 2. Error: Prometheus cannot match error

### Problem description and logs

```
## After executing the script install.sh. The following error occurred
error: unable to recognize "kindling-prometheus-servicemonitor.yml": 
no matches for kind "ServiceMonitor" in version"monitoring.coreos.com/v1"
```

### Solution

If you have not installed Prometheus, please visit  [Prometheus-Operator ](https://github.com/prometheus-operator/prometheus-operator)to install it.

If you have installed Prometheus without operator, please ignore this error and manually configure the exposed metrics URL of Kindling Agent in Prometheus.The url is `localhost:9500/metrics`.

## 3. kindling probe init err: xxxxxx: Permission denied

### Problem description and logs

```c
kindling probe init err: can't create map: Permission denied
```
   or
```c
insmod error:cloud not insert xxx.ko:Permission denied
```

### Solution
- Confirm that the kindling agent has enabled the privileged mode.
- Confirm that SELinux is turned off on the node where the kindling agent is located. See details at [Disabling SELinux](https://www.ibm.com/docs/ja/ahts/4.0?topic=t-disabling-selinux).
- Confirm that CRI is running with root privileges.