- As [@jaredallard](https://github.com/jaredallard) [pointed out](https://github.com/rancher/k3d/pull/48), people running `k3d` on a system with **btrfs**, may need to mount `/dev/mapper` into the nodes for the setup to work.
- k3s currently has [no support for ZFS](ttps://github.com/rancher/k3s/issues/66) and thus, creating multi-server setups (e.g. `k3d cluster create multiserver --servers 3`) fails, because the initializing server node (server flag `--cluster-init`) errors out with the following log:
starting kubernetes: preparing server: start cluster and https: raft_init(): io: create I/O capabilities probe file: posix_allocate: operation not supported on socket
```
- This issue can be worked around by providing docker with a different filesystem (that's also better for docker-in-docker stuff).
- A possible solution can be found here: [https://github.com/rancher/k3s/issues/1688#issuecomment-619570374](https://github.com/rancher/k3s/issues/1688#issuecomment-619570374)
- What causes this issue: it's a [known issue with dqlite in `k3s`](https://github.com/rancher/k3s/issues/1391) which doesn't allow the initializing server node to go down
- What's the solution: Hopefully, this will be solved by the planned [replacement of dqlite with embedded etcd in k3s](https://github.com/rancher/k3s/pull/1770)
- Related issues: [#262](https://github.com/rancher/k3d/issues/262)
- Note: There are many ways to use the `"` and `'` quotes, just be aware, that sometimes shells also try to interpret/interpolate parts of the commands
## How to access services (like a database) running on my Docker Host Machine
- As of version v3.1.0, we're injecting the `host.k3d.internal` entry into the k3d containers (k3s nodes) and into the CoreDNS ConfigMap, enabling you to access your host system by referring to it as `host.k3d.internal`
Running k3d behind a corporate proxy can lead to some issues with k3d that have already been reported in more than one issue.
Some can be fixed by passing the `HTTP_PROXY` environment variables to k3d, some have to be fixed in docker's `daemon.json` file and some are as easy as adding a volume mount.
### Pods fail to start: `x509: certificate signed by unknown authority`
- Example Error Message: `Failed to create pod sandbox: rpc error: code = Unknown desc = failed to get sandbox image "docker.io/rancher/pause:3.1": failed to pull image "docker.io/rancher/pause:3.1": failed to pull and unpack image "docker.io/rancher/pause:3.1": failed to resolve reference "docker.io/rancher/pause:3.1": failed to do request: Head https://registry-1.docker.io/v2/rancher/pause/manifests/3.1: x509: certificate signed by unknown authority`
- Problem: inside the container, the certificate of the corporate proxy cannot be validated
- Possible Solution: Mounting the CA Certificate from your host into the node containers at start time via `k3d cluster create --volume /path/to/your/certs.crt:/etc/ssl/certs/yourcert.crt`