feat: Docker registry mirror (#478)

Changes:

- Switched to use `jq` in startup.sh
- Enable docker registry mirror configuration which is useful when e.g. avoiding the Docker Hub rate-limiting

Check #478 for how this feature is tested and supposed to be used.

api/v1alpha1/runner_types.go

@@ -18,6 +18,7 @@ package v1alpha1
 
 import (
 	"errors"
+
 	"k8s.io/apimachinery/pkg/api/resource"
 
 	corev1 "k8s.io/api/core/v1"
@@ -98,6 +99,8 @@ type RunnerSpec struct {
 	// +optional
 	DockerMTU *int64 `json:"dockerMTU,omitempty"`
 	// +optional
+	DockerRegistryMirror *string `json:"dockerRegistryMirror,omitempty"`
+	// +optional
 	HostAliases []corev1.HostAlias `json:"hostAliases,omitempty"`
 	// +optional
 	VolumeSizeLimit *resource.Quantity `json:"volumeSizeLimit,omitempty"`

api/v1alpha1/zz_generated.deepcopy.go

@@ -706,6 +706,11 @@ func (in *RunnerSpec) DeepCopyInto(out *RunnerSpec) {
 		*out = new(int64)
 		**out = **in
 	}
+	if in.DockerRegistryMirror != nil {
+		in, out := &in.DockerRegistryMirror, &out.DockerRegistryMirror
+		*out = new(string)
+		**out = **in
+	}
 	if in.HostAliases != nil {
 		in, out := &in.HostAliases, &out.HostAliases
 		*out = make([]v1.HostAlias, len(*in))