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Linux DNS error

Linux DNS error injects chaos to disrupt the DNS resolution on a Linux machine.

Linux DNS error

Use cases​

  • Induces DNS error on the target Linux machines.
  • Simulates loss of access to host by blocking the DNS resolution of host names.
note
  • This fault can be executed on Ubuntu 16 or higher, Debian 10 or higher, CentOS 7 or higher, RHEL 7 or higher, Fedora 30 or higher, and openSUSE LEAP 15.4 or higher.
  • The linux-chaos-infrastructure systemd service should be in an active state, and the infrastructure should be in CONNECTED state.

Fault permissions​

The fault uses the root Linux user and root user group.

Optional tunables​

Tunable Description Notes
hostNames List of the target host names or keywords. For example, google.com,litmuschaos.io. If not provided, all host names are targeted.
matchScheme Determines whether the DNS query has to exactly match one of the targets or can have any of the targets as substring. It can be exact or substring. If not provided, it is set to exact
upstreamServer URL of the DNS upstream server.
dnsPort Port of the DNS server.
duration Duration through which chaos is injected into the target resource. Should be provided in [numeric-hours]h[numeric-minutes]m[numeric-seconds]s format. Default: 30s. Examples: 1m25s, 1h3m2s, 1h3s
rampTime Period to wait before and after injecting chaos. Should be provided in [numeric-hours]h[numeric-minutes]m[numeric-seconds]s format. Default: 0s. Examples: 1m25s, 1h3m2s, 1h3s

Host names​

The hostNames input variable subjects the comma-separated host names to chaos.

The following YAML snippet illustrates the use of this environment variable:

# target host names
apiVersion: litmuchaos.io/v1alpha1
kind: LinuxFault
metadata:
  name: linux-dns-error
  labels:
    name: dns-error
spec:
  dnsChaos/inputs:
    hostNames: 'litmuschaos.io,google.com'

Match scheme​

The matchScheme input variable either exactly matches one of the targets to the DNS query or has any of the targets as a substring of the DNS query.

The following YAML snippet illustrates the use of this environment variable:

# dns query match scheme
apiVersion: litmuchaos.io/v1alpha1
kind: LinuxFault
metadata:
  name: linux-dns-error
  labels:
    name: dns-error
spec:
  stressChaos/inputs:
    matchScheme: 'exact'