How can I add a new host to an existing Ingress in kubernetes?

Question

As I see on the next page, I can configure two or three hosts in one input. https://kubernetes.io/docs/concepts/services-networking/ingress/#name-based-virtual-hosting

But how do I add a new host to an existing input? I tried commands like apply or patch, but that didn't work.

Does anyone know this solution?

kubectl patch -f sample-ingress.yml -p ' 
  {"metadata": {"name": "sample-ingress"}, "spec": [{
    "host": "39500000.sample.com",
    "http": {"paths": [{
      "backend": {"serviceName": "39500000", "servicePort": 8080}
    }]
  }}]
}'
The Ingress "sample-ingress" is invalid: spec.backend.serviceName: Required value

Answer 1

Here is my unedited bash solution for this.

If there is any interest, I can rewrite it to make it more portable. I will post comments in a script to help you.

#!/bin/bash
# Update ingress with potential new hosts
# REQUIREMENTS: [An existing ingress with at least one host, and jq installed on host]
kubectl get ingress laravel-ingress -n=gitlab-ci -o json > original_json #CHANGE THIS VALUE TO QUERY YOUR EXISTING INGRESS
existing_hosts=()
exisiting_host_names=()

 # I pass 3 arguments into the script. The first 2 are potential new hosts (if they aren't in the ingress already, and the 3rd arg helps me build the service name)
 API_HOST=$1
 DASHBOARD_HOST=$2
 NAME=$3

name="$NAME"
potential_new_hosts=(
     "$API_HOST"
     "$DASHBOARD_HOST"
)
new_hosts=()

while read -r value
do
  existing_host_names+=("$value")
done < <(cat original_json | jq ['.spec.rules[] | .host'])

# Loop through potential new hosts and add any non-existing ones to a new array.
for potential_new_host in "${potential_new_hosts[@]}"; do
    i=0
    for existing_host in "${existing_host_names[@]}"; do
       if [[ "$existing_host" == "\"$potential_new_host\"," ]] ; then
           i=1
       fi
    done
    if [[ "$i" == 0 ]] ; then
        # A non-existing host, add to an array
        new_hosts+=("$potential_new_host")
    fi
done

while read -r value2
do
  existing_hosts+=("$value2")
done < <(cat original_json | jq ['.spec.rules[] | .'])

# Enable for debugging
#echo "Original json"
#cat original_json
#echo "Existing host names"
#printf '%s\n' "${existing_host_names[@]}"
#echo "New hosts"
#printf '%s\n' "${new_hosts[@]}"
#echo "Existing hosts before adding"
#printf '%s\n' "${existing_hosts[@]}"
#echo "Hosts after adding new ones"
########    

# Begin building of hosts json to patch ingress with
output_json=""
for existing_host in "${existing_hosts[@]}"; do
    output_json=("$output_json$existing_host")
done

# Truncate the last char in our json string (it a ']', and we want to potentially add to this array for patching
output_json=${output_json::-1}

i=0
for new_host in "${new_hosts[@]}"; do
    # Add to our json object the new host names with my hard-coded config
    output_json=("$output_json,{\"host\":\"$new_host\",\"http\":{ \"paths\": [{ \"backend\":{ \"serviceName\":\"$name-laravel-web\",\"servicePort\":80} } ]} }")
i=1
done
printf '%s]\n' "$output_json" > new_json

if [[  "$i" == 1 ]] ; then
    echo "Ingress json has changed and should be updated."
    echo "OLD:"
    cat original_json
    echo "PATCH: \"spec\": {\"rules\": $output_json]}"
    kubectl patch ingress laravel-ingress -n=gitlab-ci -p="\"spec\": {\"rules\": $output_json]}"
else
    echo "Ingress json has not changed and will not be updated."
fi

Edit (fixed bugs and converted to a single host when running the script)

#!/bin/bash
# Update ingress with potential new host
NEW_HOST=$1
INGRESS_NAME=$2
SERVICE_NAME=$3

echo "Running update-ingress for New host: $NEW_HOST, ingress: $INGRESS_NAME, service: $SERVICE_NAME"
echo " Downloading existing ingress config"
kubectl get ingress "$INGRESS_NAME" -n=gitlab-ci -o json > original_json
existing_hosts=()
exisiting_host_names=()

echo " $ kubectl get ingress $INGRESS_NAME -n=gitlab-ci -o json > original json && cat original_json"
cat original_json

name="$SERVICE_NAME"
potential_new_host="$NEW_HOST"
new_hosts=()

echo "Looping through json values1"
cat original_json | jq ['.spec.rules[] | .host']
for value in $(cat original_json | jq ['.spec.rules[] | .host']); 
do 
  # Replace all commas with ""
  value=${value/,/""}
  existing_host_names+=("$value")
  echo "Looping v1: value:$value"
  #printf 'Array: %s' "${existing_host_names[*]}"
done
echo "Right after values1"
i=0
for existing_host in "${existing_host_names[@]}"; do
   echo "Looping through existing host: $existing_host == $potential_new_host"
   if [[ "$existing_host" == "\"$potential_new_host\"" ]] ; then
       i=1
   fi
done
if [[ "$i" == 0 ]] ; then
    new_hosts+=("$potential_new_host")
fi

echo "Looping through json values2"
for value2 in $(cat original_json | jq ['.spec.rules[] | .']);
do
  existing_hosts+=("$value2")
  #echo "existing host! $values2"
  #printf 'Array: %s' "{existing_hosts[*]}"
done

echo "Original json"
#cat original_json

echo "Existing host names"
printf '%s\n' "${existing_host_names[@]}"
echo "New hosts"
printf '%s\n' "${new_hosts[@]}"
echo "Existing hosts before adding"
printf '%s\n' "${existing_hosts[@]}"
echo "Hosts after adding new ones"

output_json=""
for existing_host in "${existing_hosts[@]}"; do
    output_json=("$output_json$existing_host")
done

output_json=${output_json::-1}

i=0
for new_host in "${new_hosts[@]}"; do
    output_json=("$output_json,{\"host\":\"$new_host\",\"http\":{ \"paths\": [{ \"backend\":{ \"serviceName\":\"$SERVICE_NAME-laravel-web\",\"servicePort\":80} }, { \"backend\":{ \"serviceName\":\"$SERVICE_NAME-laravel-web\",\"servicePort\":443} } ]} }")
i=1
done
printf '%s]\n' "$output_json" > new_json

if [[  "$i" == 1 ]] ; then
    echo "Ingress json has changed and should be updated."
    echo "OLD:"
    cat original_json
    echo "PATCH: \"spec\": {\"rules\": $output_json]}"
    kubectl patch ingress "$INGRESS_NAME" -n=gitlab-ci -p="\"spec\": {\"rules\": $output_json]}"
else
    echo "Ingress json has not changed and will not be updated."
fi

Answer 2

kubectl edit, kubectl edit ing sample-ingress .

kubectl get ing sample-ingress -o json, sample-ingress json, , , kubectl replace -f.

Answer 3

PATCH kubernetes.

: kubectl patch ingress my-ingress --type json --patch "$(cat patch.json)"

patch.json

[
    {
        "op" : "add" ,
        "path" : "/spec/rules/-" ,
        "value" : {
            "host": "evil.facebook.com",
            "http": {
                "paths": [
                    {
                        "backend": {
                            "serviceName": "tracker-app",
                            "servicePort": 80
                        }
                    }
                ]
            }
        }
    }
]

: - my-ingress - - json "$ (cat patch.json)"

In addition, the main thing in this solution is that it uses its own capabilities of kubernetes to combine json in accordance with these rules .

More information about patching from an official source can be found here .