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fix DNS issues with unresolvable backends with ExternalName #12952

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Merged
merged 2 commits into from
Mar 6, 2025
Merged

fix DNS issues with unresolvable backends with ExternalName #12952

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e93385a
fix issue with unresolved backends with ExternalName
neerfri Feb 17, 2024
1b65a96
Update rootfs/etc/nginx/lua/balancer.lua
neerfri Jan 3, 2025
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18 changes: 12 additions & 6 deletions rootfs/etc/nginx/lua/balancer.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -77,8 +77,10 @@ local function resolve_external_names(original_backend)
local endpoints = {}
for _, endpoint in ipairs(backend.endpoints) do
local ips = dns_lookup(endpoint.address)
for _, ip in ipairs(ips) do
table.insert(endpoints, { address = ip, port = endpoint.port })
if #ips ~= 1 or ips[1] ~= endpoint.address then
for _, ip in ipairs(ips) do
table.insert(endpoints, { address = ip, port = endpoint.port })
end
end
end
backend.endpoints = endpoints
Expand All @@ -104,15 +106,19 @@ local function is_backend_with_external_name(backend)
end

local function sync_backend(backend)
-- We resolve external names before checking if the endpoints are empty
-- because the behavior for resolve_external_names when the name was not
-- resolved is to return an empty table so we set the balancer to nil below
-- see https://github.com/kubernetes/ingress-nginx/pull/10989
if is_backend_with_external_name(backend) then
backend = resolve_external_names(backend)
end

if not backend.endpoints or #backend.endpoints == 0 then
balancers[backend.name] = nil
return
end

if is_backend_with_external_name(backend) then
backend = resolve_external_names(backend)
end

backend.endpoints = format_ipv6_endpoints(backend.endpoints)

local implementation = get_implementation(backend)
Expand Down