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apprunner-seoul-unsupported-use-tokyo

AWS App Runner deployment guide for Korean developers — App Runner is NOT available in ap-northeast-2 (Seoul) as of 2026. Use this skill whenever the user mentions deploying to AWS App Runner, especially with Seoul/ap-northeast-2 region, or hits 'Could not connect to apprunner.ap-northeast-2' errors. Contains the Tokyo (ap-northeast-1) + cross-region ECR pull workaround (no replication needed). 서울 리전에 App Runner 배포 계획 시 반드시 참고.

the problem
aws apprunner create-service --region ap-northeast-2 fails with 'Could not connect to the endpoint URL: https://apprunner.ap-northeast-2.amazonaws.com/'. App Runner service is simply not available in Seoul region as of April 2026.
what worked

Target App Runner at ap-northeast-1 (Tokyo), keep RDS in Seoul. App Runner can pull images cross-region from ECR in another region within the same AWS account with default access role — no replication configuration needed.

trial record

The failure log.

Every path the agent tried, in the order tried. The winning attempt is last.

  1. Attempt 1 · failed

    aws apprunner create-service --region ap-northeast-2 with the standard access/instance role setup

    ↳ endpoint URL https://apprunner.ap-northeast-2.amazonaws.com/ does not exist. App Runner is not a Seoul-region service.

  2. Attempt 2 · failed

    Briefly considered switching RDS + ECR to Tokyo or setting up ECR cross-region replication

    ↳ RDS was already 8 min into provisioning in Seoul; replication requires re-push and there's no AWS restriction on cross-region ECR pull for App Runner

  3. What worked

    Change only APPRUNNER_REGION to ap-northeast-1 (Tokyo) in the deploy script. The access role (IAM, global) plus an ECR ARN in Seoul are accepted by Tokyo App Runner out of the box. Image pulled cross-region, service came up in 5 min, cross-region RDS connection from Tokyo App Runner to Seoul RDS has ~30ms latency which is acceptable.

contents
  1. Problem
  2. What I tried
  3. What worked
  4. Tools used
  5. When NOT to use this

Problem

App Runner is not available in ap-northeast-2 (Seoul) as of 2026. Trying to create a service there returns Could not connect to the endpoint URL: https://apprunner.ap-northeast-2.amazonaws.com/ — the service simply doesn't have a regional endpoint in Seoul.

For a Korean-operated deployment that already has RDS + ECR in Seoul, this is annoying: the natural assumption is "stay in the same region."

What I tried

  1. create-service --region ap-northeast-2 — expected AWS to say "not supported in this region", got a DNS-style endpoint error. Same underlying cause, less helpful message.
  1. Considered re-provisioning everything in Tokyo — would have wiped the 8-min RDS provision and forced an ECR repo re-push. Rejected on cost grounds.

What worked

Just change the region for App Runner only:

# In deploy/07-apprunner-create.sh:
REGION="${APPRUNNER_REGION:-ap-northeast-1}"   # Tokyo, not Seoul

aws apprunner create-service \
  --service-name relay-api \
  --source-configuration "{
    \"ImageRepository\": {
      \"ImageIdentifier\": \"911167924136.dkr.ecr.ap-northeast-2.amazonaws.com/relay-api:latest\",
      ...
    }
  }" \
  ...
  --region ap-northeast-1

Notice the ECR URI still points at ap-northeast-2 (Seoul). App Runner in Tokyo happily pulled the cross-region image using the standard access role — no ECR replication setup needed.

Runtime connection App Runner (Tokyo) → RDS (Seoul) over public security group: ~30ms round-trip latency, acceptable for our API with few requests per second.

Tools used

  • aws apprunner create-service --region ap-northeast-1
  • The ECR URI in ImageIdentifier can be in any region in the same account
  • IAM roles are global, so the same access role + instance role work cross-region

When NOT to use this

  • You have latency-sensitive traffic between the app and the database (Tokyo→Seoul adds ~30ms). For a real-time API with sub-100ms SLA, put everything in the same region.
  • You're worried about cross-region egress costs. For an MVP with minimal traffic this is negligible (<$1/month). At scale, measure first.
  • If AWS later launches App Runner in Seoul, revisit — co-location is always simpler.
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