[新サービス] AWS Emulator 発表！実 AWS と比べ、Claude Code にローカルでテストと修正を繰り返させてみた

% podman machine start
Starting machine "podman-machine-default"
API forwarding listening on: /var/run/docker.sock
Docker API clients default to this address. You do not need to set DOCKER_HOST.

Machine "podman-machine-default" started successfully

FROM public.ecr.aws/amazonlinux/amazonlinux:2023-minimal
ADD https://downloads.aws.com/aws-emulator/packages/aws-emulator/LTS/latest/aws-emulator-aarch64.rpm /tmp/aws-emulator.rpm
RUN rpm -i /tmp/aws-emulator.rpm && rm /tmp/aws-emulator.rpm \
    && mkdir -p /home/emulator && chown 1000 /home/emulator
USER 1000
ENV HOME=/home/emulator
EXPOSE 9297
ENTRYPOINT ["aws-emulator", "-b", "0.0.0.0"]

% time docker build -t aws-emulator .
STEP 1/7: FROM public.ecr.aws/amazonlinux/amazonlinux:2023-minimal
...
STEP 2/7: ADD https://downloads.aws.com/aws-emulator/packages/aws-emulator/LTS/latest/aws-emulator-aarch64.rpm /tmp/aws-emulator.rpm
--> 8805988b0a0c
STEP 3/7: RUN rpm -i /tmp/aws-emulator.rpm && rm /tmp/aws-emulator.rpm     && mkdir -p /home/emulator && chown 1000 /home/emulator
warning: /tmp/aws-emulator.rpm: Header V4 RSA/SHA512 Signature, key ID d940f624: NOKEY
--> 608eeecaa5be
...
STEP 7/7: ENTRYPOINT ["aws-emulator", "-b", "0.0.0.0"]
COMMIT aws-emulator
--> fceb8e9812bb
Successfully tagged localhost/aws-emulator:latest
fceb8e9812bbe0681b42c3b1803f583a1eafeea2268ea2a6fbe1964068da1e3b
docker build -t aws-emulator .  0.01s user 0.01s system 0% cpu 26.930 total

% docker run --rm aws-emulator -v
Version: 1.0.322
Release date: 2026.11.10
Commit: 7753983c6e495ec3612695b1336bf4936fc7b7fd
% docker images localhost/aws-emulator
REPOSITORY              TAG         IMAGE ID      CREATED         SIZE
localhost/aws-emulator  latest      fceb8e9812bb  17 seconds ago  1.16 GB

% mkdir -p ~/.aws/emulator
% PORT=9297
% docker run -d --rm --name aws-emulator-$PORT \
  --user "$(id -u):$(id -g)" \
  --memory=2g --memory-swap=2g \
  -p 127.0.0.1:$PORT:$PORT \
  -e HOME="$HOME" -v "$HOME/.aws/emulator:$HOME/.aws/emulator" \
  aws-emulator -p $PORT --telemetry off --idle-timeout 3600
5e95e140a6ade96698a5db7a048e0d9c5179bdd85a0d64c275346fb8293e442d
% docker ps --filter name=aws-emulator --format "{{.Names}}  {{.Status}}  {{.Ports}}"
aws-emulator-9297  Up 5 seconds  127.0.0.1:9297->9297/tcp
% docker logs aws-emulator-9297
{"timestamp":"2026-11-11T23:49:07.133428Z","level":"INFO","fields":{"message":"aws-emulator emulator starting"},"target":"aws_emulator"}
{"timestamp":"2026-11-11T23:49:07.160958Z","level":"INFO","fields":{"message":"request authentication enabled","credentials_file":"/Users/classmethod/.aws/emulator/9297/emulator_credentials"},"target":"aws_emulator_server"}
{"timestamp":"2026-11-11T23:49:07.164124Z","level":"INFO","fields":{"message":"emulator server information","endpoint_url":"https://127.0.0.1:9297","health_check_url":"https://127.0.0.1:9297/__admin/health","config_file":"/Users/classmethod/.aws/emulator/9297/config","ca_file":"/Users/classmethod/.aws/emulator/9297/ca.pem","java_truststore_file":"/Users/classmethod/.aws/emulator/9297/truststore.p12"},"target":"aws_emulator_server"}
{"timestamp":"2026-11-11T23:49:07.164139Z","level":"WARN","fields":{"message":"the emulator listens on 0.0.0.0, not loopback: other machines that can reach port 9297 can call it; bind 127.0.0.1 (-b 127.0.0.1) unless that is intended","bind_address":"0.0.0.0"},"target":"aws_emulator_server"}
This emulator collects usage and error telemetry: disabled (via the embedding configuration) — to turn it back on, remove every opt-out setting and restart
% ls -l ~/.aws/emulator/9297
total 32
-rw-------@ 1 ishikawa.satoru  staff  566 Nov 12 08:49 ca.pem
-rw-------@ 1 ishikawa.satoru  staff  160 Nov 12 08:49 config
-rw-------@ 1 ishikawa.satoru  staff  116 Nov 12 08:49 emulator_credentials
-rw-------@ 1 ishikawa.satoru  staff  551 Nov 12 08:49 truststore.p12

export AWS_ENDPOINT_URL=https://127.0.0.1:9297
export AWS_SHARED_CREDENTIALS_FILE=$HOME/.aws/emulator/9297/emulator_credentials
export AWS_CONFIG_FILE=$HOME/.aws/emulator/9297/config
export AWS_CA_BUNDLE=$HOME/.aws/emulator/9297/ca.pem
export AWS_EC2_METADATA_DISABLED=true
export AWS_DISABLE_HOST_PREFIX_INJECTION=true
export AWS_REGION=us-east-1
export AWS_DEFAULT_REGION=us-east-1
unset AWS_ACCESS_KEY_ID AWS_SECRET_ACCESS_KEY AWS_SESSION_TOKEN AWS_PROFILE

% curl --cacert ~/.aws/emulator/9297/ca.pem https://127.0.0.1:9297/__admin/health
ok
% aws sts get-caller-identity
{
    "UserId": "AIDAH5I7GEMO7ADXNFAZU",
    "Account": "000000000000",
    "Arn": "arn:aws:iam::000000000000:user/emulator"
}
% aws configure list
NAME       : VALUE                    : TYPE             : LOCATION
profile    : <not set>                : None             : None
access_key : ****************9D85     : shared-credentials-file : 
secret_key : ****************A66C     : shared-credentials-file : 
region     : us-east-1                : env              : ['AWS_REGION', 'AWS_DEFAULT_REGION']

% echo "hello from the emulator" > hello.txt
% aws s3 mb s3://emu-demo-4dc2bf03
make_bucket: emu-demo-4dc2bf03
% aws s3 cp hello.txt s3://emu-demo-4dc2bf03/
upload: ./hello.txt to s3://emu-demo-4dc2bf03/hello.txt
% aws s3 ls s3://emu-demo-4dc2bf03/
2026-11-12 08:49:42         24 hello.txt
% aws s3api list-buckets --query "Buckets[].Name" --output text
emu-demo-4dc2bf03

% aws dynamodb create-table --table-name ab \
    --attribute-definitions AttributeName=id,AttributeType=S \
    --key-schema AttributeName=id,KeyType=HASH \
    --billing-mode PAY_PER_REQUEST

aws: [ERROR]: An error occurred (ValidationException) when calling the CreateTable operation: 1 validation error detected: Value 'ab' at 'tableName' failed to satisfy constraint: Member must have length greater than or equal to 3

% aws sts get-caller-identity --query "[Account,Arn]" --output text
111122223333	arn:aws:sts::111122223333:assumed-role/<ロール名>/<セッション名>
% echo "region: $AWS_REGION / endpoint override: ${AWS_ENDPOINT_URL:-(none)}"
region: ap-northeast-1 / endpoint override: (none)
% aws dynamodb create-table --table-name ab \
    --attribute-definitions AttributeName=id,AttributeType=S \
    --key-schema AttributeName=id,KeyType=HASH \
    --billing-mode PAY_PER_REQUEST \
    --tags Key=run_id,Value=emu-20261112-4dc2bf03 Key=owner,Value=tried-it Key=purpose,Value=blog-verification Key=ttl,Value=20261112T0150Z

aws: [ERROR]: An error occurred (ValidationException) when calling the CreateTable operation: 1 validation error detected: Value 'ab' at 'tableName' failed to satisfy constraint: Member must have length greater than or equal to 3

% aws dynamodb create-table --table-name emu-demo-orders \
    --attribute-definitions AttributeName=id,AttributeType=S \
    --key-schema AttributeName=id,KeyType=HASH \
    --billing-mode PAY_PER_REQUEST \
    --query "TableDescription.[TableName,TableStatus]" --output text
emu-demo-orders	CREATING
% aws dynamodb wait table-exists --table-name emu-demo-orders
% aws dynamodb put-item --table-name emu-demo-orders \
    --item '{"id": {"S": "order-1"}, "status": {"S": "NEW"}}'
% aws dynamodb get-item --table-name emu-demo-orders --key '{"id": {"S": "order-1"}}'
{
    "Item": {
        "id": {
            "S": "order-1"
        },
        "status": {
            "S": "NEW"
        }
    }
}

% aws dynamodb create-table --table-name emu-not-yet-active \
    --attribute-definitions AttributeName=id,AttributeType=S \
    --key-schema AttributeName=id,KeyType=HASH \
    --billing-mode PAY_PER_REQUEST \
    --query "TableDescription.TableStatus" --output text
CREATING
% aws dynamodb put-item --table-name emu-not-yet-active --item '{"id": {"S": "1"}}'

aws: [ERROR]: An error occurred (ResourceNotFoundException) when calling the PutItem operation: Requested resource not found
% echo "exit=$?"
exit=254
% aws dynamodb describe-table --table-name emu-not-yet-active --query "Table.TableStatus" --output text
ACTIVE

#!/bin/zsh
# 受信したメッセージが可視性タイムアウトまで他の受信者から見えないことを確かめる
# usage: sqs_visibility.sh <queue-name> [tags]
set -u
QUEUE_NAME=$1
TAGS=${2:-}

if [[ -n $TAGS ]]; then
  QURL=$(aws sqs create-queue --queue-name "$QUEUE_NAME" --tags "$TAGS" --query QueueUrl --output text)
else
  QURL=$(aws sqs create-queue --queue-name "$QUEUE_NAME" --query QueueUrl --output text)
fi
echo "QueueUrl: $QURL"

aws sqs send-message --queue-url "$QURL" --message-body "job-1" --query MessageId --output text

T0=$(date +%s)
elapsed() { echo "t=+$(( $(date +%s) - T0 ))s"; }

receive() {
  aws sqs receive-message --queue-url "$QURL" \
    --visibility-timeout 5 --wait-time-seconds 0 \
    --message-system-attribute-names ApproximateReceiveCount \
    --query 'Messages[].[Body,Attributes.ApproximateReceiveCount]' --output text
}

echo "[1回目の受信] $(elapsed)"; receive
echo "[直後に再受信] $(elapsed)"; R=$(receive); echo "${R:-(メッセージなし)}"
sleep 6
echo "[6秒後に再受信] $(elapsed)"; receive

% ./scripts/sqs_visibility.sh emu-visibility-4dc2bf03
QueueUrl: https://sqs.us-east-1.amazonaws.com/000000000000/emu-visibility-4dc2bf03
b69d4d89-51ba-4f83-bc20-b169ea2bb467
[1回目の受信] t=+0s
job-1	1
[直後に再受信] t=+0s
None
[6秒後に再受信] t=+7s
job-1	2

% ./scripts/sqs_visibility.sh emu-visibility-4dc2bf03 run_id=emu-20261112-4dc2bf03,owner=tried-it,purpose=blog-verification,ttl=20261112T0150Z
QueueUrl: https://sqs.ap-northeast-1.amazonaws.com/111122223333/emu-visibility-4dc2bf03
308f9c73-152c-48b1-9815-79a2f8cf753b
[1回目の受信] t=+0s
job-1	1
[直後に再受信] t=+0s
None
[6秒後に再受信] t=+7s
job-1	2

# ジョブワーカーの仕様

`worker.process_one(sqs, dynamodb, queue_url, table_name)` は、Amazon SQS のキューからメッセージを 1 件受け取り、Amazon DynamoDB のテーブルに結果を書き込む。

## 入力

- メッセージ本文は JSON: `{"job_id": "<文字列>", "amount": <整数>}`
- テーブルのパーティションキーは `job_id`（文字列）

## 振る舞い

1. キューが空なら `None` を返す
2. 本文が正しければ、テーブルに `{"job_id": ..., "amount": ..., "status": "DONE"}` を書き込み、メッセージを削除して `True` を返す
3. 同じ `job_id` のメッセージが再び届いても、テーブルの項目は 1 件のまま（既存の項目を上書きしない）。このメッセージも削除して `True` を返す
4. 本文が JSON として読めない、または `job_id` がない場合は、メッセージを削除せずに `False` を返す。メッセージは可視性タイムアウトの後に再び受信できる

## 合格条件

`tests/test_worker.py` のテストがすべて AWS Emulator 上で成功すること。

@pytest.fixture(scope="session", autouse=True)
def only_against_the_emulator():
    """AWS Emulator 以外（実 AWS）に接続していたらテストを始めない。"""
    endpoint = os.environ.get("AWS_ENDPOINT_URL", "")
    if not re.fullmatch(r"https://127\.0\.0\.1:\d+", endpoint):
        pytest.exit(f"AWS_ENDPOINT_URL がループバックではありません: {endpoint!r}", returncode=3)
    account = boto3.client("sts").get_caller_identity()["Account"]
    if account != "000000000000":
        pytest.exit(f"エミュレーターではないアカウントです: {account}", returncode=3)
...
@pytest.fixture
def table_name(dynamodb):
    name = f"job-results-{uuid.uuid4().hex[:8]}"
    dynamodb.create_table(
        TableName=name,
        AttributeDefinitions=[{"AttributeName": "job_id", "AttributeType": "S"}],
        KeySchema=[{"AttributeName": "job_id", "KeyType": "HASH"}],
        BillingMode="PAY_PER_REQUEST",
    )
    dynamodb.get_waiter("table_exists").wait(TableName=name)
    yield name
    dynamodb.delete_table(TableName=name)

def test_invalid_message_is_kept_for_retry(sqs, dynamodb, queue_url, table_name):
    send(sqs, queue_url, "not-json")

    assert process_one(sqs, dynamodb, queue_url, table_name) is False

    assert items(dynamodb, table_name) == []
    assert receive_all(sqs, queue_url) == []  # 可視性タイムアウト中は見えない
    time.sleep(3)
    again = receive_all(sqs, queue_url)
    assert [m["Body"] for m in again] == ["not-json"]
    assert again[0]["Attributes"]["ApproximateReceiveCount"] == "2"

% uv run pytest -q
...
FAILED tests/test_worker.py::test_empty_queue_returns_none - NotImplementedError
FAILED tests/test_worker.py::test_processes_message_and_deletes_it - NotImple...
FAILED tests/test_worker.py::test_duplicate_job_is_written_once - NotImplemen...
FAILED tests/test_worker.py::test_invalid_message_is_kept_for_retry - NotImpl...
4 failed in 12.27s

import json

from botocore.exceptions import ClientError

def process_one(sqs, dynamodb, queue_url, table_name):
    """SQS から 1 件受け取り、DynamoDB に書き込む。仕様は SPEC.md を参照。"""
    messages = sqs.receive_message(
        QueueUrl=queue_url, MaxNumberOfMessages=1, WaitTimeSeconds=0
    ).get("Messages", [])
    if not messages:
        return None
    message = messages[0]

    try:
        job = json.loads(message["Body"])
        job_id = job["job_id"]
    except (json.JSONDecodeError, KeyError):
        return False  # 削除しない: 可視性タイムアウト後に再配信される

    try:
        dynamodb.put_item(
            TableName=table_name,
            Item={
                "job_id": {"S": job_id},
                "amount": {"N": str(job["amount"])},
                "status": {"S": "DONE"},
            },
            ConditionExpression="attribute_not_exists(job_id)",
        )
    except ClientError as e:
        if e.response["Error"]["Code"] != "ConditionalCheckFailedException":
            raise
        # 同じ job_id は処理済み。上書きせずにメッセージだけ削除する

    sqs.delete_message(QueueUrl=queue_url, ReceiptHandle=message["ReceiptHandle"])
    return True

% uv run pytest -q --durations=0
....                                                                     [100%]
============================== slowest durations ===============================
3.09s setup    tests/test_worker.py::test_empty_queue_returns_none
3.04s setup    tests/test_worker.py::test_duplicate_job_is_written_once
3.04s call     tests/test_worker.py::test_duplicate_job_is_written_once
3.04s call     tests/test_worker.py::test_processes_message_and_deletes_it
3.04s call     tests/test_worker.py::test_invalid_message_is_kept_for_retry
3.02s setup    tests/test_worker.py::test_invalid_message_is_kept_for_retry
3.02s setup    tests/test_worker.py::test_processes_message_and_deletes_it
0.01s teardown tests/test_worker.py::test_invalid_message_is_kept_for_retry
0.01s teardown tests/test_worker.py::test_duplicate_job_is_written_once
0.01s teardown tests/test_worker.py::test_processes_message_and_deletes_it

(2 durations < 0.005s hidden.  Use -vv to show these durations.)
4 passed in 21.33s

% uv run python measure_latency.py
sts.get_caller_identity                           6.4 ms
sqs.create_queue                                  2.0 ms
sqs.send_message                                  1.1 ms
sqs.receive_message                               0.9 ms
dynamodb.create_table                             2.3 ms
  -> TableStatus                             CREATING
dynamodb: CREATING -> ACTIVE (polling 0.1s)    3003.9 ms
dynamodb.put_item                                 5.3 ms
dynamodb.get_item                                 4.2 ms
dynamodb.get_waiter('table_exists').wait          50.8 ms

@@ -46,6 +46,5 @@
         KeySchema=[{"AttributeName": "job_id", "KeyType": "HASH"}],
         BillingMode="PAY_PER_REQUEST",
     )
-    dynamodb.get_waiter("table_exists").wait(TableName=name)
     yield name
     dynamodb.delete_table(TableName=name)

% uv run pytest -q --tb=line
...
E   botocore.errorfactory.ResourceInUseException: An error occurred (ResourceInUseException) when calling the DeleteTable operation: Attempt to change a resource which is still in use: Table is being ...
E   botocore.errorfactory.ResourceNotFoundException: An error occurred (ResourceNotFoundException) when calling the PutItem operation: Requested resource not found
E   botocore.errorfactory.ResourceNotFoundException: An error occurred (ResourceNotFoundException) when calling the Scan operation: Requested resource not found
FAILED tests/test_worker.py::test_processes_message_and_deletes_it - botocore...
FAILED tests/test_worker.py::test_duplicate_job_is_written_once - botocore.er...
FAILED tests/test_worker.py::test_invalid_message_is_kept_for_retry - botocor...
ERROR tests/test_worker.py::test_empty_queue_returns_none - botocore.errorfac...
ERROR tests/test_worker.py::test_processes_message_and_deletes_it - botocore....
ERROR tests/test_worker.py::test_duplicate_job_is_written_once - botocore.err...
ERROR tests/test_worker.py::test_invalid_message_is_kept_for_retry - botocore...
3 failed, 1 passed, 4 errors in 0.14s

% uv run pytest -q
....                                                                     [100%]
4 passed in 21.34s

% aws s3 ls
2026-11-12 08:49:41 emu-demo-4dc2bf03
% aws dynamodb list-tables --query "length(TableNames)"
10
% aws sqs list-queues --query "length(QueueUrls)"
1
% aws configure list | grep access_key
access_key : ****************9D85     : shared-credentials-file : 
% docker stop aws-emulator-9297
aws-emulator-9297
:
:
:
% docker run -d --rm --name aws-emulator-$PORT --user "$(id -u):$(id -g)" --memory=2g --memory-swap=2g \
  -p 127.0.0.1:$PORT:$PORT -e HOME="$HOME" -v "$HOME/.aws/emulator:$HOME/.aws/emulator" \
  aws-emulator -p $PORT --telemetry off --idle-timeout 3600 >/dev/null
% for i in $(seq 30); do
  curl -sf --cacert ~/.aws/emulator/9297/ca.pem https://127.0.0.1:9297/__admin/health && break
  sleep 1
done; echo
ok
% aws s3 ls
% aws dynamodb list-tables --query "length(TableNames)"
0
% aws sqs list-queues
% aws configure list | grep access_key
access_key : ****************2AC6     : shared-credentials-file : 

% QURL=$(aws sqs get-queue-url --queue-name emu-visibility-4dc2bf03 --query QueueUrl --output text)
% aws sqs list-queue-tags --queue-url "$QURL" --output table
--------------------------------------------------------------------------------
|                                 ListQueueTags                                |
+------------------------------------------------------------------------------+
||                                    Tags                                    ||
|+----------+---------------------+-------------------------+-----------------+|
||   owner  |       purpose       |         run_id          |       ttl       ||
|+----------+---------------------+-------------------------+-----------------+|
||  tried-it|  blog-verification  |  emu-20261112-4dc2bf03  |  20261112T0150Z ||
|+----------+---------------------+-------------------------+-----------------+|
% aws sqs delete-queue --queue-url "$QURL" && echo "deleted: $QURL"
deleted: https://sqs.ap-northeast-1.amazonaws.com/111122223333/emu-visibility-4dc2bf03

% aws resourcegroupstaggingapi get-resources --tag-filters Key=run_id,Values=emu-20261112-4dc2bf03 --query "ResourceTagMappingList[].ResourceARN"
[]
% aws sqs list-queues --queue-name-prefix emu- --query "QueueUrls" --output text
None
% aws dynamodb list-tables --query "TableNames[?starts_with(@, 'emu-') || @ == 'ab']"
[]

% docker stop aws-emulator-9297
aws-emulator-9297
% find ~/.aws/emulator -maxdepth 2 | sort
/Users/classmethod/.aws/emulator
/Users/classmethod/.aws/emulator/9297
/Users/classmethod/.aws/emulator/9297.env
% rm ~/.aws/emulator/9297.env && rmdir ~/.aws/emulator/9297 ~/.aws/emulator && echo "removed ~/.aws/emulator"
removed ~/.aws/emulator
% podman machine stop
Machine "podman-machine-default" stopped successfully