AWS ECS Fargateにおいて、タスク内でコンテナ間通信ができない

前提・実現したいこと

ECS Fargate上でシンプルなLAMPアプリを動かしたい

発生している問題・エラーメッセージ

PHP（Laravel）コンテナからMariadbコンテナへアクセスができない

（ECS Execでphp artisan migrateでも同じエラー）

こちらの記事では、同じタスク内においてはlocalhostで通信ができるようですが、アクセスができなく困っております。

SQLSTATE[HY000] [2002] No such file or directory (SQL: ・・・

該当のインフラ定義

Laravel・MariaDB両者のコンテナはビルドしたDockerfileをECRで管理

*現状、ツッコミどころが色々ありますが、まずは動かすことを目的にしているので、余計な部分もあります。

Laravel-Dockerfile

FROM php:7.4.24-apache

#install all the system dependencies and enable PHP modules 
RUN apt-get update \
  && apt-get install -y zlib1g-dev \
  && apt-get install -y zip unzip \
  && apt-get -y install libzip-dev libonig-dev \
  && docker-php-ext-install pdo_mysql mysqli zip \
  && docker-php-ext-enable mysqli \
  && a2enmod rewrite

# タイムゾーン設定
ENV TZ=Asia/Tokyo

# cronのインストール
RUN apt-get update && apt-get install -y \
  busybox-static \
  && apt-get clean

#install composer
RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/bin/ --filename=composer
ENV COMPOSER_ALLOW_SUPERUSER 1
ENV COMPOSER_HOME /composer
ENV PATH $PATH:/composer/vendor/bin

#set our application folder as an environment variable
ENV APP_HOME /var/www/html

#change uid and gid of apache to docker user uid/gid
RUN usermod -u 1000 www-data && groupmod -g 1000 www-data

COPY ./php/vhost.conf /etc/apache2/conf-enabled/vhost.conf

# enable apache module rewrite
RUN a2enmod rewrite

#copy source files and run composer
COPY . $APP_HOME

RUN mkdir bootstrap/sessions
#RUN mkdir storage/framework/sessions && \
#    mkdir storage/framework/views && \
#    mkdir storage/framework/cache

# install all PHP dependencies
RUN composer install --no-dev --no-interaction

#change ownership of our applications
RUN chown -R www-data:www-data $APP_HOME
#    chmod -R 0777 bootstrap && \
 #   chmod -R 0777 storage
RUN mv .env.production .env

EXPOSE 80

MariaDB-Dockerfile

FROM mariadb:10.4

ENV MYSQL_USER=dbuser \
    MYSQL_PASSWORD=**** \
    MYSQL_DATABASE=simplememo \
    MYSQL_ROOT_PASSWORD=****

COPY ./init.sql /docker-entrypoint-initdb.d

EXPOSE 3306

タスク定義(ECS)

json
1{
2  "ipcMode": null,
3  "executionRoleArn": "arn:aws:iam::995962138333:role/ecsTaskExecusionRole",
4  "containerDefinitions": [
5    {
6      "dnsSearchDomains": null,
7      "environmentFiles": null,
8      "logConfiguration": {
9        "logDriver": "awslogs",
10        "secretOptions": null,
11        "options": {
12          "awslogs-group": "/ecs/fargate-laravel",
13          "awslogs-region": "ap-northeast-1",
14          "awslogs-stream-prefix": "ecs"
15        }
16      },
17      "entryPoint": null,
18      "portMappings": [
19        {
20          "hostPort": 80,
21          "protocol": "tcp",
22          "containerPort": 80
23        }
24      ],
25      "command": null,
26      "linuxParameters": null,
27      "cpu": 0,
28      "environment": [
29        {
30          "name": "DB_DATABASE",
31          "value": "simplememo"
32        },
33        {
34          "name": "DB_HOST",
35          "value": "localhost"
36        },
37        {
38          "name": "DB_PASSWORD",
39          "value": "simplememodbuse"
40        },
41        {
42          "name": "DB_USER",
43          "value": "dbuser"
44        }
45      ],
46      "resourceRequirements": null,
47      "ulimits": null,
48      "dnsServers": null,
49      "mountPoints": [],
50      "workingDirectory": null,
51      "secrets": null,
52      "dockerSecurityOptions": null,
53      "memory": null,
54      "memoryReservation": 127,
55      "volumesFrom": [],
56      "stopTimeout": null,
57      "image": "995962138333.dkr.ecr.ap-northeast-1.amazonaws.com/laravelecs:latest",
58      "startTimeout": null,
59      "firelensConfiguration": null,
60      "dependsOn": null,
61      "disableNetworking": null,
62      "interactive": null,
63      "healthCheck": null,
64      "essential": true,
65      "links": null,
66      "hostname": null,
67      "extraHosts": null,
68      "pseudoTerminal": null,
69      "user": null,
70      "readonlyRootFilesystem": null,
71      "dockerLabels": null,
72      "systemControls": null,
73      "privileged": null,
74      "name": "laravel"
75    },
76    {
77      "dnsSearchDomains": null,
78      "environmentFiles": null,
79      "logConfiguration": {
80        "logDriver": "awslogs",
81        "secretOptions": null,
82        "options": {
83          "awslogs-group": "/ecs/fargate-laravel",
84          "awslogs-region": "ap-northeast-1",
85          "awslogs-stream-prefix": "ecs"
86        }
87      },
88      "entryPoint": null,
89      "portMappings": [
90        {
91          "hostPort": 3306,
92          "protocol": "tcp",
93          "containerPort": 3306
94        }
95      ],
96      "command": null,
97      "linuxParameters": null,
98      "cpu": 0,
99      "environment": [],
100      "resourceRequirements": null,
101      "ulimits": null,
102      "dnsServers": null,
103      "mountPoints": [],
104      "workingDirectory": null,
105      "secrets": null,
106      "dockerSecurityOptions": null,
107      "memory": null,
108      "memoryReservation": 128,
109      "volumesFrom": [],
110      "stopTimeout": null,
111      "image": "995962138333.dkr.ecr.ap-northeast-1.amazonaws.com/mariadb:latest",
112      "startTimeout": null,
113      "firelensConfiguration": null,
114      "dependsOn": null,
115      "disableNetworking": null,
116      "interactive": null,
117      "healthCheck": null,
118      "essential": true,
119      "links": null,
120      "hostname": null,
121      "extraHosts": null,
122      "pseudoTerminal": null,
123      "user": null,
124      "readonlyRootFilesystem": null,
125      "dockerLabels": null,
126      "systemControls": null,
127      "privileged": null,
128      "name": "mariadb"
129    }
130  ],
131  "placementConstraints": [],
132  "memory": "512",
133  "taskRoleArn": "arn:aws:iam::995962138333:role/ecsTaskExecusionRole",
134  "compatibilities": [
135    "EC2",
136    "FARGATE"
137  ],
138  "taskDefinitionArn": "arn:aws:ecs:ap-northeast-1:995962138333:task-definition/fargate-laravel:4",
139  "family": "fargate-laravel",
140  "requiresAttributes": [
141    {
142      "targetId": null,
143      "targetType": null,
144      "value": null,
145      "name": "com.amazonaws.ecs.capability.logging-driver.awslogs"
146    },
147    {
148      "targetId": null,
149      "targetType": null,
150      "value": null,
151      "name": "ecs.capability.execution-role-awslogs"
152    },
153    {
154      "targetId": null,
155      "targetType": null,
156      "value": null,
157      "name": "com.amazonaws.ecs.capability.ecr-auth"
158    },
159    {
160      "targetId": null,
161      "targetType": null,
162      "value": null,
163      "name": "com.amazonaws.ecs.capability.docker-remote-api.1.19"
164    },
165    {
166      "targetId": null,
167      "targetType": null,
168      "value": null,
169      "name": "com.amazonaws.ecs.capability.docker-remote-api.1.21"
170    },
171    {
172      "targetId": null,
173      "targetType": null,
174      "value": null,
175      "name": "com.amazonaws.ecs.capability.task-iam-role"
176    },
177    {
178      "targetId": null,
179      "targetType": null,
180      "value": null,
181      "name": "ecs.capability.execution-role-ecr-pull"
182    },
183    {
184      "targetId": null,
185      "targetType": null,
186      "value": null,
187      "name": "com.amazonaws.ecs.capability.docker-remote-api.1.18"
188    },
189    {
190      "targetId": null,
191      "targetType": null,
192      "value": null,
193      "name": "ecs.capability.task-eni"
194    }
195  ],
196  "pidMode": null,
197  "requiresCompatibilities": [
198    "FARGATE"
199  ],
200  "networkMode": "awsvpc",
201  "cpu": "256",
202  "revision": 4,
203  "status": "ACTIVE",
204  "inferenceAccelerators": null,
205  "proxyConfiguration": null,
206  "volumes": []
207}