docker compose mysql works differently on remote server than on windows docker desktop - access denied for user 'root'#'172.18.0.2' - mysql

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Lou K wants to draw more attention to this question.
I have a docker compose set of images with one of them based on mysql. The stack was adapted from https://github.com/docker/awesome-compose/tree/c2f8036fd353dae457eba7b9b436bf3a1c85d937/nginx-flask-mysql
This runs fine on my ("local") Windows 10 docker desktop (docker v20.10.22), but when I try to run it on my ("remote") centos7 server (Docker version 23.0.0, build e92dd87, remote server hosted at digitalocean), I see Access denied for user 'root'#'172.18.0.3' (using password: YES) when trying to connect with the database.
I should note I've seen answers like https://stackoverflow.com/a/59839180/799921, and I have (repeatedly) tried removing the volume on the remote server.
This failure happens whether I use root and MYSQL_ROOT_PASSWORD or MYSQL_USER (user) and MYSQL_PASSWORD. I've verified I can connect to the database from the mysql container, but the app container does not have mysql installed so I haven't been able to manually test the connection from the app container.
Following https://hub.docker.com/_/mysql, "Connect to MySQL from the MySQL command line client", I'm able to connect, so this is a problem with the app according to https://dev.mysql.com/doc/refman/8.0/en/problems-connecting.html, "If you have access problems with a Perl, PHP, Python, or ODBC program, try to connect to the server with mysql -u user_name db_name or mysql -u user_name -ppassword db_name. If you are able to connect using the mysql client, the problem lies with your program", but I'm not sure what.
$ docker run -it --network webmodules_backend-network --rm mysql mysql -hdb -uroot -p
Enter password:
Welcome to the MySQL monitor.
...
I've looked at the mysql.user table on both running versions and nothing jumps out at me as being incorrect.
mysql.user on local:
mysql> select * from mysql.user where user='root';
+-----------+------+-------------+-------------+-------------+-------------+-------------+-----------+-------------+---------------+--------------+-----------+------------+-----------------+------------+------------+--------------+------------+-----------------------+------------------+--------------+-----------------+------------------+------------------+----------------+---------------------+--------------------+------------------+------------+--------------+------------------------+----------+------------------------+--------------------------+----------------------------+---------------+-------------+-----------------+----------------------+-----------------------+-------------------------------------------+------------------+-----------------------+-------------------+----------------+------------------+----------------+------------------------+---------------------+--------------------------+-----------------+
| Host | User | Select_priv | Insert_priv | Update_priv | Delete_priv | Create_priv | Drop_priv | Reload_priv | Shutdown_priv | Process_priv | File_priv | Grant_priv | References_priv | Index_priv | Alter_priv | Show_db_priv | Super_priv | Create_tmp_table_priv | Lock_tables_priv | Execute_priv | Repl_slave_priv | Repl_client_priv | Create_view_priv | Show_view_priv | Create_routine_priv | Alter_routine_priv | Create_user_priv | Event_priv | Trigger_priv | Create_tablespace_priv | ssl_type | ssl_cipher | x509_issuer | x509_subject | max_questions | max_updates | max_connections | max_user_connections | plugin | authentication_string | password_expired | password_last_changed | password_lifetime | account_locked | Create_role_priv | Drop_role_priv | Password_reuse_history | Password_reuse_time | Password_require_current | User_attributes |
+-----------+------+-------------+-------------+-------------+-------------+-------------+-----------+-------------+---------------+--------------+-----------+------------+-----------------+------------+------------+--------------+------------+-----------------------+------------------+--------------+-----------------+------------------+------------------+----------------+---------------------+--------------------+------------------+------------+--------------+------------------------+----------+------------------------+--------------------------+----------------------------+---------------+-------------+-----------------+----------------------+-----------------------+-------------------------------------------+------------------+-----------------------+-------------------+----------------+------------------+----------------+------------------------+---------------------+--------------------------+-----------------+
| % | root | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | | 0x | 0x | 0x | 0 | 0 | 0 | 0 | mysql_native_password | *52594A4243313A7447185F38CB9D3859DDC5FF77 | N | 2023-02-14 21:20:23 | NULL | N | Y | Y | NULL | NULL | NULL | NULL |
| localhost | root | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | | 0x | 0x | 0x | 0 | 0 | 0 | 0 | mysql_native_password | *52594A4243313A7447185F38CB9D3859DDC5FF77 | N | 2023-02-14 21:20:23 | NULL | N | Y | Y | NULL | NULL | NULL | NULL |
+-----------+------+-------------+-------------+-------------+-------------+-------------+-----------+-------------+---------------+--------------+-----------+------------+-----------------+------------+------------+--------------+------------+-----------------------+------------------+--------------+-----------------+------------------+------------------+----------------+---------------------+--------------------+------------------+------------+--------------+------------------------+----------+------------------------+--------------------------+----------------------------+---------------+-------------+-----------------+----------------------+-----------------------+-------------------------------------------+------------------+-----------------------+-------------------+----------------+------------------+----------------+------------------------+---------------------+--------------------------+-----------------+
2 rows in set (0.00 sec)
mysql.user on remote:
mysql> select * from mysql.user where user='root';
+-----------+------+-------------+-------------+-------------+-------------+-------------+-----------+-------------+---------------+--------------+-----------+------------+-----------------+------------+------------+--------------+------------+-----------------------+------------------+--------------+-----------------+------------------+------------------+----------------+---------------------+--------------------+------------------+------------+--------------+------------------------+----------+------------------------+--------------------------+----------------------------+---------------+-------------+-----------------+----------------------+-----------------------+-------------------------------------------+------------------+-----------------------+-------------------+----------------+------------------+----------------+------------------------+---------------------+--------------------------+-----------------+
| Host | User | Select_priv | Insert_priv | Update_priv | Delete_priv | Create_priv | Drop_priv | Reload_priv | Shutdown_priv | Process_priv | File_priv | Grant_priv | References_priv | Index_priv | Alter_priv | Show_db_priv | Super_priv | Create_tmp_table_priv | Lock_tables_priv | Execute_priv | Repl_slave_priv | Repl_client_priv | Create_view_priv | Show_view_priv | Create_routine_priv | Alter_routine_priv | Create_user_priv | Event_priv | Trigger_priv | Create_tablespace_priv | ssl_type | ssl_cipher | x509_issuer | x509_subject | max_questions | max_updates | max_connections | max_user_connections | plugin | authentication_string | password_expired | password_last_changed | password_lifetime | account_locked | Create_role_priv | Drop_role_priv | Password_reuse_history | Password_reuse_time | Password_require_current | User_attributes |
+-----------+------+-------------+-------------+-------------+-------------+-------------+-----------+-------------+---------------+--------------+-----------+------------+-----------------+------------+------------+--------------+------------+-----------------------+------------------+--------------+-----------------+------------------+------------------+----------------+---------------------+--------------------+------------------+------------+--------------+------------------------+----------+------------------------+--------------------------+----------------------------+---------------+-------------+-----------------+----------------------+-----------------------+-------------------------------------------+------------------+-----------------------+-------------------+----------------+------------------+----------------+------------------------+---------------------+--------------------------+-----------------+
| % | root | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | | 0x | 0x | 0x | 0 | 0 | 0 | 0 | mysql_native_password | *CFBC0A14FD2027A55F04E2A65FAF93B5D528800B | N | 2023-02-14 21:22:12 | NULL | N | Y | Y | NULL | NULL | NULL | NULL |
| localhost | root | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | | 0x | 0x | 0x | 0 | 0 | 0 | 0 | mysql_native_password | *CFBC0A14FD2027A55F04E2A65FAF93B5D528800B | N | 2023-02-14 21:22:12 | NULL | N | Y | Y | NULL | NULL | NULL | NULL |
+-----------+------+-------------+-------------+-------------+-------------+-------------+-----------+-------------+---------------+--------------+-----------+------------+-----------------+------------+------------+--------------+------------+-----------------------+------------------+--------------+-----------------+------------------+------------------+----------------+---------------------+--------------------+------------------+------------+--------------+------------------------+----------+------------------------+--------------------------+----------------------------+---------------+-------------+-----------------+----------------------+-----------------------+-------------------------------------------+------------------+-----------------------+-------------------+----------------+------------------+----------------+------------------------+---------------------+--------------------------+-----------------+
2 rows in set (0.01 sec)
This is started with the following on local:
docker compose -f docker-compose.yml -f docker-compose.dev.yml up -d
and on remote (from the local machine):
docker --context webmodules compose -f docker-compose.yml -f docker-compose-prod.yml up -d
where
docker-compose.yml:
version: "3.8"
services:
db:
# https://github.com/docker-library/mysql/issues/275#issuecomment-636831964
image: mysql:8.0.32 # 32 gives access denied on centos7 server for both root and user
# command: '--default-authentication-plugin=mysql_native_password'
command: '--default-authentication-plugin=mysql_native_password --log_error_verbosity=3' # mysql
# restart: always
secrets:
- db-password
- user-password
volumes:
- db-data:/var/lib/mysql
networks:
- backend-network
environment:
- MYSQL_DATABASE=webmodules
- MYSQL_ROOT_PASSWORD_FILE=/run/secrets/db-password
- MYSQL_USER=user
- MYSQL_PASSWORD_FILE=/run/secrets/user-password
app:
build: app
restart: always
secrets:
- db-password
- user-password
networks:
- backend-network
- frontend-network
web:
build: web
restart: always
ports:
- 8000:80
networks:
- frontend-network
volumes:
db-data:
secrets:
db-password:
file: db/password.txt
user-password:
file: db/userpassword.txt
networks:
backend-network:
frontend-network:
docker-compose.dev.yml:
version: '3.8'
services:
app:
ports:
- 5678:5678
volumes:
- ./app/src:/app
environment:
- FLASK_DEBUG=True
docker-compose-prod.yml:
version: '3.8'
secrets:
db-password:
file: /home/appuser/.docker/webmodules-db-password.txt
user-password:
file: /home/appuser/.docker/webmodules-user-password.txt
app/Dockerfile:
# For more information, please refer to https://aka.ms/vscode-docker-python
FROM python:3.9-slim
EXPOSE 5000
# Keeps Python from generating .pyc files in the container
ENV PYTHONDONTWRITEBYTECODE=1
# Turns off buffering for easier container logging
ENV PYTHONUNBUFFERED=1
# set the working directory in the container
WORKDIR /app
# Install pip requirements
COPY requirements.txt .
RUN python -m pip install -r requirements.txt
# copy the content of the local src directory to the working directory
# this isn't needed when developing as there's a bind under volumes: in the docker-compose.dev.yml file
COPY src .
# Creates a non-root user with an explicit UID and adds permission to access the /app folder
# For more info, please refer to https://aka.ms/vscode-docker-python-configure-containers
RUN adduser -u 5678 --disabled-password --gecos "" appuser && chown -R appuser /app
USER appuser
# During debugging, this entry point will be overridden. For more information, please refer to https://aka.ms/vscode-docker-python-debug
CMD ["gunicorn", "--reload", "--bind", "0.0.0.0:5000", "app:app"]
The full log file from the mysql container on remote:
$ docker logs webmodules-db-1
2023-02-15 12:35:06+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 8.0.32-1.el8 started.
2023-02-15 12:35:07+00:00 [Note] [Entrypoint]: Switching to dedicated user 'mysql'
2023-02-15 12:35:07+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 8.0.32-1.el8 started.
'/var/lib/mysql/mysql.sock' -> '/var/run/mysqld/mysqld.sock'
2023-02-15T12:35:08.185441Z 0 [Note] [MY-013667] [Server] Error-log destination "stderr" is not a file. Can not restore error log messages from previous run.
2023-02-15T12:35:08.174478Z 0 [Warning] [MY-011068] [Server] The syntax '--skip-host-cache' is deprecated and will be removed in a future release. Please use SET GLOBAL host_cache_size=0 instead.
2023-02-15T12:35:08.182644Z 0 [Warning] [MY-010918] [Server] 'default_authentication_plugin' is deprecated and will be removed in a future release. Please use authentication_policy instead.
2023-02-15T12:35:08.182660Z 0 [Note] [MY-013932] [Server] BuildID[sha1]=6b049f17400f850658b2eb3ff165ec9a085d9655
2023-02-15T12:35:08.182673Z 0 [Note] [MY-010949] [Server] Basedir set to /usr/.
2023-02-15T12:35:08.182694Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.32) starting as process 1
2023-02-15T12:35:08.195754Z 0 [Note] [MY-012366] [InnoDB] Using Linux native AIO
2023-02-15T12:35:08.195970Z 0 [Note] [MY-010747] [Server] Plugin 'FEDERATED' is disabled.
2023-02-15T12:35:08.196046Z 0 [Note] [MY-010747] [Server] Plugin 'ndbcluster' is disabled.
2023-02-15T12:35:08.196062Z 0 [Note] [MY-010747] [Server] Plugin 'ndbinfo' is disabled.
2023-02-15T12:35:08.196069Z 0 [Note] [MY-010747] [Server] Plugin 'ndb_transid_mysql_connection_map' is disabled.
2023-02-15T12:35:08.197842Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2023-02-15T12:35:08.197887Z 1 [Note] [MY-013546] [InnoDB] Atomic write enabled
2023-02-15T12:35:08.197923Z 1 [Note] [MY-012932] [InnoDB] PUNCH HOLE support available
2023-02-15T12:35:08.197942Z 1 [Note] [MY-012944] [InnoDB] Uses event mutexes
2023-02-15T12:35:08.197948Z 1 [Note] [MY-012945] [InnoDB] GCC builtin __atomic_thread_fence() is used for memory barrier
2023-02-15T12:35:08.197956Z 1 [Note] [MY-012948] [InnoDB] Compressed tables use zlib 1.2.13
2023-02-15T12:35:08.206838Z 1 [Note] [MY-012951] [InnoDB] Using hardware accelerated crc32 and polynomial multiplication.
2023-02-15T12:35:08.207494Z 1 [Note] [MY-012203] [InnoDB] Directories to scan './'
2023-02-15T12:35:08.207577Z 1 [Note] [MY-012204] [InnoDB] Scanning './'
2023-02-15T12:35:08.212659Z 1 [Note] [MY-012208] [InnoDB] Completed space ID check of 4 files.
2023-02-15T12:35:08.213682Z 1 [Note] [MY-012955] [InnoDB] Initializing buffer pool, total size = 128.000000M, instances = 1, chunk size =128.000000M
2023-02-15T12:35:08.228723Z 1 [Note] [MY-012957] [InnoDB] Completed initialization of buffer pool
2023-02-15T12:35:08.385456Z 0 [Note] [MY-011952] [InnoDB] If the mysqld execution user is authorized, page cleaner thread priority can be changed. See the man page of setpriority().
2023-02-15T12:35:08.386138Z 1 [Note] [MY-013532] [InnoDB] Using './#ib_16384_0.dblwr' for doublewrite
2023-02-15T12:35:08.386668Z 1 [Note] [MY-013532] [InnoDB] Using './#ib_16384_1.dblwr' for doublewrite
2023-02-15T12:35:08.432730Z 1 [Note] [MY-013566] [InnoDB] Double write buffer files: 2
2023-02-15T12:35:08.432776Z 1 [Note] [MY-013565] [InnoDB] Double write buffer pages per instance: 4
2023-02-15T12:35:08.432817Z 1 [Note] [MY-013532] [InnoDB] Using './#ib_16384_0.dblwr' for doublewrite
2023-02-15T12:35:08.432849Z 1 [Note] [MY-013532] [InnoDB] Using './#ib_16384_1.dblwr' for doublewrite
2023-02-15T12:35:08.531818Z 1 [Note] [MY-013883] [InnoDB] The latest found checkpoint is at lsn = 31919058 in redo log file ./#innodb_redo/#ib_redo9.
2023-02-15T12:35:08.532211Z 1 [Note] [MY-013086] [InnoDB] Starting to parse redo log at lsn = 31918620, whereas checkpoint_lsn = 31919058 and start_lsn = 31918592
2023-02-15T12:35:08.585369Z 1 [Note] [MY-013083] [InnoDB] Log background threads are being started...
2023-02-15T12:35:08.760113Z 1 [Note] [MY-012532] [InnoDB] Applying a batch of 0 redo log records ...
2023-02-15T12:35:08.760147Z 1 [Note] [MY-012535] [InnoDB] Apply batch completed!
2023-02-15T12:35:08.760387Z 1 [Note] [MY-013252] [InnoDB] Using undo tablespace './undo_001'.
2023-02-15T12:35:08.763735Z 1 [Note] [MY-013252] [InnoDB] Using undo tablespace './undo_002'.
2023-02-15T12:35:08.768232Z 1 [Note] [MY-012910] [InnoDB] Opened 2 existing undo tablespaces.
2023-02-15T12:35:08.768318Z 1 [Note] [MY-011980] [InnoDB] GTID recovery trx_no: 2832
2023-02-15T12:35:08.788140Z 1 [Note] [MY-013777] [InnoDB] Time taken to initialize rseg using 1 thread: 19811 ms.
2023-02-15T12:35:08.788273Z 1 [Note] [MY-012923] [InnoDB] Creating shared tablespace for temporary tables
2023-02-15T12:35:08.788341Z 1 [Note] [MY-012265] [InnoDB] Setting file './ibtmp1' size to 12 MB. Physically writing the file full; Please wait ...
2023-02-15T12:35:08.835413Z 1 [Note] [MY-012266] [InnoDB] File './ibtmp1' size is now 12 MB.
2023-02-15T12:35:08.835602Z 1 [Note] [MY-013627] [InnoDB] Scanning temp tablespace dir:'./#innodb_temp/'
2023-02-15T12:35:09.003141Z 1 [Note] [MY-013018] [InnoDB] Created 128 and tracked 128 new rollback segment(s) in the temporary tablespace. 128 are now active.
2023-02-15T12:35:09.037574Z 1 [Note] [MY-012976] [InnoDB] 8.0.32 started; log sequence number 31919068
2023-02-15T12:35:09.038169Z 1 [System] [MY-013577] [InnoDB] InnoDB initialization has ended.
2023-02-15T12:35:09.046561Z 1 [Note] [MY-011089] [Server] Data dictionary restarting version '80023'.
2023-02-15T12:35:09.184823Z 1 [Note] [MY-012357] [InnoDB] Reading DD tablespace files
2023-02-15T12:35:09.185738Z 1 [Note] [MY-012356] [InnoDB] Scanned 6 tablespaces. Validated 6.
2023-02-15T12:35:09.246031Z 1 [Note] [MY-010006] [Server] Using data dictionary with version '80023'.
2023-02-15T12:35:09.252593Z 0 [Note] [MY-011332] [Server] Plugin mysqlx reported: 'IPv6 is available'
2023-02-15T12:35:09.254590Z 0 [Note] [MY-011323] [Server] Plugin mysqlx reported: 'X Plugin ready for connections. bind-address: '::' port: 33060'
2023-02-15T12:35:09.254626Z 0 [Note] [MY-011323] [Server] Plugin mysqlx reported: 'X Plugin ready for connections. socket: '/var/run/mysqld/mysqlx.sock''
2023-02-15T12:35:09.278358Z 0 [Note] [MY-010902] [Server] Thread priority attribute setting in Resource Group SQL shall be ignored due to unsupported platform or insufficient privilege.
2023-02-15T12:35:09.310954Z 0 [Note] [MY-013911] [Server] Crash recovery finished in binlog engine. No attempts to commit, rollback or prepare any transactions.
2023-02-15T12:35:09.311015Z 0 [Note] [MY-013911] [Server] Crash recovery finished in InnoDB engine. No attempts to commit, rollback or prepare any transactions.
2023-02-15T12:35:09.316319Z 0 [Note] [MY-012487] [InnoDB] DDL log recovery : begin
2023-02-15T12:35:09.316414Z 0 [Note] [MY-012488] [InnoDB] DDL log recovery : end
2023-02-15T12:35:09.322395Z 0 [Note] [MY-011946] [InnoDB] Loading buffer pool(s) from /var/lib/mysql/ib_buffer_pool
2023-02-15T12:35:09.322785Z 0 [Note] [MY-011946] [InnoDB] Buffer pool(s) load completed at 230215 12:35:09
2023-02-15T12:35:09.433353Z 0 [Note] [MY-010913] [Server] You have not provided a mandatory server-id. Servers in a replication topology must have unique server-ids. Please refer to the proper server start-up parameters documentation.
2023-02-15T12:35:09.435029Z 0 [Note] [MY-010182] [Server] Found ca.pem, server-cert.pem and server-key.pem in data directory. Trying to enable SSL support using them.
2023-02-15T12:35:09.435065Z 0 [Note] [MY-010304] [Server] Skipping generation of SSL certificates as certificate files are present in data directory.
2023-02-15T12:35:09.438539Z 0 [Warning] [MY-010068] [Server] CA certificate ca.pem is self signed.
2023-02-15T12:35:09.438584Z 0 [System] [MY-013602] [Server] Channel mysql_main configured to support TLS. Encrypted connections are now supported for this channel.
2023-02-15T12:35:09.438630Z 0 [Note] [MY-010308] [Server] Skipping generation of RSA key pair through --sha256_password_auto_generate_rsa_keys as key files are present in data directory.
2023-02-15T12:35:09.438643Z 0 [Note] [MY-010308] [Server] Skipping generation of RSA key pair through --caching_sha2_password_auto_generate_rsa_keys as key files are present in data directory.
2023-02-15T12:35:09.438802Z 0 [Note] [MY-010252] [Server] Server hostname (bind-address): '*'; port: 3306
2023-02-15T12:35:09.438849Z 0 [Note] [MY-010253] [Server] IPv6 is available.
2023-02-15T12:35:09.438857Z 0 [Note] [MY-010264] [Server] - '::' resolves to '::';
2023-02-15T12:35:09.438885Z 0 [Note] [MY-010251] [Server] Server socket created on IP: '::'.
2023-02-15T12:35:09.440185Z 0 [Warning] [MY-011810] [Server] Insecure configuration for --pid-file: Location '/var/run/mysqld' in the path is accessible to all OS users. Consider choosing a different directory.
2023-02-15T12:35:09.461816Z 0 [Note] [MY-011025] [Repl] Failed to start slave threads for channel ''.
2023-02-15T12:35:09.463840Z 5 [Note] [MY-010051] [Server] Event Scheduler: scheduler thread started with id 5
2023-02-15T12:35:09.464101Z 0 [Note] [MY-011240] [Server] Plugin mysqlx reported: 'Using SSL configuration from MySQL Server'
2023-02-15T12:35:09.464743Z 0 [Note] [MY-011243] [Server] Plugin mysqlx reported: 'Using OpenSSL for TLS connections'
2023-02-15T12:35:09.464917Z 0 [System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.32' socket: '/var/run/mysqld/mysqld.sock' port: 3306 MySQL Community Server - GPL.
2023-02-15T12:35:09.464973Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Bind-address: '::' port: 33060, socket: /var/run/mysqld/mysqlx.sock
2023-02-15T12:36:06.574103Z 8 [Note] [MY-010926] [Server] Access denied for user 'root'#'172.18.0.2' (using password: YES)
And not sure if this is relevant, but the python code is in app.py:
import mysql.connector
from flask import Flask, jsonify
from ptvsd import enable_attach
# enable python visual studio debugger
enable_attach(address=('0.0.0.0', 5678))
app = Flask(__name__)
conn = None
# adapted from https://github.com/aiordache/demos/blob/c7aa37cc3e2f8800296f668138b4cf208b27380a/dockercon2020-demo/app/src/server.py
# similar to https://github.com/docker/awesome-compose/blob/e6b1d2755f2f72a363fc346e52dce10cace846c8/nginx-flask-mysql/backend/hello.py
class DBManager:
def __init__(self, database='example', host="db", user="root", password_file=None):
pf = open(password_file, 'r')
self.connection = mysql.connector.connect(
user=user,
password=pf.read(),
host=host, # name of the mysql service as set in the docker compose file
database=database,
auth_plugin='mysql_native_password'
)
pf.close()
self.cursor = self.connection.cursor()
def populate_db(self):
self.cursor.execute('DROP TABLE IF EXISTS blog')
self.cursor.execute('CREATE TABLE blog (id INT AUTO_INCREMENT PRIMARY KEY, title VARCHAR(255))')
self.cursor.executemany('INSERT INTO blog (id, title) VALUES (%s, %s);', [(i, 'Blog post #%d'% i) for i in range (1,5)])
self.connection.commit()
def query_titles(self):
self.cursor.execute('SELECT title FROM blog')
rec = []
for c in self.cursor:
rec.append(c[0])
return rec
#app.route('/')
def hello_world():
return 'Hello, Docker!'
#app.route('/blogs')
def listBlog():
global conn
if not conn:
conn = DBManager(host='db', database='webmodules', user='root', password_file='/run/secrets/db-password')
conn.populate_db()
rec = conn.query_titles()
result = []
for c in rec:
result.append(c)
return jsonify({"response": result})
if __name__ == "__main__":
app.run(host ='0.0.0.0', port=5000)
my.cnf (local and remote identical):
# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/8.0/en/server-configuration-defaults.html
[mysqld]
#
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
#
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
#
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
# Remove leading # to revert to previous value for default_authentication_plugin,
# this will increase compatibility with older clients. For background, see:
# https://dev.mysql.com/doc/refman/8.0/en/server-system-variables.html#sysvar_default_authentication_plugin
# default-authentication-plugin=mysql_native_password
skip-host-cache
skip-name-resolve
datadir=/var/lib/mysql
socket=/var/run/mysqld/mysqld.sock
secure-file-priv=/var/lib/mysql-files
user=mysql
pid-file=/var/run/mysqld/mysqld.pid
[client]
socket=/var/run/mysqld/mysqld.sock
!includedir /etc/mysql/conf.d/

Answer 1

You should replace the following line in app.py
password=pf.read(),
by this line:
password=pf.read().strip(),
The reason is that python will also read the newline at the end of the file as part of the password string, and mysql will cut that off.
On Windows you might have used an editor which doesn't place a newline at the end of the file or it might have added a carriage return whereas on Linux the line ending is just a linefeed character.
Alternatively you can make sure you password file doesn't contain a newline at the end, but most editors will not allow this.
Using the 'echo -n' command you can achieve this:
> echo -n "bla" >password_no_lf.txt
> od -c < password_no_lf.txt
0000000 b l a
0000003
> echo "bla" >password_with_lf.txt
> od -c < password_with_lf.txt
0000000 b l a \n
0000004