How do I connect to host MySQL from AWS SAM local docker instance?

Question

I am trying to invoke my Lambda function using sam local invoke but find that it cannot connect to my host MySQL. I tried adding --docker-network host but it also cannot connect

Traceback (most recent call last):   File "/usr/lib/python3.6/site-packages/docker/api/client.py", line 229, in _raise_for_status     response.raise_for_status()   File "/usr/lib/python3.6/site-packages/requests/models.py", line 935, in raise_for_status     raise HTTPError(http_error_msg, response=self) requests.exceptions.HTTPError: 400 Client Error: Bad Request for url: http+docker://localhost/v1.35/networks/6ad3bd87e8437e8410145d169a4edf68d1b0247a67257ce7dd1208dac3664c82/connect  During handling of the above exception, another exception occurred:  Traceback (most recent call last):   File "/usr/bin/sam", line 11, in <module>     load_entry_point('aws-sam-cli==0.5.0', 'console_scripts', 'sam')()   File "/usr/lib/python3.6/site-packages/click/core.py", line 722, in __call__     return self.main(*args, **kwargs)   File "/usr/lib/python3.6/site-packages/click/core.py", line 697, in main     rv = self.invoke(ctx)   File "/usr/lib/python3.6/site-packages/click/core.py", line 1066, in invoke     return _process_result(sub_ctx.command.invoke(sub_ctx))   File "/usr/lib/python3.6/site-packages/click/core.py", line 1066, in invoke     return _process_result(sub_ctx.command.invoke(sub_ctx))   File "/usr/lib/python3.6/site-packages/click/core.py", line 895, in invoke     return ctx.invoke(self.callback, **ctx.params)   File "/usr/lib/python3.6/site-packages/click/core.py", line 535, in invoke     return callback(*args, **kwargs)   File "/usr/lib/python3.6/site-packages/click/decorators.py", line 64, in new_func     return ctx.invoke(f, obj, *args[1:], **kwargs)   File "/usr/lib/python3.6/site-packages/click/core.py", line 535, in invoke     return callback(*args, **kwargs)   File "/usr/lib/python3.6/site-packages/samcli/commands/local/invoke/cli.py", line 47, in cli     docker_network, log_file, skip_pull_image, profile)  # pragma: no cover   File "/usr/lib/python3.6/site-packages/samcli/commands/local/invoke/cli.py", line 79, in do_cli     stderr=context.stderr)   File "/usr/lib/python3.6/site-packages/samcli/commands/local/lib/local_lambda.py", line 80, in invoke     stdout=stdout, stderr=stderr)   File "/usr/lib/python3.6/site-packages/samcli/local/lambdafn/runtime.py", line 83, in invoke     self._container_manager.run(container)   File "/usr/lib/python3.6/site-packages/samcli/local/docker/manager.py", line 61, in run     container.create()   File "/usr/lib/python3.6/site-packages/samcli/local/docker/container.py", line 115, in create     network.connect(self.id)   File "/usr/lib/python3.6/site-packages/docker/models/networks.py", line 57, in connect     container, self.id, *args, **kwargs   File "/usr/lib/python3.6/site-packages/docker/utils/decorators.py", line 19, in wrapped     return f(self, resource_id, *args, **kwargs)   File "/usr/lib/python3.6/site-packages/docker/api/network.py", line 248, in connect_container_to_network     self._raise_for_status(res)   File "/usr/lib/python3.6/site-packages/docker/api/client.py", line 231, in _raise_for_status     raise create_api_error_from_http_exception(e)   File "/usr/lib/python3.6/site-packages/docker/errors.py", line 31, in create_api_error_from_http_exception     raise cls(e, response=response, explanation=explanation) docker.errors.APIError: 400 Client Error: Bad Request ("container cannot be disconnected from host network or connected to host network") 

I noticed the last line:

docker.errors.APIError: 400 Client Error: Bad Request ("container cannot be disconnected from host network or connected to host network")

How do I fix this?

Answer 1

I can't say why --docker-network host produces this error, but I don't think you need it. I can connect to MySQL running on my local machine from within SAM local, without any network overrides.

I do this by simply using my local IP (as opposed to localhost or 127.0.0.1) to connect to the database.

The following lambda function connects to my local MySQL just fine, provided I use my local IP, as revealed a tool like ipconfig.

'use strict'; var mysql      = require('mysql'); var connection = mysql.createConnection({   host     : '192.168.1.6',   user     : 'mike',   password : 'password',   database : 'logtest' });  module.exports.hello = (event, context, callback) => {    connection.connect();    connection.query('SELECT 1 + 1 AS solution', function (error, results, fields) {     if (error) throw error;     console.log('The solution is: ', results[0].solution);     const response = {       statusCode: 200,       body: JSON.stringify({solution: results[0].solution})     };      connection.end();      callback(null, response);       }); }; 

Partial ipconfig output:

Ethernet adapter Local Area Connection 6:     Connection-specific DNS Suffix  . :    Link-local IPv6 Address . . . . . : fe80::95c2:495c:7226:8ac2%39    IPv4 Address. . . . . . . . . . . : 10.251.19.6    Subnet Mask . . . . . . . . . . . : 255.255.255.0    Default Gateway . . . . . . . . . :  Wireless LAN adapter Wireless Network Connection:     Connection-specific DNS Suffix  . :    Link-local IPv6 Address . . . . . : fe80::496a:d34d:8380:3b1c%15    IPv4 Address. . . . . . . . . . . : 192.168.1.6    Subnet Mask . . . . . . . . . . . : 255.255.255.0    Default Gateway . . . . . . . . . : 192.168.1.1 

In this case, my lambda function can connect to local MySQL using 10.251.19.6 or 192.168.1.6.

Minimal example here.