[DPE-2561] POC - Start with provided config option: config-server, sh…

…ard (#246)

This PR enables the user to pass the following config options:
`replication`(default), `shard`, and `config-server`. This PR supports
this options by starting the charm as a `shard` or a `config-server`. If
the config option `config-server` is provided, then the charm starts an
internal `mongos` service that runs on 0.0.0.0 and is configured to the
provided config server.

As a POC there are not tests included in this PR. Testing was performed
by hand with:
```
charmcraft pack
juju deploy ./*charm --config role="shard" shard-one
juju deploy ./*charm --config role="config-server" config-server

watch -n1 --color juju status --color

juju ssh shard-one/0
systemctl status snap.charmed-mongodb.mongod.service
exit
juju ssh config-server/0
systemctl status snap.charmed-mongodb.mongod.service
systemctl status snap.charmed-mongodb.mongos.service
exit
```

New snap revison packages a new version of the PBM tool which updated
how errors were handled when querying PBM status, commit
[4bf9d5f](4bf9d5f)
reflects these necessary changes

Follow up PR is to be made immediately after merging of this feature is
completed and is a requirement of finishing
[DPE-2561](https://warthogs.atlassian.net/browse/DPE-2561). For this PR
this will be starting `mongos` with a `--auth` and the same `--keyFile`
used to start the`mongod` service

Future PR is to be started after the follow up PR has been made. Once
`mongos` is started with auth
[DPE-2562](https://warthogs.atlassian.net/browse/DPE-2562) will be
started. This includes creating a basic shared library between
`config-server` and `shard` components. In this PR we will:
- implement keyfile sharing across shard and config server components
- implement adding shards to cluster

(Shard removal is saved for later.)

As a POC this PR doesn't include handling edge cases, intelligent status
reporting, unit tests, or integration tests. These will be handled later
on down the line. Specifically:
1. block config change events for changing role of charm
2. report status of internal `mongos` in `update_status`
3. unit tests and integration tests

[DPE-2561]:
https://warthogs.atlassian.net/browse/DPE-2561?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ

---------

Co-authored-by: Pedro Guimaraes <[email protected]>

lib/charms/mongodb/v1/helpers.py

@@ -1,14 +1,13 @@
 """Simple functions, which can be used in both K8s and VM charms."""
 # Copyright 2023 Canonical Ltd.
 # See LICENSE file for licensing details.
-from ctypes import Union
 import json
 import logging
 import os
 import secrets
 import string
 import subprocess
-from typing import List, Optional
+from typing import List
 
 from charms.mongodb.v0.mongodb import MongoDBConfiguration, MongoDBConnection
 from ops.model import (
@@ -243,24 +242,6 @@ def copy_licenses_to_unit():
     )
 
 
-_StrOrBytes = Union[str, bytes]
-
-
-def process_pbm_error(error_string: Optional[_StrOrBytes]) -> str:
-    """Parses pbm error string and returns a user friendly message."""
-    message = "couldn't configure s3 backup option"
-    if not error_string:
-        return message
-    if type(error_string) is bytes:
-        error_string = error_string.decode("utf-8")
-    if "status code: 403" in error_string:  # type: ignore
-        message = "s3 credentials are incorrect."
-    elif "status code: 404" in error_string:  # type: ignore
-        message = "s3 configurations are incompatible."
-    elif "status code: 301" in error_string:  # type: ignore
-        message = "s3 configurations are incompatible."
-    return message
-
 def current_pbm_op(pbm_status: str) -> str:
     """Parses pbm status for the operation that pbm is running."""
     pbm_status = json.loads(pbm_status)
@@ -285,4 +266,4 @@ def process_pbm_status(pbm_status: str) -> StatusBase:
     if current_op["type"] == "resync":
         return WaitingStatus("waiting to sync s3 configurations.")
 
-    return ActiveStatus()
+    return ActiveStatus()

lib/charms/mongodb/v1/mongodb_backups.py

@@ -681,7 +681,6 @@ def process_pbm_error(self, pbm_status: Optional[_StrOrBytes]) -> str:
         """Returns errors found in PBM status."""
         if type(pbm_status) is bytes:
             pbm_status = pbm_status.decode("utf-8")
-
         try:
             error_message = self.retrieve_error_message(json.loads(pbm_status))
         except json.decoder.JSONDecodeError:

src/charm.py

@@ -1377,4 +1377,4 @@ class EarlyRemovalOfConfigServerError(Exception):
 
 
 if __name__ == "__main__":
-    main(MongodbOperatorCharm)
+    main(MongodbOperatorCharm)

src/config.py

@@ -86,4 +86,4 @@ class Secrets:
         SECRET_KEYFILE_NAME = "keyfile"
         SECRET_INTERNAL_LABEL = "internal-secret"
         SECRET_DELETED_LABEL = "None"
-        MAX_PASSWORD_LENGTH = 4096
+        MAX_PASSWORD_LENGTH = 4096

src/machine_helpers.py

@@ -46,4 +46,4 @@ def add_args_to_env(var: str, args: str):
         env_vars.append(f"{var}={args}")
 
     with open(Config.ENV_VAR_PATH, "w") as service_file:
-        service_file.writelines(env_vars)
+        service_file.writelines(env_vars)