Use docker exec to create database backups

.travis.yml

@@ -4,7 +4,7 @@ sudo: false
 
 matrix:
   include:
-      python: 3.7
+      python: 3.8
       dist: bionic
       sudo: true
 

src/restic_compose_backup/cli.py

@@ -105,10 +105,10 @@ def status(config, containers):
             logger.info(
                 ' - %s (is_ready=%s) -> %s',
                 instance.container_type,
-                ping == 0,
+                ping,
                 instance.backup_destination_path(),
             )
-            if ping != 0:
+            if not ping:
                 logger.error("Database '%s' in service %s cannot be reached",
                              instance.container_type, container.service_name)
 

src/restic_compose_backup/commands.py

@@ -1,52 +1,66 @@
 import logging
-from typing import List, Tuple
+from typing import List, Tuple, Union
 from subprocess import Popen, PIPE
 
+from restic_compose_backup import utils
+
 logger = logging.getLogger(__name__)
 
 
 def test():
     return run(['ls', '/volumes'])
 
 
-def ping_mysql(host, port, username) -> int:
+def ping_mysql(container_id, host, port, username, password) -> int:
     """Check if the mysql is up and can be reached"""
-    return run([
+    return docker_exec(container_id, [
         'mysqladmin',
         'ping',
-        '--host',
-        host,
-        '--port',
-        port,
         '--user',
         username,
-    ])
+    ], environment={
+        'MYSQL_PWD': password
+    })
 
 
-def ping_mariadb(host, port, username) -> int:
+def ping_mariadb(container_id, host, port, username, password) -> int:
     """Check if the mariadb is up and can be reached"""
-    return run([
+    return docker_exec(container_id, [
         'mysqladmin',
         'ping',
-        '--host',
-        host,
-        '--port',
-        port,
         '--user',
         username,
-    ])
+    ], environment={
+        'MYSQL_PWD': password
+    })
 
 
-def ping_postgres(host, port, username, password) -> int:
+def ping_postgres(container_id, host, port, username, password) -> int:
     """Check if postgres can be reached"""
-    return run([
+    return docker_exec(container_id, [
         "pg_isready",
         f"--host={host}",
         f"--port={port}",
         f"--username={username}",
     ])
 
 
+def docker_exec(container_id: str, cmd: List[str], environment: Union[dict, list] = []) -> int:
+    """Execute a command within the given container"""
+    client = utils.docker_client()
+    logger.debug('docker exec inside %s: %s', container_id, ' '.join(cmd))
+    exit_code, (stdout, stderr) = client.containers.get(container_id).exec_run(cmd, demux=True, environment=environment)
+
+    if stdout:
+        log_std('stdout', stdout.decode(),
+                logging.DEBUG if exit_code == 0 else logging.ERROR)
+
+    if stderr:
+        log_std('stderr', stderr.decode(), logging.ERROR)
+
+    return exit_code
+
+
 def run(cmd: List[str]) -> int:
     """Run a command with parameters"""
     logger.debug('cmd: %s', ' '.join(cmd))

src/restic_compose_backup/containers_db.py

@@ -25,20 +25,19 @@ def ping(self) -> bool:
         """Check the availability of the service"""
         creds = self.get_credentials()
 
-        with utils.environment('MYSQL_PWD', creds['password']):
-            return commands.ping_mariadb(
-                creds['host'],
-                creds['port'],
-                creds['username'],
-            )
+        return commands.ping_mariadb(
+            self.id,
+            creds['host'],
+            creds['port'],
+            creds['username'],
+            creds['password']
+        ) == 0
 
     def dump_command(self) -> list:
         """list: create a dump command restic and use to send data through stdin"""
         creds = self.get_credentials()
         return [
             "mysqldump",
-            f"--host={creds['host']}",
-            f"--port={creds['port']}",
             f"--user={creds['username']}",
             "--all-databases",
         ]
@@ -47,12 +46,15 @@ def backup(self):
         config = Config()
         creds = self.get_credentials()
 
-        with utils.environment('MYSQL_PWD', creds['password']):
-            return restic.backup_from_stdin(
-                config.repository,
-                self.backup_destination_path(),
-                self.dump_command(),
-            )
+        return restic.backup_from_stdin(
+            config.repository,
+            self.backup_destination_path(),
+            self.id,
+            self.dump_command(),
+            environment={
+                'MYSQL_PWD': creds['password']
+            }
+        )
 
     def backup_destination_path(self) -> str:
         destination = Path("/databases")
@@ -84,20 +86,19 @@ def ping(self) -> bool:
         """Check the availability of the service"""
         creds = self.get_credentials()
 
-        with utils.environment('MYSQL_PWD', creds['password']):
-            return commands.ping_mysql(
-                creds['host'],
-                creds['port'],
-                creds['username'],
-            )
+        return commands.ping_mysql(
+            self.id,
+            creds['host'],
+            creds['port'],
+            creds['username'],
+            creds['password']
+        ) == 0
 
     def dump_command(self) -> list:
         """list: create a dump command restic and use to send data through stdin"""
         creds = self.get_credentials()
         return [
             "mysqldump",
-            f"--host={creds['host']}",
-            f"--port={creds['port']}",
             f"--user={creds['username']}",
             "--all-databases",
         ]
@@ -106,12 +107,15 @@ def backup(self):
         config = Config()
         creds = self.get_credentials()
 
-        with utils.environment('MYSQL_PWD', creds['password']):
-            return restic.backup_from_stdin(
-                config.repository,
-                self.backup_destination_path(),
-                self.dump_command(),
-            )
+        return restic.backup_from_stdin(
+            config.repository,
+            self.backup_destination_path(),
+            self.id,
+            self.dump_command(),
+            environment={
+                "MYSQL_PWD": creds['password']
+            }
+        )
 
     def backup_destination_path(self) -> str:
         destination = Path("/databases")
@@ -144,34 +148,32 @@ def ping(self) -> bool:
         """Check the availability of the service"""
         creds = self.get_credentials()
         return commands.ping_postgres(
+            self.id,
             creds['host'],
             creds['port'],
             creds['username'],
             creds['password'],
-        )
+        ) == 0
 
     def dump_command(self) -> list:
         """list: create a dump command restic and use to send data through stdin"""
         # NOTE: Backs up a single database from POSTGRES_DB env var
         creds = self.get_credentials()
         return [
             "pg_dump",
-            f"--host={creds['host']}",
-            f"--port={creds['port']}",
             f"--username={creds['username']}",
             creds['database'],
         ]
 
     def backup(self):
         config = Config()
-        creds = self.get_credentials()
 
-        with utils.environment('PGPASSWORD', creds['password']):
-            return restic.backup_from_stdin(
-                config.repository,
-                self.backup_destination_path(),
-                self.dump_command(),
-            )
+        return restic.backup_from_stdin(
+            config.repository,
+            self.backup_destination_path(),
+            self.id,
+            self.dump_command(),
+        )
 
     def backup_destination_path(self) -> str:
         destination = Path("/databases")

src/restic_compose_backup/restic.py

@@ -2,9 +2,10 @@
 Restic commands
 """
 import logging
-from typing import List, Tuple
+from typing import List, Tuple, Union
 from subprocess import Popen, PIPE
 from restic_compose_backup import commands
+from restic_compose_backup import utils
 
 logger = logging.getLogger(__name__)
 
@@ -27,9 +28,10 @@ def backup_files(repository: str, source='/volumes'):
     ]))
 
 
-def backup_from_stdin(repository: str, filename: str, source_command: List[str]):
+def backup_from_stdin(repository: str, filename: str, container_id: str,
+                      source_command: List[str], environment: Union[dict, list] = None):
     """
-    Backs up from stdin running the source_command passed in.
+    Backs up from stdin running the source_command passed in within the given container.
     It will appear in restic with the filename (including path) passed in.
     """
     dest_command = restic(repository, [
@@ -39,20 +41,43 @@ def backup_from_stdin(repository: str, filename: str, source_command: List[str])
         filename,
     ])
 
-    # pipe source command into dest command
-    source_process = Popen(source_command, stdout=PIPE, bufsize=65536)
-    dest_process = Popen(dest_command, stdin=source_process.stdout, stdout=PIPE, stderr=PIPE, bufsize=65536)
+    client = utils.docker_client()
+
+    logger.debug('docker exec inside %s: %s', container_id, ' '.join(source_command))
+
+    # Create and start source command inside the given container
+    handle = client.api.exec_create(container_id, source_command, environment=environment)
+    exec_id = handle["Id"]
+    stream = client.api.exec_start(exec_id, stream=True, demux=True)
+    source_stderr = ""
+
+    # Create the restic process to receive the output of the source command
+    dest_process = Popen(dest_command, stdin=PIPE, stdout=PIPE, stderr=PIPE, bufsize=65536)
+
+    # Send the ouptut of the source command over to restic in the chunks received
+    for stdout_chunk, stderr_chunk in stream:
+        if stdout_chunk:
+            dest_process.stdin.write(stdout_chunk)
+
+        if stderr_chunk:
+            source_stderr += stderr_chunk.decode()
+
+    # Wait for restic to finish
     stdout, stderr = dest_process.communicate()
 
     # Ensure both processes exited with code 0
-    source_exit, dest_exit = source_process.poll(), dest_process.poll()
-    exit_code = 0 if (source_exit == 0 and dest_exit == 0) else 1
+    source_exit = client.api.exec_inspect(exec_id).get("ExitCode")
+    dest_exit = dest_process.poll()
+    exit_code = source_exit or dest_exit
 
     if stdout:
         commands.log_std('stdout', stdout, logging.DEBUG if exit_code == 0 else logging.ERROR)
 
+    if source_stderr:
+        commands.log_std(f'stderr ({source_command[0]})', source_stderr, logging.ERROR)
+
     if stderr:
-        commands.log_std('stderr', stderr, logging.ERROR)
+        commands.log_std('stderr (restic)', stderr, logging.ERROR)
 
     return exit_code
 

src/restic_compose_backup/utils.py

@@ -3,6 +3,7 @@
 from typing import List, TYPE_CHECKING
 from contextlib import contextmanager
 import docker
+from docker import DockerClient
 
 if TYPE_CHECKING:
     from restic_compose_backup.containers import Container
@@ -12,7 +13,7 @@
 TRUE_VALUES = ['1', 'true', 'True', True, 1]
 
 
-def docker_client():
+def docker_client() -> DockerClient:
     """
     Create a docker client from the following environment variables::
 

tox.ini

@@ -53,4 +53,4 @@ norecursedirs = tests/* .venv/* .tox/* build/ docs/
 ignore = H405,D100,D101,D102,D103,D104,D105,D200,D202,D203,D204,D205,D211,D301,D400,D401,W503
 show-source = True
 max-line-length = 120
-exclude = .tox,env,tests,build,conf.py
+exclude = .tox,env,tests,build,conf.py,.venv