Docker: avoid changing userid unnecessarily (#11209)

* Docker image: avoid changing user during `generate`

The intention was always that the config files get written as the initial user
(normally root) - only the data directory needs to be writable by Synapse. This
got changed in https://github.com/matrix-org/synapse/pull/5970, but that seems
to have been a mistake.

* Avoid changing user if no explicit UID is given

* changelog
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Richard van der Hoff 2021-11-01 13:55:30 +00:00 committed by GitHub
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commit 0b99d4c8d2
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3 changed files with 28 additions and 23 deletions

1
changelog.d/11209.docker Normal file
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@ -0,0 +1 @@
Avoid changing userid when started as a non-root user, and no explicit `UID` is set.

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@ -65,7 +65,8 @@ The following environment variables are supported in `generate` mode:
* `SYNAPSE_DATA_DIR`: where the generated config will put persistent data
such as the database and media store. Defaults to `/data`.
* `UID`, `GID`: the user id and group id to use for creating the data
directories. Defaults to `991`, `991`.
directories. If unset, and no user is set via `docker run --user`, defaults
to `991`, `991`.
## Running synapse
@ -97,7 +98,9 @@ The following environment variables are supported in `run` mode:
`<SYNAPSE_CONFIG_DIR>/homeserver.yaml`.
* `SYNAPSE_WORKER`: module to execute, used when running synapse with workers.
Defaults to `synapse.app.homeserver`, which is suitable for non-worker mode.
* `UID`, `GID`: the user and group id to run Synapse as. Defaults to `991`, `991`.
* `UID`, `GID`: the user and group id to run Synapse as. If unset, and no user
is set via `docker run --user`, defaults to `991`, `991`. Note that this user
must have permission to read the config files, and write to the data directories.
* `TZ`: the [timezone](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones) the container will run with. Defaults to `UTC`.
For more complex setups (e.g. for workers) you can also pass your args directly to synapse using `run` mode. For example like this:

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@ -120,6 +120,7 @@ def generate_config_from_template(config_dir, config_path, environ, ownership):
]
if ownership is not None:
log(f"Setting ownership on /data to {ownership}")
subprocess.check_output(["chown", "-R", ownership, "/data"])
args = ["gosu", ownership] + args
@ -144,12 +145,18 @@ def run_generate_config(environ, ownership):
config_path = environ.get("SYNAPSE_CONFIG_PATH", config_dir + "/homeserver.yaml")
data_dir = environ.get("SYNAPSE_DATA_DIR", "/data")
if ownership is not None:
# make sure that synapse has perms to write to the data dir.
log(f"Setting ownership on {data_dir} to {ownership}")
subprocess.check_output(["chown", ownership, data_dir])
# create a suitable log config from our template
log_config_file = "%s/%s.log.config" % (config_dir, server_name)
if not os.path.exists(log_config_file):
log("Creating log config %s" % (log_config_file,))
convert("/conf/log.config", log_config_file, environ)
# generate the main config file, and a signing key.
args = [
"python",
"-m",
@ -168,29 +175,23 @@ def run_generate_config(environ, ownership):
"--open-private-ports",
]
# log("running %s" % (args, ))
if ownership is not None:
# make sure that synapse has perms to write to the data dir.
subprocess.check_output(["chown", ownership, data_dir])
args = ["gosu", ownership] + args
os.execv("/usr/sbin/gosu", args)
else:
os.execv("/usr/local/bin/python", args)
def main(args, environ):
mode = args[1] if len(args) > 1 else "run"
desired_uid = int(environ.get("UID", "991"))
desired_gid = int(environ.get("GID", "991"))
synapse_worker = environ.get("SYNAPSE_WORKER", "synapse.app.homeserver")
if (desired_uid == os.getuid()) and (desired_gid == os.getgid()):
ownership = None
else:
ownership = "{}:{}".format(desired_uid, desired_gid)
if ownership is None:
log("Will not perform chmod/gosu as UserID already matches request")
# if we were given an explicit user to switch to, do so
ownership = None
if "UID" in environ:
desired_uid = int(environ["UID"])
desired_gid = int(environ.get("GID", "991"))
ownership = f"{desired_uid}:{desired_gid}"
elif os.getuid() == 0:
# otherwise, if we are running as root, use user 991
ownership = "991:991"
synapse_worker = environ.get("SYNAPSE_WORKER", "synapse.app.homeserver")
# In generate mode, generate a configuration and missing keys, then exit
if mode == "generate":