From 5d6f4494b6e26c5ff43025669910fed8ebe7d95d Mon Sep 17 00:00:00 2001
From: Michael Kaye <1917473+michaelkaye@users.noreply.github.com>
Date: Tue, 10 Sep 2019 14:53:18 +0100
Subject: [PATCH 1/3] Allow passing SYNAPSE_WORKER envvar

---
 docker/start.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/docker/start.py b/docker/start.py
index 260f2d9943ed..e41ea20e700f 100755
--- a/docker/start.py
+++ b/docker/start.py
@@ -182,6 +182,7 @@ def main(args, environ):
     mode = args[1] if len(args) > 1 else None
     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:
@@ -245,7 +246,7 @@ def main(args, environ):
 
     log("Starting synapse with config file " + config_path)
 
-    args = ["python", "-m", "synapse.app.homeserver", "--config-path", config_path]
+    args = ["python", "-m", synapse_worker, "--config-path", config_path]
     if ownership is not None:
         args = ["su-exec", ownership] + args
         os.execv("/sbin/su-exec", args)

From 4cd5fe27a03a0fb2e14aa92d1a52388546ffc0e3 Mon Sep 17 00:00:00 2001
From: Michael Kaye <1917473+michaelkaye@users.noreply.github.com>
Date: Wed, 18 Sep 2019 17:21:06 +0100
Subject: [PATCH 2/3] changelog.d

---
 changelog.d/6058.docker | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog.d/6058.docker

diff --git a/changelog.d/6058.docker b/changelog.d/6058.docker
new file mode 100644
index 000000000000..30be6933c981
--- /dev/null
+++ b/changelog.d/6058.docker
@@ -0,0 +1 @@
+Provide SYNAPSE_WORKER envvar to specify python module.

From 6e4271450d13888d6c8ee081833c67f51dbedebe Mon Sep 17 00:00:00 2001
From: Michael Kaye <1917473+michaelkaye@users.noreply.github.com>
Date: Thu, 19 Sep 2019 17:21:03 +0100
Subject: [PATCH 3/3] Document SYNAPSE_WORKER.

Attempting to imply that you don't need to change this default
unless you're in worker mode.

Also aware that there's a bigger problem of attempting to document
a complete working configuration of workers using docker, as we
currently only document to use `synctl` for worker mode, and synctl
doesn't work that way in docker.
---
 docker/README.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/docker/README.md b/docker/README.md
index d5879c2f2cdb..4b712f3f5cf2 100644
--- a/docker/README.md
+++ b/docker/README.md
@@ -89,6 +89,8 @@ The following environment variables are supported in run mode:
   `/data`.
 * `SYNAPSE_CONFIG_PATH`: path to the config file. Defaults to
   `<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`.
 * `TZ`: the [timezone](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones) the container will run with. Defaults to `UTC`.