Bash script for creating multiple stream writers (#13271)

Add another bash script to the contrib directory. It creates multiple stream writers and also prints out the example configuration for homeserver.yaml.

Signed-off-by: Ville Petteri Huh.

changelog.d/13271.doc

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+Add another `contrib` script to help set up worker processes. Contributed by @villepeh.

contrib/workers-bash-scripts/create-multiple-generic-workers.md

@@ -1,4 +1,4 @@
-# Creating multiple workers with a bash script
+# Creating multiple generic workers with a bash script
 
 Setting up multiple worker configuration files manually can be time-consuming.
 You can alternatively create multiple worker configuration files with a simple `bash` script. For example:

contrib/workers-bash-scripts/create-multiple-stream-writers.md

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+# Creating multiple stream writers with a bash script
+
+This script creates multiple [stream writer](https://github.com/matrix-org/synapse/blob/develop/docs/workers.md#stream-writers) workers.
+
+Stream writers require both replication and HTTP listeners.
+
+It also prints out the example lines for Synapse main configuration file.
+
+Remember to route necessary endpoints directly to a worker associated with it.
+
+If you run the script as-is, it will create workers with the replication listener starting from port 8034 and another, regular http listener starting from 8044. If you don't need all of the stream writers listed in the script, just remove them from the ```STREAM_WRITERS``` array.
+
+```sh
+#!/bin/bash
+
+# Start with these replication and http ports.
+# The script loop starts with the exact port and then increments it by one.
+REP_START_PORT=8034
+HTTP_START_PORT=8044
+
+# Stream writer workers to generate. Feel free to add or remove them as you wish.
+# Event persister ("events") isn't included here as it does not require its
+# own HTTP listener.
+
+STREAM_WRITERS+=( "presence" "typing" "receipts" "to_device" "account_data" )
+
+NUM_WRITERS=$(expr ${#STREAM_WRITERS[@]})
+
+i=0
+
+while [ $i -lt "$NUM_WRITERS" ]
+do
+cat << EOF > ${STREAM_WRITERS[$i]}_stream_writer.yaml
+worker_app: synapse.app.generic_worker
+worker_name: ${STREAM_WRITERS[$i]}_stream_writer
+
+# The replication listener on the main synapse process.
+worker_replication_host: 127.0.0.1
+worker_replication_http_port: 9093
+
+worker_listeners:
+  - type: http
+    port: $(expr $REP_START_PORT + $i)
+    resources:
+      - names: [replication]
+
+  - type: http
+    port: $(expr $HTTP_START_PORT + $i)
+    resources:
+      - names: [client]
+
+worker_log_config: /etc/matrix-synapse/stream-writer-log.yaml
+EOF
+HOMESERVER_YAML_INSTANCE_MAP+=$"  ${STREAM_WRITERS[$i]}_stream_writer:
+    host: 127.0.0.1
+    port: $(expr $REP_START_PORT + $i)
+"
+
+HOMESERVER_YAML_STREAM_WRITERS+=$"  ${STREAM_WRITERS[$i]}: ${STREAM_WRITERS[$i]}_stream_writer
+"
+
+((i++))
+done
+
+cat << EXAMPLECONFIG
+# Add these lines to your homeserver.yaml.
+# Don't forget to configure your reverse proxy and
+# necessary endpoints to their respective worker.
+
+# See https://github.com/matrix-org/synapse/blob/develop/docs/workers.md
+# for more information.
+
+# Remember: Under NO circumstances should the replication
+# listener be exposed to the public internet;
+# it has no authentication and is unencrypted.
+
+instance_map:
+$HOMESERVER_YAML_INSTANCE_MAP
+stream_writers:
+$HOMESERVER_YAML_STREAM_WRITERS
+EXAMPLECONFIG
+```
+
+Copy the code above save it to a file ```create_stream_writers.sh``` (for example).
+
+Make the script executable by running ```chmod +x create_stream_writers.sh```.
+
+## Run the script to create workers and print out a sample configuration
+
+Simply run the script to create YAML files in the current folder and print out the required configuration for ```homeserver.yaml```.
+
+```console
+$ ./create_stream_writers.sh
+
+# Add these lines to your homeserver.yaml.
+# Don't forget to configure your reverse proxy and
+# necessary endpoints to their respective worker.
+
+# See https://github.com/matrix-org/synapse/blob/develop/docs/workers.md
+# for more information
+
+# Remember: Under NO circumstances should the replication
+# listener be exposed to the public internet;
+# it has no authentication and is unencrypted.
+
+instance_map:
+  presence_stream_writer:
+    host: 127.0.0.1
+    port: 8034
+  typing_stream_writer:
+    host: 127.0.0.1
+    port: 8035
+  receipts_stream_writer:
+    host: 127.0.0.1
+    port: 8036
+  to_device_stream_writer:
+    host: 127.0.0.1
+    port: 8037
+  account_data_stream_writer:
+    host: 127.0.0.1
+    port: 8038
+
+stream_writers:
+  presence: presence_stream_writer
+  typing: typing_stream_writer
+  receipts: receipts_stream_writer
+  to_device: to_device_stream_writer
+  account_data: account_data_stream_writer
+```
+
+Simply copy-and-paste the output to an appropriate place in your Synapse main configuration file.
+
+## Write directly to Synapse configuration file
+
+You could also write the output directly to homeserver main configuration file. **This, however, is not recommended** as even a small typo (such as replacing >> with >) can erase the entire ```homeserver.yaml```. 
+
+If you do this, back up your original configuration file first:
+
+```console
+# Back up homeserver.yaml first
+cp /etc/matrix-synapse/homeserver.yaml /etc/matrix-synapse/homeserver.yaml.bak 
+
+# Create workers and write output to your homeserver.yaml
+./create_stream_writers.sh >> /etc/matrix-synapse/homeserver.yaml 
+```