start.py

#!/usr/local/bin/python

import jinja2
import os
import sys
import subprocess
import glob
import codecs

# Utility functions
convert = lambda src, dst, environ: open(dst, "w").write(
    jinja2.Template(open(src).read()).render(**environ)
)


def check_arguments(environ, args):
    for argument in args:
        if argument not in environ:
            print("Environment variable %s is mandatory, exiting." % argument)
            sys.exit(2)


def generate_secrets(environ, secrets):
    for name, secret in secrets.items():
        if secret not in environ:
            filename = "/data/%s.%s.key" % (environ["SYNAPSE_SERVER_NAME"], name)
            if os.path.exists(filename):
                with open(filename) as handle:
                    value = handle.read()
            else:
                print("Generating a random secret for {}".format(name))
                value = codecs.encode(os.urandom(32), "hex").decode()
                with open(filename, "w") as handle:
                    handle.write(value)
            environ[secret] = value


# Prepare the configuration
mode = sys.argv[1] if len(sys.argv) > 1 else None
environ = os.environ.copy()
ownership = "{}:{}".format(environ.get("UID", 991), environ.get("GID", 991))
args = ["python", "-m", "synapse.app.homeserver"]

# In generate mode, generate a configuration, missing keys, then exit
if mode == "generate":
    check_arguments(
        environ, ("SYNAPSE_SERVER_NAME", "SYNAPSE_REPORT_STATS", "SYNAPSE_CONFIG_PATH")
    )
    args += [
        "--server-name",
        environ["SYNAPSE_SERVER_NAME"],
        "--report-stats",
        environ["SYNAPSE_REPORT_STATS"],
        "--config-path",
        environ["SYNAPSE_CONFIG_PATH"],
        "--generate-config",
    ]
    os.execv("/usr/local/bin/python", args)

# In normal mode, generate missing keys if any, then run synapse
else:
    if "SYNAPSE_CONFIG_PATH" in environ:
        config_path = environ["SYNAPSE_CONFIG_PATH"]
    else:
        check_arguments(environ, ("SYNAPSE_SERVER_NAME", "SYNAPSE_REPORT_STATS"))
        generate_secrets(
            environ,
            {
                "registration": "SYNAPSE_REGISTRATION_SHARED_SECRET",
                "macaroon": "SYNAPSE_MACAROON_SECRET_KEY",
            },
        )
        environ["SYNAPSE_APPSERVICES"] = glob.glob("/data/appservices/*.yaml")
        if not os.path.exists("/compiled"):
            os.mkdir("/compiled")

        config_path = "/compiled/homeserver.yaml"

        # Convert SYNAPSE_NO_TLS to boolean if exists
        if "SYNAPSE_NO_TLS" in environ:
            tlsanswerstring = str.lower(environ["SYNAPSE_NO_TLS"])
            if tlsanswerstring in ("true", "on", "1", "yes"):
                environ["SYNAPSE_NO_TLS"] = True
            else:
                if tlsanswerstring in ("false", "off", "0", "no"):
                    environ["SYNAPSE_NO_TLS"] = False
                else:
                    print(
                        'Environment variable "SYNAPSE_NO_TLS" found but value "'
                        + tlsanswerstring
                        + '" unrecognized; exiting.'
                    )
                    sys.exit(2)

        convert("/conf/homeserver.yaml", config_path, environ)
        convert("/conf/log.config", "/compiled/log.config", environ)
        subprocess.check_output(["chown", "-R", ownership, "/data"])

    args += [
        "--config-path",
        config_path,
        # tell synapse to put any generated keys in /data rather than /compiled
        "--keys-directory",
        "/data",
    ]

    # Generate missing keys and start synapse
    subprocess.check_output(args + ["--generate-keys"])
    os.execv("/sbin/su-exec", ["su-exec", ownership] + args)