setup: Add certbot support.

The task is to generate a self-signed cert so Zulip can be started, then
to wait until Zulip is up before using certbot to generate new certs.
Zulip needs to be up so it can meet certbot's challenge. Using a deploy
hook, certs are persisted in the data directory. The same applies to
renewal.

Tweaked by tabbott mostly to edit comments remove an unnecessary
setting before merging.

Fixes #120.

Dockerfile

@@ -84,6 +84,7 @@ RUN apt-get -q dist-upgrade -y && \
     rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 
 COPY entrypoint.sh /sbin/entrypoint.sh
+COPY certbot-deploy-hook /sbin/certbot-deploy-hook
 
 VOLUME ["$DATA_DIR"]
 EXPOSE 80 443

README.md

@@ -168,11 +168,11 @@ which you need to encode in the YAML file.  For example,
   comma-separated list of the backend names
   (E.g. `"EmailAuthBackend,GitHubAuthBackend"`).
 
-**SSL Certificates**.  By default, the image will generate a
-  self-signed cert.  We
-  [will soon also support certbot](https://github.com/zulip/docker-zulip/issues/120)
-  for this, just like we do in normal Zulip installations
-  (contributions welcome!).
+**SSL Certificates**.  By default, the image will generate a self-signed cert.
+You can set `SSL_CERTIFICATE_GENERATION: "certbot"` within `docker-compose.yml`
+to enable automatically-renewed Let's Encrypt certificates.  By using certbot
+here, you are agreeing to the [Let's Encrypt
+ToS](https://community.letsencrypt.org/tos).
 
 You can also provide an SSL certificate for your Zulip server by
 putting it in `/opt/docker/zulip/zulip/certs/` (by default, the

certbot-deploy-hook

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+backup() {
+    if [ -e "$1" ]; then
+        # If the user is setting up our automatic certbot-management on a
+        # system that already has certs for Zulip, use some extra caution
+        # to keep the old certs available. This naming is consistent with Zulip's
+        # own setup-certbot backups.
+        mv -f --backup=numbered "$1" "$1".setup-certbot || true
+    fi
+}
+
+source_cert_dir=/etc/letsencrypt/live/"$SETTING_EXTERNAL_HOST"
+dest_cert_dir="$DATA_DIR"/certs
+
+# Persist the certs to the data directory.
+backup "$dest_cert_dir"/zulip.key
+backup "$dest_cert_dir"/zulip.combined-chain.crt
+cp -f "$source_cert_dir"/privkey.pem "$dest_cert_dir"/zulip.key
+cp -f "$source_cert_dir"/fullchain.pem "$dest_cert_dir"/zulip.combined-chain.crt
+
+# Ensure nginx can find them.
+ln -nsf "$dest_cert_dir"/zulip.key /etc/ssl/private/zulip.key
+ln -nsf "$dest_cert_dir"/zulip.combined-chain.crt /etc/ssl/certs/zulip.combined-chain.crt
+
+# Restart various services so the new certs can be used.
+supervisorctl restart nginx

entrypoint.sh

@@ -168,12 +168,18 @@ configureCerts() {
             ;;
     esac
     if [ ! -e "$DATA_DIR/certs/zulip.key" ] && [ ! -e "$DATA_DIR/certs/zulip.combined-chain.crt" ]; then
+
         if [ "$GENERATE_CERTBOT_CERT" = "True" ]; then
-            echo "Certbot not yet supported"
-            exit 1
-            # TODO: Run setup-certbot and move /etc/letsencrypt to the data dir?
-            # /home/zulip/deployments/current/setup/setup-certbot "$SETTING_EXTERNAL_HOST"
-        elif [ "$GENERATE_SELF_SIGNED_CERT" = "True" ]; then
+            # Zulip isn't yet running, so the certbot's challenge can't be met.
+            # We'll schedule this for later.
+            echo "Scheduling LetsEncrypt cert generation ..."
+            GENERATE_CERTBOT_CERT_SCHEDULED=True
+
+            # Generate self-signed certs just to get Zulip going.
+            GENERATE_SELF_SIGNED_CERT=True
+        fi
+
+        if [ "$GENERATE_SELF_SIGNED_CERT" = "True" ]; then
             echo "Generating self-signed certificates ..."
             mkdir -p "$DATA_DIR/certs"
             /home/zulip/deployments/current/scripts/setup/generate-self-signed-cert "$SETTING_EXTERNAL_HOST"
@@ -407,12 +413,43 @@ runPostSetupScripts() {
     set -e
     echo "Post setup scripts execution succeeded."
 }
+function runCertbotAsNeeded() {
+    if [ ! "$GENERATE_CERTBOT_CERT_SCHEDULED" = "True" ]; then
+        echo "Certbot is not scheduled to run."
+        return
+    fi
+
+    echo "Waiting for nginx to come online before generating certbot certificate ..."
+    while ! curl -sk "$SETTING_EXTERNAL_HOST" >/dev/null 2>&1; do
+        sleep 1;
+    done
+
+    echo "Generating LetsEncrypt/certbot certificate ..."
+
+    # Remove the self-signed certs which were only needed to get Zulip going.
+    rm -f "$DATA_DIR"/certs/zulip.key "$DATA_DIR"/certs/zulip.combined-chain.crt
+
+    ZULIP_CERTBOT_DEPLOY_HOOK="/sbin/certbot-deploy-hook"
+
+    # Accept the terms of service automatically.
+    /home/zulip/deployments/current/scripts/setup/setup-certbot \
+        --agree-tos \
+        --hostname="$SETTING_EXTERNAL_HOST" \
+        --email="$SETTING_ZULIP_ADMINISTRATOR" \
+        --deploy-hook "$ZULIP_CERTBOT_DEPLOY_HOOK"
+
+    echo "LetsEncrypt cert generated."
+}
 bootstrappingEnvironment() {
     echo "=== Begin Bootstrap Phase ==="
     waitingForDatabase
     zulipFirstStartInit
     zulipMigration
     runPostSetupScripts
+    # Hack: We run this in the background, since we need nginx to be
+    # started before we can create the certificate.  See #142 for
+    # details on how we can clean this up.
+    runCertbotAsNeeded &
     echo "=== End Bootstrap Phase ==="
 }
 # END appRun functions