feat: add backward compatibility layer

Author: dunglas

Dockerfile

@@ -8,8 +8,6 @@ LABEL org.opencontainers.image.source=https://github.com/dunglas/mercure
 LABEL org.opencontainers.image.licenses=AGPL-3.0-or-later
 LABEL org.opencontainers.image.vendor="Kévin Dunglas"
 
-ENV MERCURE_TRANSPORT_URL=bolt:///data/mercure.db
-
 COPY mercure /usr/bin/caddy
 COPY Caddyfile /etc/caddy/Caddyfile
 COPY dev.Caddyfile /etc/caddy/dev.Caddyfile

caddy/caddy.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"net/http"
 	"net/url"
+	"os"
 	"strconv"
 	"strings"
 	"time"
@@ -153,7 +154,7 @@ func (m *Mercure) populateJWTConfig() error {
 //
 //nolint:wrapcheck,ireturn
 func createTransportLegacy(m *Mercure) (mercure.Transport, error) {
-	m.logger.Warn(`Setting transport_url is deprecated, use the "transport" directive instead`)
+	m.logger.Warn(`Setting the transport_url or the MERCURE_TRANSPORT_URL environment variable is deprecated, use the "transport" directive instead`)
 
 	destructor, _, err := transports.LoadOrNew(m.TransportURL, func() (caddy.Destructor, error) {
 		u, err := url.Parse(m.TransportURL)
@@ -490,6 +491,15 @@ func (m *Mercure) UnmarshalCaddyfile(d *caddyfile.Dispenser) error { //nolint:fu
 		}
 	}
 
+	// BC layer with old versions of the built-in Caddyfile
+	if m.TransportRaw == nil && m.TransportURL == "" {
+		deprecatedTransportURL := os.Getenv("MERCURE_TRANSPORT_URL")
+
+		if deprecatedTransportURL != "" {
+			m.TransportURL = deprecatedTransportURL
+		}
+	}
+
 	return nil
 }
 

charts/mercure/templates/deployment.yaml

@@ -57,11 +57,13 @@ spec:
                 secretKeyRef:
                   name: {{ include "mercure.secretName" . }}
                   key: caddy-extra-directives
+            {{- if .Values.transportUrl }}
             - name: MERCURE_TRANSPORT_URL
               valueFrom:
                 secretKeyRef:
                   name: {{ include "mercure.secretName" . }}
                   key: transport-url
+            {{- end }}
             - name: MERCURE_PUBLISHER_JWT_KEY
               valueFrom:
                 secretKeyRef:
@@ -92,6 +94,9 @@ spec:
                 secretKeyRef:
                   name: {{ include "mercure.secretName" . }}
                   key: license
+          {{- if .Values.extraEnvs }}
+            {{- toYaml .Values.extraEnvs | nindent 12 }}
+          {{- end }}
           {{- if .Values.persistence.enabled }}
           volumeMounts:
             - mountPath: /data

charts/mercure/templates/secrets.yaml

@@ -7,7 +7,9 @@ metadata:
     {{- include "mercure.labels" . | nindent 4 }}
 type: Opaque
 data:
+  {{- if .Values.transportUrl }}
   transport-url: {{ .Values.transportUrl | b64enc | quote }}
+  {{- end }}
   publisher-jwt-key: {{ .Values.publisherJwtKey | default (randAlphaNum 40) | b64enc | quote }}
   subscriber-jwt-key: {{ .Values.subscriberJwtKey | default (randAlphaNum 40) | b64enc | quote }}
   extra-directives: {{ .Values.extraDirectives | b64enc | quote }}

charts/mercure/values.yaml

@@ -8,8 +8,8 @@ globalOptions: ""
 caddyExtraConfig: ""
 # -- Enable the development mode, including the debug UI and the demo.
 dev: false
-# -- The URL representation of the transport to use.
-transportUrl: bolt:///data/mercure.db
+# -- Deprecated: The URL representation of the transport to use.
+transportUrl: ""
 # -- Inject extra Mercure directives in the Caddyfile.
 extraDirectives: ""
 # -- Inject extra Caddy directives in the Caddyfile.
@@ -25,10 +25,18 @@ subscriberJwtKey: ""
 # -- The JWT algorithm to use for subscribers.
 subscriberJwtAlg: HS256
 
+# -- Additional environment variables to set
+extraEnvs: []
+# extraEnvs:
+#   - name: FOO
+#     valueFrom:
+#       secretKeyRef:
+#         key: FOO
+#         name: secret-resource
+
 # -- Allows to pass an existing secret name, the above values will be used if empty.
 existingSecret: ""
 # These keys must exist in the provided secret:
-# -  transport-url
 # -  publisher-jwt-key
 # -  subscriber-jwt-key
 # -  extra-directives:

docs/UPGRADE.md

@@ -2,9 +2,16 @@
 
 ## 0.17
 
-The `TRANSPORT_URL` environment variable has been removed and the `transport_url` directive has been deprecated.
+The `MERCURE_TRANSPORT_URL` environment variable and the `transport_url` directive have been deprecated.
 Use the new `transport` directive instead.
 
+The `MERCURE_TRANSPORT_URL` environement variable has been removed from the default `Caddyfile`s,
+but a backward compatibility layer is provided.
+
+If both the `transport` and the deprecated `transport_url` are not explicitly set
+and the `MERCURE_TRANSPORT_URL` environement variable is set, the `transport_url` will be automatically populated.
+To disable this behavior, unset `MERCURE_TRANSPORT_URL` or set it to an empty string.
+
 Before:
 
 ```caddyfile