add a switch to always go to the real backend

This is useful for VCL simplification

src/Makefile.am

@@ -30,6 +30,7 @@ TESTS = \
 	vtc/cfg.vtc		\
 	vtc/deep.vtc		\
 	vtc/deep_stk.vtc	\
+	vtc/direct.vtc	\
 	vtc/shallow.vtc		\
 	vtc/lazy.vtc		\
 	vtc/lazy_shard.vtc

src/vmod_cluster.c

@@ -83,6 +83,7 @@ struct vmod_cluster_cluster_param {
 	unsigned				magic;
 #define VMOD_CLUSTER_CLUSTER_PARAM_MAGIC	0x3ba2a0d5
 	VCL_BOOL				uncacheable_direct;
+	VCL_BOOL				direct;
 	VCL_BACKEND				cluster;
 	VCL_BACKEND				real;
 	int					nblack;
@@ -439,6 +440,19 @@ vmod_cluster_get_uncacheable_direct(VRT_CTX, struct vmod_cluster_cluster *vc)
 	CLUSTER_R(ctx, vc, uncacheable_direct, 0);
 }
 
+VCL_VOID
+vmod_cluster_set_direct(VRT_CTX,
+    struct vmod_cluster_cluster *vc, VCL_BOOL bool)
+{
+	CLUSTER_L(ctx, vc, direct, bool);
+}
+
+VCL_BOOL
+vmod_cluster_get_direct(VRT_CTX, struct vmod_cluster_cluster *vc)
+{
+	CLUSTER_R(ctx, vc, direct, 0);
+}
+
 static inline VCL_BACKEND
 by_resolve(VRT_CTX, VCL_BACKEND r, enum resolve_e resolve)
 {
@@ -458,7 +472,8 @@ cluster_resolve(VRT_CTX,
 {
 	VCL_BACKEND r;
 
-	if (pr->uncacheable_direct && ctx->bo &&
+	if (pr->direct ||
+	    pr->uncacheable_direct && ctx->bo &&
 	    (ctx->bo->do_pass || ctx->bo->uncacheable))
 		return (by_resolve(ctx, pr->real, resolve));
 

src/vmod_cluster.vcc

@@ -172,6 +172,21 @@ Return the currently configured behaviour.
 
 See :ref:`meth_ctx` for limitations.
 
+$Method VOID .set_direct(BOOL)
+
+A ``true`` argument instructs the director to select a `real` backend
+always.
+
+A ``false`` argument restores the original behavior.
+
+See :ref:`meth_ctx` for limitations.
+
+$Method BOOL .get_direct()
+
+Return the current `direct` value as set with :ref:`func_cluster.get_direct`.
+
+See :ref:`meth_ctx` for limitations.
+
 $Method BACKEND .backend(ENUM {LAZY, SHALLOW, DEEP, NOW} resolve=LAZY,
 	[ BACKEND deny ], [ BACKEND real ],
 	[ BOOL uncacheable_direct ])

src/vtc/direct.vtc

+varnishtest "vmod_cluster test shard director layering and backend.list"
+
+server s1 {
+} -start
+
+server s2 {
+}
+
+server s3 -repeat 2 -keepalive {
+    rxreq
+    txresp
+} -start
+
+varnish v1 -vcl+backend {
+    import cluster;
+    import directors;
+
+    sub vcl_init {
+	new shard = directors.shard();
+	shard.add_backend(s1);
+	shard.add_backend(s2);
+	shard.reconfigure();
+	new cl = cluster.cluster(shard.backend(), deny=s2, real=s3);
+	cl.set_uncacheable_direct(false);
+    }
+    sub vcl_recv {
+	return (pass);
+    }
+    sub vcl_backend_fetch {
+	set bereq.http.shard = shard.backend();
+	set bereq.http.unc = cl.get_uncacheable_direct();
+	set bereq.http.dir1 = cl.get_direct();
+	cl.set_direct(bereq.http.shard != "s2");
+	set bereq.backend = cl.backend();
+	set bereq.http.dir2 = cl.get_direct();
+    }
+    sub vcl_backend_response {
+	set beresp.http.shard = bereq.http.shard;
+	set beresp.http.unc = bereq.http.unc;
+	set beresp.http.backend = beresp.backend;
+	set beresp.http.dir1 = bereq.http.dir1;
+	set beresp.http.dir2 = bereq.http.dir2;
+    }
+} -start
+
+varnish v1 -cliexpect "shard.*healthy" "backend.list"
+varnish v1 -cliexpect "cl.*healthy" "backend.list"
+
+client c1 {
+	txreq
+	rxresp
+	expect resp.status == 200
+	expect resp.http.unc == "false"
+	expect resp.http.shard == "s2"
+	expect resp.http.backend == "s3"
+	expect resp.http.dir1 == "false"
+	expect resp.http.dir2 == "false"
+	txreq -url "/foo"
+	rxresp
+	expect resp.status == 200
+	expect resp.http.unc == "false"
+	expect resp.http.shard == "s1"
+	expect resp.http.backend == "s3"
+	expect resp.http.dir1 == "false"
+	expect resp.http.dir2 == "true"
+} -run